LARA R2 Series Sys Integr Manual (UBX 16010573)

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LARA-R2 series
Size-optimized LTE Cat 1 modules
in single and multi-mode configurations
System Integration Manual

Abstract
This document describes the features and the system integration of
LARA-R2 series multi-mode cellular modules.
These modules are a complete, cost efficient and performance
optimized LTE Cat 1 / 3G / 2G multi-mode solution covering up to
4 LTE bands, up to 2 UMTS/HSPA bands and up to 2 GSM/EGPRS
bands in the very small and compact LARA form factor.

www.u-blox.com
UBX-16010573 - R12

LARA-R2 series - System Integration Manual

Document Information
Title

LARA-R2 series

Subtitle

Size-optimized LTE Cat 1 modules
in single and multi-mode configurations

Document type

System Integration Manual

Document number

UBX-16010573

Revision, date

R12

25-May-2018

Disclosure restriction

Product Status

Corresponding content status

Functional Sample

Draft

For functional testing. Revised and supplementary data will be published later.

In Development /
Prototype

Objective Specification

Target values. Revised and supplementary data will be published later.

Engineering Sample

Advance Information

Data based on early testing. Revised and supplementary data will be published later.

Initial Production

Early Prod. Information

Data from product verification. Revised and supplementary data may be published later.

Mass Production /
End of Life

Production Information

Final product specification.

This document applies to the following products:
Name

Type number

Modem version

Application version

PCN reference

Product status

LARA-R202

LARA-R202-02B-00

30.42

A01.00

UBX-17057959

End of Life

LARA-R202-02B-01

30.42

A01.01

UBX-18018067

Initial Production

LARA-R203-02B-00

30.39

A01.00

UBX-17048311

End of Life

LARA-R203-02B-01

30.39

A01.02

UBX-18018067

Initial Production

LARA-R204-02B-00

31.34

A01.00

UBX-17012269

End of Life

LARA-R204-02B-01

31.35

A01.03

UBX-18013471

Initial Production

LARA-R211-02B-00

30.31

A01.00

UBX-17012270

Initial Production

LARA-R211-02B-01

30.31

TBD

UBX-17054295

In Development

LARA-R220

LARA-R220-62B-00

30.44

A01.03

UBX-17061668

Initial Production

LARA-R280

LARA-R280-02B-00

30.43

A01.01

UBX-17063950

End of Life

LARA-R280-02B-01

30.43

A01.02

UBX-18018067

Initial Production

LARA-R203
LARA-R204
LARA-R211

u-blox reserves all rights to this document and the information contained herein. Products, names, logos and designs described herein may in
whole or in part be subject to intellectual property rights. Reproduction, use, modification or disclosure to third parties of this document or
any part thereof without the express permission of u-blox is strictly prohibited.
The information contained herein is provided “as is” and u-blox assumes no liability for the use of the information. No warranty, either express
or implied, is given, including but not limited, with respect to the accuracy, correctness, reliability and fitness for a particular purpose of the
information. This document may be revised by u-blox at any time. For most recent documents, please visit www.u-blox.com.
Copyright © 2018, u-blox AG
u-blox is a registered trademark of u-blox Holding AG in the EU and other countries. Microsoft and Windows are either registered trademarks
or trademarks of Microsoft Corporation in the United States and/or other countries. All other registered trademarks or trademarks mentioned
in this document are property of their respective owners.

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Preface
u-blox Technical Documentation
As part of our commitment to customer support, u-blox maintains an extensive volume of technical documentation
for our products. In addition to our product-specific technical data sheets, the following manuals are available to
assist u-blox customers in product design and development.


AT Commands Manual: This document provides the description of the AT commands supported by the
u-blox cellular modules.



System Integration Manual: This document provides the description of u-blox cellular modules’ system from
the hardware and the software point of view, it provides hardware design guidelines for the optimal
integration of the cellular modules in the application device and it provides information on how to set up
production and final product tests on application devices integrating the cellular modules.



Application Notes: These documents provide guidelines and information on specific hardware and/or
software topics on u-blox cellular modules. See Related documents for a list of application notes related to
your cellular module.

How to use this Manual
The LARA-R2 series System Integration Manual provides the necessary information to successfully design in and
configure these u-blox cellular modules.
This manual has a modular structure. It is not necessary to read it from the beginning to the end.
The following symbols are used to highlight important information within the manual:
An index finger points out key information pertaining to module integration and performance.
A warning symbol indicates actions that could negatively impact or damage the module.

Questions
If you have any questions about u-blox cellular Integration:


Read this manual carefully.



Contact our information service on the homepage http://www.u-blox.com

Technical Support
Worldwide Web
Our website (http://www.u-blox.com) is a rich pool of information. Product information and technical documents
can be accessed 24h a day.
By E-mail
If you have technical problems or cannot find the required information in the provided documents, contact the
closest Technical Support office. To ensure that we process your request as soon as possible, use our service pool
email addresses rather than personal staff email addresses. Contact details are at the end of the document.
Helpful Information when Contacting Technical Support
When contacting Technical Support, have the following information ready:


Module type (e.g. LARA-R204) and firmware version



Module configuration



Clear description of your question or the problem



A short description of the application



Your complete contact details

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Contents
Preface ................................................................................................................................ 3
Contents.............................................................................................................................. 4
1

System description ....................................................................................................... 8
1.1
Overview .............................................................................................................................................. 8
1.2
Architecture........................................................................................................................................ 11
1.3
Pin-out ............................................................................................................................................... 12
1.4
Operating modes ................................................................................................................................ 17
1.5
Supply interfaces ................................................................................................................................ 19
1.5.1
Module supply input (VCC) ......................................................................................................... 19
1.5.2
RTC supply input/output (V_BCKP) .............................................................................................. 27
1.5.3
Generic digital interfaces supply output (V_INT)........................................................................... 28
1.6
System function interfaces .................................................................................................................. 29
1.6.1
Module power-on ....................................................................................................................... 29
1.6.2
Module power-off ....................................................................................................................... 31
1.6.3
Module reset ............................................................................................................................... 34
1.6.4
Module / host configuration selection ......................................................................................... 34
1.7
Antenna interface ............................................................................................................................... 35
1.7.1
Antenna RF interfaces (ANT1 / ANT2) .......................................................................................... 35
1.7.2
Antenna detection interface (ANT_DET) ...................................................................................... 37
1.8
SIM interface ...................................................................................................................................... 37
1.8.1
SIM card interface ....................................................................................................................... 37
1.8.2
SIM card detection interface (SIM_DET) ....................................................................................... 37
1.9
Data communication interfaces .......................................................................................................... 38
1.9.1
UART interface ............................................................................................................................ 38
1.9.2
USB interface .............................................................................................................................. 49
1.9.3
HSIC interface ............................................................................................................................. 52
1.9.4
DDC (I2C) interface ...................................................................................................................... 53
1.9.5
SDIO interface ............................................................................................................................. 54
1.10 Audio interface ................................................................................................................................... 55
1.10.1 Digital audio interface ................................................................................................................. 55
1.11 Clock output ...................................................................................................................................... 56
1.12 General Purpose Input/Output (GPIO) ................................................................................................. 56
1.13 Reserved pins (RSVD) .......................................................................................................................... 56
1.14 System features .................................................................................................................................. 57
1.14.1 Network indication ...................................................................................................................... 57
1.14.2 Antenna detection ...................................................................................................................... 57
1.14.3 Jamming detection ...................................................................................................................... 57
1.14.4 Dual stack IPv4/IPv6 ..................................................................................................................... 58
1.14.5 PPP .............................................................................................................................................. 58
1.14.6 TCP/IP and UDP/IP ....................................................................................................................... 58
1.14.7 FTP .............................................................................................................................................. 58

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1.14.8
1.14.9
1.14.10
1.14.11
1.14.12
1.14.13
1.14.14
1.14.15
1.14.16
1.14.17

2

HTTP ........................................................................................................................................... 58
SSL/TLS ........................................................................................................................................ 59
Bearer Independent Protocol ....................................................................................................... 60
AssistNow clients and GNSS integration ...................................................................................... 60
Hybrid positioning and CellLocate® .............................................................................................. 61
Wi-Fi integration ......................................................................................................................... 63
Firmware upgrade Over AT (FOAT) .............................................................................................. 63
Firmware update Over The Air (FOTA) ......................................................................................... 64
Smart temperature management................................................................................................. 64
Power Saving .............................................................................................................................. 66

Design-in ..................................................................................................................... 67
2.1
Overview ............................................................................................................................................ 67
2.2
Supply interfaces ................................................................................................................................ 68
2.2.1
Module supply (VCC) .................................................................................................................. 68
2.2.2
RTC supply (V_BCKP)................................................................................................................... 82
2.2.3
Interface supply (V_INT) ............................................................................................................... 84
2.3
System functions interfaces ................................................................................................................ 85
2.3.1
Module power-on (PWR_ON) ...................................................................................................... 85
2.3.2
Module reset (RESET_N) .............................................................................................................. 86
2.3.3
Module / host configuration selection ......................................................................................... 87
2.4
Antenna interface ............................................................................................................................... 88
2.4.1
Antenna RF interface (ANT1 / ANT2) ........................................................................................... 88
2.4.2
Antenna detection interface (ANT_DET) ...................................................................................... 95
2.5
SIM interface ...................................................................................................................................... 97
2.6
Data communication interfaces ........................................................................................................ 103
2.6.1
UART interface .......................................................................................................................... 103
2.6.2
USB interface ............................................................................................................................ 108
2.6.3
HSIC interface ........................................................................................................................... 110
2.6.4
DDC (I2C) interface .................................................................................................................... 112
2.6.5
SDIO interface ........................................................................................................................... 116
2.7
Audio interface ................................................................................................................................. 117
2.7.1
Digital audio interface ............................................................................................................... 117
2.8
General Purpose Input/Output (GPIO) ............................................................................................... 121
2.9
Reserved pins (RSVD) ........................................................................................................................ 122
2.10 Module placement ........................................................................................................................... 122
2.11 Module footprint and paste mask ..................................................................................................... 123
2.12 Thermal guidelines ........................................................................................................................... 124
2.13 ESD guidelines .................................................................................................................................. 125
2.13.1 ESD immunity test overview ...................................................................................................... 125
2.13.2 ESD immunity test of u-blox LARA-R2 series reference designs .................................................. 125
2.13.3 ESD application circuits.............................................................................................................. 126
2.14 Schematic for LARA-R2 series module integration............................................................................. 128
2.15 Design-in checklist ............................................................................................................................ 129
2.15.1 Schematic checklist ................................................................................................................... 129

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2.15.2
2.15.3

3

Layout checklist ......................................................................................................................... 130
Antenna checklist ...................................................................................................................... 130

Handling and soldering ........................................................................................... 131
3.1
Packaging, shipping, storage and moisture preconditioning ............................................................. 131
3.2
Handling........................................................................................................................................... 131
3.3
Soldering .......................................................................................................................................... 132
3.3.1
Soldering paste ......................................................................................................................... 132
3.3.2
Reflow soldering ....................................................................................................................... 132
3.3.3
Optical inspection ...................................................................................................................... 133
3.3.4
Cleaning.................................................................................................................................... 133
3.3.5
Repeated reflow soldering ......................................................................................................... 134
3.3.6
Wave soldering ......................................................................................................................... 134
3.3.7
Hand soldering .......................................................................................................................... 134
3.3.8
Rework...................................................................................................................................... 134
3.3.9
Conformal coating .................................................................................................................... 134
3.3.10 Casting...................................................................................................................................... 134
3.3.11 Grounding metal covers ............................................................................................................ 134
3.3.12 Use of ultrasonic processes ........................................................................................................ 134

4

Approvals .................................................................................................................. 135
4.1
Product certification approval overview............................................................................................. 135
4.2
US Federal Communications Commission notice............................................................................... 136
4.2.1
Safety warnings review the structure ......................................................................................... 136
4.2.2
Declaration of conformity .......................................................................................................... 136
4.2.3
Modifications ............................................................................................................................ 137
4.3
Innovation, Science and Economic Development Canada notice ....................................................... 138
4.3.1
Declaration of Conformity ......................................................................................................... 138
4.3.2
Modifications ............................................................................................................................ 139
4.4
European Conformance CE mark...................................................................................................... 141

5

Product testing ......................................................................................................... 142
5.1
u-blox in-series production test ......................................................................................................... 142
5.2
Test parameters for OEM manufacturers .......................................................................................... 143
5.2.1
“Go/No go” tests for integrated devices .................................................................................... 143
5.2.2
Functional tests providing RF operation ..................................................................................... 143

Appendix ........................................................................................................................ 145
A Migration between SARA-U2 and LARA-R2 ........................................................... 145
A.1
A.2
A.3

B

Overview .......................................................................................................................................... 145
Pin-out comparison between SARA-U2 and LARA-R2 ....................................................................... 149
Schematic for SARA-U2 and LARA-R2 integration............................................................................. 151

Glossary .................................................................................................................... 152

Related documents ........................................................................................................ 155
Revision history .............................................................................................................. 156

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Contact ............................................................................................................................ 157

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1 System description
1.1 Overview
The LARA-R2 series comprises LTE Cat 1 / 3G / 2G multi-mode modules supporting up to four LTE bands, up to
two 3G UMTS/HSPA bands and up to two 2G GSM/(E)GPRS bands for voice and/or data transmission in the very
small LARA LGA form-factor (26.0 x 24.0 mm, 100-pin), easy to integrate in compact designs:


LARA-R202 is designed mainly for operation in America (on the AT&T LTE and 3G networks)



LARA-R203 is designed mainly for operation in America (on the AT&T LTE network)



LARA-R204 is designed primarily for operation in North America (on the Verizon network)



LARA-R211 is designed primarily for operation in Europe, Asia and other countries



LARA-R220 is designed mainly for operation in Japan (on the NTT DoCoMo LTE network)



LARA-R280 is designed mainly for operation in Asia, Oceania and other countries, on the LTE and 3G networks

LARA-R2 series modules are form-factor compatible with the u-blox SARA, LISA and TOBY cellular module families:
this facilitates easy migration from u-blox GSM/GPRS, CDMA, UMTS/HSPA, and LTE high data rate modules,
maximizes the investments of customers, simplifies logistics, and enables very short time-to-market.
The modules are ideal for applications that are transitioning to LTE from 2G and 3G, due to the long term
availability and scalability of LTE networks.
With a range of interface options and an integrated IP stack, the modules are designed to support a wide range
of data-centric applications. The unique combination of performance and flexibility make these modules ideally
suited for medium speed M2M applications, such as smart energy gateways, remote access video cameras, digital
signage, telehealth and telematics.
LARA-R2 series modules provide Voice over LTE (VoLTE)1 as well as Circuit-Switched-Fall-Back (CSFB)2 voice service
over 3G / 2G (CSFB) for applications that require voice, such as security and surveillance systems.

1
2

Not supported by LARA-R204 and LARA-R280 modules “02” product version, LARA-R220 modules “62” product version.
Not supported by LARA-R203, LARA-R204 and LARA-R220 modules.

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Table 1 summarizes the main features and interfaces of the LARA-R2 series modules.

Features

Grade

SDIO *

DDC (I2C)

GPIOs

1

1

1

1

9

● ● ● ● ● □ ● ● ●

●

2,4,12

●

●

●

1

1

1

1

1

9

● ● ● ● ● □ ● ● ●

●

North
America

4,13

□

□

□

1

1

1

1

1

9

□ ● □ ● ● □ ● ● ●

●

LARA-R211

Europe,
APAC

3,7,20

□

□

□

1

1

1

1

1

9

● ● ● ● ● □ ● ● ● □ ●

LARA-R220

Japan

1,19

●

●

●

1

1

1

1

1

9

□ ● □ ● ● □ ● ● ●

●

LARA-R280

APAC

3,8,28

●

●

●

1

1

1

1

1

9

● ● ■ ● ● □ ● ● ●

●

2,4
5,12

850
1900

LARA-R203

North
America

LARA-R204

● = Available in any firmware

900
1800

2100

■ = CSFB only

Digital audio
Network indication

HSIC *

1

North
America

Analog audio

USB 2.0

●

LARA-R202

GSM Bands

●

UMTS Bands

●

LTE Bands3

UART

VoLTE
Antenna supervisor
Rx Diversity
Jamming detection
Embedded TCP/UDP stack
Embedded HTTP,FTP,SSL
FOTA
eCall / ERA GLONASS
Dual stack IPv4/IPv6
Standard
Professional
Automotive

Audio

CellLocate®

Interfaces

AssistNow Software

Region Radio Access Technology Positioning

GNSS via modem

Model

□ = Available in future firmware

* = HW ready

Table 1: LARA-R2 series main features summary

3

LTE band 12 is a superset that includes band 17: the LTE band 12 is supported along with Multi-Frequency Band Indicator (MFBI) feature

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Table 2 reports a summary of cellular radio access technologies characteristics of LARA-R2 series modules.
4G LTE

3G UMTS/HSDPA/HSUPA

2G GSM/GPRS/EDGE

3GPP Release 9
Long Term Evolution (LTE)
Evolved Univ.Terrestrial Radio Access (E-UTRA)
Frequency Division Duplex (FDD)
DL Rx diversity

3GPP Release 9
High Speed Packet Access (HSPA)
UMTS Terrestrial Radio Access (UTRA)
Frequency Division Duplex (FDD)
DL Rx Diversity

3GPP Release 9
Enhanced Data rate GSM Evolution (EDGE)
GSM EGPRS Radio Access (GERA)
Time Division Multiple Access (TDMA)
DL Advanced Rx Performance Phase 1

Band support:

LARA-R202:

Band 5 (850 MHz)

Band 2 (1900 MHz)

Band support:

4

Band support :

LARA-R202:
5

Band 12 (700 MHz)

Band 5 (850 MHz)

Band 4 (1700 MHz)

Band 2 (1900 MHz)


LARA-R203:
5

Band 12 (700 MHz)

Band 4 (1700 MHz)

Band 2 (1900 MHz)



LARA-R204:

Band 13 (700 MHz)

Band 4 (1700 MHz)



LARA-R211:

Band 20 (800 MHz)

Band 3 (1800 MHz)

Band 7 (2600 MHz)



LARA-R220:

Band 19 (850 MHz)

Band 1 (2100 MHz)



LARA-R280:

Band 28 (700 MHz)

Band 8 (900 MHz)

Band 3 (1800 MHz)





LARA-R211:

E-GSM 900 MHz

DCS 1800 MHz

LARA-R280:

Band 1 (2100 MHz)

LTE Power Class

Power Class 3 (23 dBm)

UMTS/HSDPA/HSUPA Power Class

Class 3 (24 dBm)

GSM/GPRS (GMSK) Power Class

Power Class 4 (33 dBm) for E-GSM band

Power Class 1 (30 dBm) for DCS band
EDGE (8-PSK) Power Class

Power Class E2 (27 dBm) for E-GSM band

Power Class E2 (26 dBm) for DCS band

Data rate

LTE category 1:
up to 10.3 Mb/s DL, 5.2 Mb/s UL

Data rate

HSDPA category 8:
up to 7.2 Mb/s DL

HSUPA category 6:
up to 5.76 Mb/s UL

Data Rate
7

GPRS multi-slot class 33 , CS1-CS4,
up to 107 kb/s DL, up to 85.6 kb/s UL
7

EDGE multi-slot class 33 , MCS1-MCS9,
up to 296 kb/s DL, up to 236.8 kb/s UL

6

Table 2: LARA-R2 series LTE, 3G and 2G characteristics

4

LARA-R2 series modules support all the E-UTRA channel bandwidths for each operating band according to 3GPP TS 36.521-1 [13].
LTE band 12 is a superset that includes band 17: the LTE band 12 is supported along with Multi-Frequency Band Indicator (MFBI) feature
GPRS/EDGE multi-slot class determines the number of timeslots available for upload and download and thus the speed at which data can be
transmitted and received, with higher classes typically allowing faster data transfer rates.
7
GPRS/EDGE multi-slot class 33 implies a maximum of 5 slots in DL (reception) and 4 slots in UL (transmission) with 6 slots in total.
5
6

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1.2 Architecture
Figure 1 summarizes the internal architecture of the LARA-R2 series modules.

Duplexer

ANT1

Switch

Filters

Filters

LNAs

Filters

ANT_DET
SIM

26 MHz

DDC(I2C)
PAs

Filters

LNAs

Filters

Filters

LNAs

Filters

Filters

LNAs

Filters

Duplexer
Filters

ANT2

PAs

SDIO
RF
transceiver

UART

Memory
Cellular
Base-band
processor

Switch

32.768 kHz

USB
HSIC
GPIO
Digital audio (I2S)

Host Select

VCC (Supply)
V_BCKP (RTC)

Power Management Unit

V_INT (I/O)

Power On
External Reset

Figure 1: LARA-R2 series modules simplified block diagram

LARA-R2 series modules internally consist of the RF, Baseband and Power Management sections described herein
with more details than the simplified block diagrams of Figure 1.

RF section
The RF section is composed of an RF transceiver, PAs, LNAs, crystal oscillator, filters, duplexers and RF switches.
The Tx signal is pre-amplified by the RF transceiver, then output to the primary antenna input/output port (ANT1)
of the module via power amplifier (PA), SAW band pass filters band, specific duplexer and antenna switch.
Dual receiving paths are implemented according to LTE Receiver Diversity radio technology supported by the
modules as LTE category 1 User Equipments: incoming signal is received through the primary (ANT1) and the
secondary (ANT2) antenna input ports which are connected to the RF transceiver via specific antenna switch,
diplexer, duplexer, LNA, SAW band pass filters.


RF transceiver performs modulation, up-conversion of the baseband I/Q signals for Tx, down-conversion and
demodulation of the dual RF signals for Rx. The RF transceiver contains:
Single chain high linearity receivers with integrated LNAs for multi band multi mode operation,
Highly linear RF demodulator / modulator capable GMSK, 8-PSK, QPSK, 16-QAM,
RF synthesizer,
VCO.



Power Amplifiers (PA) amplify the Tx signal modulated by the RF transceiver



RF switches connect primary (ANT1) and secondary (ANT2) antenna ports to the suitable Tx / Rx path



SAW duplexers and band pass filters separate the Tx and Rx signal paths and provide RF filtering



26 MHz voltage-controlled temperature-controlled crystal oscillator generates the clock reference in active
mode or connected mode.

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Baseband and power management section
The Baseband and Power Management section is composed of the following main elements:


A mixed signal ASIC, which integrates
Microprocessor for control functions
DSP core for cellular Layer 1 and digital processing of Rx and Tx signal paths
Memory interface controller
Dedicated peripheral blocks for control of the USB, SIM and generic digital interfaces
Interfaces to RF transceiver ASIC



Memory system, which includes NAND flash and LPDDR2 RAM



Voltage regulators to derive all the subsystem supply voltages from the module supply input VCC



Voltage sources for external use: V_BCKP and V_INT



Hardware power on



Hardware reset



Low power idle mode support



32.768 kHz crystal oscillator to provide the clock reference in the low power idle mode, which can be set by
enable power saving configuration using the AT+UPSV command.

1.3 Pin-out
Table 3 lists the pin-out of the LARA-R2 series modules, with pins grouped by function.
Function

Pin Name

Pin No

I/O

Description

Remarks

Power

VCC

51, 52, 53

I

Module supply
input

VCC supply circuit affects the RF performance and compliance
of the device integrating the module with applicable required
certification schemes.
See section 1.5.1 for description and requirements.
See section 2.2.1 for external circuit design-in.

GND

1, 3, 5, 14, 20,
22, 30, 32, 43,
50, 54, 55, 57,
58, 60, 61, 63,
64, 65-96

N/A

Ground

GND pins are internally connected each other.
External ground connection affects the RF and thermal
performance of the device.
See section 1.5.1 for functional description.
See section 2.2.1 for external circuit design-in.

V_BCKP

2

I/O

RTC supply
input/output

V_BCKP = 1.8 V (typical) generated by internal regulator when
valid VCC supply is present.
See section 1.5.2 for functional description.
See section 2.2.2 for external circuit design-in.

V_INT

4

O

Generic Digital
Interfaces supply
output

V_INT = 1.8 V (typical), generated by internal DC/DC regulator
when the module is switched on.
Test-Point for diagnostic access is recommended.
See section 1.5.3 for functional description.
See section 2.2.3 for external circuit design-in.

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Function

Pin Name

Pin No

I/O

Description

Remarks

System

PWR_ON

15

I

Power-on input

Internal 10 k pull-up resistor to V_BCKP.
See section 1.6.1 for functional description.
See section 2.3.1 for external circuit design-in.

RESET_N

18

I

External reset
input

Internal 10 k pull-up resistor to V_BCKP.
Test-Point for diagnostic access is recommended.
See section 1.6.3 for functional description.
See section 2.3.2 for external circuit design-in.

HOST_SELECT

21

I/O

Selection of
module / host
configuration

Not supported by “02” and “62” product versions.
Pin available to select, enable, connect, disconnect and
subsequently re-connect the HSIC interface.
Test-Point for diagnostic access is recommended.
See section 1.6.4 for functional description.
See section 2.3.3 for external circuit design-in.

ANT1

56

I/O

Primary antenna

Main Tx / Rx antenna interface.

Antenna

50  nominal characteristic impedance.
Antenna circuit affects the RF performance and compliance of
the device integrating the module with applicable required
certification schemes.
See section 1.7 for description and requirements.
See section 2.4 for external circuit design-in.
ANT2

62

I

Secondary antenna

Rx only for Rx diversity.
50  nominal characteristic impedance.
Antenna circuit affects the RF performance and compliance of
the device integrating the module with applicable required
certification schemes.
See section 1.7 for description and requirements.
See section 2.4 for external circuit design-in.

SIM

ANT_DET

59

I

Input for antenna
detection

ADC for antenna presence detection function.
See section 1.7.2 for functional description.
See section 2.4.2 for external circuit design-in.

VSIM

41

O

SIM supply output

VSIM = 1.8 V / 3 V output as per the connected SIM type.
See section 1.8 for functional description.
See section 2.5 for external circuit design-in.

SIM_IO

39

I/O

SIM data

Data input/output for 1.8 V / 3 V SIM
Internal 4.7 k pull-up to VSIM.
See section 1.8 for functional description.
See section 2.5 for external circuit design-in.

SIM_CLK

38

O

SIM clock

3.25 MHz clock output for 1.8 V / 3 V SIM
See section 1.8 for functional description.
See section 2.5 for external circuit design-in.

SIM_RST

40

O

SIM reset

Reset output for 1.8 V / 3 V SIM
See section 1.8 for functional description.
See section 2.5 for external circuit design-in.

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Function

Pin Name

Pin No

I/O

Description

Remarks

UART

RXD

13

O

UART data output

1.8 V output, Circuit 104 (RXD) in ITU-T V.24,
for AT commands, data communication, FOAT, FW update by
u-blox EasyFlash tool and diagnostic.
Test-Point and series 0  for diagnostic access recommended.
See section 1.9.1 for functional description.
See section 2.6.1 for external circuit design-in.

TXD

12

I

UART data input

1.8 V input, Circuit 103 (TXD) in ITU-T V.24,
for AT commands, data communication, FOAT, FW update by
u-blox EasyFlash tool and diagnostic.
Internal active pull-up to V_INT.
Test-Point and series 0  for diagnostic access recommended.
See section 1.9.1 for functional description.
See section 2.6.1 for external circuit design-in.

CTS

11

O

UART clear to send
output

1.8 V output, Circuit 106 (CTS) in ITU-T V.24.
See section 1.9.1 for functional description.
See section 2.6.1 for external circuit design-in.

RTS

10

I

UART ready to
send input

1.8 V input, Circuit 105 (RTS) in ITU-T V.24.
Internal active pull-up to V_INT.
See section 1.9.1 for functional description.
See section 2.6.1 for external circuit design-in.

DSR

6

O

UART data set
ready output

1.8 V output, Circuit 107 (DSR) in ITU-T V.24.
See section 1.9.1 for functional description.
See section 2.6.1 for external circuit design-in.

RI

7

O

UART ring
indicator output

1.8 V output, Circuit 125 (RI) in ITU-T V.24.
See section 1.9.1 for functional description.
See section 2.6.1 for external circuit design-in.

DTR

9

I

UART data
terminal ready
input

1.8 V input, Circuit 108/2 (DTR) in ITU-T V.24.
Internal active pull-up to V_INT.

UART data carrier
detect output

1.8 V input, Circuit 109 (DCD) in ITU-T V.24.

DCD

USB

8

O

Test-Point and series 0  for diagnostic access recommended.
See section 1.9.1 for functional description.
See section 2.6.1 for external circuit design-in.
Test-Point and series 0  for diagnostic access recommended.
See section 1.9.1 for functional description.
See section 2.6.1 for external circuit design-in.

VUSB_DET

17

I

USB detect input

VBUS (5 V typical) USB supply generated by the host must be
connected to this input pin to enable the USB interface.
If the USB interface is not used by the Application Processor,
Test-Point for diagnostic / FW update access recommended.
See section 1.9.2 for functional description.
See section 2.6.2 for external circuit design-in.

USB_D-

28

I/O

USB Data Line D-

USB interface for AT commands, data communication, FOAT,
FW update by u-blox EasyFlash tool and diagnostic.
90  nominal differential impedance (Z0)
30  nominal common mode impedance (ZCM)
Pull-up or pull-down resistors and external series resistors as
required by the USB 2.0 specifications [9] are part of the USB
pin driver and need not be provided externally.
If the USB interface is not used by the Application Processor,
Test-Point for diagnostic / FW update access is recommended.
See section 1.9.2 for functional description.
See section 2.6.2 for external circuit design-in.

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Function

Pin Name

Pin No

I/O

Description

Remarks

USB_D+

29

I/O

USB Data Line D+

USB interface for AT commands, data communication, FOAT,
FW update by u-blox EasyFlash tool and diagnostic.
90  nominal differential impedance (Z0)
30  nominal common mode impedance (ZCM)
Pull-up or pull-down resistors and external series resistors as
required by the USB 2.0 specifications [9] are part of the USB
pin driver and need not be provided externally.
If the USB interface is not used by the Application Processor,
Test-Point for diagnostic / FW update access is recommended
See section 1.9.2 for functional description.
See section 2.6.2 for external circuit design-in.

HSIC

HSIC_DATA

99

I/O

HSIC USB data line

Not supported by “02” and “62” product versions.
USB High-Speed Inter-Chip compliant interface for AT
commands, data communication, FOAT, FW update by u-blox
EasyFlash tool and diagnostic.
50  nominal characteristic impedance.
Test-Point for diagnostic / FW update access is recommended.
See section 1.9.3 for functional description.
See section 2.6.3 for external circuit design-in.

HSIC_STRB

100

I/O

HSIC USB strobe
line

Not supported by “02” and “62” product versions.
HSIC interface for AT commands, data communication, FOAT,
FW update by u-blox EasyFlash tool and diagnostic.
50  nominal characteristic impedance.
Test-Point for diagnostic / FW update access is recommended.
See section 1.9.3 for functional description.
See section 2.6.3 for external circuit design-in.

DDC

SDIO

2

1.8 V open drain, for communication with I2C-slave devices.
See section 1.9.4 for functional description.
See section 2.6.4 for external circuit design-in.

I C bus data line

2

1.8 V open drain, for communication with I2C-slave devices.
See section 1.9.4 for functional description.
See section 2.6.4 for external circuit design-in.

I/O

SDIO serial data [0]

Not supported by “02” and “62” product versions.
SDIO interface for communication with u-blox Wi-Fi module
See section 1.9.5 for functional description.
See section 2.6.5 for external circuit design-in.

49

I/O

SDIO serial data [1]

Not supported by “02” and “62” product versions.
SDIO interface for communication with u-blox Wi-Fi module
See section 1.9.5 for functional description.
See section 2.6.5 for external circuit design-in.

SDIO_D2

44

I/O

SDIO serial data [2]

Not supported by “02” and “62” product versions.
SDIO interface for communication with u-blox Wi-Fi module
See section 1.9.5 for functional description.
See section 2.6.5 for external circuit design-in.

SDIO_D3

48

I/O

SDIO serial data [3]

Not supported by “02” and “62” product versions.
SDIO interface for communication with u-blox Wi-Fi module
See section 1.9.5 for functional description.
See section 2.6.5 for external circuit design-in.

SDIO_CLK

45

O

SDIO serial clock

Not supported by “02” and “62” product versions.
SDIO interface for communication with u-blox Wi-Fi module
See section 1.9.5 for functional description.
See section 2.6.5 for external circuit design-in.

SCL

27

O

I C bus clock line

SDA

26

I/O

SDIO_D0

47

SDIO_D1

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Function

Pin Name

Pin No

I/O

Description

Remarks

SDIO_CMD

46

I/O

SDIO command

Not supported by “02” and “62” product versions.
SDIO interface for communication with u-blox Wi-Fi module
See section 1.9.5 for functional description.
See section 2.6.5 for external circuit design-in.

I2S_TXD

35

O/
I/O

I S transmit data /
GPIO

I2S_RXD

37

I/
I/O

I S receive data /
GPIO

I2S_CLK

36

I/O /
I/O

I S clock /
GPIO

I2S_WA

34

I/O /
I/O

I S word alignment / I2S word alignment, alternatively configurable as GPIO.
2
GPIO
I S not supported by LARA-R204-02B and LARA-R220-62B.
See sections 1.10 and 1.12 for functional description.
See sections 2.7 and 2.8 for external circuit design-in.

Clock
output

GPIO6

19

O

Clock output

1.8 V configurable clock output.
See section 1.11 for functional description.
See section 2.7 for external circuit design-in.

GPIO

GPIO1

16

I/O

GPIO

1.8 V GPIO with alternatively configurable functions.
See section 1.12 for functional description.
See section 2.8 for external circuit design-in.

GPIO2

23

I/O

GPIO

1.8 V GPIO with alternatively configurable functions.
See section 1.12 for functional description.
See section 2.8 for external circuit design-in.

GPIO3

24

I/O

GPIO

1.8 V GPIO with alternatively configurable functions.
See section 1.12 for functional description.
See section 2.8 for external circuit design-in.

GPIO4

25

I/O

GPIO

1.8 V GPIO with alternatively configurable functions.
See section 1.12 for functional description.
See section 2.8 for external circuit design-in.

GPIO5

42

I/O

GPIO

1.8 V GPIO with alternatively configurable functions.
See section 1.12 for functional description.
See section 2.8 for external circuit design-in.

RSVD

33

N/A

RESERVED pin

This pin must be connected to ground.
See sections 1.13 and 2.9

RSVD

31, 97, 98

N/A

RESERVED pin

Internally not connected. Leave unconnected.
See sections 1.13 and 2.9

Audio

Reserved

2

I S transmit data output, alternatively configurable as GPIO.
2
I S not supported by LARA-R204-02B and LARA-R220-62B.
See sections 1.10 and 1.12 for functional description.
See sections 2.7 and 2.8 for external circuit design-in.

2

I S receive data input, alternatively configurable as GPIO.
2
I S not supported by LARA-R204-02B and LARA-R220-62B.
See sections 1.10 and 1.12 for functional description.
See sections 2.7 and 2.8 for external circuit design-in.

2

I S serial clock, alternatively configurable as GPIO.
2
I S not supported by LARA-R204-02B and LARA-R220-62B.
See sections 1.10 and 1.12 for functional description.
See sections 2.7 and 2.8 for external circuit design-in.

2

2

2

2

Table 3: LARA-R2 series modules pin definition, grouped by function

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1.4 Operating modes
LARA-R2 series modules have several operating modes. The operating modes defined in Table 4 and described in
detail in Table 5 provide general guidelines for operation.
General Status

Operating Mode

Definition

Power-down

Not-powered Mode

VCC supply not present or below operating range: module is switched off.

Power-off Mode

VCC supply within operating range and module is switched off.

Idle mode

Module processor core runs with 32 kHz reference generated by the internal oscillator.

Active mode

Module processor core runs with 26 MHz reference generated by the internal oscillator.

Connected mode

RF Tx/Rx data connection enabled and processor core runs with 26 MHz reference.

Normal operation

Table 4: Module operating modes definition

Mode

Description

Transition between operating modes

Not-powered

Module is switched off.
Application interfaces are not accessible.

When VCC supply is removed, the module enters not-powered mode.
When in not-powered mode, the modules cannot be switched on by
PWR_ON, RESET_N or RTC alarm.
When in not-powered mode, the modules can be switched on applying
VCC supply (see 1.6.1) so that the module switches from not-powered
to active mode.

Power-off

Module is switched off: normal shutdown by an
appropriate power-off event (see 1.6.2).
Application interfaces are not accessible.

When the module is switched off by an appropriate switch-off event
(see 1.6.2), the module enters power-off mode from active mode.
When in power-off mode, the modules can be switched on by
PWR_ON, RESET_N or RTC alarm (see 1.6.1): the module switches
from power-off to active mode.
When in power-off mode, the modules enter not-powered mode by
removing the VCC supply.

Idle

Module is switched on with application
interfaces temporarily disabled or suspended:
the module is temporarily not ready to
communicate with an external device by means
of the application interfaces as configured to
reduce the current consumption.
The module enters the low power idle mode
whenever possible if power saving is enabled by
AT+UPSV (see u-blox AT Commands Manual [2])
reducing power consumption (see 1.5.1.5).
The CTS output line indicates when the UART
interface is disabled/enabled due to the module
idle/active mode according to power saving and
HW flow control settings (see 1.9.1.3, 1.9.1.4).
Power saving configuration is not enabled by
default: it can be enabled by AT+UPSV (see the
u-blox AT Commands Manual [2]).

The module automatically switches from active mode to idle mode
whenever possible if power saving is enabled (see sections 1.5.1.5,
1.9.1.4, 1.9.2.4 and to the u-blox AT Commands Manual [2], AT+UPSV
command).
The module wakes up from idle to active mode in the following events:

Automatic periodic monitoring of the paging channel for the
paging block reception according to network conditions (see
1.5.1.4, 1.9.1.4)

Automatic periodic enable of the UART interface to receive and
send data, if AT+UPSV=1 power saving is set (see 1.9.1.4)

Data received on UART interface, according to HW flow control
(AT&K) and power saving (AT+UPSV) settings (see 1.9.1.4)

RTS input set ON by the host DTE, with HW flow control disabled
and AT+UPSV=2 (see 1.9.1.4)

DTR input set ON by the host DTE, with AT+UPSV=3 (see 1.9.1.4)

USB detection, applying 5 V (typ.) to VUSB_DET input (see 1.9.2)

The connected USB host forces a remote wakeup of the module
as USB device (see 1.9.2.4)

The connected u-blox GNSS receiver forces a wakeup of the
cellular module using the GNSS Tx data ready function over the
GPIO3 pin (see 1.9.4)

The connected SDIO device forces a wakeup of the module as
SDIO host (see 1.9.5)

RTC alarm occurs (see u-blox AT Commands Manual [2], +CALA)

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Mode

Description

Transition between operating modes

Active

The module is ready to communicate with an
external device by means of the application
interfaces unless power saving configuration is
enabled by the AT+UPSV command (see
sections 1.5.1.4, 1.9.1.4 and to the u-blox AT
Commands Manual [2]).

When the module is switched on by an appropriate power-on event
(see 2.3.1), the module enters active mode from not-powered or
power-off mode.
If power saving configuration is enabled by the AT+UPSV command,
the module automatically switches from active to idle mode whenever
possible and the module wakes up from idle to active mode in the
events listed above (see idle to active transition description).
When a voice call or a data call is initiated, the module switches from
active mode to connected mode.

Connected

A voice call or a data call is in progress.
The module is ready to communicate with an
external device by means of the application
interfaces unless power saving configuration is
enabled by the AT+UPSV command (see
sections 1.5.1.4, 1.9.1.4 and the u-blox AT
Commands Manual [2]).

When a data or voice connection is initiated, the module enters
connected mode from active mode.
Connected mode is suspended if Tx/Rx data is not in progress, due to
connected discontinuous reception and fast dormancy capabilities of
the module and according to network environment settings and
scenario. In such case, the module automatically switches from
connected to active mode and then, if power saving configuration is
enabled by the AT+UPSV command, the module automatically switches
to idle mode whenever possible. Vice-versa, the module wakes up from
idle to active mode and then connected mode if RF Tx/Rx is necessary.
When a data connection is terminated, the module returns to the
active mode.

Table 5: Module operating modes descriptions

Figure 2 describes the transition between the different operating modes.

Not
powered

Remove VCC

Switch ON:
• Apply VCC

Power off
Switch ON:
• PWR_ON
• RTC alarm
• RESET_N

Switch OFF:
• AT+CPWROFF
• PWR_ON

Incoming/outgoing call or
other dedicated device
network communication

Connected

If power saving is enabled
and there is no activity for
a defined time interval

Active
No RF Tx/Rx in progress,
Call terminated,
Communication dropped

Idle
Any wake up event described
in the module operating
modes summary table above

Figure 2: Operating modes transition

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1.5

Supply interfaces

1.5.1 Module supply input (VCC)
The modules must be supplied via the three VCC pins that represent the module power supply input.
The VCC pins are internally connected to the RF power amplifier and to the integrated Power Management Unit:
all supply voltages needed by the module are generated from the VCC supply by integrated voltage regulators,
including the V_BCKP Real Time Clock supply, V_INT digital interfaces supply and VSIM SIM card supply.
During operation, the current drawn by the LARA-R2 series modules through the VCC pins can vary by several
orders of magnitude. This ranges from the pulse of current consumption during GSM transmitting bursts at
maximum power level in connected mode (as described in section 1.5.1.2) to the low current consumption during
low power idle mode with power saving enabled (as described in section 1.5.1.5).
LARA-R211 modules provide separate supply inputs over the three VCC pins:


VCC pins #52 and #53 represent the supply input for the internal RF power amplifier, demanding most of the
total current drawn of the module when RF transmission is enabled during a voice/data call



VCC pin #51 represents the supply input for the internal baseband Power Management Unit and the internal
transceiver, demanding minor part of the total current drawn of the module when RF transmission is enabled
during a voice/data call

Figure 3 provides a simplified block diagram of LARA-R2 series modules internal VCC supply routing.
LARA-R2 series

LARA-R211

(except LARA-R211)
LTE PA

VCC 53

RF PMU

VCC 51

VCC 53
Transceiver

VCC 52

Power
Management
Unit

LTE / 2G PAs

Baseband
Processor

RF PMU
Transceiver

VCC 52
VCC 51

Memory

Power
Management
Unit

Baseband
Processor
Memory

Figure 3: LARA-R2 series modules internal VCC supply routing simplified block diagram

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1.5.1.1 VCC supply requirements
Table 6 summarizes the requirements for the VCC module supply. See section 2.2.1 for all the suggestions to
properly design a VCC supply circuit compliant to the requirements listed in Table 6.
VCC supply circuit affects the RF compliance of the device integrating LARA-R2 series modules
with applicable required certification schemes as well as antenna circuit design. Compliance is
guaranteed if the VCC requirements summarized in the Table 6 are fulfilled.
Item

Requirement

Remark

VCC nominal voltage

Within VCC normal operating range:
3.30 V min. / 4.40 V max.

RF performance is guaranteed when VCC PA voltage is
inside the normal operating range limits.
RF performance may be affected when VCC PA voltage is
outside the normal operating range limits, though the
module is still fully functional until the VCC voltage is inside
the extended operating range limits.

VCC voltage during
normal operation

Within VCC extended operating range:
3.00 V min. / 4.50 V max.

VCC voltage must be above the extended operating range
minimum limit to switch-on the module.
The module may switch-off when the VCC voltage drops
below the extended operating range minimum limit.
Operation above VCC extended operating range is not
recommended and may affect device reliability.

VCC average current

Support with adequate margin the highest averaged
VCC current consumption value in connected mode
conditions specified in LARA-R2 series Data Sheet [1]

The highest averaged VCC current consumption can be
greater than the specified value according to the actual
antenna mismatching, temperature and VCC voltage.
See 1.5.1.2, 1.5.1.4 for connected mode current profiles.

VCC peak current

Support with margin the highest peak VCC current
consumption value in connected mode conditions
specified in LARA-R2 series Data Sheet [1]

The specified highest peak of VCC current consumption
occurs during GSM single transmit slot in 850/900 MHz
connected mode, in case of a mismatched antenna.
See 1.5.1.2 for 2G connected mode current profiles.

VCC voltage drop
during 2G Tx slots

Lower than 400 mV

VCC voltage drop directly affects the RF compliance with
applicable certification schemes.
Figure 5 describes VCC voltage drop during Tx slots.

VCC voltage ripple
during 2G/3G/LTE Tx

Noise in the supply must be minimized

VCC voltage ripple directly affects the RF compliance with
applicable certification schemes.
Figure 5 describes VCC voltage ripple during Tx slots.

VCC under/over-shoot
at start/end of Tx slots

Absent or at least minimized

VCC under/over-shoot directly affects the RF compliance
with applicable certification schemes.
Figure 5 describes VCC voltage under/over-shoot.

Table 6: Summary of VCC supply requirements

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1.5.1.2 VCC current consumption in 2G connected mode
When a GSM call is established, the VCC consumption is determined by the current consumption profile typical of
the GSM transmitting and receiving bursts.
The current consumption peak during a transmission slot is strictly dependent on the transmitted power, which is
regulated by the network. The transmitted power in the transmit slot is also the more relevant factor for
determining the average current consumption.
If the module is transmitting in 2G single-slot mode (as in GSM talk mode) in the 850 or 900 MHz bands, at the
maximum RF power control level (approximately 2 W or 33 dBm in the Tx slot/burst), the current consumption can
reach an high peak / pulse (see LARA-R2 series Data Sheet [1]) for 576.9 µs (width of the transmit slot/burst) with
a periodicity of 4.615 ms (width of 1 frame = 8 slots/burst), so with a 1/8 duty cycle according to GSM TDMA
(Time Division Multiple Access).
If the module is transmitting in 2G single-slot mode in the 1800 or 1900 MHz bands, the current consumption
figures are quite less high than the one in the low bands, due to the 3GPP transmitter output power specifications.
During a GSM call, current consumption is not so significantly high in receiving or in monitor bursts and it is low
in the bursts unused to transmit / receive.
Figure 4 shows an example of the module current consumption profile versus time in GSM talk mode.
Current [A]
2.0

1900 mA

1.5
Peak current depends
on TX power and
actual antenna load

1.0

0.5
200 mA
60-120 mA

0.0

RX
slot

60-120 mA

10-40 mA

unused unused
slot
slot

TX
slot

unused unused
slot
slot

MON
slot

unused
slot

RX
slot

unused unused
slot
slot

GSM frame
4.615 ms
(1 frame = 8 slots)

TX
slot

unused unused
slot
slot

MON
slot

unused
slot

Time [ms]

GSM frame
4.615 ms
(1 frame = 8 slots)

Figure 4: VCC current consumption profile versus time during a GSM call (1 TX slot, 1 RX slot)

Figure 5 illustrates VCC voltage profile versus time during a GSM call, according to the related VCC current
consumption profile described in Figure 4.
Voltage
overshoot
3.8 V
(typ)

drop

ripple
RX
slot

unused unused
slot
slot

TX
slot

undershoot
unused unused
slot
slot

GSM frame
4.615 ms
(1 frame = 8 slots)

MON
slot

unused
slot

RX
slot

unused unused
slot
slot

TX
slot

unused unused
slot
slot

GSM frame
4.615 ms
(1 frame = 8 slots)

MON
slot

unused
slot

Time

Figure 5: Description of the VCC voltage profile versus time during a GSM call (1 TX slot, 1 RX slot)

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When a GPRS connection is established, more than one slot can be used to transmit and/or more than one slot
can be used to receive. The transmitted power depends on network conditions, which set the peak current
consumption, but following the 3GPP specifications the maximum Tx RF power is reduced if more than one slot is
used to transmit, so the maximum peak of current is not as high as can be the case with a 2G single-slot call.
The multi-slot transmission power can be further reduced by configuring the actual Multi-Slot Power Reduction
profile with the dedicated AT command, AT+UDCONF=40 (see the u-blox AT Commands Manual [2]).
If the module transmits in GPRS class 12 in the 850 or 900 MHz bands, at the maximum RF power control level,
the current consumption can reach a quite high peak but lower than the one achievable in 2G single-slot mode.
This happens for 2.307 ms (width of the 4 transmit slots/bursts) with a periodicity of 4.615 ms (width of 1 frame
= 8 slots/bursts), so with a 1/2 duty cycle, according to 2G TDMA.
If the module is in GPRS connected mode in the 1800 or 1900 MHz bands, the current consumption figures are
quite less high than the one in the low bands, due to 3GPP transmitter output power specifications.
Figure 6 reports the current consumption profiles in GPRS class 12 connected mode, in the 850 or 900 MHz bands,
with 4 slots used to transmit and 1 slot used to receive.
Current [A]
2.0
1600 mA

1.5

1.0
Peak current depends
on TX power and
actual antenna load

0.5
200mA

60-130mA

0.0

RX
slot

unused
slot

TX
slot

TX
slot

TX
slot

TX
slot

GSM frame
4.615 ms
(1 frame = 8 slots)

MON
slot

unused
slot

RX
slot

unused
slot

TX
slot

TX
slot

TX
slot

TX
slot

MON
slot

unused
slot

Time [ms]

GSM frame
4.615 ms
(1 frame = 8 slots)

Figure 6: VCC current consumption profile versus time during a 2G GPRS/EDGE multi-slot connection (4 TX slots, 1 RX slot)

For EDGE connections, the VCC current consumption profile is very similar to the GPRS current profile, so the
image shown in Figure 6, representing the current consumption profile in GPRS class 12 connected mode, is valid
for the EDGE class 12 connected mode as well.

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1.5.1.3 VCC current consumption in 3G connected mode
During a 3G connection, the module can transmit and receive continuously due to the Frequency Division Duplex
(FDD) mode of operation with the Wideband Code Division Multiple Access (WCDMA).
The current consumption depends on output RF power, which is always regulated by the network (the current
base station) sending power control commands to the module. These power control commands are logically
divided into a slot of 666 µs, so the rate of power change can reach a maximum rate of 1.5 kHz.
There are no high current peaks as in the 2G connection, since transmission and reception are continuously
enabled due to FDD WCDMA implemented in the 3G that differs from the TDMA implemented in the 2G case.
In the worst case scenario, corresponding to a continuous transmission and reception at maximum output power
(approximately 250 mW or 24 dBm), the average current drawn by the module at the VCC pins is considerable
(see the “Current consumption” section in LARA-R2 series Data Sheet [1]). At the lowest output RF power
(approximately 0.01 µW or –50 dBm), the current drawn by the internal power amplifier is strongly reduced. The
total current drawn by the module at the VCC pins is due to baseband processing and transceiver activity.
Figure 7 shows an example of the current consumption profile of the module in 3G WCDMA/HSPA continuous
transmission mode.
Current [mA]

700
600
850 mA
500
400

Current consumption value
depends on TX power and
actual antenna load

300
200

170 mA

100

0

1 slot
666 µs

Time
[ms]

3G frame
10 ms
(1 frame = 15 slots)
Figure 7: VCC current consumption profile versus time during a 3G connection (TX and RX continuously enabled)

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1.5.1.4 VCC current consumption in LTE connected mode
During an LTE connection, the module can transmit and receive continuously due to the Frequency Division Duplex
(FDD) mode of operation used in LTE radio access technology.
The current consumption depends on output RF power, which is always regulated by the network (the current
base station) sending power control commands to the module. These power control commands are logically
divided into a slot of 0.5 ms (time length of one Resource Block), thus the rate of power change can reach a
maximum rate of 2 kHz.
The current consumption profile is similar to that in 3G radio access technology. Unlike the 2G connection mode,
which uses the TDMA mode of operation, there are no high current peaks since transmission and reception are
continuously enabled in FDD.
In the worst case scenario, corresponding to a continuous transmission and reception at maximum output power
(approximately 250 mW or 24 dBm), the average current drawn by the module at the VCC pins is considerable
(see the “Current consumption” section in LARA-R2 series Data Sheet [1]). At the lowest output RF power
(approximately 0.1 µW or –40 dBm), the current drawn by the internal power amplifier is strongly reduced and
the total current drawn by the module at the VCC pins is due to baseband processing and transceiver activity.
Figure 8 shows an example of the module current consumption profile versus time in LTE connected mode.
Detailed current consumption values can be found in LARA-R2 series Data Sheet [1].

Current [mA]
700
600
500
Current consumption value
depends on TX power and
actual antenna load

400
300

200
100
0
1 Slot
1 Resource Block
(0.5 ms)

1 LTE Radio Frame
(10 ms)

Time
[ms]

Figure 8: VCC current consumption profile versus time during LTE connection (TX and RX continuously enabled)

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1.5.1.5 VCC current consumption in cyclic idle/active mode (power saving enabled)
The power saving configuration is disabled by default, but it can be enabled using the appropriate AT command
(see u-blox AT Commands Manual [2], AT+UPSV command). When power saving is enabled, the module
automatically enters low power idle mode whenever possible, reducing current consumption.
When the power saving configuration is enabled and the module is registered or attached to a network, the
module automatically enters the low power idle mode whenever possible, but it must periodically monitor the
paging channel of the current base station (paging block reception), in accordance to the 2G / 3G / LTE system
requirements, even if connected mode is not enabled by the application. When the module monitors the paging
channel, it wakes up to the active mode to enable the reception of the paging block. In between, the module
switches to low power idle mode. This is known as discontinuous reception (DRX).
The module processor core is activated during the paging block reception, and automatically switches its reference
clock frequency from 32 kHz to the 26 MHz used in active mode.
The time period between two paging block receptions is defined by the network. This is the paging period
parameter, fixed by the base station through broadcast channel sent to all users on the same serving cell:


For 2G radio access technology, the paging period can vary from 470.8 ms (DRX = 2, length of 2 x 51 2G
frames = 2 x 51 x 4.615 ms) up to 2118.4 ms (DRX = 9, length of 9 x 51 2G frames = 9 x 51 x 4.615 ms)



For 3G radio access technology, the paging period can vary from 640 ms (DRX = 6, i.e. length of 26 3G frames
= 64 x 10 ms) up to 5120 ms (DRX = 9, length of 29 3G frames = 512 x 10 ms).



For LTE radio access technology, the paging period can vary from 320 ms (DRX = 5, i.e. length of 25 LTE frames
= 32 x 10 ms) up to 2560 ms (DRX = 8, length of 28 LTE frames = 256 x 10 ms).
Figure 9 illustrates a typical example of the module current consumption profile when power saving is enabled.
The module is registered with the network, automatically enters the low power idle mode and periodically wakes
up to active mode to monitor the paging channel for the paging block reception. Detailed current consumption
values can be found in the LARA-R2 series Data Sheet [1]).
Current [mA]

100

0

Time [s]
Current [mA]

IDLE MODE

ACTIVE MODE

2G case: 0.44-2.09 s
3G case: 0.61-5.09 s
LTE case: 0.27-2.51 s

~50 ms

100

0
Active Mode
Enabled

IDLE MODE

RX
Enabled

Idle Mode
Enabled
~50 ms

ACTIVE MODE

Time [ms]

IDLE MODE

Figure 9: VCC current consumption profile with power saving enabled and module registered with the network: the module is in
low-power idle mode and periodically wakes up to active mode to monitor the paging channel for paging block reception

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1.5.1.6 VCC current consumption in fixed active mode (power saving disabled)
Power saving configuration is disabled by default, or it can be disabled using the appropriate AT command (see
the u-blox AT Commands Manual [2], AT+UPSV command). When power saving is disabled, the module does not
automatically enter idle mode whenever possible: the module remains in active mode.
The module processor core is activated during active mode, and the 26 MHz reference clock frequency is used.
Figure 10 illustrates a typical example of the module current consumption profile when power saving is disabled.
In such case, the module is registered with the network and while active mode is maintained, the receiver is
periodically activated to monitor the paging channel for paging block reception. Detailed current consumption
values can be found in the LARA-R2 series Data Sheet [1].
Current [mA]

100

0

Time [s]
Current [mA]

Paging period
2G case: 0.44-2.09 s
3G case: 0.61-5.09 s
LTE case: 0.32-2.56 s

100

0
RX
Enabled

Time [ms]

ACTIVE MODE
Figure 10: VCC current consumption profile with power saving disabled and module registered with the network: active mode is
always held and the receiver is periodically activated to monitor the paging channel for paging block reception

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1.5.2 RTC supply input/output (V_BCKP)
The V_BCKP pin of LARA-R2 series modules connects the supply for the Real Time Clock (RTC) and Power-On
internal logic. This supply domain is internally generated by a linear LDO regulator integrated in the Power
Management Unit, as described in Figure 11. The output of this linear regulator is always enabled when the main
voltage supply provided to the module through the VCC pins is within the valid operating range, with the module
switched off or switched on.

LARA-R2 series

VCC 51

Power
Management

Baseband
Processor

Linear
LDO

RTC

VCC 52
VCC 53

V_BCKP 2
32 kHz

Figure 11: RTC supply input/output (V_BCKP) and 32 kHz RTC timing reference clock simplified block diagram

The RTC provides the module time reference (date and time) that is used to set the wake-up interval during the
low power idle mode periods, and is able to make the programmable alarm functions available.
The RTC functions are also available in power-down mode when the V_BCKP voltage is within its valid range
(specified in the “Input characteristics of Supply/Power pins” table in LARA-R2 series Data Sheet [1]). The RTC can
be supplied from an external back-up battery through the V_BCKP, when the main module voltage supply is not
applied to the VCC pins. This lets the time reference (date and time) run until the V_BCKP voltage is within its
valid range, even when the main supply is not provided to the module.
Consider that the module cannot switch on if a valid voltage is not present on VCC, even when the RTC is supplied
through V_BCKP (meaning that VCC is mandatory to switch on the module).
The RTC has a very low current consumption, but is highly temperature dependent. For example, V_BCKP current
consumption at the maximum operating temperature can be higher than the typical value at +25 °C specified in
the “Input characteristics of Supply/Power pins” table in the LARA-R2 series Data Sheet [1].
If V_BCKP is left unconnected and the module main voltage supply is removed from VCC, the RTC is supplied
from the bypass capacitor mounted inside the module. However, this capacitor is not able to provide a long
buffering time: within a few milliseconds, the voltage on V_BCKP will drop below the valid range. This has no
impact on cellular connectivity, as all the module functionalities do not rely on date and time settings.

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1.5.3 Generic digital interfaces supply output (V_INT)
The V_INT output pin of the LARA-R2 series modules is connected to an internal 1.8 V supply with a current
capability specified in the LARA-R2 series Data Sheet [1]. This supply is internally generated by a switching stepdown regulator integrated in the Power Management Unit and it is internally used to source the generic digital
I/O interfaces of the cellular module, as described in Figure 12. The output of this regulator is enabled when the
module is switched on and it is disabled when the module is switched off.

LARA-R2 series

VCC 51

Power
Management

Baseband
Processor

Switching
Step-Down

Digital I/O
Interfaces

VCC 52

VCC 53
V_INT 4

Figure 12: LARA-R2 series interfaces supply output (V_INT) simplified block diagram

The switching regulator operates in Pulse Width Modulation (PWM) mode for greater efficiency at high output
loads and it automatically switches to Pulse Frequency Modulation (PFM) power save mode for greater efficiency
at low output loads. The V_INT output voltage ripple is specified in the LARA-R2 series Data Sheet [1].

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1.6 System function interfaces
1.6.1 Module power-on
When the LARA-R2 series modules are in the not-powered mode (switched off, i.e. the VCC module supply is not
applied), they can be switched on as following:


Rising edge on the VCC input to a valid voltage for module supply, i.e. applying module supply: the modules
switch on if the VCC supply is applied, starting from a voltage value of less than 2.1 V, with a rise time from
2.3 V to 2.8 V of less than 4 ms, reaching a proper nominal voltage value within the VCC operating range.
Alternately, in case for example the fast rise time on VCC rising edge cannot be guaranteed by the application,
LARA-R2 series modules can be switched on from not-powered mode as following:


RESET_N input pin is held low by the external application during the VCC rising edge, so that the modules
will switch on when the external application releases the RESET_N input pin from the low logic level after the
VCC supply voltage stabilizes at its proper nominal value within the operating range



PWR_ON input pin is held low by the external application during the VCC rising edge, so that the modules
will switch on when the external application releases the PWR_ON input pin from the low logic level after the
VCC supply voltage stabilizes at its proper nominal value within the operating range

When the LARA-R2 series modules are in the power-off mode (i.e. properly switched off as described in section
1.6.2, with valid VCC module supply applied), they can be switched on as following:


Low pulse on the PWR_ON pin, which is normally set high by an internal pull-up, for a valid time period: the
modules start the internal switch-on sequence when the external application releases the PWR_ON pin from
the low logic level after that it has been set low for an appropriate time period



Rising edge on the RESET_N pin, i.e. releasing the pin from the low level, as that the pin is normally set high
by an internal pull-up: the modules start the internal switch-on sequence when the external application
releases the RESET_N pin from the low logic level



RTC alarm, i.e. pre-programmed alarm by AT+CALA command (see the u-blox AT Commands Manual [2]).

As described in Figure 13, the LARA-R2 series PWR_ON input is equipped with an internal active pull-up resistor
to the V_BCKP supply: the PWR_ON input voltage thresholds are different from the other generic digital
interfaces. Detailed electrical characteristics are described in the LARA-R2 series Data Sheet [1].

LARA-R2 series
V_BCKP

2

Power
Management

Baseband
Processor

Power-on

Power-on

10k

PWR_ON 15

Figure 13: LARA-R2 series PWR_ON input description

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Figure 14 shows the module switch-on sequence from the not-powered mode, describing the following phases:


The external supply is applied to the VCC module supply inputs, representing the start-up event.



The V_BCKP RTC supply output is suddenly enabled by the module as VCC reaches a valid voltage value.



The PWR_ON and the RESET_N pins suddenly rise to high logic level due to internal pull-ups.



All the generic digital pins of the module are tri-stated until the switch-on of their supply source (V_INT).



The internal reset signal is held low: the baseband core and all the digital pins are held in the reset state. The
reset state of all the digital pins is reported in the pin description table of LARA-R2 series Data Sheet [1].



When the internal reset signal is released, any digital pin is set in a proper sequence from the reset state to
the default operational configured state. The duration of this pins’ configuration phase differs within generic
digital interfaces and the USB interface due to host / device enumeration timings (see section 1.9.2).



The module is fully ready to operate after all interfaces are configured.

Start of interface
configuration

Start-up
event

Module interfaces
are configured

VCC
V_BCKP
PWR_ON
RESET_N
V_INT
Internal Reset
OFF

System State
BB Pads State

Tristate / Floating

ON
Internal Reset Internal Reset → Operational Operational

Figure 14: LARA-R2 series switch-on sequence description

The greeting text can be activated by means of the +CSGT AT command (see u-blox AT Commands Manual [2])
to notify the external application that the module is ready to operate (i.e. ready to reply to AT commands) and the
first AT command can be sent to the module, given that autobauding must be disabled on the UART to let the
module sending the greeting text: the UART must be configured at a fixed baud rate (the baud rate of the
application processor) instead of the default autobauding, otherwise the module does not know the baud rate to
be used for sending the greeting text (or any other URC) at the end of the internal boot sequence.
The Internal Reset signal is not available on a module pin, but the host application can monitor the V_INT
pin to sense the start of the LARA-R2 series module switch-on sequence.
Before the switch-on of the generic digital interface supply source (V_INT) of the module, no voltage driven
by an external application should be applied to any generic digital interface of the module.
Before the LARA-R2 series module is fully ready to operate, the host application processor should not send
any AT command over the AT communication interfaces (USB, UART) of the module.
The duration of the LARA-R2 series modules’ switch-on routine can vary depending on the application /
network settings and any concurrent module activities.

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1.6.2 Module power-off
LARA-R2 series can be properly switched off by:


AT+CPWROFF command (see u-blox AT Commands Manual [2]). The current parameter settings are saved in
the module’s non-volatile memory and a proper network detach is performed.



Low pulse on the PWR_ON pin, which is normally set high by an internal pull-up, for a valid time period (see
the LARA-R2 series Data Sheet [1]): the modules start the internal switch-off sequence when the external
application releases the PWR_ON line from the low logic level, after that it has been set low for an appropriate
time period.

An abrupt under-voltage shutdown occurs on LARA-R2 series modules when the VCC module supply is removed.
If this occurs, it is not possible to perform the storing of the current parameter settings in the module’s non-volatile
memory or to perform a proper network detach.
It is highly recommended to avoid an abrupt removal of the VCC supply during LARA-R2 series modules
normal operations: the switch-off procedure must be started by the AT+CPWROFF command, waiting for
the command response for an appropriate time period (see the u-blox AT Commands Manual [2]), and then
a proper VCC supply must be held at least until the end of the modules’ internal switch-off sequence, which
occurs when the generic digital interfaces supply output (V_INT) is switched off by the module.
An abrupt hardware shutdown occurs on LARA-R2 series modules when a low level is applied on the RESET_N
pin. In this case, the current parameter settings are not saved in the module’s non-volatile memory and a proper
network detach is not performed.
It is highly recommended to avoid an abrupt hardware shutdown of the module by forcing a low level on
the RESET_N input pin during module normal operation: the RESET_N line should be set low only if a reset
or shutdown via AT commands fails or if the module does not reply to a specific AT command after a time
period longer than the one defined in the u-blox AT Commands Manual [2].
An over-temperature or an under-temperature shutdown occurs on LARA-R2 series modules when the
temperature measured within the cellular module reaches the dangerous area, if the optional Smart Temperature
Supervisor feature is enabled and configured by the dedicated AT command. For more details, see section 1.14.16
and u-blox AT Commands Manual [2], +USTS AT command.

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Figure 15 illustrates the LARA-R2 series modules switch-off sequence started by means of the AT+CPWROFF
command, allowing storage of the current parameter settings in the module’s non-volatile memory and a proper
network detach, with the following phases:


When the +CPWROFF AT command is sent, the module starts the switch-off routine.



The module replies OK on the AT interface: the switch-off routine is in progress.



At the end of the switch-off routine, all the digital pins are tri-stated and all the internal voltage regulators are
turned off, including the generic digital interfaces supply (V_INT), except the RTC supply (V_BCKP).



Then the module remains in power-off mode as long as a -on event does not occur (e.g. applying a proper
low level to the PWR_ON input, or applying a proper low level to the RESET_N input), and enters not-powered
mode if the supply is removed from the VCC pins.
AT+CPWROFF
sent to the module

OK
replied by the module

VCC
can be removed

VCC
V_BCKP
PWR_ON
RESET_N
V_INT
Internal Reset
ON

System State
BB Pads State

Operational
0s

OFF
Tristate / Floating

Operational → Tristate
~2.5 s

~5 s

Figure 15: LARA-R2 series switch-off sequence by means of AT+CPWROFF command

The Internal Reset signal is not available on a module pin, but the application can monitor the V_INT pin to
sense the end of the LARA-R2 series switch-off sequence.
The VCC supply can be removed only after the end of the module internal switch-off routine, i.e. only after
that the V_INT voltage level has gone low.
The duration of each phase in the LARA-R2 series modules’ switch-off routines can largely vary depending
on the application / network settings and the concurrent module activities.

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Figure 16 illustrates the LARA-R2 series modules’ switch-off sequence started by means of the PWR_ON input pin,
allowing storage of current parameter settings in the module’s non-volatile memory and a proper network detach,
with the following phases:


A low pulse with appropriate time duration (see LARA-R2 series Data Sheet [1]) is applied at the PWR_ON
input pin, which is normally set high by an internal pull-up: the module starts the switch-off routine when the
PWR_ON signal is released from the low logical level.



At the end of the switch-off routine, all the digital pins are tri-stated and all the internal voltage regulators are
turned off, including the generic digital interfaces supply (V_INT), except the RTC supply (V_BCKP).



Then the module remains in power-off mode as long as a switch-on event does not occur (e.g. applying a
proper low level to the PWR_ON input, or applying a proper low level to the RESET_N input), and enters notpowered mode if the supply is removed from the VCC pins.
The module starts
the switch-off routine

VCC
can be removed

VCC
V_BCKP
PWR_ON
RESET_N
V_INT
Internal Reset
ON

System State
BB Pads State

Operational
0s

OFF
Operational -> Tristate

~2.5 s

Tristate / Floating

~5 s

Figure 16: LARA-R2 series switch-off sequence by means of PWR_ON pin

The Internal Reset signal is not available on a module pin, but the application can monitor the V_INT pin to
sense the end of the switch-off sequence.
The VCC supply can be removed only after the end of the module internal switch-off routine, i.e. only after
that the V_INT voltage level has gone low.
The duration of each phase in the LARA-R2 series modules’ switch-off routines can largely vary depending
on the application / network settings and the concurrent module activities.

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1.6.3 Module reset
LARA-R2 series modules can be properly reset (rebooted) by:
 AT+CFUN command (see the u-blox AT Commands Manual [2] for more details).
This command causes an “internal” or “software” reset of the module, which is an asynchronous reset of the
module baseband processor. The current parameter settings are saved in the module’s non-volatile memory and
a proper network detach is performed: this is the correct way to reset the modules.
An abrupt hardware reset occurs on LARA-R2 series modules when a low level is applied on the RESET_N input
pin for a specific time period. In this case, the current parameter settings are not saved in the module’s non-volatile
memory and a proper network detach is not performed.
It is highly recommended to avoid an abrupt hardware reset of the module by forcing a low level on the
RESET_N input during modules normal operation: the RESET_N line should be set low only if reset or
shutdown via AT commands fails or if the module does not provide a reply to a specific AT command after
a time period longer than the one defined in the u-blox AT Commands Manual [2].
As described in Figure 17, the RESET_N input pins are equipped with an internal pull-up to the V_BCKP supply.

LARA-R2 series
V_BCKP

2

Power
Management

Baseband
Processor

Reset

Reset

10k

RESET_N 18

Figure 17: LARA-R2 series RESET_N input equivalent circuit description

For more electrical characteristics details, see the LARA-R2 series Data Sheet [1].

1.6.4 Module / host configuration selection
The functionality of the HOST_SELECT pin is not supported by the “02” and “62” product versions.
The modules include one pin (HOST_SELECT) to select the module / host application processor configuration: the
pin is available to select, enable, connect, disconnect and subsequently re-connect the HSIC interface.
The LARA-R2 series Data Sheet [1] describes the detailed electrical characteristics of the HOST_SELECT pin.

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1.7 Antenna interface
1.7.1 Antenna RF interfaces (ANT1 / ANT2)
LARA-R2 series modules provide two RF interfaces for connecting the external antennas:


The ANT1 represents the primary RF input/output for transmission and reception of LTE/3G/2G RF signals.
The ANT1 pin has a nominal characteristic impedance of 50  and must be connected to the primary Tx / Rx
antenna through a 50  transmission line to allow proper RF transmission and reception.



The ANT2 represents the secondary RF input for the reception of the LTE / 3G RF signals for the Down-Link
Rx diversity radio technology supported by LARA-R2 modules as a required feature for LTE category 1 UEs.
The ANT2 pin has a nominal characteristic impedance of 50  and must be connected to the secondary Rx
antenna through a 50  transmission line to allow proper RF reception.

1.7.1.1 Antenna RF interface requirements
Table 7, Table 8 and Table 9 summarize the requirements for the antennas RF interfaces (ANT1 / ANT2). See
section 2.4.1 for suggestions to properly design antennas circuits compliant with these requirements.
The antenna circuits affect the RF compliance of the device integrating LARA-R2 series modules
with applicable required certification schemes (for more details see section 4). Compliance is
guaranteed if the antenna RF interfaces (ANT1 / ANT2) requirements summarized in Table 7, Table
8 and Table 9 are fulfilled.
Item

Requirements

Remarks

Impedance

50  nominal characteristic impedance

The impedance of the antenna RF connection must match the 50 
impedance of the ANT1 port.

Frequency Range

See the LARA-R2 series Data Sheet [1]

The required frequency range of the antenna connected to the ANT1
port depends on the operating bands of the used cellular module and
the used mobile network.

Return Loss

S11 < -10 dB (VSWR < 2:1) recommended
S11 < -6 dB (VSWR < 3:1) acceptable

The Return loss or the S11, as the VSWR, refers to the amount of
reflected power, measuring how well the antenna RF connection
matches the 50  characteristic impedance of the ANT1 port.
The impedance of the antenna termination must match as much as
possible the 50  nominal impedance of the ANT1 port over the
operating frequency range, reducing as much as possible the amount
of reflected power.

Efficiency

> -1.5 dB ( > 70% ) recommended
> -3.0 dB ( > 50% ) acceptable

The radiation efficiency is the ratio of the radiated power to the power
delivered to the antenna input: the efficiency is a measure of how well
an antenna receives or transmits.
The radiation efficiency of the antenna connected to the ANT1 port
needs to be enough high over the operating frequency range to
comply with the Over-The-Air (OTA) radiated performance
requirements, as the Total Radiated Power (TRP) and the Total Isotropic
Sensitivity (TIS), specified by the applicable related certification
schemes.

Maximum Gain

According to radiation exposure limits

The power gain of an antenna is the radiation efficiency multiplied by
the directivity: the gain describes how much power is transmitted in
the direction of peak radiation to that of an isotropic source.
The maximum gain of the antenna connected to the ANT1 port must
not exceed the herein stated value to comply with regulatory agencies
radiation exposure limits.
For additional info, see sections 4.2.2, 4.3.1 and/or 4.4.

Input Power

> 33 dBm ( > 2 W ) for LARA-R211
> 24 dBm ( > 250 mW ) for other LARA-R2

The antenna connected to the ANT1 port must support the maximum
power transmitted by the modules with an adequate margin.

Table 7: Summary of primary Tx/Rx antenna RF interface (ANT1) requirements

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Item

Requirements

Remarks

Impedance

50  nominal characteristic impedance

The impedance of the antenna RF connection must match the 50 
impedance of the ANT2 port.

Frequency Range

See the LARA-R2 series Data Sheet [1]

The required frequency range of the antennas connected to the ANT2
port depends on the operating bands of the used cellular module and
the used mobile network.

Return Loss

S11 < -10 dB (VSWR < 2:1) recommended
S11 < -6 dB (VSWR < 3:1) acceptable

The Return loss or the S11, as the VSWR, refers to the amount of
reflected power, measuring how well the antenna RF connection
matches the 50  characteristic impedance of the ANT2 port.
The impedance of the antenna termination must match as much as
possible the 50  nominal impedance of the ANT2 port over the
operating frequency range, reducing as much as possible the amount
of reflected power.

Efficiency

> -1.5 dB ( > 70% ) recommended
> -3.0 dB ( > 50% ) acceptable

The radiation efficiency is the ratio of the radiated power to the power
delivered to antenna input: the efficiency is a measure of how well an
antenna receives or transmits.
The radiation efficiency of the antenna connected to the ANT2 port
needs to be enough high over the operating frequency range to
comply with the Over-The-Air (OTA) radiated performance
requirements, as the TIS, specified by applicable related certification
schemes.

Table 8: Summary of secondary Rx antenna RF interface (ANT2) requirements

Item

Requirements

Remarks

Efficiency
imbalance

< 0.5 dB recommended
< 1.0 dB acceptable

The radiation efficiency imbalance is the ratio of the primary (ANT1)
antenna efficiency to the secondary (ANT2) antenna efficiency: the
efficiency imbalance is a measure of how much better an antenna
receives or transmits compared to the other antenna.
The radiation efficiency of the secondary antenna needs to be roughly
the same of the radiation efficiency of the primary antenna for good
RF performance.

Envelope
Correlation
Coefficient

< 0.4 recommended
< 0.5 acceptable

The Envelope Correlation Coefficient (ECC) between the primary
(ANT1) and the secondary (ANT2) antennas is an indicator of the 3D
radiation pattern similarity between the two antennas: low ECC arises
from antenna patterns with radiation lobes in different directions.
The ECC between primary and secondary antennas needs to be
sufficently low to comply with radiated performance requirements
specified by the related certification schemes.

Isolation

> 15 dB recommended
> 10 dB acceptable

The antenna to antenna isolation is the loss between the primary
(ANT1) and the secondary (ANT2) antennas: high isolation arises from
weakly coupled antennas.
The isolation between primary and secondary antenna needs to be
high for good RF performance.

Table 9: Summary of the primary (ANT1) and secondary (ANT2) antennas relationship requirements

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1.7.2 Antenna detection interface (ANT_DET)
The antenna detection is based on ADC measurement. The ANT_DET pin is an Analog to Digital Converter (ADC)
provided to sense the antenna presence.
The antenna detection function provided by the ANT_DET pin is an optional feature that can be implemented if
the application requires it. The antenna detection is forced by the +UANTR AT command. See the u-blox AT
Commands Manual [2] for more details on this feature.
The ANT_DET pin generates a DC current (for detailed characteristics, see the LARA-R2 series Data Sheet [1]) and
measures the resulting DC voltage, thus determining the resistance from the antenna connector provided on the
application board to GND. The requirements to achieve antenna detection functionality are the following:


an RF antenna assembly with a built-in resistor (diagnostic circuit) must be used

 an antenna detection circuit must be implemented on the application board
See section 2.4.2 for the antenna detection circuit on the application board and the diagnostic circuit on the
antenna assembly design-in guidelines.

1.8 SIM interface
1.8.1 SIM card interface
LARA-R2 series modules provide a high-speed SIM/ME interface, including automatic detection and configuration
of the voltage required by the connected SIM card or chip.
Both 1.8 V and 3 V SIM types are supported: activation and deactivation with an automatic voltage switch from
1.8 V to 3 V is implemented, according to the ISO-IEC 7816-3 specifications. The VSIM supply output pin provides
internal short circuit protection to limit the start-up current and protect the device in short circuit situations.
The SIM driver supports the PPS (Protocol and Parameter Selection) procedure for baud-rate selection, according
to the values determined by the SIM Card.

1.8.2 SIM card detection interface (SIM_DET)
The GPIO5 pin is configured by default to detect the external SIM card mechanical / physical presence. The pin is
configured as input, and it can sense SIM card presence as intended to be properly connected to the mechanical
switch of a SIM card holder as described in section 2.5:


Low logic level at GPIO5 input pin is recognized as SIM card not present

 High logic level at GPIO5 input pin is recognized as SIM card present
The SIM card detection function provided by the GPIO5 pin is an optional feature that can be implemented / used
or not according to the application requirements: an Unsolicited Result Code (URC) is generated each time that
there is a change of status (for more details, see the u-blox AT Commands Manual [2], +UGPIOC, +CIND, +CMER).
The optional function “SIM card hot insertion/removal” can be additionally configured on the GPIO5 pin by the
specific AT command (see the u-blox AT Commands Manual [2], +UDCONF=50), in order to enable / disable the
SIM interface upon detection of the external SIM card physical insertion / removal.

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1.9 Data communication interfaces
LARA-R2 series modules provide the following serial communication interfaces:


UART interface: Universal Asynchronous Receiver/Transmitter serial interface available for the communication
with a host application processor (AT commands, data communication, FW update by means of FOAT), for
FW update by means of the u-blox EasyFlash tool and for diagnostics (see section 1.9.1).



USB interface: Universal Serial Bus 2.0 compliant interface available for the communication with a host
application processor (AT commands, data communication, FW update by means of the FOAT feature), for
FW update by means of the u-blox EasyFlash tool and for diagnostics (see section 1.9.2).



HSIC interface: High-Speed Inter-Chip USB compliant interface available for the communication with a host
application processor (AT commands, data communication, FW update by means of the FOAT feature), for
FW update by means of the u-blox EasyFlash tool and for diagnostics (see section 1.9.3).



DDC interface: I2C bus compatible interface available for the communication with u-blox GNSS positioning
chips or modules and with external I2C devices as an audio codec (see section 1.9.4).



SDIO interface: Secure Digital Input Output interface available for the communication with compatible u-blox
short range radio communication Wi-Fi modules (see section 1.9.5).

1.9.1 UART interface
1.9.1.1 UART features
The UART interface is a 9-wire 1.8 V unbalanced asynchronous serial interface available on all the LARA-R2 series
modules, supporting:


AT command mode8



Data mode and Online command mode8



Multiplexer protocol functionality (see 1.9.1.5)



FW upgrades by means of the FOAT feature (see 1.14.14 and the Firmware update application note [23])



FW upgrades by means of the u-blox EasyFlash tool (see the Firmware update application note [23])



Trace log capture (diagnostic purposes)

The UART interface provides RS-232 functionality conforming to the ITU-T V.24 Recommendation [5], with CMOS
compatible signal levels: 0 V for low data bit or ON state, and 1.8 V for high data bit or OFF state (for the detailed
electrical characteristics, see the LARA-R2 series Data Sheet [1]), providing:


data lines (RXD as output, TXD as input),



hardware flow control lines (CTS as output, RTS as input),

 modem status and control lines (DTR as input, DSR as output, DCD as output, RI as output).
LARA-R2 series modules are designed to operate as cellular modems, i.e. as the data circuit-terminating equipment
(DCE) according to the ITU-T V.24 Recommendation [5]. A host application processor connected to the module
through the UART interface represents the data terminal equipment (DTE).
UART signal names of the modules conform to the ITU-T V.24 Recommendation [5]: e.g. TXD line represents
data transmitted by the DTE (host processor output) and received by the DCE (module input).
LARA-R2 series modules’ UART interface is configured by default in AT command mode: the module waits for AT
command instructions and interprets all the characters received as commands to execute.

8

See the u-blox AT Commands Manual [2] for the definition of the command mode, data mode, and online command mode.

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All the functionalities supported by LARA-R2 series modules can be set and configured by AT commands:


AT commands according to 3GPP TS 27.007 [6], 3GPP TS 27.005 [7], 3GPP TS 27.010 [8]



u-blox AT commands (for the complete list and syntax, see the u-blox AT Commands Manual [2])

All flow control handshakes are supported by the UART interface and can be set by appropriate AT commands
(see u-blox AT Commands Manual [2], &K, +IFC, \Q AT commands): hardware, software, or none flow control.
Hardware flow control is enabled by default.
The one-shot autobauding is supported: the automatic baud rate detection is performed only once, at module
start-up. After the detection, the module works at the detected baud rate and the baud rate can only be changed
by an AT command (see the u-blox AT Commands Manual [2], +IPR command).
One-shot automatic baud rate recognition (autobauding) is enabled by default.
The following baud rates can be configured by AT command (see u-blox AT Commands Manual [2], +IPR):


9,600 bit/s



19,200 bit/s



38,400 bit/s



57,600 bit/s



115,200 bit/s, default value when one-shot autobauding is disabled



230,400 bit/s



460,800 bit/s



921,600 bit/s



3,000,000 bit/s



3,250,000 bit/s



6,000,000 bit/s



6,500,000 bit/s
Baud rates higher than 460,800 bit/s cannot be automatically detected by LARA-R2 series modules.

The modules support one-shot automatic frame recognition in conjunction with one-shot autobauding. The
following frame formats can be configured by an AT command (see the u-blox AT Commands Manual [2], +ICF):


8N1 (8 data bits, no parity, 1 stop bit), default frame configuration with a fixed baud rate, see Figure 18



8E1 (8 data bits, even parity, 1 stop bit)



8O1 (8 data bits, odd parity, 1 stop bit)



8N2 (8 data bits, no parity, 2 stop bits)



7E1 (7 data bits, even parity, 1 stop bit)



7O1 (7 data bits, odd parity, 1 stop bit)
Normal Transfer, 8N1
Start of 1-Byte
transfer

D0

D1

Possible Start of
next transfer

D2

D3

D4

D5

Start Bit
(Always 0)

D6

D7

Stop Bit
(Always 1)
tbit = 1/(Baudrate)

Figure 18: Description of the UART 8N1 frame format (8 data bits, no parity, 1 stop bit)

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1.9.1.2 UART AT interface configuration
The UART interface of LARA-R2 series modules is available as the AT command interface with the default
configuration described in Table 10 (for more details and information about further settings, see the u-blox AT
Commands Manual [2]).
Interface

AT Settings

Comments

UART interface

AT interface: enabled

AT command interface is enabled by default on the UART physical interface

AT+IPR=0

One-shot autobauding enabled by default on the modules

AT+ICF=3,1

8N1 frame format enabled by default

AT&K3

HW flow control enabled by default

AT&S1

DSR line (Circuit 107 in ITU-T V.24) set ON in data mode and set OFF in command mode

AT&D1

Upon an ON-to-OFF transition of the DTR line (Circuit 108/2 in ITU-T V.24), the module
9
(DCE) enters online command mode and issues an OK result code

AT&C1

DCD line (Circuit 109 in ITU-T V.24) changes in accordance with the Carrier detect status;
ON if the Carrier is detected, OFF otherwise

MUX protocol: disabled

Multiplexing mode is disabled by default and it can be enabled by the AT+CMUX
command. For more details, see the Mux Implementation Application Note [21].
The following virtual channels are defined:

Channel 0: control channel

Channel 1 – 5: AT commands / data connection
10

Channel 6: GNSS tunneling

9

Table 10: Default UART AT interface configuration

1.9.1.3 UART signal behavior
At the module switch-on, before the UART interface initialization (as described in the power-on sequence reported
in Figure 14), each pin is first tri-stated and then is set to its related internal reset state11. At the end of the boot
sequence, the UART interface is initialized, the module is by default in active mode, and the UART interface is
enabled as an AT commands interface.
The configuration and the behavior of the UART signals after the boot sequence are described below. See section
1.4 for the definition and description of the module operating modes referred to in this section.
RXD signal behavior
The module data output line (RXD) is set by default to the OFF state (high level) at UART initialization. The module
holds RXD in the OFF state until the module does not transmit any data.
TXD signal behavior
The module data input line (TXD) is set by default to the OFF state (high level) at UART initialization. The TXD line
is then held by the module in the OFF state if the line is not activated by the DTE: an active pull-up is enabled inside
the module on the TXD input.

9

See the u-blox AT Commands Manual [2] for the definition of the command mode, data mode, and online command mode
Not supported by LARA-R204-02B and LARA-R211-02B-00 product versions.
11
Refer to the pin description table in the LARA-R2 series Data Sheet [1].
10

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CTS signal behavior
The module hardware flow control output (CTS line) is set to the ON state (low level) at UART initialization.
If the hardware flow control is enabled, as it is by default, the CTS line indicates when the UART interface is
enabled (data can be sent and received). The module drives the CTS line to the ON state or to the OFF state when
it is either able or not able to accept data from the DTE over the UART (see 1.9.1.4 for more details).
If hardware flow control is enabled, then when the CTS line is OFF it does not necessarily mean that the
module is in low power idle mode, but only that the UART is not enabled, as the module could be forced
to stay in active mode for other activities, e.g. related to the network or related to other interfaces.
When the multiplexer protocol is active, the CTS line state is mapped to FCon / FCoff MUX command for
flow control issues outside the power saving configuration while the physical CTS line is still used as a power
state indicator. For more details, see Mux Implementation Application Note [21].
The CTS hardware flow control setting can be changed by using AT commands (for more details, see the u-blox
AT Commands Manual [2], AT&K, AT\Q, AT+IFC, AT+UCTS AT command).
When the power saving configuration is enabled by the AT+UPSV command and the hardware flow-control
is not implemented in the DTE/DCE connection, data sent by the DTE can be lost: the first character sent
when the module is in low power idle mode will not be a valid communication character (see section 1.9.1.4
and in particular the sub-section “Wake-up via data reception” for further details).
RTS signal behavior
The hardware flow control input (RTS line) is set by default to the OFF state (high level) at UART initialization. The
module then holds the RTS line in the OFF state if the line is not activated by the DTE: an active pull-up is enabled
inside the module on the RTS input.
If the HW flow control is enabled, as it is by default, the module monitors the RTS line to detect permission from
the DTE to send data to the DTE itself. If the RTS line is set to the OFF state, any on-going data transmission from
the module is interrupted until the subsequent RTS line changes to the ON state.
The DTE must still be able to accept a certain number of characters after the RTS line is set to the OFF state:
the module guarantees the transmission interruption within two characters from RTS state change.
Module behavior according to RTS hardware flow control status can be configured by using AT commands (for
more details, see the u-blox AT Commands Manual [2], AT&K, AT\Q, AT+IFC command descriptions).
If AT+UPSV=2 is set and HW flow control is disabled, the module monitors the RTS line to manage the power
saving configuration (for more details, see section 1.9.1.4 and the u-blox AT Commands Manual [2], AT+UPSV):


When an OFF-to-ON transition occurs on the RTS input, the UART is enabled and the module is forced to
active mode. After ~20 ms, the switch is completed and data can be received without loss. The module cannot
enter low power idle mode and the UART is enabled as long as the RTS is in the ON state.



If the RTS input line is set to the OFF state by the DTE, the UART is disabled (held in low power mode) and the
module automatically enters low power idle mode whenever possible.

DSR signal behavior
If AT&S1 is set, as it is by default, the DSR module output line is set by default to the OFF state (high level) at UART
initialization. The DSR line is then set to the OFF state when the module is in command mode12 or in online
command mode12 and is set to the ON state when the module is in data mode12.
If AT&S0 is set, the DSR module output line is set by default to the ON state (low level) at UART initialization and
is then always held in the ON state.

12

See the u-blox AT Commands Manual [2] for the definition of the command mode, data mode, and online command mode

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DTR signal behavior
The DTR module input line is set by default to the OFF state (high level) at UART initialization. The module then
holds the DTR line in the OFF state if the line is not activated by the DTE: an active pull-up is enabled inside the
module on the DTR input.
Module behavior according to DTR status can be changed by AT command (for more details, see the u-blox AT
Commands Manual [2], AT&D command description).
If AT+UPSV=3 is set, the DTR line is monitored by the module to manage the power saving configuration (for
more details, see section 1.9.1.4 and the u-blox AT Commands Manual [2], AT+UPSV command):


When an OFF-to-ON transition occurs on the DTR input, the UART is enabled and the module is forced to
active mode. After ~20 ms, the switch is completed and data can be received without loss. The module cannot
enter low power idle mode and the UART is enabled as long as the DTR is in the ON state



If the DTR input line is set to the OFF state by the DTE, the UART is disabled (held in low power mode) and
the module automatically enters low power idle mode whenever possible

DCD signal behavior
If AT&C1 is set, as it is by default, the DCD module output line is set by default to the OFF state (high level) at
UART initialization. The module then sets the DCD line according to the carrier detect status: ON if the carrier is
detected, OFF otherwise.
For voice calls, DCD is set to the ON state when the call is established.
For data calls, there are the following scenarios regarding the DCD signal behavior:


Packet Switched Data call: Before activating the PPP protocol (data mode) a dial-up application must provide
the ATD*99***# to the module: with this command the module switches from command
mode to data mode and can accept PPP packets. The module sets the DCD line to the ON state, then answers
with a CONNECT to confirm the ATD*99 command. The DCD ON is not related to the context activation but
with the data mode.



Circuit Switched Data call: To establish a data call, the DTE can send the ATD command to the
module which sets an outgoing data call to a remote modem (or another data module). Data can be
transparent (non reliable) or non transparent (with the reliable RLP protocol). When the remote DCE accepts
the data call, the module DCD line is set to ON and the CONNECT  string is
returned by the module. At this stage, the DTE can send characters through the serial line to the data module
which sends them through the network to the remote DCE attached to a remote DTE
The DCD is set to ON during the execution of the +CMGS, +CMGW, +USOWR, +USODL AT commands
requiring input data from the DTE: the DCD line is set to the ON state as soon as the switch to binary/text
input mode is completed and the prompt is issued; DCD line is set to OFF as soon as the input mode is
interrupted or completed (for more details see the u-blox AT Commands Manual [2]).
The DCD line is kept in the ON state, even during the online command mode13, to indicate that the data
call is still established even if suspended, while if the module enters command mode13, the DSR line is set
to the OFF state. For more details, see DSR signal behavior description.
For scenarios when the DCD line setting is requested for different reasons (e.g. SMS texting during online
command mode13), the DCD line changes to guarantee the correct behavior for all the scenarios. For
example, for SMS texting in online command mode13, if the data call is released, DCD is kept ON until the
SMS command execution is completed (even if the data call release would request DCD set OFF).

If AT&C0 is set, the DCD module output line is set by default to the ON state (low level) at UART initialization and
is then always held in the ON state.

13

See the u-blox AT Commands Manual [2] for the definition of the command mode, data mode, and online command mode

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RI signal behavior
The RI module output line is set by default to the OFF state (high level) at UART initialization. Then, during an
incoming call, the RI line is switched from the OFF state to the ON state with a 4:1 duty cycle and a 5 s period (ON
for 1 s, OFF for 4 s, see Figure 19), until the DTE attached to the module sends the ATA string and the module
accepts the incoming data call. The RING string sent by the module (DCE) to the serial port at constant time
intervals is not correlated with the switch of the RI line to the ON state.
1s
RI OFF

RI ON
0

5

10

15

time [s]

Call incomes

Figure 19: RI behavior during an incoming call

The RI line can notify an SMS arrival. When the SMS arrives, the RI line switches from OFF to ON for 1 s (see Figure
20), if the feature is enabled by the AT+CNMI command (see the u-blox AT Commands Manual [2]).
1s
RI OFF

RI ON
0

time [s]

SMS arrives

Figure 20: RI behavior at SMS arrival

This behavior allows the DTE to stay in power saving mode until the DCE related event requests service.
For SMS arrival, if several events occur coincidently or in quick succession, each event independently triggers the
RI line, although the line will not be deactivated between each event. As a result, the RI line may stay at ON for
more than 1 s.
If an incoming call is answered within less than 1 s (with ATA or if auto-answering is set to ATS0=1), then the RI
line is set to OFF earlier.
As a result:
RI line monitoring cannot be used by the DTE to determine the number of received SMSes.
For multiple events (incoming call plus SMS received), the RI line cannot be used to discriminate the two
events, but the DTE must rely on the subsequent URCs and interrogate the DCE with proper commands.
The RI line can additionally notify all the URCs and all the incoming data in PPP and Direct Link connections, if the
feature is enabled by the AT+URING command (for more details, see the u-blox AT Commands Manual [2]): the
RI line is asserted when one of the configured events occur and it remains asserted for 1 s unless another
configured event will happen, with the same behavior described in Figure 20.

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1.9.1.4 UART and power-saving
The power saving configuration is controlled by the AT+UPSV command (for the complete description, see the
u-blox AT Commands Manual [2]). When power saving is enabled, the module automatically enters low power
idle mode whenever possible, and otherwise the active mode is maintained by the module (see section 1.4 for the
definition and description of module operating modes referred to in this section).
The AT+UPSV command configures both the module power saving and also the UART behavior in relation to
power saving. The conditions for the module entering low power idle mode also depend on the UART power
saving configuration, as the module does not enter the low power idle mode according to any required activity
related to the network (within or outside an active call) or any other required concurrent activity related to the
functions and interfaces of the module, including the UART interface.
Three different power saving configurations can be set by the AT+UPSV command:


AT+UPSV=0, power saving disabled (default configuration)



AT+UPSV=1, power saving enabled cyclically



AT+UPSV=2, power saving enabled and controlled by the UART RTS input line



AT+UPSV=3, power saving enabled and controlled by the UART DTR input line

The various power saving configurations that can be set by the +UPSV AT command are described in detail in the
following subsections. Table 11 summarizes the UART interface communication process in the various power
saving configurations, in relation with HW flow control settings and RTS input line status. For more details on the
+UPSV AT command description, refer to the u-blox AT commands Manual [2].
AT+UPSV HW flow control

RTS line

DTR line

Communication during idle mode and wake up

0

Enabled (AT&K3)

ON

ON or OFF

Data sent by the DTE are correctly received by the module.
Data sent by the module is correctly received by the DTE.

0

Enabled (AT&K3)

OFF

ON or OFF

Data sent by the DTE are correctly received by the module.
Data sent by the module is buffered by the module and will be correctly
received by the DTE when it is ready to receive data (i.e. RTS line will be ON).

0

Disabled (AT&K0)

ON or OFF

ON or OFF

Data sent by the DTE is correctly received by the module.
Data sent by the module is correctly received by the DTE if it is ready to receive
data, otherwise data is lost.

1

Enabled (AT&K3)

ON

ON or OFF

Data sent by the DTE is buffered by the DTE and will be correctly received by
the module when it is ready to receive data (when UART is enabled).
Data sent by the module is correctly received by the DTE.

1

Enabled (AT&K3)

OFF

ON or OFF

Data sent by the DTE is buffered by the DTE and will be correctly received by
the module when it is ready to receive data (when UART is enabled).
Data sent by the module is buffered by the module and will be correctly
received by the DTE when it is ready to receive data (i.e. RTS line will be ON).

1

Disabled (AT&K0)

ON or OFF

ON or OFF

The first character sent by the DTE is lost by the module, but after ~20 ms the
UART and the module are woken up: recognition of subsequent characters is
guaranteed only after the UART / module complete wake-up (after ~20 ms).
Data sent by the module is correctly received by the DTE if it is ready to receive
data, otherwise the data is lost.

2

Enabled (AT&K3)

ON or OFF

ON or OFF

Not Applicable: HW flow control cannot be enabled with AT+UPSV=2.

2

Disabled (AT&K0)

ON

ON or OFF

Data sent by the DTE is correctly received by the module.
Data sent by the module is correctly received by the DTE if it is ready to receive
data, otherwise data is lost.

2

Disabled (AT&K0)

OFF

ON or OFF

Data sent by the DTE is lost by the module.
Data sent by the module is correctly received by the DTE if it is ready to receive
data, otherwise data is lost.

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AT+UPSV HW flow control

RTS line

DTR line

Communication during idle mode and wake up

3

Enabled (AT&K3)

ON

ON

Data sent by the DTE is correctly received by the module.
Data sent by the module is correctly received by the DTE.

3

Enabled (AT&K3)

ON

OFF

Data sent by the DTE is lost by the module.
Data sent by the module is correctly received by the DTE.

3

Enabled (AT&K3)

OFF

ON

Data sent by the DTE is correctly received by the module.
Data sent by the module is buffered by the module and will be correctly
received by the DTE when it is ready to receive data (i.e. RTS line will be ON).

3

Enabled (AT&K3)

OFF

OFF

Data sent by the DTE is lost by the module.
Data sent by the module is buffered by the module and will be correctly
received by the DTE when it is ready to receive data (i.e. RTS line will be ON).

3

Disabled (AT&K0)

ON or OFF

ON

Data sent by the DTE is correctly received by the module.
Data sent by the module is correctly received by the DTE if it is ready to receive
data, otherwise data are lost.

3

Disabled (AT&K0)

ON or OFF

OFF

Data sent by the DTE is lost by the module.
Data sent by the module is correctly received by the DTE if it is ready to receive
data, otherwise data are lost.

Table 11: UART and power-saving summary

AT+UPSV=0: power saving disabled, fixed active mode
The module does not enter low power idle mode and the UART interface is enabled (data can be sent and received):
the CTS line is always held in the ON state after UART initialization. This is the default configuration.
AT+UPSV=1: power saving enabled, cyclic idle/active mode
When the AT+UPSV=1 command is issued by the DTE, the UART will be normally disabled, and then periodically
or upon necessity enabled as following:


During the periodic UART wake-up to receive or send data, also according to the module wake up for the
paging reception (see section 1.5.1.5) or other activities



If the module needs to transmit some data (e.g. URC), the UART is temporarily enabled to send data



If the DTE sends data with HW flow control disabled, the first character sent causes the UART and module
wake-up after ~20 ms: recognition of subsequent characters is guaranteed only after the complete wake-up
(see the following subsection “wake up via data reception”)

The module automatically enters the low power idle mode whenever possible, but it wakes up to active mode
according to the UART periodic wake-up so that the module cyclically enters the low power idle mode and the
active mode. Additionally, the module wakes up to active mode according to any required activity related to the
network (e.g. for the periodic paging reception described in section 1.5.1.5, or for any other required RF Tx / Rx)
or any other required activity related to module functions / interfaces (including the UART itself).
The time period of the UART enable/disable cycle is configured differently when the module is registered with a
2G network compared to when the module is registered with a 3G or LTE network:


2G: UART is enabled synchronously with some paging receptions: UART is enabled concurrently to a paging
reception, and then, as data has not been received or sent, UART is disabled until the first paging reception
that occurs after a timeout of 2.0 s, and so the interface is then enabled again



3G or LTE: UART is asynchronously enabled to paging receptions, as UART is enabled for ~20 ms, and then, if
data are not received or sent, UART is disabled for 2.5 s, and afterwards the interface is enabled again



Not registered: when a module is not registered with a network, UART is enabled for ~20 ms, and then, if
data has not been received or sent, UART is disabled for 2.5 s, and afterwards the interface is enabled again

When the UART interface is enabled, data can be received. When a character is received, it forces the UART
interface to stay enabled for a longer time and it forces the module to stay in the active mode for a longer time,
according to the timeout configured by the second parameter of the +UPSV AT command. The timeout can be

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set from 40 2G-frames (i.e. 40 x 4.615 ms = 184 ms) up to 65,000 2G-frames (i.e. 65,000 x 4.615 ms = 300 s).
Default value is 2,000 2G-frames (i.e. 2,000 x 4.615 ms = 9.2 s). Every subsequent character received during the
active mode, resets and restarts the timer; hence the active mode duration can be extended indefinitely.
The CTS output line is driven to the ON or OFF state when the module is either able or not able to accept data
from the DTE over the UART: Figure 21 illustrates the CTS output line toggling due to paging reception and data
received over the UART, with the AT+UPSV=1 configuration.
Data input

CTS OFF

CTS ON

time [s]
~9.2 s (default)

Figure 21: CTS output pin indicates when the module’s UART is enabled (CTS = ON = low level) or disabled (CTS = OFF = high
level)

AT+UPSV=2: power saving enabled and controlled by the RTS line
This configuration can only be enabled with the module hardware flow control disabled (i.e. AT&K0 setting).
The UART interface is disabled after the DTE sets the RTS line to OFF.
Afterwards, the UART is enabled again, and the module does not enter low power idle mode, as following:


If an OFF-to-ON transition occurs on the RTS input, this causes the UART / module wake-up after ~20 ms:
recognition of subsequent characters is guaranteed only after the complete wake-up, and the UART is kept
enabled as long as the RTS input line is set to ON.



If the module needs to transmit some data (e.g. URC), the UART is temporarily enabled to send data

The module automatically enters the low power idle mode whenever possible but it wakes up to active mode
according to any required activity related to the network (e.g. for the periodic paging reception described in section
1.5.1.5, or for any other required RF transmission / reception) or any other required activity related to the module
functions / interfaces (including the UART itself).
AT+UPSV=3: power saving enabled and controlled by the DTR line
The UART interface is disabled after the DTE sets the DTR line to OFF.
Afterwards, the UART is enabled again, and the module does not enter low power idle mode, as following:


If an OFF-to-ON transition occurs on the DTR input, this causes the UART / module wake-up after ~20 ms:
recognition of subsequent characters is guaranteed only after the complete wake-up, and the UART is kept
enabled as long as the DTR input line is set to ON.



If the module needs to transmit some data (e.g. URC), the UART is temporarily enabled to send data.

The module automatically enters the low power idle mode whenever possible, but it wakes up to active mode
according to any required activity related to the network (e.g. for the periodic paging reception described in section
1.5.1.5, or for any other required RF signal transmission or reception) or any other required activity related to the
functions / interfaces of the module.
The AT+UPSV=3 configuration can be enabled regardless of the flow control setting on the UART. In particular,
the HW flow control can be enabled (AT&K3) or disabled (AT&K0) on the UART during this configuration. In both
cases, with the AT+UPSV=3 configuration, the CTS line indicates when the module is either able or not able to
accept data from the DTE over the UART.
When the AT+UPSV=3 configuration is enabled, the DTR input line can still be used by the DTE to control the
module behavior according to the AT&D command configuration (see the u-blox AT commands Manual [2]).
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Wake-up via data reception
The UART wake-up via data reception consists of a special configuration of the module TXD input line that causes
the system wake-up when a low-to-high transition occurs on the TXD input line. In particular, the UART is enabled
and the module switches from the low power idle mode to active mode within ~20 ms from the first character
received: this is the system “wake-up time”.
As a consequence, the first character sent by the DTE when the UART is disabled (i.e. the wake up character) is
not a valid communication character, even if the wake up via data reception configuration is active, because it
cannot be recognized, and the recognition of the subsequent characters is guaranteed only after the complete
system wake-up (i.e. after ~20 ms).
The UART wake-up via data reception configuration is active in the following cases:


AT+UPSV=1 is set with HW flow control disabled

Figure 22 and Figure 23 show examples of common scenarios and timing constraints:


AT+UPSV=1 power saving configuration is active and the timeout from last data received to idle mode start is
set to 2000 frames (AT+UPSV=1,2000)



Hardware flow control is disabled

Figure 22 shows the case where the UART module is disabled and only a wake-up is forced. In this scenario, the
only character sent by the DTE is the wake-up character; as a consequence, the DCE module UART is disabled
when the timeout from last data received expires (2000 frames without data reception, as the default case).
UART
DCE UART is enabled for 2000 GSM frames (~9.2 s)

OFF
ON

time

TXD input

Wake up time: ~20 ms

OFF
ON

Wake up character
Not recognized by DCE

time

Figure 22: Wake-up via data reception without further communication

Figure 23 shows the case where in addition to the wake-up character, further (valid) characters are sent. The wakeup character wakes up the UART module. The other characters must be sent after the “wake up time” of ~20 ms.
If this condition is satisfied, the module (DCE) recognizes characters. The module will disable the UART after 2000
GSM frames from the latest data reception.
UART

DCE UART is enabled for 2000 GSM frames (~9.2s)
after the last data received

OFF
ON

TXD input

Wake up time: ~20 ms

time

OFF
ON

Wake up character
Not recognized by DCE

Valid characters
Recognized by DCE

time

Figure 23: Wake-up via data reception with further communication

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The “wake-up via data reception” feature cannot be disabled.
In command mode14, with “wake-up via data reception” enabled and autobauding enabled, the DTE should
always send a dummy character to the module before the “AT” prefix set at the beginning of each
command line: the first dummy character is ignored if the module is in active mode, or it represents the
wake-up character if the module is in low power idle mode.
In command mode14, with “wake-up via data reception” enabled and autobauding disabled, the DTE should
always send a dummy “AT” to the module before each command line: the first dummy “AT” is not ignored
if the module is in active mode (i.e. the module replies “OK”), or it represents the wake-up character if the
module is in low power idle mode (i.e. the module does not reply).
Additional considerations
If the USB is connected and not suspended, the module is kept ready to communicate over USB regardless of the
AT+UPSV settings, which have effect instead on the UART behavior, as they configure the UART power saving, so
that UART is enabled / disabled according to the AT+UPSV settings.
To set the AT+UPSV=1, AT+UPSV=2 or AT+UPSV=3 configuration over the USB interface, the autobauding must
be previously disabled on the UART by the +IPR AT command over the used USB AT interface, and this +IPR AT
command configuration must be saved in the module’s non-volatile memory (see the u-blox AT Commands
Manual [2]). Then after the subsequent module re-boot, AT+UPSV=1, AT+UPSV=2 or AT+UPSV=3 can be issued
over the used AT interface (the USB): all the AT profiles are updated accordingly.

1.9.1.5 Multiplexer protocol (3GPP TS 27.010)
LARA-R2 series modules include multiplexer functionality on the UART physical link as per 3GPP TS 27.010 [8].
This is a data link protocol which uses HDLC-like framing and operates between the module (DCE) and the
application processor (DTE) and allows a number of simultaneous sessions over the used physical link (UART): the
user can concurrently use AT interface on one MUX channel and data communication on another MUX channel.
The following virtual channels are defined (for more details, see the Mux implementation Application Note [21]):


Channel 0: Multiplexer control



Channels 1 – 5: AT commands / data connection



Channel 6: GNSS data tunneling
GNSS data tunneling is not supported by LARA-R204-02B and LARA-R211-02B-00 product versions.

14

See the u-blox AT Commands Manual [2] for the definition of the command mode, data mode, and online command mode.

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1.9.2 USB interface
1.9.2.1 USB features
LARA-R2 series modules include a High-Speed USB 2.0 compliant interface with a 480 Mbit/s maximum data rate,
representing the main interface for transferring high speed data with a host application processor, supporting:


AT command mode15



Data mode and Online command mode15



FW upgrades by means of the FOAT feature (see 1.14.14 and the Firmware update application note [23])



FW upgrades by means of the u-blox EasyFlash tool (see the Firmware update application note [23])



Trace log capture (diagnostic purposes)

The module itself acts as a USB device and can be connected to a USB host such as a Personal Computer or an
embedded application microprocessor equipped with compatible drivers.
The USB_D+/USB_D- lines carry USB serial bus data and signaling according to the Universal Serial Bus Revision
2.0 specification [9], while the VUSB_DET input pin senses the VBUS USB supply presence (nominally 5 V at the
source) to detect the host connection and enable the interface.
The USB interface of the module is enabled only if a valid voltage is detected by the VUSB_DET input (see the
LARA-R2 series Data Sheet [1]). Neither the USB interface, nor the whole module is supplied by the VUSB_DET
input: the VUSB_DET senses the USB supply voltage and absorbs only a few microamperes.
The USB interface is controlled and operated with:


AT commands according to 3GPP TS 27.007 [6], 3GPP TS 27.005 [7]



u-blox AT commands (for the complete list and syntax, see the u-blox AT Commands Manual [2])

The USB interface of LARA-R2 series modules, according to the configured USB profile, can provide several USB
functions with various capabilities and purposes, such as:


CDC-ACM for AT commands and data communication



CDC-ACM for GNSS tunneling



CDC-ACM for SAP (SIM Access Profile)



CDC-ACM for Diagnostic logs



CDC-NCM for Ethernet-over-USB
CDC-ACM for GNSS tunneling is not supported by the LARA-R204-02B and LARA-R211-02B-00 product
versions
CDC-ACM for SAP and CDC-NCM for Ethernet-over-USB are not supported by the “02” and “62” versions
The RI virtual signal is not supported over USB CDC-ACM by the “02” and “62” product versions

The USB profile of LARA-R2 series modules identifies itself by its VID (Vendor ID) and PID (Product ID) combination,
included in the USB device descriptor according to the USB 2.0 specification [9].
If the USB is connected to the host before the module is switched on, or if the module is reset (rebooted) with the
USB connected to the host, the VID and PID are automatically updated during the boot of the module. First, VID
and PID are the following:


VID = 0x8087



PID = 0x0716

15

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This VID and PID combination identifies a USB profile where no USB function described above is available: AT
commands must not be sent to the module over the USB profile identified by this VID and PID combination.
Then, after a time period (which depends on the host / device enumeration timings), the VID and PID are updated
to the ones related to the default USB profile providing the following set of USB functions:


6 CDC-ACM modem COM ports enumerated as follows:
o USB1: AT and data
o USB2: AT and data
o USB3: AT and data
o USB4: GNSS tunneling
o USB5: SAP (SIM Access Profile)
o USB6: Primary Log (diagnostic purpose)
VID and PID of this USB profile with the set of functions described above (6 CDC-ACM) are the following:


VID = 0x1546

 PID = 0x110A
Figure 24 summarizes the USB endpoints available with the default USB profile.
Default profile configuration
Function AT and Data
Interface 0

Abstract Control Model
EndPoint

Transfer: Interrupt

EndPoint

Transfer: Bulk

EndPoint

Transfer: Bulk

Interface 1

Function AT and Data

Data

Interface 2

Abstract Control Model

EndPoint

Transfer: Interrupt

EndPoint

Transfer: Bulk

Interface 3

Data
EndPoint

Function AT and Data
Interface 4

EndPoint

Transfer: Interrupt

EndPoint

Transfer: Bulk

Interface 5

Data
EndPoint

Function GNSS tunneling
Interface 6

EndPoint

Transfer: Interrupt

EndPoint

Transfer: Bulk

EndPoint

Transfer: Bulk

Data

Interface 8

Abstract Control Model

EndPoint

Transfer: Interrupt

EndPoint

Transfer: Bulk

EndPoint

Transfer: Bulk

Interface 9

Function Primary Log

Transfer: Bulk
Abstract Control Model

Interface 7

Function SAP

Transfer: Bulk
Abstract Control Model

Data

Interface 10

Abstract Control Model
EndPoint

Transfer: Interrupt

EndPoint

Transfer: Bulk

EndPoint

Transfer: Bulk

Interface 11

Data

Figure 24: LARA-R2 series USB Endpoints summary for the default USB profile configuration

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1.9.2.2 USB in Windows
USB drivers are provided for Windows operating system platforms and should be properly installed / enabled by
following the step-by-step instructions available in the EVK-R2xx User Guide [3] or in the Windows Embedded OS
USB Driver Installation Application Note [4].
USB drivers are available for the following operating system platforms:


Windows 7



Windows 8



Windows 8.1



Windows 10



Windows Embedded CE 6.0



Windows Embedded Compact 7



Windows Embedded Compact 2013

 Windows 10 IoT
The module firmware can be upgraded over the USB interface by means of the FOAT feature, or using the u-blox
EasyFlash tool (for more details, see the Firmware Update Application Note [23].

1.9.2.3 USB in Linux/Android
It is not required to install a specific driver for each Linux-based or Android-based operating system (OS) to use the
USB module interface, which is compatible with standard Linux/Android USB kernel drivers.
The full capability and configuration of the USB module interface can be reported by running “lsusb –v” or an
equivalent command available in the host operating system when the module is connected.

1.9.2.4 USB and power saving
The modules automatically enter the USB suspended state when the device has observed no bus traffic for a
specific time period according to the USB 2.0 specifications [9]. In the suspended state, the module maintains any
USB internal status as device. In addition, the module enters the suspended state when the hub port it is attached
to is disabled. This is referred to as a USB selective suspend.
If the USB is suspended and a power saving configuration is enabled by the AT+UPSV command, the module
automatically enters the low power idle mode whenever possible, but it wakes up to active mode according to
any required activity related to the network (e.g. the periodic paging reception described in section 1.5.1.5) or any
other required activity related to the functions / interfaces of the module.
The USB exits suspend mode when there is bus activity. If the USB is connected and not suspended, the module is
kept ready to communicate over USB regardless of the AT+UPSV settings, therefore the AT+UPSV settings are
overruled but they do have effect on the power saving configuration of the other interfaces (see 1.9.1.4).
The modules are capable of USB remote wake-up signaling: i.e. it may request the host to exit suspend mode or
selective suspend by using electrical signaling to indicate remote wake-up, for example due to an incoming call,
URCs, data reception on a socket. The remote wake-up signaling notifies the host that it should resume from its
suspended mode, if necessary, and service the external event. Remote wake-up is accomplished using electrical
signaling described in the USB 2.0 specifications [9].
For the module current consumption description with power saving enabled and USB suspended, or with power
saving disabled and USB not suspended, see sections 1.5.1.5, 1.5.1.6 and the LARA-R2 series Data Sheet [1].
The additional VUSB_DET input pin available on the LARA-R2 series modules provides the complete bus detach
functionality: the modules disable the USB interface when a low logic level is sensed after a high-to-low logic level
transition on the VUSB_DET input pin. This allows a further reduction of the module current consumption, in
particular as compared to the USB suspended status during low-power idle mode with power saving enabled.

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1.9.3 HSIC interface
The HSIC interface is not supported by the “02” and “62” product versions except for diagnostic purposes.
1.9.3.1 HSIC features
LARA-R2 series modules include a USB High-Speed Inter-Chip compliant interface with a maximum 480 Mb/s data
rate according to the High-Speed Inter-Chip USB Electrical Specification Version 1.0 [10] and the USB Specification
Revision 2.0 [9]. The module itself acts as a device and can be connected to any compatible host.
The HSIC interface provides:


AT command mode16



Data mode and Online command mode16



FW upgrades by means of the FOAT feature (see 1.14.14 and the Firmware update application note [23])



FW upgrades by means of the u-blox EasyFlash tool (see the Firmware update application note [23])



Trace log capture (diagnostic purpose)

The HSIC interface consists of a bi-directional DDR data line (HSIC_DATA) for transmitting and receiving data
synchronously with the bi-directional strobe line (HSIC_STRB).
The modules also include the HOST_SELECT pin to select the module / host application processor configuration:
the pin is available to select, enable, connect, disconnect and subsequently re-connect the HSIC interface.
The USB interface is controlled and operated with:


AT commands according to 3GPP TS 27.007 [6], 3GPP TS 27.005 [7]



u-blox AT commands (for the complete list and syntax, see the u-blox AT Commands Manual [2])

16

See the u-blox AT Commands Manual [2] for the definition of the command mode, data mode, and online command mode.

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1.9.4 DDC (I2C) interface
Communication with u-blox GNSS receivers over the I2C bus compatible Display Data Channel interface,
AssistNow embedded GNSS positioning aiding, CellLocate® positioning through cellular info, and custom
functions over GPIOs for the integration with u-blox positioning chips / modules are not supported by the
LARA-R204-02B and LARA-R211-02B-00 product versions.
The SDA and SCL pins represent an I2C bus compatible Display Data Channel (DDC) interface available for


communication with u-blox GNSS chips / modules,

 communication with other external I2C devices as audio codecs.
The AT command interface is not available on the DDC (I2C) interface.
DDC (I2C) slave-mode operation is not supported: the LARA-R2 series module can act as the I2C master that can
communicate with more I2C slaves in accordance to the I2C bus specifications [11].
The DDC (I2C) interface pins of the module, serial data (SDA) and serial clock (SCL), are open drain outputs
conforming to the I2C bus specifications [11].
u-blox has implemented special features to ease the design effort required for the integration of a u-blox cellular
module with a u-blox GNSS receiver.
Combining a u-blox cellular module with a u-blox GNSS receiver allows designers to have full access to the
positioning receiver directly via the cellular module: it relays control messages to the GNSS receiver via a dedicated
DDC (I2C) interface. A second interface connected to the positioning receiver is not necessary: AT commands via
the UART or USB serial interface of the cellular module allow for full control of the GNSS receiver from any host
processor.
The modules feature embedded GNSS aiding, that is, a set of specific features developed by u-blox to enhance
GNSS performance, decreasing the Time-To-First-Fix (TTFF), thus allowing the calculation of the position in a shorter
time with higher accuracy.
These GNSS aiding types are available:


Local aiding



AssistNow Online



AssistNow Offline

 AssistNow Autonomous
The embedded GNSS aiding features can be used only if the DDC (I2C) interface of the cellular module is connected
to the u-blox GNSS receivers.
The cellular modules provide additional custom functions over GPIO pins to improve the integration with u-blox
positioning chips and modules. GPIO pins can handle:


GNSS receiver power-on/off: the “GNSS supply enable” function provided by GPIO2 improves the positioning
receiver power consumption. When the GNSS functionality is not required, the positioning receiver can be
completely switched off by the cellular module that is controlled by AT commands.



The wake-up from idle mode when the GNSS receiver is ready to send data: “GNSS Tx data ready” function
provided by GPIO3 improves the cellular module power consumption. When power saving is enabled in the
cellular module by the AT+UPSV command and the GNSS receiver does not send data by the DDC (I2C)
interface, the module automatically enters idle mode whenever possible. With the “GNSS Tx data ready”
function, the GNSS receiver can indicate to the cellular module that it is ready to send data by the DDC (I2C)
interface: the positioning receiver can wake up the cellular module if it is in idle mode, so the cellular module
does not lose the data sent by the GNSS receiver even if power saving is enabled.



The RTC synchronization signal to the GNSS receiver: “GNSS RTC sharing” function provided by GPIO4
improves GNSS receiver performance, decreasing the Time-To-First-Fix (TTFF), and thus allowing the calculation

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of the position in a shorter time with higher accuracy. When GPS local aiding is enabled, the cellular module
automatically uploads data such as position, time, ephemeris, almanac, health and ionospheric parameters
from the positioning receiver into its local memory, and restores this to the GNSS receiver at the next powerup of the positioning receiver.
The “GNSS RTC sharing” function is not supported by the “02” and “62” product versions.
For more details regarding the handling of the DDC (I2C) interface, the GNSS aiding features and the GNSS
related functions over GPIOs, see section 1.12, the u-blox AT Commands Manual [2] (AT+UGPS, AT+UGPRF,
AT+UGPIOC AT commands) and the GNSS Implementation Application Note [22].
“GNSS Tx data ready” and “GNSS RTC sharing” functions are not supported by all u-blox GNSS receivers
HW or ROM/FW versions. See the GNSS Implementation Application Note [22] or the Hardware Integration
Manual of the u-blox GNSS receivers for the supported features.
As an additional improvement for the GNSS receiver performance, the V_BCKP supply output of the cellular
modules can be connected to the V_BCKP supply input pin of u-blox positioning chips and modules to provide
the supply for the GNSS real time clock and backup RAM when the VCC supply of the cellular module is within its
operating range and the VCC supply of the GNSS receiver is disabled.
This enables the u-blox positioning receiver to recover from a power breakdown with either a hot start or a warm
start (depending on the duration of the GNSS receiver VCC outage) and to maintain the configuration settings
saved in the backup RAM.

1.9.5

SDIO interface
The Secure Digital Input Output interface is not supported by the “02” and “62” product versions.

LARA-R2 series modules include a 4-bit Secure Digital Input Output interface (SDIO_D0, SDIO_D1, SDIO_D2,
SDIO_D3, SDIO_CLK, SDIO_CMD) designed to communicate with an external u-blox short range Wi-Fi module:
the cellular module acts as an SDIO host controller which can communicate over the SDIO bus with a compatible
u-blox short range radio communication Wi-Fi module acting as an SDIO device.
The SDIO interface is the only interface of LARA-R2 series modules dedicated for communication between the
u-blox cellular module and the u-blox short range Wi-Fi module.
The AT command interface is not available on the SDIO interface of the LARA-R2 series modules.
Combining a u-blox cellular module with a u-blox short range communication module gives designers full access
to the Wi-Fi module directly via the cellular module, so that a second interface connected to the Wi-Fi module is
not necessary. AT commands via the AT interfaces of the cellular module allow for full control of the Wi-Fi module
from any host processor, because Wi-Fi control messages are relayed to the Wi-Fi module via the dedicated SDIO
interface.
u-blox has implemented special features in the cellular modules to ease the design effort for the integration of a
u-blox cellular module with a u-blox short range Wi-Fi module to provide router functionality.
Additional custom function over GPIO pins is designed to improve the integration with u-blox Wi-Fi modules:


Wi-Fi enable

Switch-on / switch-off the Wi-Fi

Wi-Fi enable function over GPIO is not supported by the “02” and “62” product versions.

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1.10 Audio interface
Audio is not supported by the LARA-R204-02B and LARA-R220-62B product versions.

1.10.1 Digital audio interface
LARA-R2 series modules include a 4-wire I2S digital audio interface (I2S_TXD data output, I2S_RXD data input,
I2S_CLK clock input/output, I2S_WA world alignment / synchronization signal input/output), which can be
configured by AT commands for digital audio communication with external digital audio devices as an audio codec
(for more details, see the u-blox AT Commands Manual [2], +UI2S AT command).
The I2S interface can be alternatively set in different modes by the  parameter of the AT+UI2S
command:


PCM mode (short synchronization signal): I2S word alignment signal is set high for 1 or 2 clock cycles for the
synchronization, and then is set low for 16 clock cycles according to the 17 or 18 clock cycle frame length.



Normal I2S mode (long synchronization signal): the I2S word alignment is set high / low with a 50% duty cycle
(high for 16 clock cycles / low for 16 clock cycles, according to the 32 clock cycle frame length).

The I2S interface can be alternatively set in different roles by the  parameter of AT+UI2S:


Master mode



Slave mode

The sample rate of transmitted/received words, which corresponds to the I2S word alignment / synchronization
signal frequency, can be alternatively set by the  parameter of AT+UI2S to:


8 kHz



11.025 kHz



12 kHz



16 kHz



22.05 kHz



24 kHz



32 kHz



44.1 kHz



48 kHz

The modules support I2S transmit and I2S receive data 16-bit words long, linear, mono (or also dual mono in Normal
I2S mode). Data is transmitted and read in 2’s complement notation. MSB is transmitted and read first.
I2S clock signal frequency depends on the frame length, the sample rate and the selected mode of operation:


17 x  or 18 x  in PCM mode (short synchronization signal)



16 x 2 x  in normal I2S mode (long synchronization signal)
For the complete description of the possible configurations and settings of the I2S digital audio interface for
PCM and Normal I2S modes, refer to the u-blox AT Commands Manual [2], +UI2S AT command.

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1.11 Clock output
LARA-R2 series modules provide the master digital clock output function on the GPIO6 pin, which can be
configured to provide a 13 MHz or 26 MHz square wave. This is mainly designed to feed the master clock input
of an external audio codec, as the clock output can be configured in “Audio dependent” mode (generating the
square wave only when the audio path is active), or in “Continuous” mode.
For more details, see the u-blox AT Commands Manual [2], +UMCLK AT command.

1.12 General Purpose Input/Output (GPIO)
LARA-R2 series modules include 9 pins (GPIO1-GPIO5, I2S_TXD, I2S_RXD, I2S_CLK, I2S_WA) which can be
configured as General Purpose Input/Output or to provide custom functions via u-blox AT commands (for more
details, see the u-blox AT Commands Manual [2], +UGPIOC, +UGPIOR, +UGPIOW AT commands), as summarized
in Table 12.
Function

Description

Default GPIO

Configurable GPIOs

Network status
indication

Network status: registered home network, registered
roaming, data transmission, no service

--

GPIO1-GPIO4

Enable/disable the supply of u-blox GNSS receiver
connected to the cellular module

GPIO2

GPIO1-GPIO4

Sense when u-blox GNSS receiver connected to the
2
module is ready for sending data by the DDC (I C)

GPIO3

GPIO3

RTC synchronization signal to the u-blox GNSS receiver
connected to the cellular module

--

GPIO4

SIM card detection

External SIM card physical presence detection

GPIO5

GPIO5

SIM card hot
insertion/removal

Enable / disable SIM interface upon detection of external
SIM card physical insertion / removal

--

GPIO5

I S digital audio interface

I2S_RXD, I2S_TXD,
I2S_CLK, I2S_WA

I2S_RXD, I2S_TXD,
I2S_CLK, I2S_WA

Control of an external Wi-Fi chip or module

--

--

General purpose input

Input to sense high or low digital level

--

All

General purpose output

Output to set the high or the low digital level

GPIO4

All

Pin disabled

Tri-state with an internal active pull-down enabled

GPIO1

All

GNSS supply enable
GNSS data ready

17

17

GNSS RTC sharing

18

2

I S digital audio
interface
Wi-Fi control

18

2

Table 12: LARA-R2 series GPIO custom functions configuration

1.13 Reserved pins (RSVD)
LARA-R2 series modules have pins reserved for future use, named RSVD: they can all be left unconnected on the
application board, except


17
18

the RSVD pin number 33 that must be externally connected to ground

Not supported by the LARA-R204-02B and LARA-R211-02B-00 product versions: GPIO2 and GPIO3 pins are by default disabled
Not supported by the “02” and “62” product versions

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1.14 System features
1.14.1 Network indication
GPIOs can be configured by the AT command to indicate network status (for further details, see section 1.12 and
the u-blox AT Commands Manual [2], GPIO commands):


No service (no network coverage or not registered)



Registered 2G / 3G / LTE home network



Registered 2G / 3G / LTE visitor network (roaming)



Call enabled (RF data transmission / reception)

1.14.2 Antenna detection
The antenna detection function provided by the ANT_DET pin is based on an ADC measurement as an optional
feature that can be implemented if the application requires it. The antenna supervisor is forced by the +UANTR AT
command (see the u-blox AT Commands Manual [2] for more details).
The requirements to achieve antenna detection functionality are the following:


an RF antenna assembly with a built-in resistor (diagnostic circuit) must be used

 an antenna detection circuit must be implemented on the application board
See section 1.7.2 for detailed antenna detection interface functional description and see section 2.4.2 for detection
circuit on the application board and diagnostic circuit on antenna assembly design-in guidelines.

1.14.3 Jamming detection
Congestion detection (i.e. jamming detection) is not supported by the “02” and “62” product versions.
In real network situations, modules can experience various kind of out-of-coverage conditions: limited service
conditions when roaming to networks not supporting the specific SIM, limited service in cells which are not suitable
or barred due to operators’ choices, or no cell condition when moving to poorly served or highly interfered areas.
In the latter case, interference can be artificially injected in the environment by a noise generator covering a given
spectrum, thus obscuring the operator’s carriers entitled to give access to the LTE/3G/2G service.
The congestion (i.e. jamming) detection feature can be enabled and configured by the +UCD AT command: the
feature consists of detecting an anomalous source of interference and signaling the start and stop of such
conditions to the host application processor with an unsolicited indication, which can react appropriately by e.g.
switching off the radio transceiver of the module (i.e. configuring the module in “airplane mode” by means of the
+CFUN AT command) in order to reduce power consumption and monitoring the environment at constant periods
(for more details, see the u-blox AT Commands Manual [2], +UCD AT command).

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1.14.4 Dual stack IPv4/IPv6
LARA-R2 series support both Internet Protocol version 4 and Internet Protocol version 6 in parallel.
For more details about dual stack IPv4/IPv6, see the u-blox AT Commands Manual [2].

1.14.5 PPP
LARA-R2 series support a Point-to-Point Protocol in order to establish a connnection with the external application
via a serial interface (UART, MUX, or CDC-ACM): IPv4/IPv6 packets are relayed through the cellular protocol stack
with the external application.

1.14.6 TCP/IP and UDP/IP
LARA-R2 series modules provide an embedded TCP/IP and UDP/IP protocol stack: a PDP context can be configured,
established and handled via the data connection management packet switched data commands.
LARA-R2 series modules provide a Direct Link mode to establish a transparent end-to-end communication with an
already connected TCP or UDP socket via serial interfaces. In Direct Link mode, data sent to the serial interface
from an external application processor is forwarded to the network and vice-versa.
For more details about embedded TCP/IP and UDP/IP functionalities, see the u-blox AT Commands Manual [2]

1.14.7 FTP
LARA-R2 series provide embedded File Transfer Protocol (FTP) services. Files are read and stored in the local file
system of the module.
FTP files can also be transferred using FTP Direct Link:


FTP download: data coming from the FTP server is forwarded to the host processor via serial interfaces (for
FTP without Direct Link mode the data is always stored in the module’s Flash File System)



FTP upload: data coming from the host processor via serial interfaces is forwarded to the FTP server (for FTP
without Direct Link mode the data is read from the module’s Flash File System)
When Direct Link is used for a FTP file transfer, only the file content pass through USB / UART serial interface,
whereas all the FTP commands handling is managed internally by the FTP application.
For more details about embedded FTP functionalities, see the u-blox AT Commands Manual [2].

1.14.8 HTTP
LARA-R2 series modules provide the embedded Hyper-Text Transfer Protocol (HTTP) services via AT commands for
sending requests to a remote HTTP server, receiving the server response and transparently storing it in the module’s
Flash File System (FFS).
For more details about embedded HTTP functionalities, see the u-blox AT Commands Manual [2].

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1.14.9 SSL/TLS
LARA-R2 series modules support the Secure Sockets Layer (SSL) / Transport Layer Security (TLS) with certificate key
sizes up to 4096 bits to provide security over the FTP and HTTP protocols.
The SSL/TLS support provides different connection security aspects:


Server authentication: use of the server certificate verification against a specific trusted certificate or a trusted
certificates list



Client authentication: use of the client certificate and the corresponding private key

 Data security and integrity: data encryption and Hash Message Authentication Code (HMAC) generation
The security aspects used during a connection depend on the SSL/TLS configuration and features supported.
Table 13 contains the settings of the default SSL/TLS profile and Table 14 to Table 18 report the main SSL/TLS
supported capabilities of the products. For a complete list of supported configurations and settings, see the u-blox
AT Commands Manual [2].
Settings

Value

Meaning

Certificates validation level

Level 0

The server certificate will not be checked or verified

Minimum SSL/TLS version

Any

The server can use any of the TLS1.0/TLS1.1/TLS1.2 versions for the
connection

Cipher suite

Automatic

The cipher suite will be negotiated in the handshake process

Trusted root certificate internal name

None

No certificate will be used for the server authentication

Expected server host-name

None

No server host-name is expected

Client certificate internal name

None

No client certificate will be used

Client private key internal name

None

No client private key will be used

Client private key password

None

No client private key password will be used

Pre-shared key

None

No pre-shared key password will be used

Table 13: Default SSL/TLS profile

SSL/TLS Version
SSL 2.0

NO

SSL 3.0

YES

TLS 1.0

YES

TLS 1.1

YES

TLS 1.2

YES

Table 14: SSL/TLS version support
Algorithm
RSA

YES

PSK

YES

Table 15: Authentication

Algorithm
RC4

NO

DES

YES

3DES

YES

AES128

YES

AES256

YES

Table 16: Encryption

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Algorithm
MD5

NO

SHA/SHA1

YES

SHA256

YES

SHA384

YES

Table 17: Message digest

Description

Registry value

TLS_RSA_WITH_AES_128_CBC_SHA

0x00,0x2F

YES

TLS_RSA_WITH_AES_128_CBC_SHA256

0x00,0x3C

YES

TLS_RSA_WITH_AES_256_CBC_SHA

0x00,0x35

YES

TLS_RSA_WITH_AES_256_CBC_SHA256

0x00,0x3D

YES

TLS_RSA_WITH_3DES_EDE_CBC_SHA

0x00,0x0A

YES

TLS_RSA_WITH_RC4_128_MD5

0x00,0x04

NO

TLS_RSA_WITH_RC4_128_SHA

0x00,0x05

NO

TLS_PSK_WITH_AES_128_CBC_SHA

0x00,0x8C

YES

TLS_PSK_WITH_AES_256_CBC_SHA

0x00,0x8D

YES

TLS_PSK_WITH_3DES_EDE_CBC_SHA

0x00,0x8B

YES

TLS_RSA_PSK_WITH_AES_128_CBC_SHA

0x00,0x94

YES

TLS_RSA_PSK_WITH_AES_256_CBC_SHA

0x00,0x95

YES

TLS_RSA_PSK_WITH_3DES_EDE_CBC_SHA

0x00,0x93

YES

TLS_PSK_WITH_AES_128_CBC_SHA256

0x00,0xAE

YES

TLS_PSK_WITH_AES_256_CBC_SHA384

0x00,0xAF

YES

TLS_RSA_PSK_WITH_AES_128_CBC_SHA256

0x00,0xB6

YES

TLS_RSA_PSK_WITH_AES_256_CBC_SHA384

0x00,0xB7

YES

Table 18: TLS cipher suite registry

1.14.10 Bearer Independent Protocol
The Bearer Independent Protocol (BIP) is a mechanism by which a cellular module provides a SIM with access to
the data bearers supported by the network. With the BIP for Over-the-Air SIM provisioning, the data transfer from
and to the SIM uses either an already active PDP context or a new PDP context established with the APN provided
by the SIM card. For more details, see the u-blox AT Commands Manual [2].

1.14.11 AssistNow clients and GNSS integration
AssistNow clients and u-blox GNSS receiver integration are not supported by the LARA-R204-02B and
LARA-R211-02B-00 product versions.
For customers using u-blox GNSS receivers, the LARA-R2 series cellular modules feature embedded AssistNow
clients. AssistNow A-GPS provides better GNSS performance and faster Time-To-First-Fix. The clients can be
enabled and disabled with an AT command (see the u-blox AT Commands Manual [2]).
LARA-R2 series cellular modules act as a stand-alone AssistNow client, making AssistNow available with no
additional requirements for resources or software integration on an external host micro controller. Full access to
u-blox positioning receivers is available via the cellular modules, through a dedicated DDC (I2C) interface, while the
available GPIOs can handle the positioning chipset / module power-on/off. This means that the cellular module
and the GNSS receiver can be controlled through a single serial port from any host processor.

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1.14.12 Hybrid positioning and CellLocate®
Hybrid positioning and CellLocate® are not supported by LARA-R204-02B and LARA-R211-02B-00 product
versions.
Although GNSS is a widespread technology, its reliance on the visibility of extremely weak GNSS satellite signals
means that positioning is not always possible. Especially difficult environments for GNSS are indoors, in enclosed
or underground parking garages, as well as in urban canyons where GNSS signals are blocked or jammed by
multipath interference. The situation can be improved by augmenting GNSS receiver data with cellular network
information to provide positioning information even when GNSS reception is degraded or absent. This additional
information can benefit numerous applications.
Positioning through cellular information: CellLocate®
u-blox CellLocate® enables the device position estimation based on the parameters of the mobile network cells
visible to the specific device. To estimate its position, the u-blox cellular module sends the CellLocate® server the
parameters of network cells visible to it using a UDP connection. In return, the server provides the estimated
position based on the CellLocate® database. The module can either send the parameters of the visible home
network cells only (normal scan) or the parameters of all surrounding cells of all mobile operators (deep scan).
The deep scan is not supported by the “02” product versions.
The CellLocate® database is compiled from the position of devices which observed, in the past, a specific cell or
set of cells (historical observations) as follows:
1. Several devices reported their position to the CellLocate® server when observing a specific cell (the As in the
picture represent the position of the devices which observed the same cell A)

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2. CellLocate® server defines the area of Cell A visibility

3. If a new device reports the observation of Cell A, CellLocate® is able to provide the estimated position from
the area of visibility.

4. The visibility of multiple cells provides increased accuracy based on the intersection of areas of visibility.

CellLocate® is implemented using a set of two AT commands that allow configuration of the CellLocate® service
(AT+ULOCCELL) and requesting position according to the user configuration (AT+ULOC). The answer is provided
in the form of an unsolicited AT command including latitude, longitude and estimated accuracy.
The accuracy of the position estimated by CellLocate® depends on the availability of historical observations
in the specific area.

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Hybrid positioning
With u-blox hybrid positioning technology, u-blox cellular modules can be triggered to provide their current
position using either a u-blox GNSS receiver or the position estimated from CellLocate®. The choice depends on
which positioning method provides the best and fastest solution according to the user configuration, exploiting
the benefit of having multiple and complementary positioning methods.
Hybrid positioning is implemented through a set of three AT commands that allow GNSS receiver configuration
(AT+ULOCGNSS), CellLocate® service configuration (AT+ULOCCELL), and requesting the position according to the
user configuration (AT+ULOC). The answer is provided in the form of an unsolicited AT command including
latitude, longitude and estimated accuracy (if the position has been estimated by CellLocate®), and additional
parameters if the position has been computed by the GNSS receiver.
The configuration of mobile network cells does not remain static (e.g. new cells are continuously added or existing
cells are reconfigured by the network operators). For this reason, when a hybrid positioning method has been
triggered and the GNSS receiver calculates the position, a database self-learning mechanism has been
implemented so that these positions are sent to the server to update the database and maintain its accuracy.
The use of hybrid positioning requires a connection via the DDC (I2C) bus between the cellular modules and the ublox GNSS receiver (see section 2.6.4).
See the GNSS Implementation Application Note [22] for a complete description of the feature.
u-blox is extremely mindful of user privacy. When a position is sent to the CellLocate® server, u-blox is unable
to track the SIM used or the specific device.

1.14.13 Wi-Fi integration
Integration of u-blox short range communication Wi-Fi modules is not supported by the “02” and “62”
product versions.
Full access to u-blox short range communication Wi-Fi modules is available through a dedicated SDIO interface
(see sections 1.9.5 and 2.6.5). This means that combining a LARA-R2 series cellular module with a u-blox short
range communication module gives designers full access to the Wi-Fi module directly via the cellular module, so
that a second interface connected to the Wi-Fi module is not necessary.
AT commands via the AT interfaces of the cellular module (UART, USB) allows a full control of the Wi-Fi module
from any host processor, because Wi-Fi control messages are relayed to the Wi-Fi module via the dedicated SDIO
interface.
All the management software for Wi-Fi module operations runs inside the cellular module in addition to those
required for cellular-only operation.

1.14.14 Firmware upgrade Over AT (FOAT)
This feature allows upgrading the module firmware over the USB / UART serial interfaces, using AT commands.


The +UFWUPD AT command triggers a reboot followed by the upgrade procedure at a specified baud rate.



A special boot loader on the module performs firmware installation, security verifications and module reboot.



Firmware authenticity verification is performed via a security signature during the download. The firmware is
then installed, overwriting the current version. In the event of a power loss during this phase, the boot loader
detects a fault at the next wake-up, and restarts the firmware download. After completing the upgrade, the
module is reset again and wakes-up in normal boot.
For more details about the Firmware update Over AT procedure, see the Firmware Update Application Note [23]
and the u-blox AT Commands Manual [2], +UFWUPD AT command.

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1.14.15 Firmware update Over The Air (FOTA)
This feature allows upgrading the module firmware over the LTE/3G/2G air interface.
In order to reduce the amount of data to be transmitted over the air, the implemented FOTA feature requires
downloading only a “delta file” instead of the full firmware. The delta file contains only the differences between
the two firmware versions (old and new), and is compressed. The firmware update procedure can be triggered
using a dedicated AT command with the delta file stored in the module file system via over the air FTP.
For more details about the Firmware update Over The Air procedure, see the Firmware Update Application
Note [23] and the u-blox AT Commands Manual [2], +UFWINSTALL AT command.

1.14.16 Smart temperature management
Cellular modules – independently from the specific model – always have a well-defined operating temperature
range. This range should be respected to guarantee full device functionality and long life span.
Nevertheless, there are environmental conditions that can affect the operating temperature, e.g. if the device is
located near a heating/cooling source, if there is/is not air circulating, etc.
The module itself can also influence the environmental conditions; such as when it is transmitting at full power. In
this case, its temperature increases very quickly and can raise the temperature nearby.
The best solution is always to properly design the system where the module is integrated. Nevertheless an extra
check/security mechanism embedded into the module is a good solution to prevent operation of the device outside
of the specified range.
Smart Temperature Supervisor (STS)
The Smart Temperature Supervisor is activated and configured by a dedicated AT+USTS command. See the u-blox
AT Commands Manual [2] for more details. An URC indication is provided once the feature is enabled and at the
module power-on.
The cellular module measures the internal temperature (Ti) and its value is compared with predefined thresholds
to identify the actual working temperature range.
Temperature measurement is done inside the module: the measured value could be different from the
environmental temperature (Ta).

Valid temperature range

Dangerous
area

Warning
area

t-2

Safe
area

t-1

Warning
area

t+1

Dangerous
area

t+2

Figure 25: Temperature range and limits

The entire temperature range is divided into sub-regions by limits (see Figure 25) named t-2, t-1, t+1 and t+2.


Within the first limit, (t-1 < Ti < t+1), the cellular module is in the normal working range, the Safe Area.



In the Warning Area, (t-2 < Ti < t.1) or (t+1 < Ti < t+2), the cellular module is still inside the valid temperature
range, but the measured temperature is approaching the limit (upper or lower). The module sends a warning
to the user (through the active AT communication interface), who can take, if possible, the necessary actions
to return to a safer temperature range or simply ignore the indication. The module is still in a valid and good
working condition.

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

Outside the valid temperature range, (Ti < t-2) or (Ti > t+2), the device is working outside the specified range
and represents a dangerous working condition. This condition is indicated and the device shuts down to avoid
damage.
For security reasons, the shutdown is suspended whenever an emergency call is in progress. In this case,
the device switches off upon call termination.
The user can decide at anytime to enable/disable the Smart Temperature Supervisor feature. If the feature
is disabled, there is no embedded protection against disallowed temperature conditions.

Figure 26 shows the flow diagram implemented for the Smart Temperature Supervisor.
No

IF STS
enabled

Feature disabled:
no action

Yes

Feature enabled
(full logic or
indication only)

Read
temperature

Yes

IF
(t-1 5V?

No, less than 5 V

Yes, greater than 5 V

Linear LDO
Regulator

Switching Step-Down
Regulator

Figure 27: VCC supply concept selection

The DC/DC switching step-down regulator is the typical choice when the available primary supply source has a
nominal voltage much higher (e.g. greater than 5 V) than the modules VCC operating supply voltage. The use of
switching step-down provides the best power efficiency for the overall application and minimizes current drawn
from the main supply source. See sections 2.2.1.2 and 2.2.1.6, 0, 2.2.1.12 for the specific design-in.
The use of an LDO linear regulator becomes convenient for a primary supply with a relatively low voltage (e.g. less
than 5 V). In this case the typical 90% efficiency of the switching regulator diminishes the benefit of voltage stepdown and no true advantage is gained in input current savings. On the opposite side, linear regulators are not
recommended for high voltage step-down as they dissipate a considerable amount of energy in thermal power.
See sections 2.2.1.3 and 2.2.1.6, 0, 2.2.1.12 for the specific design-in.
If LARA-R2 series modules are deployed in a mobile unit where no permanent primary supply source is available,
then a battery will be required to provide VCC. A standard 3-cell Li-Ion or Li-Pol battery pack directly connected to
VCC is the usual choice for battery-powered devices. During charging, batteries with Ni-MH chemistry typically
reach a maximum voltage that is above the maximum rating for VCC, and should therefore be avoided. See
sections 2.2.1.4, 2.2.1.6, 2.2.1.7, 0, 2.2.1.12 for the specific design-in.
Keep in mind that the use of rechargeable batteries requires the implementation of a suitable charger circuit which
is not included in the modules. The charger circuit must be designed to prevent over-voltage on the VCC pins, and
it should be selected according to the application requirements: a DC/DC switching charger is the typical choice
when the charging source has an high nominal voltage (e.g. ~12 V), whereas a linear charger is the typical choice
when the charging source has a relatively low nominal voltage (~5 V). If both a permanent primary supply /

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charging source (e.g. ~12 V) and a rechargeable back-up battery (e.g. 3.7 V Li-Pol) are available at the same time
as a possible supply source, then a proper charger / regulator with integrated power path management function
can be selected to supply the module while simultaneously and independently charging the battery. See sections
2.2.1.8, 2.2.1.9, and 2.2.1.4, 2.2.1.6, 2.2.1.7, 0, 2.2.1.12 for the specific design-in.
An appropriate primary (not rechargeable) battery can be selected taking into account the maximum current
specified in the LARA-R2 series Data Sheet [1] during connected mode, considering that primary cells might have
weak power capability. See sections 2.2.1.5, 2.2.1.6, 0, and 2.2.1.12 for the specific design-in.
The usage of more than one DC supply at the same time should be carefully evaluated: depending on the supply
source characteristics, different DC supply systems can turn out as being mutually exclusive.
The usage of a regulator or a battery not able to support the highest peak of VCC current consumption specified
in the LARA-R2 series Data Sheet [1] is generally not recommended. However, if the selected regulator or battery
is not able to support the highest peak current of the module, it must be able to support at least the highest
averaged current consumption value specified in the LARA-R2 series Data Sheet [1] with an adequate margin. The
additional energy required by the module during a 2G Tx slot can be provided by an appropriate bypass tank
capacitor or super-capacitor with very large capacitance and very low ESR placed close to the module VCC pins.
Depending on the actual capability of the selected regulator or battery, the required capacitance can be
considerably larger than 1 mF and the required ESR can be in the range of few tens of m. Carefully evaluate the
super-capacitor characteristics, since aging and temperature may affect the actual characteristics.
The following sections highlight some design aspects for each of the supplies listed above, providing application
circuit design-in compliant with the module VCC requirements summarized in Table 6.

2.2.1.2 Guidelines for VCC supply circuit design using a switching regulator
The use of a switching regulator is suggested when the difference from the available supply rail to the VCC value
is high: switching regulators provide good efficiency transforming a 12 V or greater voltage supply to the typical
3.8 V value of the VCC supply.
The characteristics of the switching regulator connected to the VCC pins should meet the following prerequisites
to comply with the module’s VCC requirements summarized in Table 6:


Power capability: the switching regulator with its output circuit must be capable of providing a voltage value
to the VCC pins within the specified operating range and must be capable of delivering to the VCC pins the
specified maximum peak / pulse current consumption during Tx burst at the maximum Tx power specified in
the LARA-R2 series Data Sheet [1]



Low output ripple: the switching regulator together with its output circuit must be capable of providing a
clean (low noise) VCC voltage profile.



High switching frequency: for best performance and for smaller applications, it is recommended to select
a switching frequency ≥ 600 kHz (since the L-C output filter is typically smaller for high switching frequencies).
The use of a switching regulator with a variable switching frequency or with a switching frequency lower than
600 kHz must be evaluated carefully, since this can produce noise in the VCC voltage profile and therefore
negatively impact modulation spectrum performance.



PWM mode operation: it is preferable to select regulators with a Pulse Width Modulation (PWM) mode.
While in connected mode, the Pulse Frequency Modulation (PFM) mode and PFM/PWM modes transitions
must be avoided in order to reduce noise on the VCC voltage profile. Switching regulators can be used that
are able to switch between low ripple PWM mode and high ripple PFM mode, provided that the mode
transition occurs when the module changes status from the idle/active modes to connected mode. It is
permissible to use a regulator that switches from the PWM mode to the burst or PFM mode at an appropriate
current threshold.



Output voltage slope: the use of the soft start function provided by some voltage regulators should be
evaluated carefully, as the VCC voltage must ramp from 2.3 V to 2.8 V in less than 4 ms to switch on the
module by applying the VCC supply. The module can be otherwise switched on by forcing a low level on the
RESET_N pin during the VCC rising edge and then releasing the RESET_N pin when the VCC supply voltage
stabilizes at its proper nominal value.

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Figure 28 and the components listed in Table 20 show an example of a high reliability power supply circuit, where
the VCC module is supplied by a step-down switching regulator capable of delivering the specified maximum peak
/ pulse current to the VCC pins, with low output ripple and with fixed switching frequency in PWM mode operation
greater than 1 MHz.
12V

LARA-R2 series
4
VIN

5 RUN

R1

R2
C1

C2

C3 C4

9 VC

BOOST 2

3

6
C5

SW

VCC
VCC
53 VCC
51

1

10 RT
7 PG

R3

BD

52
C6
L1
D1

U1

R4

C7

C8

FB 8

SYNC

GND
11

R5

GND

Figure 28: Example of high reliability VCC supply application circuit using a step-down regulator
Reference

Description

Part Number - Manufacturer

C1

10 µF Capacitor Ceramic X7R 5750 15% 50 V

C5750X7R1H106MB - TDK

C2

10 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71C103KA01 - Murata

C3

680 pF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71H681KA01 - Murata

C4

22 pF Capacitor Ceramic C0G 0402 5% 25 V

GRM1555C1H220JZ01 - Murata

C5

10 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71C103KA01 - Murata

C6

470 nF Capacitor Ceramic X7R 0603 10% 25 V

GRM188R71E474KA12 - Murata

C7

22 µF Capacitor Ceramic X5R 1210 10% 25 V

GRM32ER61E226KE15 - Murata

C8

330 µF Capacitor Tantalum D_SIZE 6.3 V 45 m

T520D337M006ATE045 - KEMET

D1

Schottky Diode 40 V 3 A

MBRA340T3G - ON Semiconductor

L1

10 µH Inductor 744066100 30% 3.6 A

744066100 - Wurth Electronics

R1

470 k Resistor 0402 5% 0.1 W

2322-705-87474-L - Yageo

R2

15 k Resistor 0402 5% 0.1 W

2322-705-87153-L - Yageo

R3

22 k Resistor 0402 5% 0.1 W

2322-705-87223-L - Yageo

R4

390 k Resistor 0402 1% 0.063 W

RC0402FR-07390KL - Yageo

R5

100 k Resistor 0402 5% 0.1 W

2322-705-70104-L - Yageo

U1

Step-Down Regulator MSOP10 3.5 A 2.4 MHz

LT3972IMSE#PBF - Linear Technology

Table 20: Components for high reliability VCC supply application circuit circuit using a step-down regulator

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Figure 29 and the components listed in Table 21 show an example of a low cost power supply circuit, where the
VCC module supply is provided by a step-down switching regulator capable of delivering the specified maximum
peak / pulse current to the VCC pins, transforming a 12 V supply input.

12V

LARA-R2 series
8
VCC
OUT 1

3 INH

L1
D1

C1

6 FSW

C6
R5

U1

2 SYNC

R1

R3
C3

FB 5
COMP 4

51 VCC
52 VCC
53 VCC

C4

R4

GND
7

C2
R2

GND

C5

Figure 29: Example of low cost VCC supply application circuit using step-down regulator
Reference

Description

Part Number - Manufacturer

C1

22 µF Capacitor Ceramic X5R 1210 10% 25 V

GRM32ER61E226KE15 – Murata

C2

100 µF Capacitor Tantalum B_SIZE 20% 6.3V 15m

T520B107M006ATE015 – Kemet

C3

5.6 nF Capacitor Ceramic X7R 0402 10% 50 V

GRM155R71H562KA88 – Murata

C4

6.8 nF Capacitor Ceramic X7R 0402 10% 50 V

GRM155R71H682KA88 – Murata

C5

56 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H560JA01 – Murata

C6

220 nF Capacitor Ceramic X7R 0603 10% 25 V

GRM188R71E224KA88 – Murata

D1

Schottky Diode 25V 2 A

STPS2L25 – STMicroelectronics

L1

5.2 µH Inductor 30% 5.28A 22 m

MSS1038-522NL – Coilcraft

R1

4.7 k Resistor 0402 1% 0.063 W

RC0402FR-074K7L – Yageo

R2

910  Resistor 0402 1% 0.063 W

RC0402FR-07910RL – Yageo

R3

82  Resistor 0402 5% 0.063 W

RC0402JR-0782RL – Yageo

R4

8.2 k Resistor 0402 5% 0.063 W

RC0402JR-078K2L – Yageo

R5

39 k Resistor 0402 5% 0.063 W

RC0402JR-0739KL – Yageo

U1

Step-Down Regulator 8-VFQFPN 3 A 1 MHz

L5987TR – ST Microelectronics

Table 21: Components for a low cost VCC supply application circuit using a step-down regulator

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2.2.1.3 Guidelines for VCC supply circuit design using a Low Drop-Out (LDO) linear regulator
The use of a linear regulator is suggested when the difference from the available supply rail and the VCC value is
low: linear regulators provide high efficiency when transforming a 5 V supply to a voltage value within the module
VCC normal operating range.
The characteristics of the LDO linear regulator connected to the VCC pins should meet the following prerequisites
to comply with the module’s VCC requirements summarized in Table 6:


Power capabilities: the LDO linear regulator with its output circuit must be capable of providing a voltage
value to the VCC pins within the specified operating range and must be capable of delivering the maximum
peak / pulse current consumption to the VCC pins during a Tx burst at the maximum Tx power specified in
the LARA-R2 series Data Sheet [1].



Power dissipation: the power handling capability of the LDO linear regulator must be checked to limit its
junction temperature to the maximum rated operating range (i.e. check the voltage drop from the max input
voltage to the min output voltage to evaluate the power dissipation of the regulator).



Output voltage slope: the use of the soft start function provided by some voltage regulators should be
evaluated carefully, as the VCC voltage must ramp from 2.3 V to 2.8 V in less than 4 ms to switch on the
module by applying the VCC supply. The module can be otherwise switched on by forcing a low level on the
RESET_N pin during the VCC rising edge and then releasing the RESET_N pin when the VCC supply voltage
stabilizes at its proper nominal value.

Figure 30 and the components listed in Table 22 show an example of a high reliability power supply circuit, where
the VCC module supply is provided by an LDO linear regulator which is capable of delivering the specified highest
peak / pulse current, with the proper power handling capability. The regulator described in this example supports
a wide input voltage range, and it includes internal circuitry for reverse battery protection, current limiting, thermal
limiting and reverse current protection.
It is recommended to configure the LDO linear regulator to generate a voltage supply value slightly below the
maximum limit of the module VCC normal operating range (e.g. ~4.1 V as in the circuit described in Figure 30 and
Table 22). This reduces the power on the linear regulator and improves the whole thermal design of the supply
circuit.

LARA-R2 series
5V

2

IN

OUT

VCC
VCC
53 VCC
51

4

52

U1
C1

R1

1

SHDN

ADJ
GND
3

C2

5

R2

GND

Figure 30: Example of a high reliability VCC supply application circuit using an LDO linear regulator
Reference

Description

Part Number - Manufacturer

C1, C2

10 µF Capacitor Ceramic X5R 0603 20% 6.3 V

GRM188R60J106ME47 - Murata

R1

9.1 k Resistor 0402 5% 0.1 W

RC0402JR-079K1L - Yageo Phycomp

R2

3.9 k Resistor 0402 5% 0.1 W

RC0402JR-073K9L - Yageo Phycomp

U1

LDO Linear Regulator ADJ 3.0 A

LT1764AEQ#PBF - Linear Technology

Table 22: Components for a high reliability VCC supply application circuit using an LDO linear regulator

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Figure 31 and the components listed in Table 23 show an example of a low cost power supply circuit, where the
VCC module supply is provided by an LDO linear regulator capable of delivering the specified highest peak / pulse
current, with the proper power handling capability. The regulator described in this example supports a limited
input voltage range and it includes internal circuitry for current and thermal protection.
It is recommended to configure the LDO linear regulator to generate a voltage supply value slightly below the
maximum limit of the module VCC normal operating range (e.g. ~4.1 V as in the circuit described in Figure 31
and Table 23). This reduces the power on the linear regulator and improves the whole thermal design of the supply
circuit.

LARA-R2 series
5V

2

IN

OUT

VCC
VCC
53 VCC
51

4

52

U1
C1

R1

1

EN

ADJ
GND
3

C2

5

R2

GND

Figure 31: Example of a low cost VCC supply application circuit using an LDO linear regulator
Reference

Description

Part Number - Manufacturer

C1, C2

10 µF Capacitor Ceramic X5R 0603 20% 6.3 V

GRM188R60J106ME47 - Murata

R1

27 k Resistor 0402 5% 0.1 W

RC0402JR-0727KL - Yageo Phycomp

R2

4.7 k Resistor 0402 5% 0.1 W

RC0402JR-074K7L - Yageo Phycomp

U1

LDO Linear Regulator ADJ 3.0 A

LP38501ATJ-ADJ/NOPB - Texas Instrument

Table 23: Components for a low cost VCC supply application circuit using an LDO linear regulator

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2.2.1.4 Guidelines for VCC supply circuit design using a rechargeable Li-Ion or Li-Pol battery
Rechargeable Li-Ion or Li-Pol batteries connected to the VCC pins should meet the following prerequisites to
comply with the module VCC requirements summarized in Table 6:


Maximum pulse and DC discharge current: the rechargeable Li-Ion battery with its related output circuit
connected to the VCC pins must be capable of delivering a pulse current as the maximum peak / pulse current
consumption during a Tx burst at the maximum Tx power specified in the LARA-R2 series Data Sheet [1], and
must be capable of extensively delivering a DC current as the maximum average current consumption specified
in the LARA-R2 series Data Sheet [1]. The maximum discharge current is not always reported in the data sheets
of batteries, but the maximum DC discharge current is typically almost equal to the battery capacity in amphours divided by 1 hour.



DC series resistance: the rechargeable Li-Ion battery with its output circuit must be capable of avoiding a
VCC voltage drop below the operating range summarized in Table 6 during transmit bursts.

2.2.1.5 Guidelines for VCC supply circuit design using a primary (disposable) battery
The characteristics of a primary (non-rechargeable) battery connected to the VCC pins should meet the following
prerequisites to comply with the module’s VCC requirements summarized in Table 6:


Maximum pulse and DC discharge current: the non-rechargeable battery with its related output circuit
connected to the VCC pins must be capable of delivering a pulse current as the maximum peak current
consumption during a Tx burst at the maximum Tx power specified in the LARA-R2 series Data Sheet [1], and
must be capable of extensively delivering a DC current as the maximum average current consumption specified
in the LARA-R2 series Data Sheet [1]. The maximum discharge current is not always reported in the data sheets
of batteries, but the max DC discharge current is typically almost equal to the battery capacity in amp-hours
divided by 1 hour.



DC series resistance: the non-rechargeable battery with its output circuit must be capable of avoiding a VCC
voltage drop below the operating range summarized in Table 6 during transmit bursts.

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2.2.1.6 Additional guidelines for VCC supply circuit design
To reduce voltage drops, use a low impedance power source. The series resistance of the power supply lines
(connected to the VCC and GND pins of the module) on the application board and battery pack should also be
considered and minimized: cabling and routing must be as short as possible to minimize power losses.
Three pins are allocated for the VCC supply. Several pins are designated for the GND connection. It is
recommended to properly connect all of them to supply the module to minimize series resistance losses.
For modules supporting 2G radio access technology, to avoid voltage drop undershoot and overshoot at the start
and end of a transmit burst during a GSM call (when current consumption on the VCC supply can rise up as
specified in the LARA-R2 series Data Sheet [1]), place a bypass capacitor with large capacitance (at least 100 µF)
and low ESR near the VCC pins, for example:
 330 µF capacitance, 45 m ESR (e.g. KEMET T520D337M006ATE045, Tantalum Capacitor)
To reduce voltage ripple and noise, improving RF performance especially if the application device integrates an
internal antenna, place the following bypass capacitors near the VCC pins:


68 pF capacitor with Self-Resonant Frequency in 800/900 MHz range (e.g. Murata GRM1555C1E560J)



15 pF capacitor with Self-Resonant Frequency in 1800/1900 MHz range (e.g. Murata GRM1555C1E150J)



8.2 pF capacitor with Self-Resonant Frequency in 2500/2600 MHz range (e.g. Murata GRM1555C1H8R2D)



10 nF capacitor (e.g. Murata GRM155R71C103K) to filter digital logic noise from clocks and data sources

 100 nF capacitor (e.g. Murata GRM155R61C104K) to filter digital logic noise from clocks and data sources
A suitable series ferrite bead can be properly placed on the VCC line for additional noise filtering if required by the
specific application according to the whole application board design.

LARA-R2 series
3V8

VCC
VCC
VCC

51
52
53

+
C1

GND

C2

Recommended for
cellular modules
supporting LTE band-7

C3

C4

C5

C6

Recommended for
cellular modules
supporting 2G

Figure 32: Suggested schematic for the VCC bypass capacitors to reduce ripple / noise on the supply voltage profile
Reference

Description

Part Number - Manufacturer

C1

8.2 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H8R2DZ01 - Murata

C2

15 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H150JA01 - Murata

C3

68 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H680JA01 - Murata

C4

10 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71C103KA01 - Murata

C5

100 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71C104KA01 - Murata

C6

330 µF Capacitor Tantalum D_SIZE 6.3 V 45 m

T520D337M006ATE045 - KEMET

Table 24: Suggested components to reduce ripple / noise on VCC

The necessity of each part depends on the specific design, but it is recommended to provide all the bypass
capacitors described in Figure 32 / Table 24 if the application device integrates an internal antenna.
ESD sensitivity rating of the VCC supply pins is 1 kV (Human Body Model according to JESD22-A114). Higher
protection level can be required if the line is externally accessible on the application board, e.g. if the
accessible battery connector is directly connected to VCC pins. A higher protection level can be achieved by
mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) close to the accessible point.

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2.2.1.7 Additional guidelines for VCC supply circuit design of LARA-R211 modules
LARA-R211 modules provide separate supply inputs over the VCC pins (see Figure 3):


VCC pins #52 and #53 represent the supply input for the internal RF power amplifier, demanding most of the
total current drawn of the module when RF transmission is enabled during a voice/data call



VCC pin #51 represents the supply input for the internal baseband Power Management Unit and the internal
transceiver, demanding a minor part of the total current drawn of the module when RF transmission is enabled
during a voice/data call
LARA-R211 modules support two different extended operating voltage ranges: one for the VCC pins #52 and #53,
and another one for the VCC pin #51 (see the LARA-R2 series Data Sheet [1]).
All the VCC pins are in general intended to be connected to the same external power supply circuit, but separate
supply sources can be implemented for specific (e.g. battery-powered) applications considering that the voltage at
the VCC pins #52 and #53 can drop to a value lower than the one at the VCC pin #51, keeping the module still
switched-on and functional. Figure 33 describes a possible application circuit.

L1

D1

LARA-R211

Step-up
Regulator

VIN

51 VCC

SW

SHDNn
C7

R1

FB

C9

R2

GND

C8

U1

Li-Ion/Li-Pol
Battery

+

52 VCC
53 VCC

C1 C2 C3 C4 C5 C6

GND

Figure 33: VCC circuit example with a separate supply for LARA-R211 modules
Reference

Description

Part Number - Manufacturer

C1

330 µF Capacitor Tantalum D_SIZE 6.3 V 45 m

T520D337M006ATE045 - KEMET

C2

10 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71C103KA01 - Murata

C3

100 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R61A104KA01 - Murata

C4

68 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H680JA01 - Murata

C5

15 pF Capacitor Ceramic C0G 0402 5% 25 V

GRM1555C1E150JA01 - Murata

C6

8.2 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H8R2DZ01 - Murata

C7

10 µF Capacitor Ceramic X5R 0603 20% 6.3 V

GRM188R60J106ME47 - Murata

C8

22 µF Capacitor Ceramic X5R 1210 10% 25 V

GRM32ER61E226KE15 - Murata

C9

10 pF Capacitor Ceramic C0G 0402 5% 25 V

GRM1555C1E100JA01 - Murata

D1

Schottky Diode 40 V 1 A

SS14 - Vishay General Semiconductor

L1

10 µH Inductor 20% 1 A 276 m

SRN3015-100M - Bourns Inc.

R1

1 M Resistor 0402 5% 0.063 W

RC0402FR-071ML - Yageo Phycomp

R2

412 k Resistor 0402 5% 0.063 W

RC0402FR-07412KL - Yageo Phycomp

U1

Step-up Regulator 350 mA

AP3015 - Diodes Incorporated

Table 25: Example of components for VCC circuit with a separate supply for LARA-R211 modules

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2.2.1.8 Guidelines for external battery charging circuit
LARA-R2 series modules do not have an on-board charging circuit. Figure 34 provides an example of a battery
charger design, suitable for applications that are battery powered with a Li-Ion (or Li-Polymer) cell.
In the application circuit, a rechargeable Li-Ion (or Li-Polymer) battery cell, that features proper pulse and DC
discharge current capabilities and proper DC series resistance, is directly connected to the VCC supply input of the
module. Battery charging is completely managed by the STMicroelectronics L6924U Battery Charger IC that, from
a USB power source (5.0 V typ.), charges as a linear charger the battery, in three phases:


Pre-charge constant current (active when the battery is deeply discharged): the battery is charged with a
low current, set to 10% of the fast-charge current



Fast-charge constant current: the battery is charged with the maximum current, configured by the value of
an external resistor to a value suitable for USB power source (~500 mA)



Constant voltage: when the battery voltage reaches the regulated output voltage (4.2 V), the L6924U starts
to reduce the current until the charge termination is done. The charging process ends when the charging
current reaches the value configured by an external resistor to ~15 mA or when the charging timer reaches
the value configured by an external capacitor to ~9800 s.
Using a battery pack with an internal NTC resistor, the L6924U can monitor the battery temperature to protect
the battery from operating under unsafe thermal conditions.
The L6924U, as a linear charger, is more suitable for applications where the charging source has a relatively low
nominal voltage (~5 V), so that a switching charger is suggested for applications where the charging source has a
relatively high nominal voltage (e.g. ~12 V, see the following section 2.2.1.9 for specific design-in).
Li-Ion/Li-Polymer
Battery Charger IC

LARA-R2 series

5V
USB
Supply

VIN

VOUT

VINSNS
MODE
R1
R2
R3

VOSNS

Li-Ion/Li-Pol
Battery Pack

VREF

ISEL

C3

IUSB
IAC

51 VCC
52 VCC
53 VCC

R4

C4

TH

+
θ

IEND

C5 C6 C7 C8 C9 C10

TPRG

C1

C2

SD

GND

U1

B1

GND

D1 D2

Figure 34: Li-Ion (or Li-Polymer) battery charging application circuit
Reference

Description

Part Number - Manufacturer

B1

Li-Ion (or Li-Polymer) battery pack with 470  NTC

Various manufacturer

C1, C4

1 µF Capacitor Ceramic X7R 0603 10% 16 V

GRM188R71C105KA12 - Murata

C2, C6

10 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71C103KA01 - Murata

C3

1 nF Capacitor Ceramic X7R 0402 10% 50 V

GRM155R71H102KA01 - Murata

C5

330 µF Capacitor Tantalum D_SIZE 6.3 V 45 m

T520D337M006ATE045 - KEMET

C7

100 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R61A104KA01 - Murata

C8

68 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H680JA01 - Murata

C9

15 pF Capacitor Ceramic C0G 0402 5% 25 V

GRM1555C1E150JA01 - Murata

C10

8.2 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H8R2DZ01 - Murata

D1, D2

Low Capacitance ESD Protection

CG0402MLE-18G - Bourns

R1, R2

24 k Resistor 0402 5% 0.1 W

RC0402JR-0724KL - Yageo Phycomp

R3

3.3 k Resistor 0402 5% 0.1 W

RC0402JR-073K3L - Yageo Phycomp

R4

1.0 k Resistor 0402 5% 0.1 W

RC0402JR-071K0L - Yageo Phycomp

U1

Single Cell Li-Ion (or Li-Polymer) Battery Charger IC
for USB port and AC Adapter

L6924U - STMicroelectronics

Table 26: Suggested components for a Li-Ion (or Li-Polymer) battery charging application circuit

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2.2.1.9 Guidelines for external battery charging and power path management circuit
Application devices where both a permanent primary supply / charging source (e.g. ~12 V) and a rechargeable
back-up battery (e.g. 3.7 V Li-Pol) are available at the same time as the possible supply source should implement
a suitable charger / regulator with an integrated power path management function to supply the module and the
whole device while simultaneously and independently charging the battery.
Figure 35 illustrates a simplified block diagram circuit showing the working principle of a charger / regulator with
integrated power path management function. This component allows the system to be powered by a permanent
primary supply source (e.g. ~12 V) using the integrated regulator which simultaneously and independently
recharges the battery (e.g. 3.7 V Li-Pol) that represents the back-up supply source of the system: the power path
management feature permits the battery to supplement the system current requirements when the primary supply
source is not available or cannot deliver the peak system currents.
A power management IC should meet the following prerequisites to comply with the module VCC requirements
summarized in Table 6:


High efficiency internal step down converter, compliant with the performances specified in section 2.2.1.2



Low internal resistance in the active path Vout – Vbat, typically lower than 50 m



High efficiency switch mode charger with separate power path control

Power path management IC
12 V
Primary
Source

Vin

System

Vout
DC/DC converter
and battery FET
control logic

Vbat

Li-Ion/Li-Pol
Battery Pack

Charge
controller

GND

GND

θ

Figure 35: Charger / regulator with an integrated power path management circuit block diagram

Figure 36 and the components listed in Table 27 provide an application circuit example where the MPS MP2617
switching charger / regulator with an integrated power path management function provides the supply to the
cellular module, while concurrently and autonomously charging a suitable Li-Ion (or Li-Polymer) battery with the
proper pulse and DC discharge current capabilities and the proper DC series resistance according to the
rechargeable battery recommendations described in section 2.2.1.4.
The MP2617 IC constantly monitors the battery voltage and selects whether to use the external main primary
supply / charging source or the battery as the supply source for the module, and starts a charging phase
accordingly.
The MP2617 IC normally provides a supply voltage to the module regulated from the external main primary source
allowing immediate system operation even under missing or deeply discharged battery conditions: the integrated
switching step-down regulator is capable of provifing up to 3 A output current with low output ripple and fixed
1.6 MHz switching frequency in PWM mode operation. The module load is satisfied in priority, then the integrated
switching charger will take the remaining current to charge the battery.
Additionally, the power path control allows an internal connection from the battery to the module with a low
series internal ON resistance (40 m typical), in order to supplement additional power to the module when the
current demand increases over the external main primary source or when this external source is removed.

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Battery charging is managed in three phases:


Pre-charge constant current (active when the battery is deeply discharged): the battery is charged with a
low current, set to 10% of the fast-charge current



Fast-charge constant current: the battery is charged with the maximum current, configured by the value of
an external resistor to a value suitable for the application



Constant voltage: when the battery voltage reaches the regulated output voltage (4.2 V), the current is
progressively reduced until the charge termination is done. The charging process ends when the charging
current reaches the 10% of the fast-charge current or when the charging timer reaches the value configured
by an external capacitor.

Using a battery pack with an internal NTC resistor, the MP2617 can monitor the battery temperature to protect
the battery from operating under unsafe thermal conditions.
Several parameters, such as the charging current, the charging timings, the input current limit, the input voltage
limit, and the system output voltage, can be easily set according to the specific application requirements, as the
actual electrical characteristics of the battery and the external supply / charging source: proper resistors or
capacitors must be accordingly connected to the related pins of the IC.
Li-Ion/Li-Polymer Battery
Charger / Regulator with
Power Path Managment

BST
12V

L1

SW

Primary
Source

VIN

LARA-R2 series

C4

53 VCC

R4

C5

VLIM
R5

Li-Ion/Li-Pol
Battery Pack

BAT
R1
R2

EN

+

ILIM

NTC

ISET

VCC

TMR
C1

51 VCC
52 VCC

SYS

C2

AGND PGND

C10 C11 C12 C13 C14 C15
θ
R3
C3

C6 C7 C8

C9

GND
D1 D2

B1

U1

Figure 36: Li-Ion (or Li-Polymer) battery charging and power path management application circuit
Reference

Description

Part Number - Manufacturer

B1

Li-Ion (or Li-Polymer) battery pack with 10 k NTC

Various manufacturer

C1, C5, C6

22 µF Capacitor Ceramic X5R 1210 10% 25 V

GRM32ER61E226KE15 - Murata

C2, C4, C11

100 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R61A104KA01 - Murata

C3

1 µF Capacitor Ceramic X7R 0603 10% 25 V

GRM188R71E105KA12 - Murata

C7, C13

68 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H680JA01 - Murata

C8, C14

15 pF Capacitor Ceramic C0G 0402 5% 25 V

GRM1555C1E150JA01 - Murata

C9, C15

8.2 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H8R2DZ01 - Murata

C10

330 µF Capacitor Tantalum D_SIZE 6.3 V 45 m

T520D337M006ATE045 - KEMET

C12

10 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71C103KA01 - Murata

D1, D2

Low Capacitance ESD Protection

CG0402MLE-18G - Bourns

R1, R3, R5

10 k Resistor 0402 5% 1/16 W

RC0402JR-0710KL - Yageo Phycomp

R2

1.0 k Resistor 0402 5% 0.1 W

RC0402JR-071K0L - Yageo Phycomp

R4

22 k Resistor 0402 5% 1/16 W

RC0402JR-0722KL - Yageo Phycomp

L1

1.2 µH Inductor 6 A 21 m 20%

7447745012 - Wurth

U1

Li-Ion/Li-Polymer Battery DC/DC Charger / Regulator
with integrated Power Path Management function

MP2617 - Monolithic Power Systems (MPS)

Table 27: Suggested components for Li-Ion (or Li-Polymer) battery charging and power path management application circuit

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2.2.1.10 Guidelines for removing VCC supply
As described in section 1.6.2 and Figure 15, the VCC supply can be removed after the end of LARA-R2 series
modules internal power-off sequence, which must be properly started sending the AT+CPWROFF command (see
the u-blox AT Commands Manual [2]).
Removing the VCC power can be useful in order to minimize the current consumption when the LARA-R2 series
modules are switched off. Afterwards, the modules can be switched on again by re-applying the VCC supply.
If the VCC supply is generated by a switching or an LDO regulator, the application processor may control the input
pin of the regulator which is provided to enable / disable the output of the regulator (as for example, the RUN
input pin for the regulator described in Figure 28, the INH input pin for the regulator described in Figure 29, the
SHDNn input pin for the regulator described in Figure 30, or the EN input pin for the regulator described in Figure
31), in order to apply / remove the VCC supply.
If the regulator that generates the VCC supply does not provide an on / off pin, or for other applications such as
the battery-powered ones, the VCC supply can be switched off using an appropriate external p-channel MOSFET
controlled by the application processor by means of a proper inverting transistor as shown in Figure 37, given that
the external p-channel MOSFET has provided:


Very low RDS(ON) (for example, less than 50 m), to minimize voltage drops



Adequate maximum Drain current (see the LARA-R2 series Data Sheet [1] for module consumption figures)



Low leakage current, to minimize the current consumption
LARA-R2 series
51 VCC
52 VCC

T1

VCC Supply Source

53 VCC

R3

+

Application
Processor

GPIO

R2

GND

C1 C2 C3 C4 C5 C6
R1

T2

GND

Figure 37: Example of application circuit for a VCC supply removal
Reference

Description

Part Number - Manufacturer

R1

47 k Resistor 0402 5% 0.1 W

RC0402JR-0747KL - Yageo Phycomp

R2

10 k Resistor 0402 5% 0.1 W

RC0402JR-0710KL - Yageo Phycomp

R3

100 k Resistor 0402 5% 0.1 W

RC0402JR-07100KL - Yageo Phycomp

T1

P-Channel MOSFET Low On-Resistance

AO3415 - Alpha & Omega Semiconductor Inc.

T2

NPN BJT Transistor

BC847 - Infineon

C1

330 µF Capacitor Tantalum D_SIZE 6.3 V 45 m

T520D337M006ATE045 - KEMET

C2

10 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71C103KA01 - Murata

C3

100 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R61A104KA01 - Murata

C4

56 pF Capacitor Ceramic C0G 0402 5% 25 V

GRM1555C1E560JA01 - Murata

C5

15 pF Capacitor Ceramic C0G 0402 5% 25 V

GRM1555C1E150JA01 - Murata

C6

8.2 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H8R2DZ01 - Murata

Table 28: Components for a VCC supply removal application circuit

It is highly recommended to avoid an abrupt removal of the VCC supply during LARA-R2 series modules
normal operations: the power-off procedure must be started by the AT+CPWROFF command, waiting the
command response for a proper time period (see the u-blox AT Commands Manual [2]), and then a proper
VCC supply must be held at least until the end of the modules’ internal power-off sequence, which occurs
when the generic digital interfaces supply output (V_INT) is switched off by the module.

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2.2.1.11 Guidelines for VCC supply layout design
Good connection of the module VCC pins with a DC supply source is required for correct RF performance.
Guidelines are summarized in the following list:


All the available VCC pins must be connected to the DC source.



VCC connection must be as wide as possible and as short as possible.



Any series component with Equivalent Series Resistance (ESR) greater than few milliohms must be avoided.



VCC connection must be routed through a PCB area separated from sensitive analog signals and sensitive
functional units: it is good practice to interpose at least one layer of PCB ground between VCC track and other
signal routing.



Coupling between VCC and audio lines (especially microphone inputs) must be avoided, because the typical
GSM burst has a periodic nature of approximaely 217 Hz, which lies in the audible audio range.



The tank bypass capacitor with low ESR for current spikes smoothing described in section 2.2.1.6 should be
placed close to the VCC pins. If the main DC source is a switching DC-DC converter, place the large capacitor
close to the DC-DC output and minimize the VCC track length. Otherwise, consider using separate capacitors
for the DC-DC converter and the cellular module tank capacitor.



The bypass capacitors in the pF range described in section 2.2.1.6 should be placed as close as possible to the
VCC pins. This is highly recommended if the application device integrates an internal antenna.



Since VCC is directly connected to RF Power Amplifiers, voltage ripple at high frequency may result in
unwanted spurious modulation of the transmitter RF signal. This is more likely to happen with switching
DC-DC converters, in which case it is better to select the highest operating frequency for the switcher and
add a large L-C filter before connecting to the LARA-R2 series modules in the worst case.



Shielding of the switching DC-DC converter circuit, or at least the use of shielded inductors for the switching
DC-DC converter, may be considered since all switching power supplies may potentially generate interfering
signals as a result of high-frequency, high-power switching.



If VCC is protected by transient voltage suppressor to ensure that the voltage maximum ratings are not
exceeded, place the protecting device along the path from the DC source toward the cellular module,
preferably closer to the DC source (otherwise protection functionality may be compromised).

2.2.1.12 Guidelines for grounding layout design
Good connection of the module GND pins with the application board solid ground layer is required for correct RF
performance. It significantly reduces EMC issues and provides a thermal heat sink for the module.


Connect each GND pin with the application board solid GND layer. It is strongly recommended that each GND
pin surrounding VCC pins have one or more dedicated via down to the application board solid ground layer.



The VCC supply current flows back to the main DC source through GND as ground current: provide an
adequate return path with a suitable uninterrupted ground plane to the main DC source.



It is recommended to implement one layer of the application board as a ground plane as wide as possible.



If the application board is a multilayer PCB, then all the board layers should be filled with GND plane as much
as possible and each GND area should be connected together with a complete via stack down to the main
ground layer of the board. Use as many vias as possible to connect the ground planes



Provide a dense line of vias at the edges of each ground area, in particular along RF and high speed lines



If the whole application device is composed of more than one PCB, then it is required to provide a good and
solid ground connection between the GND areas of all the multiple PCBs.



Good grounding of GND pins also ensures thermal heat sink. This is critical during call connection, when the
real network commands the module to transmit at maximum power: proper grounding helps prevent module
overheating.

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2.2.2 RTC supply (V_BCKP)
2.2.2.1 Guidelines for V_BCKP circuit design
LARA-R2 series modules provide the V_BCKP RTC supply input/output, which can be mainly used to:


Provide RTC back-up when VCC supply is removed

If RTC timing is required to run for a time interval of T [s] when VCC supply is removed, place a capacitor with a
nominal capacitance of C [µF] at the V_BCKP pin. Choose the capacitor using the following formula:
C [µF] = (Current_Consumption [µA] x T [s]) / Voltage_Drop [V]
= 2.5 x T [s]
For example, a 100 µF capacitor can be placed at V_BCKP to provide RTC backup holding the V_BCKP voltage
within its valid range for around 40 s at +25 °C, after the VCC supply is removed. If a longer buffering time is
required, a 70 mF super-capacitor can be placed at V_BCKP, with a 4.7 k series resistor to hold the V_BCKP
voltage within its valid range for approximately 8 hours at +25 °C, after the VCC supply is removed. The purpose
of the series resistor is to limit the capacitor charging current due to the large capacitor specifications, and also to
let a fast rise time of the voltage value at the V_BCKP pin after VCC supply has been provided. These capacitors
allow the time reference to run during battery disconnection.
(a)

LARA-R2 series
2

V_BCKP

(b)

LARA-R2 series
2
R2

C1

C2
(superCap)

(c)

LARA-R2 series

V_BCKP

2

V_BCKP

D3
B3

Figure 38: Real time clock supply (V_BCKP) application circuits: (a) using a 100 µF capacitor to let the RTC run for ~1 minute after
VCC removal; (b) using a 70 mF capacitor to let the RTC run for ~10 hours after VCC removal; (c) using a non-rechargeable battery
Reference

Description

Part Number - Manufacturer

C1

100 µF Tantalum Capacitor

GRM43SR60J107M - Murata

R2

4.7 k Resistor 0402 5% 0.1 W

RC0402JR-074K7L - Yageo Phycomp

C2

70 mF Capacitor

XH414H-IV01E - Seiko Instruments

Table 29: Example of components for V_BCKP buffering

If a longer buffering time is required to allow the RTC time reference to run during a disconnection of the VCC
supply, then an external battery can be connected to the V_BCKP pin. The battery should be able to provide a
proper nominal voltage and must never exceed the maximum operating voltage for V_BCKP (specified in the Input
characteristics of Supply/Power pins table in the LARA-R2 series Data Sheet [1]). The connection of the battery to
V_BCKP should be done with a suitable series resistor for a rechargeable battery, or with an appropriate series
diode for a non-rechargeable battery. The purpose of the series resistor is to limit the battery charging current due
to the battery specifications, and also to allow a fast rise time of the voltage value at the V_BCKP pin after the
VCC supply has been provided. The purpose of the series diode is to avoid a current flow from the module V_BCKP
pin to the non-rechargeable battery.
If the RTC timing is not required when the VCC supply is removed, it is not needed to connect the V_BCKP
pin to an external capacitor or battery. In this case, the date and time are not updated when VCC is
disconnected. If VCC is always supplied, then the internal regulator is supplied from the main supply and
there is no need for an external component on V_BCKP.

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Combining a LARA-R2 series cellular module with a u-blox GNSS positioning receiver, the positioning receiver VCC
supply is controlled by the cellular module by means of the “GNSS supply enable” function provided by the GPIO2
of the cellular module. In this case, the V_BCKP supply output of the cellular module can be connected to the
V_BCKP backup supply input pin of the GNSS receiver to provide the supply for the positioning real time clock
and backup RAM when the VCC supply of the cellular module is within its operating range and the VCC supply of
the GNSS receiver is disabled. This enables the u-blox GNSS receiver to recover from a power breakdown with
either a hot start or a warm start (depending on the duration of the positioning VCC outage) and to maintain the
configuration settings saved in the backup RAM. Refer to section 2.6.4 for more details regarding the application
circuit with a u-blox GNSS receiver.
The internal regulator for V_BCKP is optimized for low leakage current and very light loads. Do not apply
loads which might exceed the limit for the maximum available current from V_BCKP supply, as this can
cause malfunctions in the module. The LARA-R2 series Data Sheet [1] describes the detailed electrical
characteristics.
The V_BCKP supply output pin provides internal short circuit protection to limit the start-up current and protect
the device in short circuit situations. No additional external short circuit protection is required.
ESD sensitivity rating of the V_BCKP supply pin is 1 kV (Human Body Model according to JESD22-A114).
Higher protection level can be required if the line is externally accessible on the application board, e.g. if an
accessible back-up battery connector is directly connected to V_BCKP pin, and it can be achieved by
mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) close to the accessible point.

2.2.2.2 Guidelines for V_BCKP layout design
The RTC supply (V_BCKP) requires careful layout: avoid injecting noise on this voltage domain, as it may affect the
stability of the 32 kHz oscillator.

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2.2.3 Interface supply (V_INT)
2.2.3.1 Guidelines for V_INT circuit design
LARA-R2 series provide the V_INT generic digital interfaces 1.8 V supply output, which can be mainly used to:


Indicate when the module is switched on (see sections 1.6.1, 1.6.2 for more details)



Pull-up SIM detection signal (see section 2.5 for more details)



Supply voltage translators to connect digital interfaces of the module to a 3.0 V device (see section 2.6.1)



Pull-up DDC (I2C) interface signals (see section 2.6.4 for more details)



Supply a 1.8 V u-blox 6 or subsequent GNSS receiver (see section 2.6.4 for more details)



Supply an external device as an external 1.8 V audio codec (see section 2.7.1 for more details)

The V_INT supply output pin provides internal short circuit protection to limit the start-up current and protect the
device in short circuit situations. No additional external short circuit protection is required.
Do not apply loads which might exceed the limit for maximum available current from V_INT supply (see the
LARA-R2 series Data Sheet [1]) as this can cause malfunctions in the internal circuitry.
Since the V_INT supply is generated by an internal switching step-down regulator, the V_INT voltage ripple
can range as specified in the LARA-R2 series Data Sheet [1]: it is not recommended to supply sensitive analog
circuitry without adequate filtering for digital noise.
V_INT can only be used as an output: do not connect any external supply source on V_INT.
ESD sensitivity rating of the V_INT supply pin is 1 kV (Human Body Model according to JESD22-A114).
A higher protection level could be required if the line is externally accessible and it can be achieved by
mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) close to the accessible point.
It is recommended to provide direct access to the V_INT pin on the application board by means of an
accessible test point directly connected to the V_INT pin.

2.2.3.2 Guidelines for V_INT layout design
The V_INT supply output is generated by an integrated switching step-down converter, used internally to supply
the generic digital interfaces. Because of this, it can be a source of noise: avoid coupling with sensitive signals.

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2.3 System functions interfaces
2.3.1 Module power-on (PWR_ON)
2.3.1.1 Guidelines for PWR_ON circuit design
LARA-R2 series modules’ PWR_ON input is equipped with an internal active pull-up resistor to the VCC module
supply as described in Figure 39: an external pull-up resistor is not required and should not be provided.
If connecting the PWR_ON input to a push button, the pin will be externally accessible on the application device.
According to EMC/ESD requirements of the application, an additional ESD protection should be provided close to
the accessible point, as described in Figure 39 and Table 30.
The ESD sensitivity rating of the PWR_ON pin is 1 kV (Human Body Model according to JESD22-A114).
A higher protection level can be required if the line is externally accessible on the application board, e.g. if
an accessible push button is directly connected to the PWR_ON pin. A higher protection level can be
achieved by mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) close to the accessible
point.
An open drain or open collector output is suitable to drive the PWR_ON input from an application processor, as
the pin is equipped with an internal active pull-up resistor to the V_BCKP supply, as described in Figure 39.
A compatible push-pull output of an application processor can also be used. In any case, take care to set the
proper level in all the possible scenarios to avoid an inappropriate module switch-on.

LARA-R2 series
2

TP

LARA-R2 series

V_BCKP
10 k

Power-on
push button

Application
Processor
2

Open
Drain
Output

15 PWR_ON

V_BCKP
10 k

TP

15

PWR_ON

ESD

Figure 39: PWR_ON application circuits using a push button and an open drain output of an application processor
Reference

Description

Remarks

ESD

CT0402S14AHSG - EPCOS

Varistor array for ESD protection

Table 30: Example of pull-up resistor and ESD protection for the PWR_ON application circuit

It is recommended to provide direct access to the PWR_ON pin on the application board by means of an
accessible testpoint directly connected to the PWR_ON pin.

2.3.1.2 Guidelines for PWR_ON layout design
The power-on circuit (PWR_ON) requires careful layout since it is the sensitive input available to switch on the
LARA-R2 series modules. It is required to ensure that the voltage level is well defined during operation and no
transient noise is coupled on this line, otherwise the module might detect a spurious power-on request.

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2.3.2 Module reset (RESET_N)
2.3.2.1 Guidelines for RESET_N circuit design
LARA-R2 series RESET_N is equipped with an internal pull-up to the V_BCKP supply as described in Figure 40. An
external pull-up resistor is not required.
If connecting the RESET_N input to a push button, the pin will be externally accessible on the application device.
According to EMC/ESD requirements of the application, an additional ESD protection device (e.g. the EPCOS
CA05P4S14THSG varistor) should be provided close to the accessible point on the line connected to this pin, as
described in Figure 40 and Table 31.
The ESD sensitivity rating of the RESET_N pin is 1 kV (Human Body Model according to JESD22-A114).
A higher protection level can be required if the line is externally accessible on the application board, e.g. if
an accessible push button is directly connected to the RESET_N pin. A higher protection level can be
achieved by mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) close to the accessible
point.
An open drain output is suitable to drive the RESET_N input from an application processor as it is equipped with
an internal pull-up to V_BCKP supply, as described in Figure 40.
A compatible push-pull output of an application processor can also be used. In any case, take care to set the
proper level in all the possible scenarios to avoid an inappropriate module reset, switch-on or switch-off.

LARA-R2 series
2

Power-on
push button

18

LARA-R2 series

V_BCKP
10 k

TP

Application
Processor

V_BCKP

2

Open
Drain
Output

RESET_N

10 k
TP

18

RESET_N

ESD

Figure 40: RESET_N application circuits using a push button and an open drain output of an application processor
Reference

Description

Remarks

ESD

Varistor for ESD protection

CT0402S14AHSG - EPCOS

Table 31: Example of ESD protection component for the RESET_N application circuit

If the external reset function is not required by the customer application, the RESET_N input pin can be left
unconnected to external components, but it is recommended to provide direct access on the application
board by means of an accessible testpoint directly connected to the RESET_N pin.

2.3.2.2 Guidelines for RESET_N layout design
The reset circuit (RESET_N) requires careful layout due to the pin function: ensure that the voltage level is well
defined during operation and no transient noise is coupled on this line, otherwise the module might detect a
spurious reset request. It is recommended to keep the connection line to RESET_N as short as possible.

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2.3.3 Module / host configuration selection
2.3.3.1

Guidelines for HOST_SELECT circuit design

The functionality of the HOST_SELECT pin is not supported by the “02” and “62” product versions.
LARA-R2 series modules include one pin (HOST_SELECT) to select the module / host application processor
configuration: the pin is available to select, enable, connect, disconnect and subsequently re-connect the HSIC
(USB High-Speed Inter-Chip) interface.
The LARA-R2 series Data Sheet [1] describes the detailed electrical characteristics of the HOST_SELECT pin.
Further guidelines for HOST_SELECT pin circuit design will be described in detail in a successive release of
the System Integration Manual.
Do not apply voltage to the HOST_SELECT pin before the switch-on of its supply source (V_INT), to avoid
latch-up of circuits and allow a proper boot of the module. If the external signal connected to the cellular
module cannot be tri-stated or set low, insert a multi-channel digital switch (e.g. TI SN74CB3Q16244,
TS5A3159, or TS5A63157) between the two-circuit connections and set to high impedance before the
V_INT switch-on.
The ESD sensitivity rating of the HOST_SELECT pin is 1 kV (HBM as per JESD22-A114). A higher protection
level could be required if the lines are externally accessible and it can be achieved by mounting an ESD
protection (e.g. EPCOS CA05P4S14THSG varistor array) close to the accessible points.
If the HOST_SELECT pin is not used, it can be left unconnected on the application board.

2.3.3.2 Guidelines for HOST_SELECT layout design
The pin for the selection of the module / host application processor configuration (HOST_SELECT) is generally not
critical for layout.

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2.4 Antenna interface
LARA-R2 series modules provide two RF interfaces for connecting the external antennas:


The ANT1 pin represents the primary RF input/output for LTE/3G/2G RF signals transmission and reception.



The ANT2 pin represents the secondary RF input for LTE/3G Rx diversity RF signals reception.

Both the ANT1 and the ANT2 pins have a nominal characteristic impedance of 50  and must be connected to
the related antenna through a 50  transmission line to allow proper transmission / reception of RF signals.
Two antennas (one connected to ANT1 pin and one connected to ANT2 pin) must be used to support the
LTE/3G Rx diversity radio technology. This is a required feature for LTE category 1 User Equipment (up to
10.2 Mb/s Down-Link data rate) according to the 3GPP specifications.

2.4.1 Antenna RF interface (ANT1 / ANT2)
2.4.1.1 General guidelines for antenna selection and design
The antenna is the most critical component to be evaluated. Designers must take care of the antennas from all
perspectives at the very start of the design phase when the physical dimensions of the application board are under
analysis/decision, since the RF compliance of the device integrating LARA-R2 series modules with all the applicable
required certification schemes depends on the antenna radiating performance.
Cellular antennas are typically available in the types of linear monopole or PCB antennas such as patches or ceramic
SMT elements.


External antennas (e.g. linear monopole)
o External antennas basically do not imply a physical restriction to the design of the PCB where the
LARA-R2 series module is mounted.
o The radiation performance mainly depends on the antennas. It is required to select antennas with optimal
radiating performance in the operating bands.
o RF cables should be carefully selected to have minimum insertion losses. Additional insertion loss will be
introduced by low quality or long cable. Large insertion loss reduces both transmit and receive radiation
performance.
o
o



A high quality 50  RF connector provides proper PCB-to-RF-cable transition. It is recommended to strictly
follow the layout and cable termination guidelines provided by the connector manufacturer.
If antenna detection functionality is required, select an antenna assembly provided with a proper built-in
diagnostic circuit with a resistor connected to ground: see guidelines in section 2.4.2.

Integrated antennas (e.g. patch-like antennas):
o Internal integrated antennas imply a physical restriction to the design of the PCB:
An integrated antenna excites RF currents on its counterpoise, typically the PCB ground plane of the device
that becomes part of the antenna: its dimension defines the minimum frequency that can be radiated.
Therefore, the ground plane can be reduced down to a minimum size that should be similar to the quarter
of the wavelength of the minimum frequency that must be radiated, given that the orientation of the
ground plane relative to the antenna element must be considered.
The isolation between the primary and the secondary antennas must be as high as possible and the
correlation between the 3D radiation patterns of the two antennas must be as low as possible. In general,
a separation of at least a quarter wavelength between the two antennas is required to achieve a good
isolation and low pattern correlation.
As a numerical example, the physical restriction to the PCB design can be considered as following:
Frequency = 750 MHz  Wavelength = 40 cm  Minimum GND plane size = 10 cm

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o

o

o

o

Radiation performance depends on the whole PCB and antenna system design, including product
mechanical design and usage. Antennas should be selected with optimal radiating performance in the
operating bands according to the mechanical specifications of the PCB and the whole product.
It is recommended to select a pair of custom antennas designed by an antennas’ manufacturer if the
required ground plane dimensions are very small (e.g. less than 6.5 cm long and 4 cm wide). The antenna
design process should begin at the start of the whole product design process.
It is highly recommended to strictly follow the detailed and specific guidelines provided by the antenna
manufacturer regarding correct installation and deployment of the antenna system, including PCB layout
and matching circuitry.
Further to the custom PCB and product restrictions, antennas may require tuning to obtain the required
performance for compliance with all the applicable required certification schemes. It is recommended to
consult the antenna manufacturer for the design-in guidelines for antenna matching relative to the custom
application.

In both cases, selecting external or internal antennas, these recommendations should be observed:


Select antennas providing optimal return loss (or VSWR) figure over all the operating frequencies.



Select antennas providing optimal efficiency figure over all the operating frequencies.



Select antennas providing similar efficiency for both the primary (ANT1) and the secondary (ANT2) antenna.



Select antennas providing appropriate gain figure (i.e. combined antenna directivity and efficiency figure) so
that the electromagnetic field radiation intensity do not exceed the regulatory limits specified in some countries
(e.g. by the FCC in the United States, as reported in section 4.2.2).



Select antennas capable to provide low Envelope Correlation Coefficient between the primary (ANT1) and the
secondary (ANT2) antenna: the 3D antenna radiation patterns should have lobes in different directions.

2.4.1.2

Guidelines for antenna RF interface design

Guidelines for ANT1 / ANT2 pins RF connection design
Proper transition between ANT1 / ANT2 pads and the application board PCB must be provided, implementing the
following design-in guidelines for the layout of the application PCB close to the ANT1 / ANT2 pads:


On a multilayer board, the whole layer stack below the RF connection should be free of digital lines.



Increase GND keep-out (i.e. clearance, a void area) around the ANT1 / ANT2 pads, on the top layer of the
application PCB, to at least 250 µm up to adjacent pads metal definition and up to 400 µm on the area below
the module, to reduce parasitic capacitance to ground, as described in the left example of Figure 41.



Add GND keep-out (i.e. clearance, a void area) on the buried metal layer below the ANT1 / ANT2 pads if the
top-layer to buried layer dielectric thickness is below 200 µm, to reduce parasitic capacitance to ground, as
described in the right example of Figure 41.
GND clearance
on top layer
around ANT1 pad

GND clearance
on very close buried layer
below ANT1 pad

GND clearance
on top layer
around ANT2 pad

GND clearance
on very close buried layer
below ANT2 pad
Min.
250 µm

Min.
250 µm

GND

ANT1

Min. 400 µm

GND

ANT2

Min. 400 µm

Figure 41: GND keep-out area on top layer around ANT1 / ANT2 pads and on very close buried layer below ANT1 / ANT2 pads

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Guidelines for RF transmission line design
Any RF transmission line, such as the ones from the ANT1 and ANT2 pads up to the related antenna connector
or up to the related internal antenna pad, must be designed so that the characteristic impedance is as close as
possible to 50 .
RF transmission lines can be designed as a micro strip (consists of a conducting strip separated from a ground
plane by a dielectric material) or a strip line (consists of a flat strip of metal which is sandwiched between two
parallel ground planes within a dielectric material). The micro strip, implemented as a coplanar waveguide, is the
most common configuration for printed circuit boards.
Figure 42 and Figure 43 provide two examples of proper 50  coplanar waveguide designs. The first example of
an RF transmission line can be implemented for a 4-layer PCB stack-up herein described, and the second example
of an RF transmission line can be implemented for a 2-layer PCB stack-up herein described.
500 µm 380 µm 500 µm
L1 Copper

35 µm

FR-4 dielectric

270 µm

L2 Copper

35 µm

FR-4 dielectric

760 µm

L3 Copper

35 µm

FR-4 dielectric

270 µm

L4 Copper

35 µm

Figure 42: Example of a 50  coplanar waveguide transmission line design for the described 4-layer board layup
400 µm 1200 µm 400 µm
L1 Copper

35 µm

FR-4 dielectric

1510 µm

L2 Copper

35 µm

Figure 43: Example of a 50  coplanar waveguide transmission line design for the described 2-layer board layup

If the two examples do not match the application PCB layup, the 50  characteristic impedance calculation can
be made using the HFSS commercial finite element method solver for electromagnetic structures from Ansys
Corporation, or using freeware tools like AppCAD from Agilent (www.agilent.com) or TXLine from Applied Wave
Research (www.mwoffice.com), taking care of the approximation formulas used by the tools for the impedance
computation.
To achieve a 50  characteristic impedance, the width of the transmission line must be chosen depending on:


the thickness of the transmission line itself (e.g. 35 µm in the examples of Figure 42 and Figure 43)



the thickness of the dielectric material between the top layer (where the transmission line is routed) and the
inner closer layer implementing the ground plane (e.g. 270 µm in Figure 42, 1510 µm in Figure 43)

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

the dielectric constant of the dielectric material (e.g. dielectric constant of the FR-4 dielectric material in Figure
42 and Figure 43)



the gap from the transmission line to the adjacent ground plane on the same layer of the transmission line
(e.g. 500 µm in Figure 42, 400 µm in Figure 43)

If the distance between the transmission line and the adjacent GND area (on the same layer) does not exceed 5
times the track width of the micro strip, use the “Coplanar Waveguide” model for the 50  calculation.
Additionally to the 50  impedance, the following guidelines are recommended for the transmission line design:


Minimize the transmission line length: the insertion loss should be minimized as much as possible, in the order
of a few tenths of a dB.



Add GND keep-out (i.e. clearance, a void area) on buried metal layers below any pad of component present
on the RF transmission line, if top-layer to buried layer dielectric thickness is below 200 µm, to reduce parasitic
capacitance to ground.



The transmission line width and spacing to GND must be uniform and routed as smoothly as possible: avoid
abrupt changes of width and spacing to GND.



Add GND vias around transmission line, as described in Figure 44.



Ensure solid metal connection of the adjacent metal layer on the PCB stack-up to the main ground layer,
providing enough on the adjacent metal layer, as described in Figure 44.



Route RF transmission lines far from any noise source (as switching supplies and digital lines) and from any
sensitive circuit (as analog audio lines).



Avoid stubs on the transmission line.



Avoid signal routing in parallel to the transmission line or crossing the transmission line on buried metal layer.



Do not route the microstrip line below discrete components or other mechanics placed on the top layer.

An example of proper RF circuit design is illustated in Figure 44. In this case, the ANT1 and ANT2 pins are directly
connected to SMA connectors by means of proper 50  transmission lines, designed with proper layout.

LARA

SMA

SMA

Figure 44: Example of the circuit and layout for antenna RF circuits on the application board

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Guidelines for RF termination design
RF terminations must provide a characteristic impedance of 50  as well as the RF transmission lines up to the RF
terminations themselves, to match the characteristic impedance of the ANT1 / ANT2 ports of the modules.
However, real antennas do not have a perfect 50  load on all the supported frequency bands. Therefore, to
reduce as much as possible any performance degradation due to antennas mismatch, the RF terminations must
provide optimal return loss (or VSWR) figure over all the operating frequencies, as summarized in Table 7 and
Table 8.
If external antennas are used, the antenna connectors represent the RF termination on the PCB:


Use suitable 50  connectors providing proper PCB-to-RF-cable transition.



Strictly follow the connector manufacturer’s recommended layout, for example:
o SMA Pin-Through-Hole connectors require GND keep-out (i.e. clearance, a void area) on all the layers
around the central pin up to annular pads of the four GND posts, as shown in Figure 44.
o U.FL surface mounted connectors require no conductive traces (i.e. clearance, a void area) in the area
below the connector between the GND land pads.



Cut out the GND layer under RF connectors and close to buried vias, in order to remove stray capacitance and
thus keep the RF line 50 , e.g. the active pad of U.FL connectors needs to have a GND keep-out (i.e.
clearance, a void area) at least on the first inner layer to reduce parasitic capacitance to ground.

If integrated antennas are used, the RF terminations are represented by the integrated antennas themselves. The
following guidelines should be followed:


Use antennas designed by an antenna manufacturer, providing the best possible return loss (or VSWR).



Provide a ground plane large enough according to the relative integrated antenna requirements. The ground
plane of the application PCB can be reduced down to a minimum size that must be similar to one quarter of
a wavelength of the minimum frequency that must be radiated. As a numerical example,
Frequency = 750 MHz  Wavelength = 40 cm  Minimum GND plane size = 10 cm



It is highly recommended to strictly follow the detailed and specific guidelines provided by the antenna
manufacturer regarding correct installation and deployment of the antenna system, including PCB layout and
matching circuitry.



Further to the custom PCB and product restrictions, antennas may require a tuning to comply with all the
applicable required certification schemes. It is recommended to consult the antenna manufacturer for the
design-in guidelines for the antenna matching relative to the custom application.

Additionally, these recommendations regarding the antenna system placement must be followed:


Do not place antennas within a closed metal case.



Do not place the antennas in close vicinity to the end user since the emitted radiation in human tissue is limited
by regulatory requirements.



Place the antennas far from sensitive analog systems or employ countermeasures to reduce EMC issues.



Take care of interaction between co-located RF systems since the cellular transmitted power may interact or
disturb the performance of companion systems.



Place the two LTE antennas providing low Envelope Correlation Coefficient (ECC) between primary (ANT1)
and secondary (ANT2) antenna: the antenna 3D radiation patterns should have lobes in different directions.
The ECC between the primary and secondary antennas needs to be enough low to comply with the radiated
performance requirements specified by related certification schemes, as indicated in Table 9.



Place the two LTE antennas providing enough high isolation (see Table 9) between primary (ANT1) and
secondary (ANT2) antenna. The isolation depends on the distance between antennas (separation of at least a
quarter wavelength required for good isolation), antenna type (using antennas with different polarization
improves isolation), and the antenna 3D radiation patterns (uncorrelated patterns improve isolation).

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Examples of antennas
Table 32 lists some examples of possible internal on-board surface-mount antennas.
Manufacturer

Part Number

Product Name

Description

Taoglas

PA.710.A

Warrior

GSM / WCDMA / LTE SMD Antenna
698..960 MHz, 1710..2170 MHz, 2300..2400 MHz, 2490..2690 MHz
40.0 x 6.0 x 5.0 mm

Taoglas

PA.711.A

Warrior II

GSM / WCDMA / LTE SMD Antenna
Pairs with the Taoglas PA.710.A Warrior for LTE MIMO applications
698..960 MHz, 1710..2170 MHz, 2300..2400 MHz, 2490..2690 MHz
40.0 x 6.0 x 5.0 mm

Taoglas

PCS.06.A

Havok

GSM / WCDMA / LTE SMD Antenna
698..960 MHz, 1710..2170 MHz, 2500..2690 MHz
42.0 x 10.0 x 3.0 mm

Antenova

SR4L002

Lucida

GSM / WCDMA / LTE SMD Antenna
698..960 MHz, 1710..2170 MHz, 2300..2400 MHz, 2490..2690 MHz
35.0 x 8.5 x 3.2 mm

Ethertronics

P822601

Prestta

GSM / WCDMA / LTE SMD Antenna
698..960 MHz, 1710..2170 MHz, 2490..2700 MHz
50.0 x 8.0 x 3.2 mm

Ethertronics

P822602

GSM / WCDMA / LTE SMD Antenna
698..960 MHz, 1710..2170 MHz, 2490..2700 MHz
50.0 x 8.0 x 3.2 mm

Table 32: Examples of internal surface-mount antennas

Table 33 lists some examples of possible internal off-board PCB-type antennas with cable and connector.
Manufacturer

Part Number

Product Name

Description

Taoglas

FXUB63.07.0150C

Taoglas

FXUB66.07.0150C

Taoglas

FXUB70.A.07.C.001

GSM / WCDMA / LTE MIMO Antenna on flexible PCB with cable and U.FL
698..960 MHz, 1575.42 MHz, 1710..2170 MHz, 2400..2690 MHz
182.2 x 21.2 mm

Ethertronics

1002289

GSM / WCDMA / LTE Antenna on flexible PCB with cable and U.FL
698..960 MHz, 1710..2700 MHz
50.0 x 8.0 x 3.2 mm

EAD

FSQS35241-UF-10

GSM / WCDMA / LTE Antenna on flexible PCB with cable and U.FL
698..960 MHz, 1575.42 MHz, 1710..2170 MHz, 2400..2690 MHz
96.0 x 21.0 mm
Maximus

SQ7

GSM / WCDMA / LTE Antenna on flexible PCB with cable and U.FL
698..960 MHz, 1390..1435 MHz, 1575.42 MHz, 1710..2170 MHz,
2400..2700 MHz, 3400..3600 MHz, 4800..6000 MHz
120.2 x 50.4 mm

GSM / WCDMA / LTE Antenna on PCB with cable and U.FL
690..960 MHz, 1710..2170 MHz, 2500..2700 MHz
110.0 x 21.0 mm

Table 33: Examples of internal antennas with cable and connector

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Table 34 lists some examples of possible external antennas.
Manufacturer

Part Number

Product Name

Description

Taoglas

GSA.8827.A.101111

Phoenix

GSM / WCDMA / LTE adhesive-mount antenna with cable and SMA(M)
698..960 MHz, 1575.42 MHz, 1710..2170 MHz, 2490..2690 MHz
105 x 30 x 7.7 mm

Taoglas

TG.30.8112

Taoglas

MA241.BI.001

Laird Tech.

TRA6927M3PW-001

GSM / WCDMA / LTE screw-mount antenna with N-type(F)
698..960 MHz, 1710..2170 MHz, 2300..2700 MHz
83.8 x Ø 36.5 mm

Laird Tech.

CMS69273

GSM / WCDMA / LTE ceiling-mount antenna with cable and N-type(F)
698..960 MHz, 1575.42 MHz, 1710..2700 MHz
86 x Ø 199 mm

Laird Tech.

OC69271-FNM

GSM / WCDMA / LTE pole-mount antenna with N-type(M)
698..960 MHz, 1710..2690 MHz
248 x Ø 24.5 mm

Laird Tech.

CMD69273-30NM

GSM / WCDMA / LTE ceiling-mount MIMO antenna with cables & N-type(M)
698..960 MHz, 1710..2700 MHz
43.5 x Ø 218.7 mm

Pulse Electronics

WA700/2700SMA

GSM / WCDMA / LTE clip-mount MIMO antenna with cables and SMA(M)
698..960 MHz,1710..2700 MHz
149 x 127 x 5.1 mm

GSM / WCDMA / LTE swivel dipole antenna with SMA(M)
698..960 MHz, 1575.42 MHz, 1710..2170 MHz, 2400..2700 MHz
148.6 x 49 x 10 mm
Genesis

GSM / WCDMA / LTE MIMO 2in1 adhesive-mount combination antenna
waterproof IP67 rated with cable and SMA(M)
698..960 MHz, 1710..2170 MHz, 2400..2700 MHz
205.8 x 58 x 12.4 mm

Table 34: Examples of external antennas

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2.4.2 Antenna detection interface (ANT_DET)
2.4.2.1 Guidelines for ANT_DET circuit design
Figure 45 and Table 35 describe the recommended schematic / components for the antennas detection circuit that
must be provided on the application board and for the diagnostic circuit that must be provided on the antennas’
assembly to achieve primary and secondary antenna detection functionality.

LARA-R2 series
ANT2 62

Z0 = 50 ohm

C3
D2

ANT1 56

J2

L2

Z0 = 50 ohm

J1

L4

Radiating
Element

Z0 = 50 ohm

Diagnostic
Circuit

R3

C4

Antenna Cable

L1

ANT_DET 59

C5

Antenna Cable

Z0 = 50 ohm

C2

Radiating
Element

Z0 = 50 ohm

Z0 = 50 ohm

L3

Diagnostic
Circuit

Secondary Antenna Assembly

R2

R1
C1

D1

Application Board

Primary Antenna Assembly

Figure 45: Suggested schematic for the antenna detection circuit on the application board and the diagnostic circuit on the
antennas assembly
Reference

Description

Part Number - Manufacturer

C1

27 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H270J - Murata

C2, C3

33 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H330J - Murata

D1

Very Low Capacitance ESD Protection

PESD0402-140 - Tyco Electronics

D2

Ultra Low Capacitance ESD Protection

ESD0P2RF-02LRH - Infineon

L1, L2

68 nH Multilayer Inductor 0402 (SRF ~1 GHz)

LQG15HS68NJ02 - Murata

R1

10 k Resistor 0402 1% 0.063 W

RK73H1ETTP1002F - KOA Speer

J1, J2

SMA Connector 50  Through Hole Jack

SMA6251A1-3GT50G-50 - Amphenol

C4, C5

22 pF Capacitor Ceramic C0G 0402 5% 25 V

GRM1555C1H220J - Murata

L3, L4

68 nH Multilayer Inductor 0402 (SRF ~1 GHz)

LQG15HS68NJ02 - Murata

R2, R3

15 k Resistor for Diagnostic

Various Manufacturers

Table 35: Suggested components for the antenna detection circuit on the application board and the diagnostic circuit on the
antennas assembly

The antenna detection circuit and diagnostic circuit suggested in Figure 45 and Table 35 are explained here:


When antenna detection is forced by the AT+UANTR command, ANT_DET generates a DC current measuring
the resistance (R2 // R3) from the antenna connectors (J1, J2) provided on the application board to GND.



DC blocking capacitors are needed at the ANT1 / ANT2 pins (C2, C3) and at the antenna radiating element
(C4, C5) to decouple the DC current generated by the ANT_DET pin.



Choke inductors with a Self Resonance Frequency (SRF) in the range of 1 GHz are needed in series at the
ANT_DET pin (L1, L2) and in series at the diagnostic resistor (L3, L4), to avoid a reduction of the RF
performance of the system, improving the RF isolation of the load resistor.



Additional components (R1, C1 and D1 in Figure 45) are needed at the ANT_DET pin as ESD protection



The ANT1 / ANT2 pins must be connected to the antenna connector by means of a transmission line with
nominal characteristics impedance as close as possible to 50 .

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The DC impedance at the RF port for some antennas may be a DC open (e.g. linear monopole) or a DC short to
reference GND (e.g. PIFA antenna). For those antennas, without the diagnostic circuit of Figure 45, the measured
DC resistance is always at the limits of the measurement range (respectively open or short), and there is no means
to distinguish between a defect on the antenna path with similar characteristics (respectively: removal of linear
antenna or RF cable shorted to GND for a PIFA antenna).
Furthermore, any other DC signal injected to the RF connection from an ANT connector to a radiating element will
alter the measurement and produce invalid results for antenna detection.
It is recommended to use an antenna with a built-in diagnostic resistor in the range from 5 k to 30 k to
assure good antenna detection functionality and avoid a reduction of module RF performance. The choke
inductor should exhibit a parallel Self Resonance Frequency (SRF) in the range of 1 GHz to improve the RF
isolation of load resistor.
For example:
Consider an antenna with a built-in DC load resistor of 15 k. Using the +UANTR AT command, the module
reports the resistance value evaluated from the antenna connector provided on the application board to GND:


Reported values close to the used diagnostic resistor nominal value (i.e. values from 13 k to 17 k if a 15 k
diagnostic resistor is used) indicate that the antenna is properly connected.



Values close to the measurement range maximum limit (approximately 50 k) or an open-circuit “over range”
report (see the u-blox AT Commands Manual [2]) means that that the antenna is not connected or the RF
cable is broken.



Reported values below the measurement range minimum limit (1 k) highlights a short to GND at the antenna
or along the RF cable.



Measurement inside the valid measurement range and outside the expected range may indicate an improper
connection, damaged antenna or wrong value of antenna load resistor for diagnostics.



The reported value could differ from the real resistance value of the diagnostic resistor mounted inside the
antenna assembly due to antenna cable length, antenna cable capacity or the measurement method used.
If the primary / secondary antenna detection function is not required by the customer application, the
ANT_DET pin can be left not connected and the ANT1 / ANT2 pins can be directly connected to the related
antenna connector by means of a 50  transmission line as described in Figure 44.

2.4.2.2 Guidelines for ANT_DET layout design
The recommended layout for the primary antenna detection circuit to be provided on the application board to
achieve the primary antenna detection functionality, implementing the recommended schematic described in
Figure 45 and Table 35, is explained here:


The ANT1 / ANT2 pins must be connected to the antenna connector by means of a 50  transmission line,
implementing the design guidelines described in section 2.4.1 and the recommendations of the SMA
connector manufacturer.



DC blocking capacitor at ANT1 / ANT2 pins (C2, C3) must be placed in series to the 50  RF line.



The ANT_DET pin must be connected to the 50  transmission line by means of a sense line.



Choke inductors in series at the ANT_DET pin (L1, L2) must be placed so that one pad is on the 50 
transmission line and the other pad represents the start of the sense line to the ANT_DET pin.



The additional components (R1, C1 and D1) on the ANT_DET line must be placed as ESD protection.

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2.5 SIM interface
2.5.1.1

Guidelines for SIM circuit design

Guidelines for SIM cards, SIM connectors and SIM chips selection
The ISO/IEC 7816, the ETSI TS 102 221 and the ETSI TS 102 671 specifications define the physical, electrical and
functional characteristics of Universal Integrated Circuit Cards (UICC) which contains the Subscriber Identification
Module (SIM) integrated circuit that securely stores all the information needed to identify and authenticate
subscribers over the cellular network.
Removable UICC / SIM card contacts mapping is defined by ISO/IEC 7816 and ETSI TS 102 221 as follows:


Contact C1 = VCC (Supply)

 It must be connected to VSIM



Contact C2 = RST (Reset)

 It must be connected to SIM_RST



Contact C3 = CLK (Clock)

 It must be connected to SIM_CLK



Contact C4 = AUX1 (Auxiliary contact)

 It must be left not connected



Contact C5 = GND (Ground)

 It must be connected to GND



Contact C6 = VPP (Programming supply)

 It can be left not connected



Contact C7 = I/O (Data input/output)

 It must be connected to SIM_IO

 Contact C8 = AUX2 (Auxiliary contact)
 It must be left not connected
A removable SIM card can have 6 contacts (C1, C2, C3, C5, C6, C7) or 8 contacts, also including the auxiliary
contacts C4 and C8. Only 6 contacts are required and must be connected to the module SIM interface.
Removable SIM cards are suitable for applications requiring a change of SIM card during the product lifetime.
A SIM card holder can have 6 or 8 positions if a mechanical card presence detector is not provided, or it can have
6+2 or 8+2 positions if two additional pins relative to the normally-open mechanical switch integrated in the SIM
connector for the mechanical card presence detection are provided. Select a SIM connector providing 6+2 or 8+2
positions if the optional SIM detection feature is required by the custom application, otherwise a connector without
an integrated mechanical presence switch can be selected.
Solderable UICC / SIM chip contact mapping (M2M UICC Form Factor) is defined by ETSI TS 102 671 as:


Case Pin 8 = UICC Contact C1 = VCC (Supply)

 It must be connected to VSIM



Case Pin 7 = UICC Contact C2 = RST (Reset)

 It must be connected to SIM_RST



Case Pin 6 = UICC Contact C3 = CLK (Clock)

 It must be connected to SIM_CLK



Case Pin 5 = UICC Contact C4 = AUX1 (Aux.contact)  It must be left not connected



Case Pin 1 = UICC Contact C5 = GND (Ground)

 It must be connected to GND



Case Pin 2 = UICC Contact C6 = VPP (Progr. supply)

 It can be left not connected



Case Pin 3 = UICC Contact C7 = I/O (Data I/O)

 It must be connected to SIM_IO

 Case Pin 4 = UICC Contact C8 = AUX2 (Aux. contact)  It must be left not connected
A solderable SIM chip has 8 contacts and can also include the auxiliary contacts C4 and C8 for other uses, but only
6 contacts are required and must be connected to the module SIM card interface as described above.
Solderable SIM chips are suitable for M2M applications where it is not required to change the SIM once installed.

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Guidelines for single SIM card connection without detection
A removable SIM card placed in a SIM card holder must be connected to the SIM card interface of LARA-R2 series
modules as described in Figure 46, where the optional SIM detection feature is not implemented.
Follow these guidelines connecting the module to a SIM connector without SIM presence detection:


Connect the UICC / SIM contacts C1 (VCC) to the VSIM pin of the module.



Connect the UICC / SIM contact C7 (I/O) to the SIM_IO pin of the module.



Connect the UICC / SIM contact C3 (CLK) to the SIM_CLK pin of the module.



Connect the UICC / SIM contact C2 (RST) to the SIM_RST pin of the module.



Connect the UICC / SIM contact C5 (GND) to ground.



Provide a 100 nF bypass capacitor (e.g. Murata GRM155R71C104K) at the SIM supply line (VSIM), close to
the related pad of the SIM connector, to prevent digital noise.



Provide a bypass capacitor of about 22 pF to 47 pF (e.g. Murata GRM1555C1H470J) on each SIM line (VSIM,
SIM_CLK, SIM_IO, SIM_RST), very close to each related pad of the SIM connector, to prevent RF coupling
especially when the RF antenna is placed closer than 10 - 30 cm from the SIM card holder.



Provide a low capacitance (i.e. less than 10 pF) ESD protection (e.g. Tyco Electronics PESD0402-140) on each
externally accessible SIM line, close to each related pad of the SIM connector: the ESD sensitivity rating of the
SIM interface pins is 1 kV (HBM), so that, according to the EMC/ESD requirements of the custom application,
a higher protection level can be required if the lines are externally accessible on the application device.



Limit the capacitance and series resistance on each signal of the SIM interface (SIM_CLK, SIM_IO, SIM_RST)
to match the SIM interface specifications requirements (27.7 ns is the maximum allowed rise time on the
SIM_CLK line, 1.0 µs is the maximum allowed rise time on the SIM_IO and SIM_RST lines).

LARA-R2 series
V_INT

4

TP

SIM CARD
HOLDER

GPIO5 42

VPP (C6)

VSIM 41

VCC (C1)

SIM_IO 39

IO (C7)

SIM_CLK 38

CLK (C3)

SIM_RST 40

RST (C2)
C1

C2

C3 C4

GND (C5)
C5

D1 D2 D3 D4

C C C C
5 6 7 8
C C C C
1 2 3 4

SIM Card
Bottom View
(contacts side)

J1

Figure 46: Application circuit for the connection to a single removable SIM card, with SIM detection not implemented
Reference

Description

Part Number - Manufacturer

C1, C2, C3, C4

47 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H470JA01 - Murata

C5

100 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71C104KA01 - Murata

D1, D2, D3, D4

Very Low Capacitance ESD Protection

PESD0402-140 - Tyco Electronics

J1

SIM Card Holder
6 positions, without card presence switch

Various Manufacturers,
C707 10M006 136 2 - Amphenol

Table 36: Example of components for the connection to a single removable SIM card, with SIM detection not implemented

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Guidelines for single SIM chip connection
A solderable SIM chip (M2M UICC Form Factor) must be connected the SIM card interface of LARA-R2 series
modules as described in Figure 47.
Follow these guidelines, connecting the module to a solderable SIM chip without SIM presence detection:


Connect the UICC / SIM contacts C1 (VCC) to the VSIM pin of the module.



Connect the UICC / SIM contact C7 (I/O) to the SIM_IO pin of the module.



Connect the UICC / SIM contact C3 (CLK) to the SIM_CLK pin of the module.



Connect the UICC / SIM contact C2 (RST) to the SIM_RST pin of the module.



Connect the UICC / SIM contact C5 (GND) to ground.



Provide a 100 nF bypass capacitor (e.g. Murata GRM155R71C104K) at the SIM supply line (VSIM) close to the
related pad of the SIM chip, to prevent digital noise.



Provide a bypass capacitor of about 22 pF to 47 pF (e.g. Murata GRM1555C1H470J) on each SIM line (VSIM,
SIM_CLK, SIM_IO, SIM_RST), to prevent RF coupling especially in case the RF antenna is placed closer than
10 - 30 cm from the SIM card holder.



Limit the capacitance and series resistance on each signal of the SIM interface (SIM_CLK, SIM_IO, SIM_RST)
to match the SIM specifications requirements (27.7 ns is the maximum allowed rise time on the SIM_CLK line,
1.0 µs is the maximum allowed rise time on the SIM_IO and SIM_RST lines).

LARA-R2 series
V_INT

TP

4

SIM CHIP

GPIO5 42
2

VSIM 41

8

SIM_IO 39

3

SIM_CLK 38

6

SIM_RST

7

40

1
C1 C2 C3 C4

C5

VPP (C6)
VCC (C1)
8 C1

C5 1

7 C2

C6 2

6 C3

C7 3

CLK (C3)

5 C4

C8 4

RST (C2)

SIM Chip
Bottom View
(contacts side)

IO (C7)

GND (C5)

U1

Figure 47: Application circuit for the connection to a single solderable SIM chip, with SIM detection not implemented
Reference

Description

Part Number - Manufacturer

C1, C2, C3, C4

47 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H470JA01 - Murata

C5

100 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71C104KA01 - Murata

U1

SIM chip (M2M UICC Form Factor)

Various Manufacturers

Table 37: Example of components for the connection to a single solderable SIM chip, with SIM detection not implemented

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Guidelines for single SIM card connection with detection
A removable SIM card placed in a SIM card holder must be connected to the SIM card interface of LARA-R2 series
modules as described in Figure 48, where the optional SIM card detection feature is implemented.
Follow these guidelines connecting the module to a SIM connector implementing SIM presence detection:


Connect the UICC / SIM contacts C1 (VCC) to the VSIM pin of the module.



Connect the UICC / SIM contact C7 (I/O) to the SIM_IO pin of the module.



Connect the UICC / SIM contact C3 (CLK) to the SIM_CLK pin of the module.



Connect the UICC / SIM contact C2 (RST) to the SIM_RST pin of the module.



Connect the UICC / SIM contact C5 (GND) to ground.



Connect one pin of the normally-open mechanical switch integrated in the SIM connector (e.g. the SW2 pin
as described in Figure 48) to the GPIO5 input pin of the module.



Connect the other pin of the normally-open mechanical switch integrated in the SIM connector (e.g. the SW1
pin as described in Figure 48) to the V_INT 1.8 V supply output of the module by means of a strong (e.g.
1 k) pull-up resistor, as the R1 resistor in Figure 48.



Provide a 100 nF bypass capacitor (e.g. Murata GRM155R71C104K) at the SIM supply line (VSIM), close to
the related pad of the SIM connector, to prevent digital noise.



Provide a bypass capacitor of about 22 pF to 47 pF (e.g. Murata GRM1555C1H470J) on each SIM line (VSIM,
SIM_CLK, SIM_IO, SIM_RST), very close to each related pad of the SIM connector, to prevent RF coupling
especially in case the RF antenna is placed closer than 10 - 30 cm from the SIM card holder.



Provide a low capacitance (i.e. less than 10 pF) ESD protection (e.g. Tyco Electronics PESD0402-140) on each
externally accessible SIM line, close to each related pad of the SIM connector: the ESD sensitivity rating of SIM
interface pins is 1 kV (HBM according to JESD22-A114), so that, according to the EMC/ESD requirements of
the custom application, higher protection level can be required if the lines are externally accessible.



Limit the capacitance and series resistance on each SIM signal to match the SIM specifications requirements
(27.7 ns = max allowed rise time on SIM_CLK, 1.0 µs = max allowed rise time on SIM_IO and SIM_RST).
SIM CARD
HOLDER

LARA-R2 series
V_INT

4

TP

SW1

R1

GPIO5 42

SW2

R2

VPP (C6)

VSIM 41

VCC (C1)

SIM_IO 39

IO (C7)

SIM_CLK 38

CLK (C3)

SIM_RST 40

RST (C2)
C1 C2 C3 C4

C5

GND (C5)
D1 D2 D3 D4 D5 D6

C C C C
5 6 7 8

C C C C
1 2 3 4

SIM Card
Bottom View
(contacts side)

J1

Figure 48: Application circuit for the connection to a single removable SIM card, with SIM detection implemented
Reference

Description

Part Number - Manufacturer

C1, C2, C3, C4

47 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H470JA01 - Murata

C5

100 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71C104KA01 - Murata

D1 – D6

Very Low Capacitance ESD Protection

PESD0402-140 - Tyco Electronics

R1

1 k Resistor 0402 5% 0.1 W

RC0402JR-071KL - Yageo Phycomp

R2

470 k Resistor 0402 5% 0.1 W

RC0402JR-07470KL- Yageo Phycomp

J1

SIM Card Holder
6 + 2 positions, with card presence switch

Various Manufacturers,
CCM03-3013LFT R102 - C&K Components

Table 38: Example of components for the connection to a single removable SIM card, with SIM detection implemented

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Guidelines for dual SIM card / chip connection
Two SIM cards / chips can be connected to the SIM interface of LARA-R2 series modules as illustrated in Figure 49.
LARA-R2 series modules do not support the usage of two SIMs at the same time, but two SIMs can be populated
on the application board, providing a proper switch to connect only the first or only the second SIM at a time to
the SIM interface of the modules, as described in Figure 49.
LARA-R2 series modules support SIM hot insertion / removal on the GPIO5 pin, to enable / disable SIM interface
upon detection of external SIM card physical insertion / removal: if the feature is enabled using the specific AT
commands (see sections 1.8.2 and 1.12, and the u-blox AT Commands Manual [2], +UGPIOC, +UDCONF=50
commands), the switch from the first SIM to the second SIM can be properly done when a Low logic level is present
on the GPIO5 pin (“SIM not inserted” = SIM interface not enabled), without the necessity of a module re-boot,
so that the SIM interface will be re-enabled by the module to use the second SIM when a high logic level is reapplied on the GPIO5 pin.
In the application circuit example represented in Figure 49, the application processor will drive the SIM switch
using its own GPIO to properly select the SIM that is used by the module. Another GPIO may be used to handle
the SIM hot insertion / removal function of LARA-R2 series modules, which can also be handled by other external
circuits or by the cellular module GPIO according to the application requirements.
The dual SIM connection circuit described in Figure 49 can be implemented for SIM chips as well, providing proper
connection between SIM switch and SIM chip as described in Figure 47.
If it is required to switch between more than 2 SIM, a circuit similar to the one described in Figure 49 can be
implemented: for a 4 SIM circuit, using proper 4-throw switch instead of the suggested 2-throw switches.
Follow these guidelines connecting the module to two SIM connectors:


Use a proper low on resistance (i.e. few ohms) and low on capacitance (i.e. few pF) 2-throw analog switch
(e.g. Fairchild FSA2567) as SIM switch to ensure high-speed data transfer according to SIM requirements.



Connect the contacts C1 (VCC) of the two UICC / SIM to the VSIM pin of the module by means of a proper
2-throw analog switch (e.g. Fairchild FSA2567).



Connect the contact C7 (I/O) of the two UICC / SIM to the SIM_IO pin of the module by means of a proper
2-throw analog switch (e.g. Fairchild FSA2567).



Connect the contact C3 (CLK) of the two UICC / SIM to the SIM_CLK pin of the module by means of a proper
2-throw analog switch (e.g. Fairchild FSA2567).



Connect the contact C2 (RST) of the two UICC / SIM to the SIM_RST pin of the module by means of a proper
2-throw analog switch (e.g. Fairchild FSA2567).



Connect the contact C5 (GND) of the two UICC / SIM to ground.



Provide a 100 nF bypass capacitor (e.g. Murata GRM155R71C104K) at the SIM supply line (VSIM), close to
the related pad of the two SIM connectors, to prevent digital noise.



Provide a bypass capacitor of about 22 pF to 47 pF (e.g. Murata GRM1555C1H470J) on each SIM line (VSIM,
SIM_CLK, SIM_IO, SIM_RST), very close to each related pad of the two SIM connectors, to prevent RF
coupling especially in case the RF antenna is placed closer than 10 - 30 cm from the SIM card holders.



Provide a very low capacitance (i.e. less than 10 pF) ESD protection (e.g. Tyco Electronics PESD0402-140) on
each externally accessible SIM line, close to each related pad of the two SIM connectors, according to the
EMC/ESD requirements of the custom application.



Limit capacitance and series resistance on each SIM signal to match the SIM specifications requirements (27.7
ns = max allowed rise time on SIM_CLK, 1.0 µs = max allowed rise time on SIM_IO and SIM_RST).

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FIRST
SIM CARD

LARA-R2 series

VSIM 41

3V8

VPP (C6)

4PDT
C11
Analog
Switch
VCC
1VSIM
VSIM
2VSIM

VCC (C1)

DAT

1DAT
2DAT

SIM_CLK 38

CLK

1CLK
2CLK

SIM_RST 40

RST

1RST
2RST

SIM_IO 39

IO (C7)
CLK (C3)
RST (C2)

C1 C2 C3 C4

C5

GND (C5)
D1 D2 D3 D4

J1

SECOND
SIM CARD
VPP (C6)

SEL
GND

VCC (C1)

U1

IO (C7)
CLK (C3)

Application
Processor

RST (C2)

GPIO
R1

C6 C7 C8 C9 C10

GND (C5)
D5 D6 D7 D8

J2

Figure 49: Application circuit for the connection to two removable SIM cards, with SIM detection not implemented
Reference

Description

Part Number - Manufacturer

C1 – C4, C6 – C9

33 pF Capacitor Ceramic C0G 0402 5% 25 V

GRM1555C1H330JZ01 - Murata

C5, C10, C11

100 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71C104KA01 - Murata

D1 – D8

Very Low Capacitance ESD Protection

PESD0402-140 - Tyco Electronics

R1

47 kΩ Resistor 0402 5% 0.1 W

RC0402JR-0747KL- Yageo Phycomp

J1, J2

SIM Card Holder
6 positions, without card presence switch

Various Manufacturers,
C707 10M006 136 2 - Amphenol

U1

4PDT Analog Switch,
with Low On-Capacitance and Low On-Resistance

FSA2567 - Fairchild Semiconductor

Table 39: Example of components for the connection to two removable SIM cards, with SIM detection not implemented

2.5.1.2 Guidelines for SIM layout design
The layout of the SIM card interface lines (VSIM, SIM_CLK, SIM_IO, SIM_RST) may be critical if the SIM card is
placed far away from the LARA-R2 series modules or in close proximity to the RF antenna: these two cases should
be avoided or at least mitigated as described below.
In the first case, the long connection can cause the radiation of some harmonics of the digital data frequency as
any other digital interface: keep the traces short and avoid coupling with RF line or sensitive analog inputs.
In the second case, the same harmonics can be picked up and create self-interference that can reduce the sensitivity
of cellular receiver channels whose carrier frequency is coincidental with harmonic frequencies: placing the RF
bypass capacitors suggested in Figure 48 near the SIM connector will mitigate the problem.
In addition, since the SIM card is typically accessed by the end user, it can be subjected to ESD discharges: add
adequate ESD protection as suggested in Figure 48 to protect the module SIM pins near the SIM connector.
Limit the capacitance and series resistance on each SIM signal to match the SIM specifications: the connections
should always be kept as short as possible.
Avoid coupling with any sensitive analog circuit, since the SIM signals can cause the radiation of some harmonics
of the digital data frequency.

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2.6 Data communication interfaces
2.6.1 UART interface
2.6.1.1

Guidelines for UART circuit design

Providing the full RS-232 functionality (using the complete V.24 link)
If RS-232 compatible signal levels are needed, two different external voltage translators can be used to provide
full RS-232 (9 lines) functionality: e.g. using the Texas Instruments SN74AVC8T245PW for the translation from
1.8 V to 3.3 V, and the Maxim MAX3237E for the translation from 3.3 V to RS-232 compatible signal level.
If a 1.8 V Application Processor (DTE) is used and complete RS-232 functionality is required, then the complete
1.8 V UART interface of the module (DCE) should be connected to a 1.8 V DTE, as described in Figure 50.
Application Processor
(1.8V DTE)

LARA-R2 series
(1.8V DCE)

TxD
RxD

0Ω

TP

0Ω

TP

0Ω

TP

12 TXD
13 RXD

RTS

10 RTS

CTS
DTR

11 CTS
9

DTR

DSR

6

DSR

RI

7

RI

8

DCD

0Ω

DCD

TP

GND

GND

Figure 50: UART interface application circuit with complete V.24 link in DTE/DCE serial communication (1.8 V DTE)

If a 3.0 V Application Processor (DTE) is used, then it is recommended to connect the 1.8 V UART interface of the
module (DCE) by means of appropriate unidirectional voltage translators using the module V_INT output as a
1.8 V supply for the voltage translators on the module side, as illustrated in Figure 51.
Application Processor
(3.0V DTE)

Unidirectional
Voltage Translator

3V0

VCC

C1

VCCA
DIR1
DIR3

LARA-R2 series
(1.8V DCE)

1V8

TP

VCCB

C2
0Ω

TP

0Ω

TP

4

V_INT

TxD

A1

B1

RxD

A2

B2

RTS

A3

B3

10 RTS

CTS

A4

B4

11 CTS

DIR2
DIR4

C3

VCCA

13 RXD

OE
GND

U1
Unidirectional
Voltage Translator

3V0

12 TXD

VCCB

DIR1

DTR

A1

B1

DSR

A2

B2

RI

A3

B3

DCD

A4

GND

DIR2
DIR3
DIR4

B4

1V8
C4
0Ω

0Ω

OE
GND

TP

TP

9

DTR

6

DSR

7

RI

8

DCD

GND

U2

Figure 51: UART interface application circuit with complete V.24 link in DTE/DCE serial communication (3.0 V DTE)
Reference

Description

Part Number - Manufacturer

C1, C2, C3, C4

100 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R61A104KA01 - Murata

U1, U2

Unidirectional Voltage Translator

SN74AVC4T774 - Texas Instruments

19

Table 40: Component for UART application circuit with complete V.24 link in DTE/DCE serial communication (3.0 V DTE)

19

Voltage translator providing partial power down feature so that the DTE 3.0 V supply can be also ramped up before V_INT 1.8 V supply

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Providing the TXD, RXD, RTS, CTS and DTR lines only (not using the complete V.24 link)
If the functionality of the DSR, DCD and RI lines is not required, or the lines are not available:


Leave the DSR, DCD and RI lines of the module floating, with a test-point on DCD.

If RS-232 compatible signal levels are needed, two different external voltage translators (e.g. Maxim MAX3237E
and Texas Instruments SN74AVC4T774) can be used. The Texas Instruments chips provide the translation from 1.8
V to 3.3 V, while the Maxim chip provides the translation from 3.3 V to RS-232 compatible signal level.
Figure 52 illustrates the circuit that should be implemented as if a 1.8 V Application Processor (DTE) is used, given
that the DTE will behave properly regardless of the DSR input setting.
Application Processor
(1.8V DTE)

LARA-R2 series
(1.8V DCE)

TxD
RxD
RTS
CTS

0Ω

TP

0Ω
0Ω

TP
TP

0Ω

TP

DTR

15 TXD

16 RXD
13 RTS
14 CTS
12 DTR

DSR

9

RI

DSR

10 RI

DCD

11 DCD

GND

GND

Figure 52: UART interface application circuit with partial V.24 link (6-wire) in the DTE/DCE serial communication (1.8 V DTE)

If a 3.0 V Application Processor (DTE) is used, then it is recommended to connect the 1.8 V UART interface of the
module (DCE) by means of appropriate unidirectional voltage translators using the module V_INT output as a
1.8 V supply for the voltage translators on the module side, as described in Figure 53, given that the DTE will
behave properly regardless of the DSR input setting.
Application Processor
(3.0V DTE)
VCC

Unidirectional
Voltage Translator

3V0

VCCA
DIR1
DIR3

C1

4

V_INT

15

TXD

16

RXD

13

RTS

14

CTS

B1
B2

12

DTR

9

DSR

OE
GND

10

RI

11

DCD

VCCB
C2

TxD

A1

B1

RxD

A2

B2

RTS

A3

B3

CTS

A4

B4

DIR2
DIR4

LARA-R2 series
(1.8V DCE)

1V8

0Ω

TP

0Ω
0Ω

TP
TP

0Ω

TP

OE
GND

U1
Unidirectional
Voltage Translator

3V0
C3

DTR
DSR

VCCA

VCCB

DIR1

DIR2

A1
A2

RI

DCD

1V8
C4

U2

GND

GND

Figure 53: UART interface application circuit with partial V.24 link (6-wire) in DTE/DCE serial communication (3.0 V DTE)
Reference

Description

Part Number - Manufacturer

C1, C2, C3, C4

100 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R61A104KA01 - Murata

U1

Unidirectional Voltage Translator

SN74AVC4T774 - Texas Instruments

U2

Unidirectional Voltage Translator

SN74AVC2T245 - Texas Instruments

20
20

Table 41: Component for UART application circuit with partial V.24 link (6-wire) in DTE/DCE serial communication (3.0 V DTE)

20

Voltage translator providing partial power down feature so that the DTE 3.0 V supply can be also ramped up before V_INT 1.8 V supply

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Providing the TXD, RXD, RTS and CTS lines only (not using the complete V.24 link)


Connect the module DTR input to GND using a 0  series resistor, since it may be useful to set DTR active if
not specifically handled (see the u-blox AT Commands Manual [2], &D, S0, +CSGT, +CNMI AT commands)



Leave the DSR, DCD and RI lines of the module floating, with a test-point on DCD

If RS-232 compatible signal levels are needed, the Maxim MAX13234E voltage level translator can be used. This
chip translates voltage levels from 1.8 V (module side) to the RS-232 standard.
If a 1.8 V Application Processor is used, the circuit should be implemented as described in Figure 54.
Application Processor
(1.8V DTE)

LARA-R2 series
(1.8V DCE)

TxD
RxD

0Ω

TP

0Ω

TP

12 TXD
13

RXD

RTS

10

RTS

CTS

11 CTS

0Ω

DTR

TP

DSR
RI

TP

DCD

9

DTR

6

DSR

7

RI

8

DCD

GND

GND

Figure 54: UART interface application circuit with partial V.24 link (5-wire) in the DTE/DCE serial communication (1.8 V DTE)

If a 3.0 V Application Processor (DTE) is used, then it is recommended to connect the 1.8 V UART interface of the
module (DCE) by means of appropriate unidirectional voltage translators using the module V_INT output as 1.8 V
supply for the voltage translators on the module side, as described in Figure 55.
Application Processor
(3.0V DTE)
VCC

Unidirectional
Voltage Translator

3V0
C1

VCCA
DIR1
DIR3

VCCB

LARA-R2 series
(1.8V DCE)

1V8

TP
C2
0Ω

TP

0Ω

TP

4

V_INT

TxD

A1

B1

RxD

A2

B2

RTS

A3

B3

10 RTS

CTS

A4

B4

11 CTS

DIR2
DIR4
U1

DTR

12 TXD
13 RXD

OE
GND
0Ω

TP

9

DTR

DSR

6

DSR

RI

7

RI

8

DCD

TP

DCD
GND

GND

Figure 55: UART interface application circuit with partial V.24 link (5-wire) in DTE/DCE serial communication (3.0 V DTE)
Reference

Description

Part Number - Manufacturer

C1, C2

100 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R61A104KA01 - Murata

U1

Unidirectional Voltage Translator

SN74AVC4T774 - Texas Instruments

21

Table 42: Component for UART application circuit with partial V.24 link (5-wire) in DTE/DCE serial communication (3.0 V DTE)

21

Voltage translator providing partial power down feature so that the DTE 3.0 V supply can be also ramped up before V_INT 1.8 V supply

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Providing the TXD and RXD lines only (not using the complete V24 link)
If the functionality of the CTS, RTS, DSR, DCD, RI and DTR lines is not required in the application, or the lines are
not available:


Connect the module RTS input line to GND or to the CTS output line of the module: since the module requires
RTS active (low electrical level) if HW flow-control is enabled (AT&K3, which is the default setting).



Connect the module DTR input to GND using a 0  series resistor, since it may be useful to set DTR active if
not specifically handled (see the u-blox AT Commands Manual [2], &D, S0, +CSGT, +CNMI AT commands)



Leave the DSR, DCD and RI lines of the module floating, with a test-point on DCD

If RS-232 compatible signal levels are needed, the Maxim MAX13234E voltage level translator can be used. This
chip translates voltage levels from 1.8 V (module side) to the RS-232 standard.
If a 1.8 V Application Processor (DTE) is used, the circuit that should be implemented as described in Figure 56:
Application Processor
(1.8V DTE)

LARA-R2 series
(1.8V DCE)

TxD

0Ω

TP

0Ω

TP

12

TXD

13

RXD

RTS

10

RTS

CTS

11

CTS

9

DTR

6

DSR

7

RI

8

DCD

RxD

0Ω

DTR

TP

DSR
RI

TP

DCD
GND

GND

Figure 56: UART interface application circuit with partial V.24 link (3-wire) in the DTE/DCE serial communication (1.8 V DTE)

If a 3.0 V Application Processor (DTE) is used, then it is recommended to connect the 1.8 V UART interface of the
module (DCE) by means of appropriate unidirectional voltage translators using the module V_INT output as 1.8 V
supply for the voltage translators on the module side, as described in Figure 57.
Application Processor
(3.0V DTE)
VCC

Unidirectional
Voltage Translator

3V0

C1

VCCA

1V8

TP

VCCB

4

C2

DIR1

TxD

A1

B1

RxD

A2

B2

DIR2

LARA-R2 series
(1.8V DCE)

0Ω

TP

0Ω

TP

V_INT

12 TXD
13 RXD

OE
GND

U1

RTS
CTS
DTR

10 RTS
0Ω

11 CTS
TP

DSR
RI
DCD
GND

TP

9

DTR

6

DSR

7

RI

8

DCD
GND

Figure 57: UART interface application circuit with partial V.24 link (3-wire) in DTE/DCE serial communication (3.0 V DTE)

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Reference

Description

Part Number - Manufacturer

C1, C2

100 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R61A104KA01 - Murata

U1

Unidirectional Voltage Translator

SN74AVC2T245 - Texas Instruments

22

Table 43: Component for UART application circuit with partial V.24 link (3-wire) in DTE/DCE serial communication (3.0 V DTE)

Additional considerations
If a 3.0 V Application Processor (DTE) is used, the voltage scaling from any 3.0 V output of the DTE to the apposite
1.8 V input of the module (DCE) can be implemented, as an alternative low-cost solution, by means of an
appropriate voltage divider. Consider the value of the pull-up integrated at the input of the module (DCE) for the
correct selection of the voltage divider resistance values and mind that any DTE signal connected to the module
must be tri-stated or set low when the module is in power-down mode and during the module power-on sequence
(at least until the activation of the V_INT supply output of the module), to avoid latch-up of circuits and allow a
proper boot of the module (see the remark below).
Moreover, the voltage scaling from any 1.8 V output of the cellular module (DCE) to the apposite 3.0 V input of
the Application Processor (DTE) can be implemented by means of an appropriate low-cost non-inverting buffer
with open drain output. The non-inverting buffer should be supplied by the V_INT supply output of the cellular
module. Consider the value of the pull-up integrated at each input of the DTE (if any) and the baud rate required
by the application for the appropriate selection of the resistance value for the external pull-up biased by the
application processor supply rail.
If power saving is enabled, the application circuit with the TXD and RXD lines only is not recommended.
During command mode, the DTE must send to the module a wake-up character or a dummy “AT” before
each command line (see section 1.9.1.4 for the complete description), but during data mode, the wake-up
character or the dummy “AT” would affect the data communication.
Do not apply voltage to any UART interface pin before the switch-on of the UART supply source (V_INT),
to avoid latch-up of circuits and allow a proper boot of the module. If the external signals connected to the
cellular module cannot be tri-stated or set low, insert a multi-channel digital switch (e.g. TI
SN74CB3Q16244, TS5A3159, or TS5A63157) between the two-circuit connections and set to high
impedance before V_INT switch-on.
The ESD sensitivity rating of the UART interface pins is 1 kV (Human Body Model according to JESD22-A114).
A higher protection level could be required if the lines are externally accessible and it can be achieved by
mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) close to the accessible points.
If the UART interface pins are not used, they can be left unconnected on the application board, but it is
recommended to provide accessible test points directly connected to the TXD, RXD, DTR and DCD pins for
diagnostic purposes, in particular providing a 0  series jumper on each line to detach each UART pin of
the module from the DTE application processor.

2.6.1.2 Guidelines for UART layout design
The UART serial interface requires the same considerations regarding electro-magnetic interference as any other
digital interface. Keep the traces short and avoid coupling with RF line or sensitive analog inputs, since the signals
can cause the radiation of some harmonics of the digital data frequency.

22

Voltage translator providing partial power down feature so that the DTE 3.0 V supply can be also ramped up before V_INT 1.8 V supply

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2.6.2 USB interface
2.6.2.1 Guidelines for USB circuit design
The USB_D+ and USB_D- lines carry the USB serial data and signaling. The lines are used in single-ended mode
for full speed signaling handshake, as well as in differential mode for high speed signaling and data transfer.
USB pull-up or pull-down resistors and external series resistors on USB_D+ and USB_D- lines as required by the
USB 2.0 specification [9] are part of the module USB pins driver and do not need to be externally provided.
The USB interface of the module is enabled only if a valid high logic level is detected by the VUSB_DET input (see
the LARA-R2 series Data Sheet [1]). Neither the USB interface, nor the whole module is supplied by the VUSB_DET
input: the VUSB_DET senses the USB supply voltage and absorbs few microamperes.
Routing the USB pins to a connector, they will be externally accessible on the application device. According to the
EMC/ESD requirements of the application, an additional ESD protection device with very low capacitance should
be provided close to the accessible point on the line connected to this pin, as described in Figure 58 and Table 44.
The USB interface pins ESD sensitivity rating is 1 kV (Human Body Model according to JESD22-A114F).
A higher protection level could be required if the lines are externally accessible and it can be achieved by
mounting a very low capacitance (i.e. less or equal to 1 pF) ESD protection (e.g. Tyco Electronics PESD0402140 ESD protection device) on the lines connected to these pins, close to accessible points.
The USB pins of the modules can be directly connected to the USB host application processor without additional
ESD protections if they are not externally accessible or according to EMC/ESD requirements.

USB DEVICE
CONNECTOR

LARA-R2 series

VBUS

17

VUSB_DET

D+

29

D-

28

GND

D1 D2

D3

C1

USB HOST
PROCESSOR

LARA-R2 series

VBUS / GPIO

17

VUSB_DET

USB_D+

D+

29

USB_D+

USB_D-

D-

28

USB_D-

GND

GND

C1

GND

Figure 58: USB Interface application circuits
Reference

Description

Part Number - Manufacturer

C1

100 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R61A104KA01 - Murata

D1, D2, D3

Very Low Capacitance ESD Protection

PESD0402-140 - Tyco Electronics

Table 44: Component for USB application circuits

If the USB interface pins are not used, they can be left unconnected on the application board, but it is
recommended to provide accessible test points directly connected to the VUSB_DET, USB_D+, USB_Dpins.

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2.6.2.2 Guidelines for USB layout design
The USB_D+ / USB_D- lines require accurate layout design to achieve reliable signaling at the high speed data
rate (up to 480 Mb/s) supported by the USB serial interface.
The characteristic impedance of the USB_D+ / USB_D- lines is specified by the Universal Serial Bus Revision 2.0
specification [9]. The most important parameter is the differential characteristic impedance applicable for the oddmode electromagnetic field, which should be as close as possible to 90  differential. Signal integrity may be
degraded if the PCB layout is not optimal, especially when the USB signaling lines are very long.
Use the following general routing guidelines to minimize signal quality problems:


Route USB_D+ / USB_D- lines as a differential pair.



Route USB_D+ / USB_D- lines as short as possible.



Ensure the differential characteristic impedance (Z0) is as close as possible to 90 .



Ensure the common mode characteristic impedance (ZCM) is as close as possible to 30 .



Consider design rules for USB_D+ / USB_D- similar to RF transmission lines, these being coupled differential
micro-strip or buried stripline: avoid any stubs, abrupt change of layout, and route on clear PCB area.



Avoid coupling with any RF line or sensitive analog inputs, since the signals can cause the radiation of some
harmonics of the digital data frequency.

Figure 59 and Figure 60 provide two examples of coplanar waveguide designs with differential characteristic
impedance close to 90  and common mode characteristic impedance close to 30 . The first transmission line
can be implemented for a 4-layer PCB stack-up herein described, the second transmission line can be implemented
for a 2-layer PCB stack-up herein described.
400 µm 350 µm 400 µm 350 µm 400 µm
L1 Copper

35 µm

FR-4 dielectric

270 µm

L2 Copper

35 µm

FR-4 dielectric

760 µm

L3 Copper

35 µm

FR-4 dielectric

270 µm

L4 Copper

35 µm

Figure 59: Example of USB line design, with Z0 close to 90  and ZCM close to 30 , for the described 4-layer board layup
410 µm 740 µm 410 µm 740 µm 410 µm

L1 Copper

35 µm

FR-4 dielectric

1510 µm

L2 Copper

35 µm

Figure 60: Example of USB line design, with Z0 close to 90  and ZCM close to 30 , for the described 2-layer board layup

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2.6.3 HSIC interface
2.6.3.1

Guidelines for HSIC circuit design

The HSIC interface is not supported by the “02” and “62” product versions except for diagnostic purposes.
LARA-R2 series modules include a USB High-Speed Inter-Chip compliant interface with a maximum 480 Mb/s data
rate according to the High-Speed Inter-Chip USB Electrical Specification Version 1.0 [10] and USB Specification
Revision 2.0 [9]. The module itself acts as a device and can be connected to any compatible host.
The HSIC interface consists of a bi-directional DDR data line (HSIC_DATA) for transmitting and receiving data
synchronously with the bi-directional strobe line (HSIC_STRB), intended to be directly connected to the Data and
Strobe pins of the compatible USB High-Speed Inter-Chip host mounted on the same PCB of the LARA-R2 series
module, without using connectors / cables, as described in Figure 61.
The modules include also the HOST_SELECT pin to select the module / host application processor configuration:
the pin is available to select, enable, connect, disconnect and subsequently re-connect the HSIC interface.

USB HSIC
HOST PROCESSOR

LARA-R2 series

DATA

99

HSIC_DATA

STROBE

100

HSIC_STRB

GND

GND

Figure 61: HSIC interface application circuit

Further guidelines for HSIC interface circuit design will be described in detail in a successive release of the
System Integration Manual.
ESD sensitivity rating of HSIC interface pins is 1 kV (HBM as per JESD22-A114). Higher protection level could
be required if the lines are externally accessible and it can be achieved by mounting an ESD protection (e.g.
EPCOS CA05P4S14THSG varistor array) close to accessible points
If the HSIC interface pins are not used, they can be left unconnected on the application board, but it is
recommended to provide accessible test points directly connected to the HSIC_DATA and HSIC_STRB pins.

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2.6.3.2 Guidelines for HSIC layout design
HSIC lines require accurate layout design to achieve reliable signaling at high speed data rates (up to 480 Mb/s),
as supported by the HSIC serial interface: signal integrity may be degraded if the PCB layout is not optimal,
especially when the HSIC lines are very long.
The characteristic impedance of the HSIC_DATA and HSIC_STRB lines must be as close as possible to 50 , as
specified by the High-Speed Inter-Chip USB Electrical Specification Version 1.0 [10].
Use the following general routing guidelines to minimize signal quality problems:


Route HSIC_DATA and HSIC_STRB lines as short as possible.



The HSIC interface is only recommended for an intra-board interconnect. The connection should be point-topoint. Connectors and cables are not recommended.



HSIC_DATA and HSIC_STRB lines must be matched in length to within 10 mils.



Ensure the characteristic impedance of HSIC_DATA and HSIC_STRB lines is as close as possible to 50 .



HSIC_DATA and HSIC_STRB signals are not differential signals and should not be routed as such.



Consider design rules for HSIC_DATA and HSIC_STRB lines similar to RF transmission lines, routing them as
micro-strips (conducting strips separated from ground plane by dielectric material) or striplines (flat strips of
metal sandwiched between two parallel ground planes within a dielectric material).



Avoid any stubs, abrupt change of layout, and route on clear PCB area.



Avoid coupling with any RF line or sensitive analog inputs, since the signals can cause the radiation of some
harmonics of the digital data frequency.

Figure 42 and Figure 43 provide two examples of proper 50  coplanar waveguide designs. The first example of
the RF transmission line can be implemented for a 4-layer PCB stack-up herein described, and the second example
of the RF transmission line can be implemented for a 2-layer PCB stack-up herein described.
If the two examples do not match the application PCB layup, the 50  characteristic impedance calculation can
be made using the HFSS commercial finite element method solver for electromagnetic structures from Ansys
Corporation, or using freeware tools like AppCAD from Agilent (www.agilent.com) or TXLine from Applied Wave
Research (www.mwoffice.com), taking care of the approximation formulas used by the tools for the impedance
computation.
To achieve a 50  characteristic impedance, the width of the transmission line must be chosen depending on:


the thickness of the transmission line itself (e.g. 35 µm in the example of Figure 42 and Figure 43)



the thickness of the dielectric material between the top layer (where the transmission line is routed) and the
inner closer layer implementing the ground plane (e.g. 270 µm in Figure 42, 1510 µm in Figure 43)



the dielectric constant of the dielectric material (e.g. dielectric constant of the FR-4 dielectric material in Figure
42 and Figure 43)



the gap from the transmission line to the adjacent ground plane on the same layer of the transmission line
(e.g. 500 µm in Figure 42, 400 µm in Figure 43)

If the distance between the transmission line and the adjacent GND area (on the same layer) does not exceed 5
times the track width of the micro strip, use the “Coplanar Waveguide” model for the 50  calculation.

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2.6.4 DDC (I2C) interface
2.6.4.1

Guidelines for DDC (I2C) circuit design

General considerations
Communication with u-blox GNSS receivers over DDC (I2C) is not supported by the LARA-R204-02B and
LARA-R211-02B-00 product versions.
The “GNSS RTC sharing” function is not supported by the “02” and “62” product versions.
The DDC I2C-bus master interface can be used to communicate with u-blox GNSS receivers and other external
I2C-bus slaves as an audio codec. Beside the general considerations explained below, see:


the following parts of this section for specific guidelines for the connection to u-blox GNSS receivers.



section 2.7.1 for an application circuit example with an external audio codec I2C-bus slave.

To be compliant to the I2C-bus specifications, the module bus interface pins are open drain output and pull-up
resistors must be mounted externally. Resistor values must conform to I2C bus specifications [11]: for example, 4.7
k resistors can be commonly used. Pull-ups must be connected to a supply voltage of 1.8 V (typical), since this is
the voltage domain of the DDC pins which are not tolerant to higher voltage values (e.g. 3.0 V).
Connect the DDC (I2C) pull-ups to the V_INT 1.8 V supply source, or another 1.8 V supply source enabled
after V_INT (e.g. as the GNSS 1.8 V supply present in Figure 62 application circuit), as any external signal
connected to the DDC (I2C) interface must not be set high before the switch-on of the V_INT supply of the
DDC (I2C) pins, to avoid latch-up of circuits and permit a proper boot of the module.
The signal shape is defined by the values of the pull-up resistors and the bus capacitance. Long wires on the bus
increase the capacitance. If the bus capacitance is increased, use pull-up resistors with a nominal resistance value
lower than 4.7 k, to match the I2C bus specifications [11] regarding the rise and fall times of the signals.
Capacitance and series resistance must be limited on the bus to match the I2C specifications (1.0 µs is the
maximum allowed rise time on the SCL and SDA lines): route connections as short as possible.
The ESD sensitivity rating of the DDC (I2C) pins is 1 kV (Human Body Model according to JESD22-A114).
A higher protection level could be required if the lines are externally accessible and it can be achieved by
mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) close to accessible points.
If the pins are not used as DDC bus interface, they can be left unconnected.

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Connection with u-blox 1.8 V GNSS receivers
Figure 62 shows an application circuit for connecting the cellular module to a u-blox 1.8 V GNSS receiver:


The SDA and SCL pins of the cellular module are directly connected to the related pins of the u-blox 1.8 V
GNSS receiver, with appropriate pull-up resistors connected to the 1.8 V GNSS supply enabled after the V_INT
supply of the I2C pins of the cellular module.



The GPIO2 pin is connected to the active-high enable pin of the voltage regulator that supplies the u-blox
1.8 V GNSS receiver providing the “GNSS supply enable” function. A pull-down resistor is provided to avoid
a switch-on of the positioning receiver when the cellular module is switched off or in the reset state.



The GPIO3 and GPIO4 pins are directly connected respectively to the TXD1 and EXTINT0 pins of the u-blox
1.8 V GNSS receiver providing “GNSS Tx data ready” and “GNSS RTC sharing” functions.



The V_BCKP supply output of the cellular module is connected to the V_BCKP backup supply input pin of the
GNSS receiver to provide the supply for the GNSS real time clock and backup RAM when the VCC supply of
the cellular module is within its operating range and the VCC supply of the GNSS receiver is disabled. This
enables the u-blox GNSS receiver to recover from a power breakdown with either a hot start or a warm start
(depending on the actual duration of the GNSS VCC outage) and to maintain the configuration settings saved
in the backup RAM.
LARA-R2 series

u-blox GNSS
1.8 V receiver

(except LARA-R204-02B-00 and
LARA-R211-02B-00)
2 V_BCKP

V_BCKP
GNSS LDO
Regulator

1V8

VCC

OUT
1V8

1V8

VMAIN

IN
SHDN

C1

GND

GNSS supply enabled

23

GPIO2

R3

U1
R1

R2

SDA2

26 SDA

SCL2
GNSS data ready

TxD1

GNSS RTC sharing

EXTINT0

27

SCL

24

GPIO3

25

GPIO4

Figure 62: Application circuit for connecting LARA-R2 series modules to u-blox 1.8 V GNSS receivers
Reference

Description

Part Number - Manufacturer

R1, R2

4.7 kΩ Resistor 0402 5% 0.1 W

RC0402JR-074K7L - Yageo Phycomp

R3

47 kΩ Resistor 0402 5% 0.1 W

RC0402JR-0747KL - Yageo Phycomp

U1

Voltage Regulator for GNSS receiver

See GNSS receiver Hardware Integration Manual

Table 45: Components for connecting LARA-R2 series modules to u-blox 1.8 V GNSS receivers

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Figure 63 illustrates an alternative solution as a supply for u-blox 1.8 V GNSS receivers: the V_INT 1.8 V regulated
supply output of the cellular module can be used to supply a u-blox 1.8 V GNSS receiver of the u-blox 6 generation
(or any newer u-blox GNSS receiver generation) instead of using an external voltage regulator as shown in the
previous Figure 62. The V_INT supply is able to support the maximum current consumption of these positioning
receivers.
The internal switching step-down regulator that generates the V_INT supply is set to 1.8 V (typical) when the
cellular module is switched on and it is disabled when the module is switched off.
The supply of the u-blox 1.8 V GNSS receiver can be switched off using an external p-channel MOSFET controlled
by the GPIO2 pin by means of a proper inverting transistor as shown in Figure 63, implementing the “GNSS supply
enable” function. If this feature is not required, the V_INT supply output can be directly connected to the u-blox
1.8 V GNSS receiver, so that it will be switched on when V_INT output is enabled.
According to the V_INT supply output voltage ripple characteristic specified in the LARA-R2 series Data Sheet [1]:


Additional filtering may be needed to properly supply an external LNA, depending on the characteristics of
the used LNA, adding a series ferrite bead and a bypass capacitor (e.g. the Murata BLM15HD182SN1 ferrite
bead and the Murata GRM1555C1H220J 22 pF capacitor) at the input of the external LNA supply line.
LARA-R2 series

u-blox GNSS
1.8 V receiver
V_BCKP

(except LARA-R204-02B-00 and
LARA-R211-02B-00)
2 V_BCKP

1V8

T1

VCC

R4

1V8
T2

R1

4

V_INT

R5

C1
1V8

TP

GNSS supply enabled

23 GPIO2

R3

R2

SDA2

26 SDA

SCL2

27 SCL
GNSS data ready

TxD1

GNSS RTC sharing

EXTINT0

24 GPIO3
25 GPIO4

Figure 63: Application circuit for connecting LARA-R2 series modules to u-blox 1.8 V GNSS receivers using V_INT as supply
Reference

Description

Part Number - Manufacturer

R1, R2

4.7 k Resistor 0402 5% 0.1 W

RC0402JR-074K7L - Yageo Phycomp

R3

47 k Resistor 0402 5% 0.1 W

RC0402JR-0747KL - Yageo Phycomp

R4

10 k Resistor 0402 5% 0.1 W

RC0402JR-0710KL - Yageo Phycomp

R5

100 k Resistor 0402 5% 0.1 W

RC0402JR-07100KL - Yageo Phycomp

T1

P-Channel MOSFET Low On-Resistance

IRLML6401 - International Rectifier or NTZS3151P - ON Semi

T2

NPN BJT Transistor

BC847 - Infineon

C1

100 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71C104KA01 - Murata

Table 46: Components for connecting LARA-R2 series modules to u-blox 1.8 V GNSS receivers using V_INT as supply

For additional guidelines regarding the design of applications with u-blox 1.8 V GNSS receivers, see the GNSS
Implementation Application Note [22] and the Hardware Integration Manual of the u-blox GNSS receivers.

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Connection with u-blox 3.0 V GNSS receivers
Figure 64 shows an application circuit for connecting the cellular module to a u-blox 3.0 V GNSS receiver:


As the SDA and SCL pins of the cellular module are not tolerant up to 3.0 V, the connection to the related
I2C pins of the u-blox 3.0 V GNSS receiver must be provided using a proper I2C-bus Bidirectional Voltage
Translator (e.g. TI TCA9406, which additionally provides the partial power down feature so that the GNSS 3.0
V supply can be ramped up before the V_INT 1.8 V cellular supply), with proper pull-up resistors.



The GPIO2 is connected to the active-high enable pin of the voltage regulator that supplies the u-blox 3.0 V
GNSS receiver providing the “GNSS supply enable” function. A pull-down resistor is provided to avoid a switchon of the positioning receiver when the cellular module is switched off or in the reset state.



As the GPIO3 and GPIO4 pins of the cellular module are not tolerant up to 3.0 V, the connection to the
related pins of the u-blox 3.0 V GNSS receiver must be provided using a proper Unidirectional General Purpose
Voltage Translator (e.g. TI SN74AVC2T245, which additionally provides the partial power down feature so
that the 3.0 V GNSS supply can be also ramped up before the V_INT 1.8 V cellular supply).



The V_BCKP supply output of the cellular module can be directly connected to the V_BCKP backup supply
input pin of the GNSS receiver as in the application circuit for a u-blox 1.8 V GNSS receiver.
u-blox GNSS
3.0 V receiver

LARA-R2 series
(except LARA-R204-02B-00 and
LARA-R211-02B-00)
2 V_BCKP

V_BCKP
3V0

GNSS LDO Regulator

VCC
C1

OUT

IN

GND

SHDNn

VMAIN
GNSS supply enabled

I2C-bus Bidirectional
Voltage Translator
C2

SDA2

R1

VCCB

1V8

VCCA

4

C3

OE

R2

SCL2

23 GPIO2

R3

U1

R4

R5

V_INT

SDA_B

SDA_A

26 SDA

SCL_B

SCL_A

27 SCL

GND
U2

Unidirectional
Voltage Translator

3V0
C4

VCCA
DIR1

VCCB

TxD1

A1

B1

EXTINT0

A2

B2

DIR2 GND

1V8
C5
GNSS data ready
GNSS RTC sharing

24 GPIO3
25 GPIO4

OEn

U3

Figure 64: Application circuit for connecting LARA-R2 series modules to u-blox 3.0 V GNSS receivers
Reference

Description

Part Number - Manufacturer

R1, R2, R4, R5

4.7 kΩ Resistor 0402 5% 0.1 W

RC0402JR-074K7L - Yageo Phycomp

R3

47 kΩ Resistor 0402 5% 0.1 W

RC0402JR-0747KL - Yageo Phycomp

C2, C3, C4, C5

100 nF Capacitor Ceramic X5R 0402 10% 10V

GRM155R71C104KA01 - Murata

U1, C1

Voltage Regulator for GNSS receiver and related
output bypass capacitor

See GNSS receiver Hardware Integration Manual

U2

I2C-bus Bidirectional Voltage Translator

TCA9406DCUR - Texas Instruments

U3

Generic Unidirectional Voltage Translator

SN74AVC2T245 - Texas Instruments

Table 47: Components for connecting LARA-R2 series modules to u-blox 3.0 V GNSS receivers

For additional guidelines regarding the design of applications with u-blox 3.0 V GNSS receivers, see the GNSS
Implementation Application Note [22] and the Hardware Integration Manual of the u-blox GNSS receivers.
2.6.4.2 Guidelines for DDC (I2C) layout design
The DDC (I2C) serial interface requires the same considerations regarding electro-magnetic interference as any
other digital interface. Keep the traces short and avoid coupling with RF line or sensitive analog inputs, since the
signals can cause the radiation of some harmonics of the digital data frequency.

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2.6.5

SDIO interface

2.6.5.1

Guidelines for SDIO circuit design

The functionality of the SDIO Secure Digital Input Output interface pins is not supported by the LARA-R2
series modules “02” and “62” product versions: the pins should not be driven by any external device.
LARA-R2 series modules include a 4-bit Secure Digital Input Output interface (SDIO_D0, SDIO_D1, SDIO_D2,
SDIO_D3, SDIO_CLK, SDIO_CMD) designed to communicate with an external u-blox short range Wi-Fi module.
Combining a u-blox cellular module with a u-blox short range communication module gives designers full access
to the Wi-Fi module directly via the cellular module, so that a second interface connected to the Wi-Fi module is
not necessary. AT commands via the AT interfaces of the cellular module allow full control of the Wi-Fi module
from any host processor, because Wi-Fi control messages are relayed to the Wi-Fi module via the dedicated SDIO
interface.
Further guidelines for SDIO interface circuit design will be described in detail in a successive release of the
System Integration Manual.
Do not apply voltage to any SDIO interface pin before the switch-on of SDIO interface supply source (V_INT),
to avoid latch-up of circuits and allow a proper boot of the module.
The ESD sensitivity rating of SDIO interface pins is 1 kV (HMB according to JESD22-A114). A higher
protection level could be required if the lines are externally accessible and this can be achieved by mounting
a very low capacitance ESD protection (e.g. Tyco Electronics PESD0402-140 ESD), close to the accessible
points.
If the SDIO interface pins are not used, they can be left unconnected on the application board.

2.6.5.2 Guidelines for SDIO layout design
The SDIO serial interface requires the same considerations regarding electro-magnetic interference as any other
high speed digital interface.
Keep the traces short, avoid stubs and avoid coupling with RF lines / parts or sensitive analog inputs, since the
signals can cause the radiation of some harmonics of the digital data frequency.
Consider the usage of low value series damping resistors to avoid reflections and other losses in signal integrity,
which may create ringing and loss of a square wave shape.

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2.7 Audio interface
Audio is not supported by LARA-R204-02B and LARA-R220-62B product versions.

2.7.1 Digital audio interface
2.7.1.1 Guidelines for digital audio circuit design
I2S digital audio interface can be connected to an external digital audio device for voice applications.
Any external digital audio device compliant with the configuration of the digital audio interface of the LARA-R2
series cellular module can be used, given that the external digital audio device must provide:


The opposite role: slave or master role, as LARA-R2 series modules may act as master or slave



The same mode and frame format: PCM / short synch mode or Normal I2S / long synch mode with
o data in 2’s complement notation, linear
o MSB transmitted first
o data word length = 16-bit (16 clock cycles)
o frame length = synch signal period:
 17-bit or 18-bit in PCM / short alignment mode (16 + 1 or 16 + 2 clock cycles, with the Word
Alignment / Synchronization signal set high for 1 clock cycle or 2 clock cycles)
 32-bit in Normal I2S mode / long alignment mode (16 x 2 clock cycles)



The same sample rate, i.e. synch signal frequency, configurable by AT+UI2S  parameter
o 8 kHz
o 11.025 kHz
o 12 kHz
o 16 kHz
o 22.05 kHz
o 24 kHz
o 32 kHz
o 44.1 kHz
o 48 kHz



The same serial clock frequency:
o 17 x  or 18 x  in PCM / short alignment mode, or
o 16 x 2 x  in Normal I2S mode / long alignment mode



Compatible voltage levels (1.80 V typ.), otherwise it is recommended to connect the 1.8 V digital audio
interface of the module to the external 3.0 V (or similar) digital audio device by means of appropriate
unidirectional voltage translators (e.g. TI SN74AVC4T774 or SN74AVC2T245, providing partial power down
feature so that the digital audio device 3.0 V supply can be also ramped up before V_INT 1.8 V supply), using
the module V_INT output as 1.8 V supply for the voltage translators on the module side

For the appropriate selection of a compliant external digital audio device, see section 1.10.1 and see the +UI2S AT
command description in the u-blox AT Commands Manual [2] for further details regarding the capabilities and the
possible settings of I2S digital audio interface of LARA-R2 series modules.
An appropriate specific application circuit must be implemented and configured according to the particular
external digital audio device or audio codec used and according to the application requirements.

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Examples of manufacturers offering compatible audio codec parts are the following:


Maxim Integrated (as the MAX9860, MAX9867, MAX9880A audio codecs)



Texas Instruments / National Semiconductor



Cirrus Logic / Wolfson Microelectronics



Nuvoton Technology



Asahi Kasei Microdevices

 Realtek Semiconductor
Figure 65 and Table 48 describe an application circuit for the I2S digital audio interface providing basic voice
capability using an external audio voice codec, in particular the Maxim MAX9860 audio codec.


DAC and ADC integrated in the external audio codec respectively converts an incoming digital data stream to
analog audio output through a mono amplifier and converts the microphone input signal to the digital bit
stream over the digital audio interface,



A digital side-tone mixer integrated in the external audio codec provides loopback of the microphones/ADC
signal to the DAC/headphone output.



The module’s I2S interface (I2S master) is connected to the related pins of the external audio codec (I2S slave).



The GPIO6 of the LARA-R2 series module (that provides a suitable digital output clock) is connected to the
clock input of the external audio codec to provide clock reference.



The external audio codec is controlled by the LARA-R2 series module using the DDC (I2C) interface, which can
concurrently communicate with other I2C devices and control an external audio codec.



The V_INT output supplies the external audio codec, defining proper digital interfaces voltage level.



Additional components are provided for EMC and ESD immunity conformity: a 10 nF bypass capacitor and a
series chip ferrite bead noise/EMI suppression filter provided on each microphone line input and speaker line
output of the external codec as described in Figure 65 and Table 48. The necessity of these or other additional
parts for EMC improvement may depend on the specific application board design.
Specific AT commands are available to configure the Maxim MAX9860 audio codec: for more details, see the
u-blox AT Commands Manual [2], +UEXTDCONF AT command.
As various external audio codecs other than the one described in Figure 65 and Table 48 can be used to provide
voice capability, the appropriate specific application circuit must be implemented and configured according to the
particular external digital audio device or audio codec used and according to the application requirements.

LARA-R2 series
(except LARA-R204-02B and LARA-R220-62B)
V_INT

1V8
4

R1

R2

R3

Audio
Codec

C1

IRQn

SDA 26
SCL 27

C2

C3

VDD

MICBIAS
C4

SDA
SCL

I2S_TXD 35

SDIN

I2S_RXD 37

SDOUT

I2S_CLK 36

BCLK

I2S_WA 34

LRCLK

GPIO6 19

MCLK

MICLP
MICLN

EMI1
C5

OUTP

EMI2

C6

J1
R5

MICGND

OUTN

Microphone
Connector MIC

R4

C12 C11

C8

C7
D1

EMI3

Speaker SPK
Connector

EMI4
J2

GND

GND

C14 C13

C10 C9

U1

D2

Figure 65: I2S interface application circuit with an external audio codec to provide voice capability

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Reference

Description

Part Number – Manufacturer

C1

100 nF Capacitor Ceramic X5R 0402 10% 10V

GRM155R71C104KA01 – Murata

C2, C4, C5, C6

1 µF Capacitor Ceramic X5R 0402 10% 6.3 V

GRM155R60J105KE19 – Murata

C3

10 µF Capacitor Ceramic X5R 0603 20% 6.3 V

GRM188R60J106ME47 – Murata

C7, C8, C9, C10

27 pF Capacitor Ceramic COG 0402 5% 25 V

GRM1555C1H270JZ01 – Murata

C11, C12, C13, C14

10 nF Capacitor Ceramic X5R 0402 10% 50V

GRM155R71C103KA88 – Murata

D1, D2

Low Capacitance ESD Protection

USB0002RP or USB0002DP – AVX

EMI1, EMI2, EMI3,
EMI4

Chip Ferrite Bead Noise/EMI Suppression Filter
1800 Ohm at 100 MHz, 2700 Ohm at 1 GHz

BLM15HD182SN1 – Murata

J1

Microphone Connector

Various manufacturers

J2

Speaker Connector

Various manufacturers

MIC

2.2 k Electret Microphone

Various manufacturers

R1, R2

4.7 k Resistor 0402 5% 0.1 W

RC0402JR-074K7L - Yageo Phycomp

R3

10 k Resistor 0402 5% 0.1 W

RC0402JR-0710KL - Yageo Phycomp

R4, R5

2.2 k Resistor 0402 5% 0.1 W

RC0402JR-072K2L – Yageo Phycomp

SPK

32  Speaker

Various manufacturers

U1

16-Bit Mono Audio Voice Codec

MAX9860ETG+ - Maxim

Table 48: Example of components for audio voice codec application circuit

Do not apply voltage to any I2S pin before the switch-on of I2S supply source (V_INT), to avoid latch-up of
circuits and allow a proper boot of the module. If the external signals connected to the cellular module
cannot be tri-stated or set low, insert a multi-channel digital switch (e.g. TI SN74CB3Q16244, TS5A3159,
or TS5A63157) between the two-circuit connections and set to high impedance before V_INT switch-on.
The ESD sensitivity rating of I2S interface pins is 1 kV (Human Body Model according to JESD22-A114).
A higher protection level could be required if the lines are externally accessible and it can be achieved by
mounting a general purpose ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) close to accessible
points.
If the I2S digital audio pins are not used, they can be left unconnected on the application board.

2.7.1.2 Guidelines for digital audio layout design
I2S interface and clock output lines require the same consideration regarding electro-magnetic interference as any
other high speed digital interface. Keep the traces short and avoid coupling with RF lines / parts or sensitive analog
inputs, since the signals can cause the radiation of some harmonics of the digital data frequency.

2.7.1.3 Guidelines for analog audio layout design
Accurate design of the analog audio circuit is very important to obtain clear and high quality audio. The GSM
signal burst has a repetition rate of 217 Hz that lies in the audible range. A careful layout is required to reduce the
risk of noise from audio lines due to both VCC burst noise coupling and RF detection.
General guidelines for the uplink path (microphone), which is commonly the most sensitive, are the following:


Avoid coupling of any noisy signal to microphone lines: it is strongly recommended to route microphone lines
away from the module VCC supply line, any switching regulator line, RF antenna lines, digital lines and any
other possible noise source.



Avoid coupling between the microphone and speaker / receiver lines.



Optimize the mechanical design of the application device, the position, orientation and mechanical fixing (for
example, using rubber gaskets) of microphone and speaker parts in order to avoid echo interference between
the uplink path and downlink path.

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

Keep ground separation from microphone lines to other noisy signals. Use an intermediate ground layer or
vias wall for coplanar signals.



For an external audio device providing differential microphone input, route the microphone signal lines as a
differential pair embedded in ground to reduce differential noise pick-up. The balanced configuration will help
reject the common mode noise.



Cross other signals lines on adjacent layers with 90° crossing.



Place bypass capacitor for RF very close to the active microphone. The preferred microphone should be
designed for GSM applications which typically have an internal built-in bypass capacitor for RF very close to
active device. If the integrated FET detects the RF burst, the resulting DC level will be in the pass-band of the
audio circuitry and cannot be filtered by any other device.

General guidelines for the downlink path (speaker / receiver) are the following:


The physical width of the audio output lines on the application board must be wide enough to minimize series
resistance since the lines are connected to low impedance speaker transducers.



Avoid coupling of any noisy signal to speaker lines: it is recommended to route speaker lines away from the
module VCC supply line, any switching regulator line, RF antenna lines, digital lines and any other possible
noise source.



Avoid coupling between speaker / receiver and microphone lines.



Optimize the mechanical design of the application device, the position, orientation and mechanical fixing (for
example, using rubber gaskets) of speaker and microphone parts in order to avoid echo interference between
the downlink path and uplink path.



For an external audio device providing differential speaker / receiver output, route the speaker signal lines as
a differential pair embedded in ground up to reduce differential noise pick-up. The balanced configuration
will help reject the common mode noise.



Cross other signals lines on adjacent layers with 90° crossing.



Place the bypass capacitor for RF close to the speaker.

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2.8 General Purpose Input/Output (GPIO)
2.8.1.1 Guidelines for GPIO circuit design
A typical usage of LARA-R2 series modules’ GPIOs can be the following:


Network indication provided over GPIO1 pin (see Figure 66 / Table 49 below)



GNSS supply enable function provided by the GPIO2 pin (see section 2.6.4)



GNSS Tx data ready function provided by the GPIO3 pin (see section 2.6.4)



GNSS RTC sharing function provided by the GPIO4 pin (see section 2.6.4)



SIM card detection provided over the GPIO5 pin (see Figure 48 / Table 38 in section 2.5)
3V8

LARA-R2 series

GPIO1 16

R3

Network Indicator

DL1

R1
T1
R2

Figure 66: Application circuit for network indication provided over GPIO1
Reference

Description

Part Number - Manufacturer

R1

10 k Resistor 0402 5% 0.1 W

Various manufacturers

R2

47 k Resistor 0402 5% 0.1 W

Various manufacturers

R3

820  Resistor 0402 5% 0.1 W

Various manufacturers

DL1

LED Red SMT 0603

LTST-C190KRKT - Lite-on Technology Corporation

T1

NPN BJT Transistor

BC847 - Infineon

Table 49: Components for network indication application circuit

Use transistors with at least an integrated resistor in the base pin or otherwise put a 10 kΩ resistor on the
board in series to the GPIO of LARA-R2 series modules.
Do not apply voltage to any GPIO of the module before the switch-on of the GPIOs supply (V_INT), to avoid
latch-up of circuits and allow a proper module boot. If the external signals connected to the module cannot
be tri-stated or set low, insert a multi-channel digital switch (e.g. TI SN74CB3Q16244, TS5A3159,
TS5A63157) between the two-circuit connections and set to high impedance before V_INT switch-on.
ESD sensitivity rating of the GPIO pins is 1 kV (Human Body Model according to JESD22-A114).
Higher protection level could be required if the lines are externally accessible and it can be achieved by
mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) close to accessible points.
If the GPIO pins are not used, they can be left unconnected on the application board.

2.8.1.2 Guidelines for GPIO layout design
The general purpose input/output pins are generally not critical for layout.

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2.9 Reserved pins (RSVD)
LARA-R2 series modules have pins reserved for future use, marked as RSVD. All the RSVD pins are to be left
unconnected on the application board except the following RSVD pin, as described in Figure 67:


the RSVD pin number 33 that must be externally connected to ground

LARA-R2
RSVD 33

RSVD

Figure 67: Application circuit for the reserved pins (RSVD)

2.10 Module placement
Optimize placement for a minimum length of RF line and a closer path from the DC source for VCC.
Make sure that the module, RF and analog parts / circuits are clearly separated from any possible source of radiated
energy, including digital circuits that can radiate some digital frequency harmonics, which can produce
Electro-Magnetic Interference affecting module, RF and analog parts / circuits’ performance or implement proper
countermeasures to avoid any possible Electro-Magnetic Compatibility issue.
Routing of noisy signals below the module, on the top layer of the application PCB, is not recommended.
Make sure that the module, RF and analog parts / circuits, high speed digital circuits are clearly separated from
any sensitive part / circuit which may be affected by Electro-Magnetic Interference or employ countermeasures to
avoid any possible Electro-Magnetic Compatibility issues.
Provide enough clearance between the module and any external part.
The heat dissipation during continuous transmission at maximum power can significantly raise the
temperature of the application base-board below the LARA-R2 series modules: avoid placing temperature
sensitive devices close to the module.

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2.11 Module footprint and paste mask
Figure 68 and Table 50 describe the suggested footprint (i.e. copper mask) and paste mask layout for LARA
modules: the proposed land pattern layout reflects the modules’ pins layout, while the proposed stencil apertures
layout is slightly different (see the F’’, H’’, I’’, J’’, O’’ parameters compared to the F’, H’, I’, J’, O’ ones).
The Non Solder Mask Defined (NSMD) pad type is recommended over the Solder Mask Defined (SMD) pad type,
implementing the solder mask opening 50 µm larger per side than the corresponding copper pad.
The recommended solder paste thickness is 150 µm, according to application production process requirements.
B
G ANT2

D

B
J’

E

E

J’’

E

H’ H’ ANT1 G

G ANT2

I’

D

K

Pin 1

I’’

K

Pin 1

M1

M1

M1

M1

M2

M2

O’
G
A

E

H’’ H’’ ANT1 G

O’

O’’
G

Foot-print

H’

A

Top View

J’

F1’
G

H’
J’

K

Top View

J’

L

F1’’

D
F2’’
L

G

H’

N

Paste-mask

H’’
J’’

D
F2’
L

O’’

G

H’’
J’’

H’’

N

K

G

J’’

L

Figure 68: LARA-R2 series modules suggested footprint and paste mask (application board top view)
Parameter

Value

Parameter

Value

Parameter

Value

A
B
C
D
E
F1’
F1’’
F2’

26.0 mm
24.0 mm
2.60 mm
2.00 mm
6.50 mm
1.05 mm
1.00 mm
5.05 mm

F2’’
G
H’
H’’
I’
I’’
J’
J’’

5.00 mm
1.10 mm
0.80 mm
0.75 mm
1.50 mm
1.55 mm
0.30 mm
0.35 mm

K
L
M1
M2
N
O’
O’’

2.75 mm
6.75 mm
1.80 mm
3.60 mm
2.10 mm
1.10 mm
1.05 mm

Table 50: LARA-R2 series modules suggested footprint and paste mask dimensions

These are recommendations only and not specifications. The exact copper, solder and paste mask
geometries, distances, stencil thicknesses and solder paste volumes must be adapted to the specific
production processes (e.g. soldering etc.) of the customer.

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2.12 Thermal guidelines
Modules’ operating temperature range is specified in the LARA-R2 series Data Sheet [1].
The most critical condition concerning module thermal performance is the uplink transmission at maximum power
(data upload in connected mode), when the baseband processor runs at full speed, radio circuits are all active and
the RF power amplifier is driven to higher output RF power. This scenario is not often encountered in real networks
(for example, see the Terminal Tx Power distribution for WCDMA, taken from operation on a live network,
described in the GSMA TS.09 Battery Life Measurement and Current Consumption Technique [17]); however the
application should be correctly designed to cope with it.
During transmission at maximum RF power, the LARA-R2 series modules generate thermal power that may exceed
2 W: this is an indicative value since the exact generated power strictly depends on operating condition such as
the actual antenna return loss, the number of allocated TX resource blocks, the transmitting frequency band, etc.
The generated thermal power must be adequately dissipated through the thermal and mechanical design of the
application.
The spreading of the Module-to-Ambient thermal resistance (Rth,M-A) depends on the module operating condition.
The overall temperature distribution is influenced by the configuration of the active components during the specific
mode of operation and their different thermal resistance toward the case interface.
The Module-to-Ambient thermal resistance value and the relative increase of module temperature will differ
according to the specific mechanical deployments of the module, e.g. application PCB with different
dimensions and characteristics, mechanical shells enclosure, or forced air flow.
The increase of the thermal dissipation, i.e. the reduction of the Module-to-Ambient thermal resistance, will
decrease the temperature of the modules’ internal circuitry for a given operating ambient temperature. This
improves the device long-term reliability in particular for applications operating at high ambient temperature.
Recommended hardware techniques to be used to improve heat dissipation in the application:


Connect each GND pin with solid ground layer of the application board and connect each ground area of the
multilayer application board with a complete thermal via stacked down to the main ground layer.



Provide a ground plane as wide as possible on the application board.



Optimize antenna return loss, to optimize overall electrical performance of the module including a decrease
of module thermal power.



Optimize the thermal design of any high-power components included in the application, such as linear
regulators and amplifiers, to optimize overall temperature distribution in the application device.



Select the material, the thickness and the surface of the box (i.e. the mechanical enclosure) of the application
device that integrates the module so that it provides good thermal dissipation.
Further hardware techniques that may be considered to improve the heat dissipation in the application:


Force ventilation air-flow within the mechanical enclosure.



Provide a heat sink component attached to the module top side, with electrically insulated / high thermal
conductivity adhesive, or on the backside of the application board, below the cellular module, as a large part
of the heat is transported through the GND pads of the LARA-R2 series LGA modules and dissipated over the
backside of the application board.
For example, the Module-to-Ambient thermal resistance (Rth,M-A) is strongly reduced with forced air ventilation
and a heat-sink installed on the back of the application board, decreasing the module temperature variation.
Beside the reduction of the Module-to-Ambient thermal resistance implemented by proper application hardware
design, the increase of module temperature can be moderated by proper application software implementation:


Enable power saving configuration using the AT+UPSV command (see section 1.14.17).



Enable module connected mode for a given time period and then disable it for a time period long enough to
properly mitigate temperature increase.

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2.13 ESD guidelines
The sections 2.13.1 and 2.13.2 are related to EMC / ESD immunity. The modules are ESD sensitive devices and the
ESD sensitivity for each pin (as Human Body Model according to JESD22-A114F) is specified in the LARA-R2 series
Data Sheet [1]. Special precautions are required when handling: see section 3.2 for handling guidelines.

2.13.1 ESD immunity test overview
The immunity of devices integrating LARA-R2 series modules to Electro-Static Discharge (ESD) is part of the
Electro-Magnetic Compatibility (EMC) conformity, which is required for products bearing the CE marking,
compliant with the Radio Equipment Directive (2014/53/EU), the EMC Directive (2014/30/EU) and the Low Voltage
Directive (2014/35/EU ) issued by the Commission of the European Community.
Compliance with these directives implies conformity to the following European Norms for device ESD immunity:
the ESD testing standard CENELEC EN 61000-4-2 [18] and the radio equipment standards ETSI EN 301 489-1 [19],
ETSI EN 301 489-52 [20] , the requirements of which are summarized in Table 51.
The ESD immunity test is performed at the enclosure port, defined by ETSI EN 301 489-1 [19] as the physical
boundary through which the electromagnetic field radiates. If the device implements an integral antenna, the
enclosure port is defined as all insulating and conductive surfaces housing the device. If the device implements a
removable antenna, the antenna port can be separated from the enclosure port. The antenna port includes the
antenna element and its interconnecting cable surfaces.
The applicability of the ESD immunity test to the whole device depends on the device classification as defined by
ETSI EN 301 489-1 [19]. Applicability of the ESD immunity test to the relative device ports or the relative
interconnecting cables to auxiliary equipments, depends on device accessible interfaces and manufacturer
requirements, as defined by ETSI EN 301 489-1 [19].
Contact discharges are performed at conductive surfaces, while air discharges are performed at insulating surfaces.
Indirect contact discharges are performed on the measurement setup horizontal and vertical coupling planes as
defined in CENELEC EN 61000-4-2 [18].
For the definition of integral antenna, removable antenna, antenna port, device classification, see ETSI EN
301 489-1 [19], whereas for contact and air discharges definitions, see CENELEC EN 61000-4-2 [18].
Application

Category

Immunity Level

All exposed surfaces of the radio equipment and ancillary equipment in a
representative configuration

Contact Discharge

4 kV

Air Discharge

8 kV

Table 51: EMC / ESD immunity requirements as defined by CENELEC EN 61000-4-2, ETSI EN 301 489-1, 301 489-52

2.13.2 ESD immunity test of u-blox LARA-R2 series reference designs
Although EMC / ESD certification is required for customized devices integrating LARA-R2 series modules for the
European Conformance CE mark, EMC certification (including ESD immunity) has been successfully performed on
LARA-R2 series modules reference design according to the European Norms summarized in Table 51.
The EMC / ESD approved u-blox reference designs consist of a LARA-R2 series module installed onto a motherboard
which provides the supply interface, SIM card and communication port. External LTE/3G/2G antennas are
connected to the provided connectors.
Since an external antenna is used, the antenna port can be separated from the enclosure port. The reference
design is not enclosed in a box so that the enclosure port is not indentified with physical surfaces. Therefore, some
test cases cannot be applied. Only the antenna port is identified as accessible for direct ESD exposure.

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Table 52 summarizes the u-blox LARA-R2 series reference designs ESD immunity test results, according to the
CENELEC EN 61000-4-2 [18], ETSI EN 301 489-1 [19], 301 489-52 [20] test requirements.
Category

Application

Immunity Level

Contact Discharge
to coupling planes
(indirect contact discharge)

Enclosure

+4 kV / –4 kV

Contact Discharges
to conducted surfaces
(direct contact discharge)

Enclosure port

Not Applicable

Test not applicable to u-blox reference design because it
does not provide enclosure surface.
The test is applicable only to equipments providing
conductive enclosure surface.

Antenna port

+4 kV / –4 kV

Test applicable to u-blox reference design because it
provides antenna with conductive & insulating surfaces.
The test is applicable only to equipments providing
antenna with conductive surface.

Enclosure port

Not Applicable

Test not applicable to the u-blox reference design because
it does not provide an enclosure surface.
The test is applicable only to equipments providing
insulating enclosure surface.

Antenna port

+8 kV / –8 kV

Test applicable to u-blox reference design because it
provides antenna with conductive & insulating surfaces.
The test is applicable only to equipments providing
antenna with insulating surface.

Air Discharge
at insulating surfaces

Remarks

Table 52: Enclosure ESD immunity level of u-blox LARA-R2 series reference designs

LARA-R2 series reference designs implement all the ESD precautions described in section 2.13.3.

2.13.3 ESD application circuits
The application circuits described in this section are recommended and should be implemented in any device that
integrates a LARA-R2 series module, according to the specific application board classification (see ETSI EN 301
489-1 [19]), to satisfy the requirements for ESD immunity test summarized in Table 51.
Antenna interface
The ANT1 port of LARA-R2 series modules provides ESD immunity up to ±4 kV for direct Contact Discharge and
up to ±8 kV for Air Discharge: no further precaution to ESD immunity test is needed, as implemented in the EMC
/ ESD approved reference design of LARA-R2 series modules.
The ANT2 port of LARA-R2 series modules, except LARA-R204 modules, provides ESD immunity up to ±4 kV for
direct Contact Discharge and up to ±8 kV for Air Discharge: no further precaution to ESD immunity test is needed,
as implemented in the EMC / ESD approved reference design of LARA-R2 series modules.
The ANT2 port of LARA-R204 modules provides ESD immunity up to ±1 kV for direct Contact Discharge and up
to ±2 kV for Air Discharge: higher protection level is required if the line is externally accessible on the device (i.e.
the application board where the LARA-R204 module is mounted). The following precautions are suggested for
satisfying the ESD immunity test requirements for the ANT2 port, using LARA-R204 modules:


If an embedded secondary antenna is used, the insulating enclosure of the device should provide protection
up to ±4 kV to direct contact discharge and up to ±8 kV to air discharge to the secondary antenna interface
 If an external secondary antenna is used, the secondary antenna and its connecting cable should provide a
completely insulated enclosure able to provide protection up to ±4 kV to direct contact discharge and up to
±8 kV to air discharge to the whole secondary antenna and cable surfaces, otherwise it is suggested to provide
an external ultra low capacitance ESD protection (e.g. Infineon ESD0P2RF-02LRH) at the secondary antenna
port, as described in Figure 45 and Table 35 (section 2.4).
The antenna interface application circuit implemented in the EMC / ESD approved reference designs of LARA-R2
series modules is described in Figure 45 and Table 35 (section 2.4).

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RESET_N pin
The following precautions are suggested for the RESET_N line of LARA-R2 series modules, depending on the
application board handling, to satisfy ESD immunity test requirements:
 It is recommended to keep the connection line to RESET_N as short as possible
Maximum ESD sensitivity rating of the RESET_N pin is 1 kV (Human Body Model according to JESD22-A114).
Higher protection level could be required if the RESET_N pin is externally accessible on the application board. The
following precautions are suggested to achieve higher protection level:


A general purpose ESD protection device (e.g. EPCOS CA05P4S14THSG varistor array or EPCOS
CT0402S14AHSG varistor) should be mounted on the RESET_N line, close to the accessible point.
The RESET_N application circuit implemented in the EMC / ESD approved reference design of LARA-R2 series
modules is described in Figure 40 and Table 31 (section 2.3.2).
SIM interface
The following precautions are suggested for the LARA-R2 series modules SIM interface (VSIM, SIM_RST, SIM_IO,
SIM_CLK), depending on the application board handling, to satisfy ESD immunity test requirements:


A bypass capacitor of about 22 pF to 47 pF (e.g. Murata GRM1555C1H470J) must be mounted on the lines
connected to the VSIM, SIM_RST, SIM_IO and SIM_CLK pins to assure SIM interface functionality when an
electrostatic discharge is applied to the application board enclosure.

 It is suggested to use as short as possible connection lines at SIM pins.
Maximum ESD sensitivity rating of SIM interface pins is 1 kV (Human Body Model according to JESD22-A114).
A higher protection level could be required if SIM interface pins are externally accessible on the application board.
The following precautions are suggested to achieve higher protection level:


A low capacitance (i.e. less than 10 pF) ESD protection device (e.g. Tyco Electronics PESD0402-140) should be
mounted on each SIM interface line, close to the accessible points (i.e. close to the SIM card holder)
The SIM interface application circuit implemented in the EMC / ESD approved reference design of LARA-R2 series
modules is described in Figure 48 and Table 38 (section 2.5).
Other pins and interfaces
All the module pins that are externally accessible on the device integrating LARA-R2 series module should be
included in the ESD immunity test, since they are considered to be a port as defined in ETSI EN 301 489-1 [19].
Depending on applicability, to satisfy ESD immunity test requirements according to ESD category level, all the
module pins that are externally accessible should be protected up to ±4 kV for direct Contact Discharge and up to
±8 kV for Air Discharge applied to the enclosure surface.
The maximum ESD sensitivity rating of all the other pins of the module is 1 kV (Human Body Model according to
JESD22-A114). Higher protection level could be required if the related pin is externally accessible on the application
board. The following precautions are suggested to achieve a higher protection level:


USB interface: a very low capacitance (i.e. less or equal to 1 pF) ESD protection device (e.g. Tyco Electronics
PESD0402-140 ESD protection device) should be mounted on the USB_D+ and USB_D- lines, close to the
accessible points (i.e. close to the USB connector).



Other pins: a general purpose ESD protection device (e.g. EPCOS CA05P4S14THSG varistor array or EPCOS
CT0402S14AHSG varistor) should be mounted on the related line, close to the accessible point.

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2.14 Schematic for LARA-R2 series module integration
Figure 69 is an example of a schematic diagram where a LARA-R2 series cellular module “02” or “62” product
version is integrated into an application board, using all the available interfaces and functions of the module.
LARA-R2 series
(‘02’ or ‘62’ product version)

+
330µF 100nF 10nF

15pF

56pF

51

VCC

52

VCC

53

VCC

8.2pF

GND

ANT1

56
82nH

ANT2

62
ESD

RTC
back-up
Application
Processor

2
100µF

V_BCKP

ANT_DET

Secondary
Cellular
Antenna

Connector

33pF

82nH

Mount for modules
supporting LTE band-7

Mount for modules
supporting 2G

Primary
Cellular
Antenna

Connector

33pF

3V8

10k

59

27pF

GND

ESD

SIM Card Holder

V_INT
V_INT

GPIO
TP
Open
Drain
Output

15

PWR_ON

TP

1k

V_INT

4

GPIO5

42

SW2

VSIM

41

CCVCC (C1)

SIM_IO

39

CCIO (C7)

SIM_CLK

38

CCCLK (C3)

SIM_RST

40

SW1

CCVPP (C6)
TP

Open
Drain
Output

18

RESET_N

CCRST (C2)
47pF 47pF 47pF 47pF 100nF

470k

1.8V DTE
0Ω

TP

0Ω

TP

12

TXD

13

RXD

10

RTS

11

CTS

9

DTR

DSR

6

DSR

RI

7

RI

8

DCD

TXD
RXD
RTS
CTS
DTR

DCD

0Ω

0Ω

TP

TP

Not supported by LARA-R204-02B and LARA-R211-02B product version

LDO Regulator

3V8

GPIO2

23

IN

OUT

SHDNn

GND

VCCB

VCCA

100nF

OE

4.7k

USB 2.0 Host
VUSB_DET

D+

29

USB_D+

D-

28

USB_D-

V_INT

100nF

TP
TP

GND

SDA2
SCL2

SN74AVC2T245
Voltage Translator

24

B1

A1

GPIO4

25

B2

A2

SDIO_D2

45

SDIO_CLK

46

SDIO_CMD

47

SDIO_D0

48

SDIO_D3

49

SDIO_D1

Network
Indicator
GPIO1
RSVD
33

EXTINT0
Not supported by LARA-R2
“02” and “62” product versions

DIR2

GND

Not supported by LARA-R204-02B and LARA-R220-62B product version

HOST_SELECT

44

16

TxD1

HSIC_DATA

V_INT

3V8

100nF

DIR1

GPIO3

100 HSIC_STRB
21

3V0

VCCA

VCCB

OEn
99

4.7k

SCL_A GND SCL_B

100nF
GND

4.7k

SDA_B

SDA_A

17

VCC

100nF

TCA9406DCUR
I2C Voltage Translator
100nF

4.7k

VBUS / GPIO

u-blox GNSS
3.0 V receiver

3V0

47k
V_INT

GND

GND

GND (C5)
ESD ESD ESD ESD ESD ESD

RSVD

Audio Codec
MAX9860

10k
IRQn

MICBIAS
SDA

26

SDA

SCL

27

SCL

MICLP

I2S_TXD

35

SDIN

I2S_RXD

37

I2S_CLK

36

SDOUT
MICGND
BCLK

I2S_WA

34

LRCLK

GPIO6

19

MCLK

MICLN

GND

100nF
1µF

1µF

10µF

2.2k

MIC

EMI

1µF

EMI

1µF
2.2k
10nF 10nF

27pF 27pF

ESD ESD

SPK
OUTP
OUTN

GND

V_INT

VDD

EMI
EMI

10nF 10nF

27pF 27pF

ESD ESD

Figure 69: Example of schematic diagram to integrate a LARA-R2 module “02” or “62” product version using all interfaces

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2.15 Design-in checklist
This section provides a design-in checklist.

2.15.1 Schematic checklist
The following are the most important points for a simple schematic check:




DC supply must provide a nominal voltage at the VCC pin within the operating range limits.



VCC voltage supply should be clean, with very low ripple/noise: provide the suggested bypass capacitors,
in particular if the application device integrates an internal antenna.





Do not apply loads which might exceed the limit for maximum available current from V_INT supply.






Capacitance and series resistance must be limited on each SIM signal to match the SIM specifications.




Capacitance and series resistance must be limited on each high speed line of the USB interface.





Capacitance and series resistance must be limited on each high speed line of the HSIC interface.






Check the digital audio interface specifications to connect a proper external audio device.




Provide proper precautions for ESD immunity as required on the application board.



All unused pins of LARA-R2 series modules can be left unconnected except the RSVD pin number 33,
which must be connected to GND.

DC supply must be capable of supporting both the highest peak and the highest averaged current
consumption values in connected mode, as specified in the LARA-R2 series Data Sheet [1].

Check that the voltage level of any connected pin does not exceed the relative operating range.
Provide accessible test points directly connected to the following pins of the LARA-R2 series modules:
V_INT, PWR_ON and RESET_N for diagnostic purposes.
Insert the suggested pF capacitors on each SIM signal and low capacitance ESD protections if accessible.
Check UART signals direction, as the modules’ signal names follow the ITU-T V.24 Recommendation [5].
Provide accessible test points directly connected to all the UART pins of the LARA-R2 series modules (TXD,
RXD, DTR, DCD) for diagnostic purpose, in particular providing a 0  series jumper on each line to detach
each UART pin of the module from the DTE application processor.
If the USB is not used, provide accessible test points directly connected to the USB interface (VUSB_DET,
USB_D+ and USB_D- pins).
Consider providing appropriate low value series damping resistors on SDIO lines to avoid reflections.
Add a proper pull-up resistor (e.g. 4.7 k) to V_INT or another proper 1.8 V supply on each DDC (I2C)
interface line, if the interface is used.
Capacitance and series resistance must be limited on master clock output line and each I2S interface line
Consider passive filtering parts on each used analog audio line.
Use transistors with at least an integrated resistor in the base pin or otherwise put a 10 k resistor on the
board in series to the GPIO when those are used to drive LEDs.
Do not apply voltage to any generic digital interface pin of LARA-R2 series modules before the switch-on
of the generic digital interface supply source (V_INT).

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2.15.2 Layout checklist
The following are the most important points for a simple layout check:



Check 50  nominal characteristic impedance of the RF transmission line connected to the ANT1 and the
ANT2 ports (antenna RF interfaces).



Ensure no coupling occurs between the RF interface and noisy or sensitive signals (primarily analog audio
input/output signals, SIM signals, high-speed digital lines such as SDIO, USB and other data lines).







Optimize placement for minimum length of RF line.




Ensure an optimal grounding connecting each GND pin with application board solid ground layer.




Keep routing short and minimize parasitic capacitance on the SIM lines to preserve signal integrity.




HSIC traces must be designed as 50  nominal characteristic impedance transmission lines.




Ensure appropriate RF precautions for the Wi-Fi and Cellular technologies coexistence.




Route analog audio signals away from noisy sources (primarily RF interface, VCC, switching supplies).

Check the footprint and paste mask designed for LARA-R2 series module as illustrated in section 2.11.
VCC line should be as wide and as short as possible.
Route VCC supply line away from RF lines / parts and other sensitive analog lines / parts.
The VCC bypass capacitors in the picoFarad range should be placed as close as possible to the VCC pins,
in particular if the application device integrates an internal antenna.
Use as many vias as possible to connect the ground planes on a multilayer application board, providing a
dense line of vias at the edges of each ground area, in particular along the RF and high speed lines.
USB_D+ / USB_D- traces should meet the characteristic impedance requirement (90  differential and
30  common mode) and should not be routed close to any RF line / part.
Keep the SDIO traces short, avoid stubs, avoid coupling with any RF line / part and consider low value
series damping resistors to avoid reflections and other losses in signal integrity.
Ensure appropriate RF precautions for the GNSS and Cellular technologies coexistence as described in the
GNSS Implementation Application Note [22].
The audio outputs lines on the application board must be wide enough to minimize series resistance.

2.15.3 Antenna checklist


Antenna termination should provide a 50  characteristic impedance with VSWR at least less than 3:1
(recommended 2:1) on operating bands in the deployment geographical area.



Follow the recommendations of the antenna producer for correct antenna installation and deployment
(PCB layout and matching circuitry).



Ensure compliance with any regulatory agency RF radiation requirement, as detailed in sections 4.2.2
and/or 4.3.1 for products marked with the FCC and/or IC.





Ensure high and similar efficiency for both the primary (ANT1) and the secondary (ANT2) antenna.



Ensure high isolation between the cellular antennas and any other antenna or transmitter.

Ensure high isolation between the primary (ANT1) and the secondary (ANT2) antenna.
Ensure a low Envelope Correlation Coefficient between the primary (ANT1) and the secondary (ANT2)
antenna: the 3D antenna radiation patterns should have radiation lobes in different directions.

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3 Handling and soldering
No natural rubbers, no hygroscopic materials or materials containing asbestos are employed.

3.1 Packaging, shipping, storage and moisture preconditioning
For information pertaining to LARA-R2 series reels / tapes, Moisture Sensitivity levels (MSD), shipment and storage
information, as well as drying for preconditioning, see the LARA-R2 series Data Sheet [1] and the u-blox Package
Information Guide [25].

3.2 Handling
The LARA-R2 series modules are Electro-Static Discharge (ESD) sensitive devices.
Ensure ESD precautions are implemented during handling of the module.
Electrostatic discharge (ESD) is the sudden and momentary electric current that flows between two objects at
different electrical potentials caused by direct contact or induced by an electrostatic field. The term is usually used
in the electronics and other industries to describe momentary unwanted currents that may cause damage to
electronic equipment.
The ESD sensitivity for each pin of the LARA-R2 series modules (as Human Body Model according to JESD22-A114F)
is specified in the LARA-R2 series Data Sheet [1].
ESD prevention is based on establishing an Electrostatic Protective Area (EPA). The EPA can be a small working
station or a large manufacturing area. The main principle of an EPA is that there are no highly charging materials
near ESD sensitive electronics, all conductive materials are grounded, workers are grounded, and charge build-up
on ESD sensitive electronics is prevented. International standards are used to define typical EPA and can be
obtained for example from International Electrotechnical Commission (IEC) or American National Standards
Institute (ANSI).
In addition to standard ESD safety practices, the following measures should be taken into account whenever
handling the LARA-R2 series modules:


Unless there is a galvanic coupling between the local GND (i.e. the work table) and the PCB GND, then the
first point of contact when handling the PCB must always be between the local GND and PCB GND.



Before mounting an antenna patch, connect the ground of the device.



When handling the module, do not come into contact with any charged capacitors and be careful when
contacting materials that can develop charges (e.g. patch antenna, coax cable, soldering iron,…).



To prevent electrostatic discharge through the RF pin, do not touch any exposed antenna area. If there is any
risk that such exposed antenna area is touched in a non-ESD protected work area, implement proper ESD
protection measures in the design.

 When soldering the module and patch antennas to the RF pin, make sure to use an ESD safe soldering iron.
For more robust designs, employ additional ESD protection measures on the application device integrating the
LARA-R2 series modules, as described in section 2.13.3.

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3.3 Soldering
3.3.1 Soldering paste
Use of "No Clean" soldering paste is strongly recommended, as it does not require cleaning after the soldering
process has taken place. The paste listed in the example below meets these criteria.
Soldering Paste:
OM338 SAC405 / Nr.143714 (Cookson Electronics)
Alloy specification:
95.5% Sn / 3.9% Ag / 0.6% Cu (95.5% Tin / 3.9% Silver / 0.6% Copper)
95.5% Sn / 4.0% Ag / 0.5% Cu (95.5% Tin / 4.0% Silver / 0.5% Copper)
Melting Temperature:
+217 °C
Stencil Thickness:
150 µm for base boards
The final choice of the soldering paste depends on the approved manufacturing procedures.
The paste-mask geometry for applying soldering paste should meet the recommendations in section 2.11.
The quality of the solder joints on the connectors (’half vias’) should meet the appropriate IPC specification.

3.3.2 Reflow soldering
A convection type-soldering oven is strongly recommended over the infrared type radiation oven.
Convection heated ovens allow precise control of the temperature and all parts will be heated up evenly, regardless
of material properties, thickness of components and surface color.
Consider the "IPC-7530 Guidelines for temperature profiling for mass soldering (reflow and wave) processes,
published 2001".
Reflow profiles are to be selected according to the following recommendations.
Failure to observe these recommendations can result in severe damage to the device!
Preheat phase
Initial heating of component leads and balls. Residual humidity will be dried out. Note that this preheat phase will
not replace prior baking procedures.


Temperature rise rate: max 3 °C/s

If the temperature rise is too rapid in the preheat phase, it may cause
excessive slumping.



Time: 60 to 120 s

If the preheat is insufficient, rather large solder balls tend to be
generated. Conversely, if performed excessively, fine balls and large
balls will be generated in clusters.



End Temperature: 150 °C to 200 °C

If the temperature is too low, non-melting tends to be caused in areas
containing large heat capacity.

Heating/ reflow phase
The temperature rises above the liquidus temperature of +217 °C. Avoid a sudden rise in temperature as the slump
of the paste could become worse.


Limit time above +217 °C liquidus temperature: 40 to 60 s



Peak reflow temperature: +245 °C

Cooling phase
A controlled cooling avoids negative metallurgical effects (solder becomes more brittle) of the solder and possible
mechanical tensions in the products. Controlled cooling helps to achieve bright solder fillets with a good shape
and low contact angle.


Temperature fall rate: max 4 °C/s

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To avoid falling off, modules should be placed on the topside of the motherboard during soldering.
The soldering temperature profile chosen at the factory depends on additional external factors, such as the choice
of soldering paste, size, thickness and properties of the base board, etc.
Exceeding the maximum soldering temperature and the maximum liquidus time limit in the
recommended soldering profile may permanently damage the module.
Preheat
[°C]
250

Heating
Peak Temp. 245°C

Cooling
[°C]
250

Liquidus Temperature
217
200

217
200
40 - 60 s
End Temp.
150 - 200°C

max 4°C/s

150

150

max 3°C/s

60 - 120 s
Typical Leadfree
Soldering Profile

100

50

100

50
Elapsed time [s]

Figure 70: Recommended soldering profile

LARA-R2 series modules must not be soldered with a damp heat process.

3.3.3 Optical inspection
After soldering the LARA-R2 series modules, inspect the modules optically to verify that the module is properly
aligned and centered.

3.3.4 Cleaning
Cleaning the soldered modules is not recommended. Residues underneath the modules cannot be easily removed
with a washing process.


Cleaning with water will lead to capillary effects where water is absorbed in the gap between the baseboard
and the module. The combination of residues of soldering flux and encapsulated water leads to short circuits
or resistor-like interconnections between neighboring pads. Water will also damage the sticker and the inkjet printed text.



Cleaning with alcohol or other organic solvents can result in soldering flux residues flooding into the two
housings, areas that are not accessible for post-wash inspections. The solvent will also damage the sticker and
the ink-jet printed text.

 Ultrasonic cleaning will permanently damage the module, in particular the quartz oscillators.
For best results, use a "no clean" soldering paste and eliminate the cleaning step after the soldering.

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3.3.5 Repeated reflow soldering
Only a single reflow soldering process is encouraged for boards with a LARA-R2 series module populated on it.

3.3.6 Wave soldering
Boards with combined through-hole technology (THT) components and surface-mount technology (SMT) devices
require wave soldering to solder the THT components. Wave soldering process is not recommended for the
LARA-R2 series LGA modules.

3.3.7 Hand soldering
Hand soldering is not recommended.

3.3.8 Rework
Rework is not recommended.
Never attempt a rework on the module itself, e.g. replacing individual components. Such actions
immediately terminate the warranty.

3.3.9 Conformal coating
Certain applications employ a conformal coating of the PCB using HumiSeal® or other related coating products.
These materials affect the RF properties of the LARA-R2 series modules and it is important to prevent them from
flowing into the module.
The RF shields do not provide 100% protection for the module from coating liquids with low viscosity, and
therefore care is required in applying the coating.
Conformal coating of the module will void the warranty.

3.3.10 Casting
If casting is required, use viscose or another type of silicon pottant. The OEM is strongly advised to qualify such
processes in combination with the LARA-R2 series modules before implementing this in production.
Casting will void the warranty.

3.3.11 Grounding metal covers
Attempts to improve grounding by soldering ground cables, wick or other forms of metal strips directly onto the
EMI covers is done at the customer's own risk. The numerous ground pins should be sufficient to provide optimum
immunity to interferences and noise.
u-blox gives no warranty for damages to the LARA-R2 series modules caused by soldering metal cables or
any other forms of metal strips directly onto the EMI covers.

3.3.12 Use of ultrasonic processes
LARA-R2 series modules contain components which are sensitive to ultrasonic waves. Use of any ultrasonic
processes (cleaning, welding etc.) may cause damage to the module.
u-blox gives no warranty against damages to the LARA-R2 series modules caused by any ultrasonic
processes.

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4 Approvals
For the complete list and specific details regarding the certification schemes approvals, see the LARA-R2
series Data Sheet [1], or please contact the u-blox office or sales representative nearest you.

4.1 Product certification approval overview
Product certification approval is the process of certifying that a product has passed all tests and criteria required
by specifications, typically called “certification schemes” that can be divided into three distinct categories:


Regulatory certification
o Country specific approval required by local government in most regions and countries, as:
 CE (Conformité Européenne) marking for European Union
 FCC (Federal Communications Commission) approval for United States



Industry certification
o Telecom industry specific approval verifying the interoperability between devices and networks:
 GCF (Global Certification Forum), a partnership between device manufacturers and network
operators to ensure and verify global interoperability between devices and networks
 PTCRB (PCS Type Certification Review Board), created by United States network operators to ensure
and verify interoperability between devices and North America networks



Operator certification
o Operator specific approval required by some mobile network operator, as:
 AT&T network operator in the United States
 Verizon Wireless network operator in the United States
Even if the LARA-R2 series modules are approved under all major certification schemes, the application device that
integrates the modules must be approved under all the certification schemes required by the specific application
device to be deployed in the market.
The required certification scheme approvals and relative testing specifications differ depending on the country or
the region where the device that integrates LARA-R2 series modules must be deployed, on the relative vertical
market of the device, on type, features and functionalities of the whole application device, and on the network
operators where the device must operate.
Check the appropriate applicability of the LARA-R2 series module’s approvals while starting the certification
process of the device integrating the module: the re-use of the u-blox cellular module’s approval can
significantly reduce the cost and time to market of the application device certification.
The certification of the application device that integrates a LARA-R2 series module and the compliance of
the application device with all the applicable certification schemes, directives and standards are the sole
responsibility of the application device manufacturer.
LARA-R2 series modules are certified according to capabilities and options stated in the Protocol Implementation
Conformance Statement document (PICS) of the module. The PICS, according to the 3GPP TS 51.010-2 [12], 3GPP
TS 34.121-2 , 3GPP TS 36.521-2 [15] and 3GPP TS 36.523-2 [16], is a statement of the implemented and supported
capabilities and options of a device.
The PICS document of the application device integrating a LARA-R2 series module must be updated from
the module PICS statement if any feature stated as supported by the module in its PICS document is not
implemented or disabled in the application device. For more details regarding the AT commands settings
that affect the PICS, see the u-blox AT Commands Manual [2].
Check the specific settings required for mobile network operators approvals as they may differ from the AT
commands settings defined in the module as integrated in the application device.

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4.2 US Federal Communications Commission notice
United States Federal Communications Commission (FCC) IDs:


u-blox LARA-R202 cellular modules:

XPY1EIQ24NN



u-blox LARA-R203 cellular modules:

XPY1DIQN3NN



u-blox LARA-R204 cellular modules:

XPY1EIQN2NN

4.2.1 Safety warnings review the structure


Equipment for building-in. The requirements for fire enclosure must be evaluated in the end product



The clearance and creepage current distances required by the end product must be withheld when the module
is installed



The cooling of the end product shall not negatively be influenced by the installation of the module



Excessive sound pressure from earphones and headphones can cause hearing loss



No natural rubbers, no hygroscopic materials nor materials containing asbestos are employed

4.2.2 Declaration of conformity
This device complies with Part 15 of the FCC rules and with the ISED Canada licence-exempt RSS standard(s).
Operation is subject to the following two conditions:


this device may not cause harmful interference



this device must accept any interference received, including interference that may cause undesired operation
Radiofrequency radiation exposure Information: this equipment complies with FCC radiation
exposure limits prescribed for an uncontrolled environment for fixed and mobile use conditions.
This equipment should be installed and operated with a minimum distance of 20 cm between the
radiator and the body of the user or nearby persons. This transmitter must not be co-located or
operating in conjunction with any other antenna or transmitter except in accordance with FCC
procedures and as authorized in the module certification filing.
The gain of the system antenna(s) used for the LARA-R2 series modules (i.e. the combined
transmission line, connector, cable losses and radiating element gain) must not exceed the value
specified in the FCC Grant for mobile and fixed or mobile operating configurations:
o LARA-R202 modules:
o 9.8 dBi in 700 MHz, i.e. LTE FDD-12 band
o 10.0 dBi in 850 MHz, i.e. LTE FDD-5 or UMTS FDD-5 band
o 6.5 dBi in 1700 MHz, i.e. LTE FDD-4 band
o 8.7 dBi in 1900 MHz, i.e. LTE FDD-2 or UMTS FDD-2 band
o LARA-R203 modules:
o 9.7 dBi in 700 MHz, i.e. LTE FDD-12 band
o 7.1 dBi in 1700 MHz, i.e. LTE FDD-4 band
o 10.5 dBi in 1900 MHz, i.e. LTE FDD-2 band
o LARA-R204 modules:
o 10.2 dBi in 750 MHz, i.e. LTE FDD-13 band
o 7.6 dBi in 1700 MHz, i.e. LTE FDD-4 band

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4.2.3 Modifications
The FCC requires the user to be notified that any changes or modifications made to this device that are not
expressly approved by u-blox could void the user's authority to operate the equipment.
Manufacturers of mobile or fixed devices incorporating the LARA-R2 series modules are
authorized to use the FCC Grants of the LARA-R2 series modules for their own final products
according to the conditions referenced in the certificates.
The FCC Label shall in the above case be visible from the outside, or the host device shall bear a
second label stating:
"Contains FCC ID: XPY1EIQ24NN" resp.
"Contains FCC ID: XPY1DIQN3NN" resp.
"Contains FCC ID: XPY1EIQN2NN" resp.
IMPORTANT: Manufacturers of portable applications incorporating the LARA-R2 series modules
are required to have their final product certified and apply for their own FCC Grant related to the
specific portable device. This is mandatory to meet the SAR requirements for portable devices.
Changes or modifications not expressly approved by the party responsible for compliance could
void the user's authority to operate the equipment.
Additional Note: as per 47CFR15.105 this equipment has been tested and found to comply with
the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. These limits are
designed to provide reasonable protection against harmful interference in a residential
installation. This equipment generates, uses and can radiate radio frequency energy and, if not
installed and used in accordance with the instructions, may cause harmful interference to radio
communications. However, there is no guarantee that interference will not occur in a particular
installation. If this equipment does cause harmful interference to radio or television reception,
which can be determined by turning the equipment off and on, the user is encouraged to try to
correct the interference by one or more of the following measures:
o Reorient or relocate the receiving antenna
o Increase the separation between the equipment and receiver
o Connect the equipment into an outlet on a circuit different from that to which the receiver is
connected
o Consultant the dealer or an experienced radio/TV technician for help

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4.3

Innovation, Science and Economic Development Canada notice

ISED Canada (formerly known as IC - Industry Canada) Certification Numbers:


u-blox LARA-R202 cellular modules:

8595A-1EIQ24NN



u-blox LARA-R203 cellular modules:

8595A-1DIQN3NN



u-blox LARA-R204 cellular modules:

8595A-1EIQN2NN

4.3.1

Declaration of Conformity

This device complies with the ISED Canada licence-exempt RSS standard(s). Operation is subject to the following
two conditions:


this device may not cause harmful interference



this device must accept any interference received, including interference that may cause undesired operation
Radiofrequency radiation exposure Information: this equipment complies with radiation
exposure limits prescribed for an uncontrolled environment for fixed and mobile use conditions.
This equipment should be installed and operated with a minimum distance of 20 cm between the
radiator and the body of the user or nearby persons. This transmitter must not be co-located or
operating in conjunction with any other antenna or transmitter except as authorized in the
certification of the product.
The gain of the system antenna(s) used for the LARA-R2 series modules (i.e. the combined
transmission line, connector, cable losses and radiating element gain) must not exceed not exceed
the value specified in the ISED Canada Certificate Grant for mobile and fixed or mobile operating
configurations:
o LARA-R202 modules:
o 6.7 dBi in 700 MHz, i.e. LTE FDD-12 band
o 6.7 dBi in 850 MHz, i.e. LTE FDD-5 or UMTS FDD-5 band
o 6.5 dBi in 1700 MHz, i.e. LTE FDD-4 band
o 8.7 dBi in 1900 MHz, i.e. LTE FDD-2 or UMTS FDD-2 band
o LARA-R203 modules:
o 6.6 dBi in 700 MHz, i.e. LTE FDD-12 band
o 7.1 dBi in 1700 MHz, i.e. LTE FDD-4 band
o 9.5 dBi in 1900 MHz, i.e. LTE FDD-2 band
o LARA-R204 modules:
o 7.0 dBi in 750 MHz, i.e. LTE FDD-13 band
o 7.6 dBi in 1700 MHz, i.e. LTE FDD-4 band

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4.3.2

Modifications

The ISED Canada requires the user to be notified that any changes or modifications made to this device that are
not expressly approved by u-blox could void the user's authority to operate the equipment.
Manufacturers of mobile or fixed devices incorporating the LARA-R2 series modules are
authorized to use the ISED Canada Certificates of the LARA-R2 series modules for their own final
products according to the conditions referenced in the certificates.
The ISED Canada Label shall in the above case be visible from the outside, or the host device shall
bear a second label stating:
"Contains IC: 8595A-1EIQ24NN" resp.
"Contains IC: 8595A-1DIQN3NN" resp.
"Contains IC: 8595A-1EIQN2NN" resp.
Innovation, Science and Economic Development Canada (ISED) Notices
This Class B digital apparatus complies with Canadian CAN ICES-3(B) / NMB-3(B) and RSS-210.
Operation is subject to the following two conditions:
o this device may not cause interference
o this device must accept any interference, including interference that may cause undesired
operation of the device
Radio Frequency (RF) Exposure Information
The radiated output power of the u-blox Cellular Module is below the Innovation, Science and
Economic Development Canada (ISED) radio frequency exposure limits. The u-blox Cellular
Module should be used in such a manner such that the potential for human contact during normal
operation is minimized.
This device has been evaluated and shown compliant with the ISED RF Exposure limits under
mobile exposure conditions (antennas are greater than 20 cm from a person's body).
This device has been certified for use in Canada. Status of the listing in the Innovation, Science
and Economic Development’s REL (Radio Equipment List) can be found at the following web
address:
http://www.ic.gc.ca/app/sitt/reltel/srch/nwRdSrch.do?lang=eng
Additional Canadian information on RF exposure also can be found at the following web address:
http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf08792.html
IMPORTANT: Manufacturers of portable applications incorporating the LARA-R2 series modules
are required to have their final product certified and apply for their own Innovation, Science and
Economic Development Certificate related to the specific portable device. This is mandatory to
meet the SAR requirements for portable devices.
Changes or modifications not expressly approved by the party responsible for compliance could
void the user's authority to operate the equipment.

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Avis d'Innovation, Sciences et Développement économique Canada (ISDE)
Cet appareil numérique de classe B est conforme aux normes canadiennes CAN ICES-3(B) /
NMB-3(B) et CNR-210.
Son fonctionnement est soumis aux deux conditions suivantes :
o cet appareil ne doit pas causer d'interférence
o cet appareil doit accepter toute interférence, notamment les interférences qui peuvent
affecter son fonctionnement
Informations concernant l'exposition aux fréquences radio (RF)
La puissance de sortie émise par l’appareil de sans fil u-blox Cellular Module est inférieure à la
limite d'exposition aux fréquences radio d'Innovation, Sciences et Développement économique
Canada (ISDE). Utilisez l’appareil de sans fil u-blox Cellular Module de façon à minimiser les
contacts humains lors du fonctionnement normal.
Ce périphérique a été évalué et démontré conforme aux limites d'exposition aux fréquences radio
(RF) d'IC lorsqu'il est installé dans des produits hôtes particuliers qui fonctionnent dans des
conditions d'exposition à des appareils mobiles (les antennes se situent à plus de 20 centimètres
du corps d'une personne).
Ce périphérique est homologué pour l'utilisation au Canada. Pour consulter l'entrée
correspondant à l’appareil dans la liste d'équipement radio (REL - Radio Equipment List)
d'Industrie Canada rendez-vous sur:
http://www.ic.gc.ca/app/sitt/reltel/srch/nwRdSrch.do?lang=fra
Pour des informations supplémentaires concernant l'exposition aux RF au Canada rendez-vous
sur: http://www.ic.gc.ca/eic/site/smt-gst.nsf/fra/sf08792.html
IMPORTANT: les fabricants d'applications portables contenant les modules LARA-R2 series
doivent faire certifier leur produit final et déposer directement leur candidature pour une
certification FCC ainsi que pour un certificat ISDE Canada délivré par l'organisme chargé de ce
type d'appareil portable. Ceci est obligatoire afin d'être en accord avec les exigences SAR pour
les appareils portables.
Tout changement ou modification non expressément approuvé par la partie responsable de la
certification peut annuler le droit d'utiliser l'équipement.

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4.4 European Conformance CE mark
LARA-R211 modules have been evaluated against the essential requirements of the Radio Equipment Directive
2014/53/EU.
In order to satisfy the essential requirements of the 2014/53/EU RED, the modules are compliant with the following
standards:


Radio Spectrum Efficiency (Article 3.2):
o EN 301 511
o EN 301 908-1
o EN 301 908-13



Electromagnetic Compatibility (Article 3.1b):
o EN 301 489-1
o EN 301 489-52



Health and Safety (Article 3.1a)
o EN 60950-1
o EN 62311
Radiofrequency radiation exposure information: this equipment complies with radiation
exposure limits prescribed for an uncontrolled environment for fixed and mobile use conditions.
This equipment should be installed and operated with a minimum distance of 20 cm between the
radiator and the body of the user or nearby persons. This transmitter must not be co-located or
operating in conjunction with any other antenna or transmitter except as authorized in the
certification of the product.
The gain of the system antenna(s) used for the LARA-R2 series modules (i.e. the combined
transmission line, connector, cable losses and radiating element gain) must not exceed the
following values for mobile and fixed or mobile operating configurations:
o LARA-R211 modules:
o 9.3 dBi in 800 MHz, i.e. LTE FDD-20 band
o 2.9 dBi in 900 MHz, i.e. GSM 900 band
o 8.8 dBi in 1800 MHz, i.e. GSM 1800 or LTE FDD-3 band
o 13.0 dBi in 2600 MHz, i.e. LTE FDD-7 band

The conformity assessment procedure for the modules, referred to in Article 17 and detailed in Annex II of Directive
2014/53/EU, has been followed.
Thus, the following marking is included in the product:

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5 Product testing
5.1 u-blox in-series production test
u-blox focuses on high quality for its products. All units produced are fully tested automatically in the production
line. A stringent quality control process has been implemented in the production line. Defective units are analyzed
in detail to improve production quality.
This is achieved with automatic test equipment (ATE) in the production line, which logs all production and
measurement data. A detailed test report for each unit can be generated from the system. Figure 71 illustrates the
typical automatic test equipment (ATE) in a production line.
The following typical tests are among the production tests.


Digital self-test (firmware download, Flash firmware verification, IMEI programming)



Measurement of voltages and currents



Adjustment of ADC measurement interfaces



Functional tests (serial interface communication, SIM card communication)



Digital tests (GPIOs and other interfaces)



Measurement and calibration of RF characteristics in all supported bands (such as receiver S/N verification,
frequency tuning of the reference clock, calibration of transmitter and receiver power levels, etc.)



Verification of RF characteristics after calibration (i.e. modulation accuracy, power levels, spectrum, etc. are
checked to ensure they are all within tolerances when calibration parameters are applied)

Figure 71: Automatic test equipment for module tests

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5.2 Test parameters for OEM manufacturers
Because of the testing performed by u-blox (with 100% coverage), an OEM manufacturer does not need to repeat
firmware tests or measurements of the module RF performance or tests over analog and digital interfaces in their
production test.
An OEM manufacturer should focus on:


Module assembly on the device; it should be verified that:
o Soldering and handling processes did not damage the module components
o All module pins are well soldered on the device board
o There are no short circuits between pins



Component assembly on the device; it should be verified that:
o Communications with host controller can be established
o The interfaces between the module and device are working
o Overall RF performance test of the device including the antenna

Dedicated tests can be implemented to check the device. For example, the measurement of module current
consumption when set in a specified status can detect a short circuit if compared with a “Golden Device” result.
In addition, module AT commands can be used to perform functional tests on digital interfaces (communication
with host controller, check SIM interface, GPIOs, etc.), on audio interfaces (audio loop for test purposes can be
enabled by the AT+UPAR=2 command as described in the u-blox AT Commands Manual [2]), and to perform RF
performance tests (see the following section 5.2.2 for details).

5.2.1 “Go/No go” tests for integrated devices
A “Go/No go” test is typically performed to compare the signal quality with a “Golden Device” in a location with
excellent network coverage and known signal quality. This test should be performed after data connection has
been established. AT+CSQ is the typical AT command used to check signal quality in term of RSSI. See the u-blox
AT Commands Manual [2] for details of the AT command.
These kinds of test may be useful as a “go/no go” test but not for RF performance measurements.
This test is suitable to check the functionality of communication with the host controller or SIM card, as well as
the power supply. It is also a means to verify if the components at antenna interface are well soldered.

5.2.2 Functional tests providing RF operation
The overall RF functional test of the device including the antenna can be performed with basic instruments such
as a spectrum analyzer (or an RF power meter) and a signal generator with the assistance of AT+UTEST command
over the AT command user interface.
The AT+UTEST command provides a simple interface to set the module to Rx or Tx test modes ignoring the cellular
signaling protocol. The command can set the module into:


transmitting mode in a specified channel and power level in all supported modulation schemes and bands



receiving mode in a specified channel to returns the measured power level in all supported bands
See the u-blox AT Commands Manual [2] and the End user test Application Note [24], for the AT+UTEST
command syntax description and examples of use.

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This feature allows the measurement of the transmitter and receiver power levels to check component assembly
related to the module antenna interface and to check other device interfaces on which RF performance depends.
To avoid module damage during transmitter test, a proper antenna according to module
specifications or a 50  termination must be connected to the ANT1 port.
To avoid module damage during receiver, test the maximum power level received at the ANT1
and ANT2 ports which must meet the module specifications.
The AT+UTEST command sets the module to emit RF power ignoring cellular signaling protocol. This
emission can generate interference that can be prohibited by law in some countries. The use of this feature
is intended for testing purposes in controlled environments by qualified users and must not be used during
normal module operation. Follow the instructions suggested in u-blox documentation. u-blox assumes no
responsibilities for the inappropriate use of this feature.
Figure 72 illustrates a typical test setup for such an RF functional test.

Application
Processor

LARA-R2 series

Cellular
antenna

Wideband
antenna

IN

Spectrum
Analyzer
or
Power
Meter

OUT

Signal
Generator

AT
commands
ANT1

TX

Application Board

Cellular
antennas

Application
Processor

Wideband
antenna

LARA-R2 series
AT
commands

ANT1

RX
ANT2

Application Board
Figure 72: Setup with spectrum analyzer or power meter and signal generator for radiated measurements

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Appendix
A Migration between SARA-U2 and LARA-R2
A.1 Overview

64 63 62 61 60 59 58 57 56 55 54

51

VCC

GND

3

50

GND

V_INT

4

49

RSVD

GND

5

6

48

RSVD

DSR

6

RI

7

47

RSVD

RI

7

DCD

8

46

RSVD

DCD

8

DTR

9

45

RSVD

DTR

9

RTS

10

44

RSVD

RTS 10

LARA-R2

CTS

11

Top View

43

GND

CTS 11

TXD

12

Pin 65-96: GND

42

SIM_DET

TXD 12

RXD

13

41

VSIM

RXD 13

GND

14

40

SIM_RST

GND 14

PWR_ON

15

39

SIM_IO

GPIO1

16

38

SIM_CLK

GPIO1 16

VUSB_DET

17

37

I2S_RXD

VUSB_DET 17

RESET_N

18

36

I2S_CLK

RESET_N 18

CODEC_CLK

19

35

I2S_TXD

GPIO6 19

GND

20

34

I2S_WA

GND 20

GND

21

33

RSVD

76

77

78

79

80

SARA-U2
81

82

83

84

85

86

87

88

89

90

91

92

93

94

95

96

GND

RSVD

GND

USB_D+

USB_D–

SCL

SDA

GPIO4

GPIO3

GND

GPIO2

22 23 24 25 26 27 28 29 30 31 32

GND

GND

VCC

51

71

VCC

50

GND

49

SDIO_D1

48

SDIO_D3

47

SDIO_D0

46

SDIO_CMD

45

SDIO_CLK

44

SDIO_D2

Top View

43

GND

Pin 65-96: GND

42

GPIO5

41

VSIM

40

SIM_RST

39

SIM_IO

38

SIM_CLK

37

I2S_RXD

36

I2S_CLK

35

I2S_TXD

34

I2S_WA

33

RSVD

72

68

73

77

69

74

97

98

70

75

76
78

79

80

81

PWR_ON 15
83

82

99

100

84

85

86

87

88

89

90

91

92

93

94

95

96

HOST_SELECT 21
22 23 24 25 26 27 28 29 30 31 32

GND

75

VCC

52

67

RSVD

74

53
66

GND

73

65

USB_D+

72

70

RSVD

DSR

71

69

HSIC_STRB

5

ANT1

2

68

USB_D–

GND

GND

V_BCKP

67

SCL

4

GND

VCC

66

RSVD

V_INT

ANT_DET

52

65

HSIC_DATA

3

GND

1

SDA

GND

GND

GND

GPIO4

2

ANT2

VCC

GPIO3

V_BCKP

64 63 62 61 60 59 58 57 56 55 54
53

GND

1

GPIO2

GND

GND

GND

GND

GND

ANT

GND

GND

GND

GND

GND

ANT_DET

GND

GND

Migrating between u-blox SARA-U2 series 3G / 2G cellular modules and LARA-R2 series LTE Cat 1 / 3G / 2G cellular
modules is a straightforward procedure that allows customers to take maximum advantage of their hardware and
software investments.
The SARA cellular modules (26.0 x 16.0 mm, 96-pin LGA) have a different form factor than the LARA cellular
modules (26.0 x 24.0 mm, 100-pin LGA), but the footprint of SARA and LARA modules has been developed to
ensure layout compatibility as described in Figure 73, so that the modules can be alternatively mounted on the
same single common application board.

Figure 73: Comparison of the SARA-U2 and LARA-R2 series modules pin layout and pin assignment

SARA-U2 and LARA-R2 series modules are basically pin-to-pin compatible, given that the LARA-R2 series modules
provide further additional functions and interfaces, as shown in Figure 73:


Secondary antenna



SDIO interface



HSIC interface



HOST_SELECT function

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SARA and LARA modules are also form-factor compatible with the u-blox LISA and TOBY cellular module families:
although SARA, LARA, LISA (33.2 x 22.4 mm, 76-pin LCC) and TOBY (35.6 x 24.8 mm, 152-pin LGA) modules
each have different form factors, the footprints of all the SARA, LARA, LISA and TOBY modules have been
developed to ensure layout compatibility.
With the u-blox “nested design” solution, any SARA, LARA, LISA or TOBY module can be alternatively mounted
on the same space of a single “nested” application board as described in Figure 74, enabling straightforward
development of products supporting different cellular radio access technologies.

TOBY cellular module
LISA cellular module
LARA cellular module

SARA cellular module

Nested application board

Figure 74: Nested design concept description: SARA, LARA, LISA and TOBY modules alternatively mounted on the same PCB

A different top-side stencil (paste mask) is needed for each form factor (SARA, LARA, LISA and TOBY) to be
alternatively mounted on the same space of a single “nested” application board, as described in Figure 75.

ANT pad

ANT pad

ANT pad

ANT pad

TOBY

LISA

SARA

LARA

TOBY mounting option
with TOBY paste mask

LISA mounting option
with LISA paste mask

SARA mounting option
with SARA paste mask

LARA mounting option
with LARA paste mask

Figure 75: Top-side stencil (paste mask) designs to alternatively mount SARA, LARA, LISA and TOBY modules on the same PCB

Detailed guidelines to implement a nested application board, a comprehensive description of the u-blox reference
nested design and detailed comparisons between the u-blox SARA, LARA, LISA and TOBY modules are provided
in the Nested Design Application Note [26].

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Table 53 summarizes the interfaces provided by the SARA-U2 and LARA-R2 series modules: all the interfaces
provided by the different modules are electrically compatible, so that the same compatible external circuit can be
implemented on the application board.

Network indication

Clock output

GNSS control

●

●

●

●

●

●

●

●

●

●

12

850
1900

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

12

900
1800

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

■

●

●

●

●

■

■

●

●

●

●

●

●

■

Wi-Fi control

GPIOs 1.8 V

●

Analog audio
Digital audio

●

DDC (I2C) 1.8 V

2,5

●

SDIO 1.8 V

6

●

HSIC

8

USB 2.0

2,5

UART 1.8 V

6

SIM detection

8

SIM 1.8 V / 3.0 V

SARA-U280

●

Host select

1,8

RESET_N

6

PWR_ON

8

Other

V_INT 1.8 V supply out

SARA-U270

Audio

V_BCKP

2,5

Serial

VCC module supply in

6

SIM

Antenna Detection

8

System

●

Rx diversity

SARA-U260

Power

12 Quad

2G bands

1,2,5
8,19

Multi-slot class

6

3G bands

8

LTE bands

SARA-U201

LTE category

HSUPA category

RF / Radio Access Technology

HSDPA category

Module

LARA-R202

1

2,4
5,12

LARA-R203

1

2,4,12

●

●

●

●

●

●

●

■

●

●

●

●

■

■

●

●

●

●

●

●

■

LARA-R204

1

4,13

●

●

●

●

●

●

●

■

●

●

●

●

■

■

●

■

●

●

●

■

■

LARA-R211

1

3,7,20

900
●
1800

●

●

●

●

●

●

■

●

●

●

●

■

■

●

●

●

●

●

■

■

LARA-R220

1

1,19

●

●

●

●

●

●

●

■

●

●

●

●

■

■

●

■

●

●

●

●

■

LARA-R280

1

3,8,28

●

●

●

●

●

●

●

■

●

●

●

●

■

■

●

●

●

●

●

●

■

12

8

6

● = supported by all product versions

1

■ = supported by all product versions except versions ‘02’ and ’62’

Table 53: Summary of SARA-U2 and LARA-R2 series modules interfaces

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Figure 76 summarizes the cellular operating frequency bands of the SARA-U2 and LARA-R2 series modules.

XIX

V
850

SARA-U201
700

750

800

V
VIII
850
900

850

900

VIII
900
950

824

960

V
850

SARA-U260
700

750

800

800

950

850
V

700

750

800

900

12

LARA-R202

700

750

800

LARA-R203

LARA-R204

12

950

699

746

700

750

13

800

850

950

900

1700

1700

850

1950

950

1700

900

950

800

800

20

900

850

2000

2050

2100

2150

2050

2100

2150

I

1800
1800

900

950

850

1850

1900

2000

1750

1800

1850

950

1950

1800

1850

2000

2050

2100

2050

2100

2
II
1900

1950

2

1750

1800

960

1700

2500

2550

2600

2650

2700

2200

2500

2550

2600

2650

2700

2200

2500

2550

2600

2650

2700

2150

2200

2500

2550

2600

2650

2700

2200

2500

2550

2600

2650

2700

2200

2500

2550

2600

2650

2700

4
2000

1850

2
1900

1950

4
2000

2050

2100

2150

2155
4

1750

1800

1850

1900

1950

2000

2050

2100

2150

2155

1750

3
1800
1800

7

1850

1900

1950

2000

2050

2100

2150

2200

1880
1750

1800

3

950

2200

2150

1850

1750

1900

3
1800

1850

2500

2550

7
2600

2650

2500
1950

2050

2100

2150

2200

2500

2550

2600

2650

2700

2500

2550

2600

2650

2700

2170
I

1900

2700

2690

1
2000

1920
8

2700

2155

890

900

2650

1990
2
II

1750

1710
1700

2600

II
1900

1
900

2550

I

1950

19

8
850

1700

2500

2170

3
1800

900

960

28
800

1700

2200

1990

1710

830

703

2150

II
1900

1900

4
800

750

750

2100

1710

13

750

28

2050

1710

19

700

1750

4

750

700

1850

4
900

2000

1710

5
V

791

LARA-R280

1800
1700

12

700

20

LARA-R220

1800

1850

894

700

1750

II
950

746 787

LARA-R211

1700

VIII
900

960

900

850

699

1950

2170

894

5
V

12

1900

V

850

824

1850

I

1710

1850

880

SARA-U280

1800
1800

894
VIII
900

750

1750

II
1900

900

SARA-U270
700

1800
1700

I
II
1900

II
1900

V
850

850

824

LEGENDA
= LTE bands
= 3G bands
= 2G bands

XIX

1950

I
2000

2050

2100

1710

2150

2200

2170

Figure 76: Summary of SARA-U2 and LARA-R2 series modules operating frequency bands

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A.2 Pin-out comparison between SARA-U2 and LARA-R2
SARA-U2

23

LARA-R2

Pin No

Pin Name

Description

Pin Name

Description

1

GND

Ground

GND

Ground

Remarks for migration

2

V_BCKP

RTC Supply I/O
Output characteristics:
1.8 V typ, 3 mA max
Input op. range:
1.0 V – 1.9 V

V_BCKP

RTC Supply I/O
Output characteristics:
1.8 V typ, 3 mA max
Input op. range:
1.0 V – 1.9 V

3

GND

Ground

GND

Ground

4

V_INT

Interfaces Supply Out
Output characteristics:
1.8 V typ, 50 mA max

V_INT

Interfaces Supply Out
Output characteristics:
1.8 V typ, 50 mA max

5

GND

Ground

GND

Ground

6

DSR

UART DSR Output
1.8 V, Driver strength: 1 mA

DSR

UART DSR Output
1.8 V, Driver strength: 6 mA

No functional difference

7

RI

UART RI Output
1.8 V, Driver strength: 2 mA

RI

UART RI Output
1.8 V, Driver strength: 6 mA

No functional difference

8

DCD

UART DCD Output
1.8 V, Driver strength: 2 mA

DCD

UART DCD Output
1.8 V, Driver strength: 6 mA

No functional difference

9

DTR

UART DTR Input
1.8 V, Internal pull-up: ~14 k

DTR

UART DTR Input
1.8 V, Internal pull-up: ~7.5 k

No functional difference

10

RTS

UART RTS Input
1.8 V, Internal pull-up: ~8 k

RTS

UART RTS Input
1.8 V, Internal pull-up: ~7.5 k

No functional difference

11

CTS

UART CTS Output
1.8 V, Driver strength: 6 mA

CTS

UART CTS Output
1.8 V, Driver strength: 6 mA

No functional difference

12

TXD

UART Data Input
1.8 V, Internal pull-up: ~8 k

TXD

UART Data Input
1.8 V, Internal pull-up: ~7.5 k

No functional difference

13

RXD

UART Data Output
1.8 V, Driver strength: 6 mA

RXD

UART Data Output
1.8 V, Driver strength: 6 mA

No functional difference

14

GND

Ground

GND

Ground

15

PWR_ON

Power-on Input
No internal pull-up
L-level: -0.30 V – 0.65 V
H-level: 1.50 V – 4.40 V
ON L-level pulse time:
50 µs min / 80 µs max
OFF L-level pulse time:
1 s min

PWR_ON

Power-on Input
10 k internal pull-up to V_BCKP
L-level: –0.30 V … 0.54 V
H-level: 1.26 V … 2.10 V
ON L-level pulse time:
50 µs min
OFF L-level pulse time:
1 s min

No functional difference

No functional difference

External  Internal pull-up
Sligtlhy different input levels
Function slightly different.

16

GPIO1

1.8 V GPIO
Driver strength: 6 mA

GPIO1

1.8 V GPIO
Driver strength: 6 mA

No functional difference

17

VUSB_DET

USB Detect Input
5 V, Supply detection

VUSB_DET

USB Detect Input
5 V, Supply detection

No functional difference

18

RESET_N

Reset signal
10 k internal pull-up
L-level: -0.30 V – 0.51 V
H-level: 1.32 V – 2.01 V
Reset L-level pulse time:
50 ms min

RESET_N

Reset signal
10 k internal pull-up
L-level: -0.30 V – 0.51 V
H-level: 1.32 V – 2.01 V
Reset L-level pulse time:
50 ms min

No functional difference

19

CODEC_CLK

1.8 V Clock Output
Driver strength: 4 mA

GPIO6

1.8 V Clock Output
Driver strength: 6 mA

No functional difference

20

GND

Ground

GND

Ground

21

GND

Ground

HOST_SELECT

1.8 V pin for module / host
configuration selection23

22

GND

Ground

GND

Ground

23

GPIO2

1.8 V GPIO
Driver strength: 1 mA

GPIO2

1.8 V GPIO
Driver strength: 6 mA

No functional difference

24

GPIO3

1.8 V GPIO
Driver strength: 6 mA

GPIO3

1.8 V GPIO
Driver strength: 6 mA

No functional difference

25

GPIO4

1.8 V GPIO
Driver strength: 6 mA

GPIO4

1.8 V GPIO
Driver strength: 6 mA

No functional difference

GND  HOST_SELECT

Not supported by “02” and “62” product versions

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SARA-U2

LARA-R2

Pin No

Pin Name

Description

Pin Name

Description

Remarks for migration

26

SDA

I2C Data I/O
1.8 V, open drain
Driver strength: 1 mA

SDA

I2C Data I/O
1.8 V, open drain
Driver strength: 1 mA

No functional difference

27

SCL

I2C Clock Output
1.8 V, open drain
Driver strength: 1 mA

SCL

I2C Clock Output
1.8 V, open drain
Driver strength: 1 mA

No functional difference

28

USB_D-

USB Data I/O (D-)
High-Speed USB 2.0

USB_D-

USB Data I/O (D-)
High-Speed USB 2.0

No functional difference

29

USB_D+

USB Data I/O (D+)
High-Speed USB 2.0

USB_D+

USB Data I/O (D+)
High-Speed USB 2.0

No functional difference

30

GND

Ground

GND

Ground

31

RSVD

Reserved

RSVD

Reserved

32

GND

Ground

GND

Ground

33

RSVD

Reserved
To be externally connected to GND

RSVD

Reserved
To be externally connected to GND

No functional difference

34

I2S_WA

I2S Word Alignment I/O, or GPIO
1.8 V, Driver strength: 2 mA

I2S_WA

I2S Word Alignment I/O24, or GPIO
1.8 V, Driver strength: 6 mA

No functional difference

35

I2S_TXD

I2S Data Output, or GPIO
1.8 V, Driver strength: 2 mA

I2S_TXD

I2S Data Output24, or GPIO
1.8 V, Driver strength: 6 mA

No functional difference

36

I2S_CLK

I2S Clock I/O, or GPIO
1.8 V, Driver strength: 2 mA

I2S_CLK

I2S Clock I/O24, or GPIO
1.8 V, Driver strength: 6 mA

No functional difference

37

I2S_RXD

I2S Data Input, or GPIO
1.8 V, Inner pull-down: ~9 k

I2S_RXD

I2S Data Input24, or GPIO
1.8 V, Inner pull-down: ~7.5 k

No functional difference

38

SIM_CLK

SIM Clock Output

SIM_CLK

SIM Clock Output

No functional difference

39

SIM_IO

SIM Data I/O

SIM_IO

SIM Data I/O

No functional difference

40

SIM_RST

SIM Reset Output

SIM_RST

SIM Reset Output

No functional difference

41

VSIM

SIM Supply Output

VSIM

SIM Supply Output

No functional difference

42

SIM_DET

1.8V SIM Detection

SIM_DET

1.8 V GPIO settable as SIM Detection

No functional difference

43

GND

Ground

GND

Ground

44

RSVD

Reserved

SDIO_D2

1.8 V, SDIO serial data [2]25

RSVD  SDIO

45

RSVD

Reserved

SDIO_CLK

1.8 V, SDIO serial clock25

RSVD  SDIO

46

RSVD

Reserved

SDIO_CMD

1.8 V, SDIO command25

RSVD  SDIO

47

RSVD

Reserved

SDIO_D0

1.8 V, SDIO serial data [0]25

RSVD  SDIO

48

RSVD

Reserved

SDIO_D3

1.8 V, SDIO serial data [3]25

RSVD  SDIO

49

RSVD

Reserved

SDIO_D1

1.8 V, SDIO serial data [1]25

RSVD  SDIO

50

GND

Ground

GND

Ground

51-53

VCC

Module Supply Input
Normal range: 3.3 V – 4.4 V
Extended range: 3.1 V – 4.5 V

VCC

Module Supply Input
Normal range: 3.3 V – 4.4 V
Extended range: 3.0 V – 4.5 V

54-55

GND

Ground

GND

Ground

56

ANT

RF Antenna Input/Output

ANT1

RF Antenna Input/Output (primary)

57-58

GND

Ground

GND

Ground

59

GND

Ground

ANT_DET

Antenna Detection Input

60-61

GND

Ground

GND

Ground

62

ANT_DET

Antenna Detection Input

ANT2

RF Antenna Input (secondary)

63-96

GND

Ground

GND

Ground

97-98

-

Not Available

RSVD

Reserved

No functional difference

99

-

Not Available

HSIC_DATA

HSIC USB data line25

Not Available  HSIC

100

-

Not Available

HSIC_STRB

HSIC USB strobe line25

Not Available  HSIC

No functional difference

No functional difference
Larger range for LARA-R2
No functional difference
GND  ANT_DET
ANT_DET  ANT2

Table 54: SARA-U2 and LARA-R2 series modules pin assignment with remarks for migration

For further details regarding the characteristics, capabilities, usage or settings applicable for each interface of the
SARA-U2 and LARA-R2 series modules, see the LARA-R2 series Data Sheet [1], the SARA-U2 series Data Sheet [27],
the SARA-G3 / SARA-U2 series System Integration Manual [28], the u-blox AT Commands Manual [2] and the
Nested Design Application Note [26].

24
25

Not supported by LARA-R204-02B and LARA-R220-62B modules product versions.
Not supported by “02” and “62” product versions.

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A.3 Schematic for SARA-U2 and LARA-R2 integration
Figure 77 shows an example of a schematic diagram where a SARA-U2 or a LARA-R2 series module can be
integrated into the same application board, using all the available interfaces and functions of the modules. The
different mounting options for the external parts are noted herein according to the functions supported by each
module.
SARA-U2 series / LARA-R2 series
BLM18EG221SN1 for SARA-U201
0Ω otherwise

3V8

0Ω

+
330µF 100nF 10nF

56pF

Mount for modules
supporting 2G

15pF

51

VCC

52

VCC

53

VCC

8.2pF

ANT / ANT1

39nH

ANT_DET / ANT2

GND

82nH

62

100µF

V_BCKP

GND / ANT_DET

ESD

10k

Secondary
Cellular
Antenna

Connector

33pF
Mount for
SARA-U2

2

Primary
Cellular
Antenna

Connector

33pF

56

Mount for modules
supporting LTE band-7

RTC
back-up

0Ω for LARA-R2

15pF

82nH

10k

59

27pF

0Ω

GND

Mount for
LARA-R2

ESD

Mount for
LARA-R2

Application
Processor

100k

Mount for
SARA-U2

GPIO
TP

15

Open
Drain
Output
TP

18

Open
Drain
Output

SIM Card Holder

V_INT

V_INT

TP

1k

V_INT

4

SIM_DET / GPIO5

42

SW2

VSIM

41

CCVCC (C1)

SIM_IO

39

CCIO (C7)

SIM_CLK

38

CCCLK (C3)

SIM_RST

40

SW1

CCVPP (C6)

PWR_ON

RESET_N

CCRST (C2)
47pF 47pF 47pF 47pF 100nF

470k

1.8V DTE
TXD
RXD
RTS
CTS

0Ω

TP

0Ω

TP

0Ω

TP

0Ω

TP

0Ω

TP

Not supported by LARA-R204-02B and LARA-R211-02B product version

12

TXD

13

RXD

10

RTS

11

CTS

9

DTR

DSR

6

DSR

RI

7

RI

8

DCD

DTR

DCD

0Ω

TP

GPIO2

23

D+
D-

TP

0Ω

TP

0Ω

TP

17

VUSB_DET

29

USB_D+

28

USB_D–

GND

TP
TP

100nF

4.7k
SDA2
SCL2

SN74AVC2T245
Voltage Translator

3V0

VCCA

100nF

100nF

DIR1

GPIO3

24

B1

A1

GPIO4

25

B2

A2
GND

TxD1
EXTINT0
Not supported by LARA-R2
“02” and “62” product versions

DIR2

HSIC_DATA
Not supported by LARA-R204-02B and LARA-R220-62B product version

GND / HOST_SELECT

44

RSVD / SDIO_D2

45

RSVD / SDIO_CLK

46

RSVD / SDIO_CMD

47

RSVD / SDIO_D0

48

RSVD / SDIO_D3

49

RSVD / SDIO_D1

V_INT

Audio Codec
MAX9860

GPIO1

IRQn

MICBIAS
SDA

26

SDA

SCL

27

SCL

RSVD

MICLP

I2S_TXD

35

SDIN

I2S_RXD

37

I2S_CLK

36

SDOUT
MICGND
BCLK

I2S_WA

34

LRCLK

CODEC_CLK / GPIO6

19

MCLK

MICLN

GND

100nF
1µF

1µF

10µF

2.2k

MIC

EMI

1µF

EMI

1µF
2.2k
10nF 10nF

27pF 27pF

ESD ESD

SPK
OUTP
OUTN

GND

V_INT

VDD

RSVD
33

4.7k

SCL_A GND SCL_B

VCCB

100 HSIC_STRB

16

VCCB

SDA_B

OEn
99

VCC

100nF

OE

4.7k

10k

Network
Indicator

GND

SDA_A

0Ω

3V8

OUT

SHDNn

VCCA
100nF
4.7k

GND

21

Mount for
SARA-U2

IN

TCA9406DCUR
I2C Voltage Translator

V_INT

100nF

u-blox GNSS
3.0 V receiver

3V0

47k
V_INT

USB 2.0 Host
0Ω

LDO Regulator

3V8

GND

GND

VBUS

GND (C5)
ESD ESD ESD ESD ESD ESD

EMI
EMI

10nF 10nF

27pF 27pF ESD ESD

Figure 77: Example of complete schematic diagram to integrate SARA-U2 and LARA-R2 modules on the same application board

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B Glossary
3GPP

3rd Generation Partnership Project

8-PSK

8 Phase-Shift Keying modulation

16QAM

16-state Quadrature Amplitude Modulation

ACM

Abstract Control Model

ADC

Analog to Digital Converter

AP

Application Processor

APN

Access Point Name

ASIC

Application-Specific Integrated Circuit

AT

AT Command Interpreter Software Subsystem, or attention

ATE

Automatic Test Equipment

BAW

Bulk Acoustic Wave

BIP

Bearer Independent Protocol

BJT

Bipolar Junction Transistor

CDC

Communication Device Class

CDMA

Code-Division Multiple Access

CE

Certification Mark for EHS compliance in the European Economic Area

CENELEC

Comité Européen de Normalisation Électrotechnique

CSFB

Circuit Switched Fall-Back

DC

Direct Current

DCE

Data Communication Equipment

DDC

Display Data Channel interface

DL

Down-Link (Reception)

DRX

Discontinuous Reception

DSP

Digital Signal Processing

DTE

Data Terminal Equipment

ECC

Envelope Correlation Coefficient

EDGE

Enhanced Data rates for GSM Evolution

EGPRS

Enhanced General Packet Radio Service

EMC

Electro-magnetic Compatibility

EMI

Electro-magnetic Interference

EPA

Electrostatic Protective Area

ESD

Electro-static Discharge

ESR

Equivalent Series Resistance

ETSI

European Telecommunications Standards Institute

FCC

Federal Communications Commission

FDD

Frequency Division Duplex

FEM

Front End Module

FOAT

(Update via) Firmware Over AT commands

FOTA

Firmware Over The Air

FTP

File Transfer Protocol

FW

Firmware

GERA

GSM EGPRS Radio Access

GMSK

Gaussian Minimum Shift Keying modulation

GLONASS

(Russian) GLObal Navigation Satellite System

GMSK

Gaussian Minimum-Shift Keying modulation

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LARA-R2 series - System Integration Manual

GND

Ground

GNSS

Global Navigation Satellite System

GPIO

General Purpose Input Output

GPRS

General Packet Radio Services

GPS

Global Positioning System

GSM

Global System for Mobile Communication

GSM

GSM (Groupe Spéciale Mobile) Association

HBM

Human Body Model

HSIC

High Speed Inter Chip

HSDPA

High Speed Downlink Packet Access

HSUPA

High Speed Uplink Packet Access

HTTP

HyperText Transfer Protocol

HW

Hardware

I/Q

In-phase and Quadrature

2

Inter-Integrated Circuit interface

2

IS

Inter IC Sound interface

IEC

International Electrotechnical Commission

IEEE

Institute of Electrical and Electronics Engineers

IMEI

International Mobile Equipment Identity

IP

Internet Protocol

ISO

International Organization for Standardization

ITU

International Telecommunications Union

LCC

Leadless Chip Carrier

LDO

Low-Dropout

LGA

Land Grid Array

LNA

Low Noise Amplifier

LPDDR

Low Power Double Data Rate synchronous dynamic RAM memory

LTE

Long Term Evolution

M2M

Machine to machine

MCS

Modulation Coding Scheme

MIMO

Multiple In Multiple Out

MSD

Moisture Sensitive Device

N/A

Not Applicable

NCM

Network Control Model

NSMD

Non Solder Mask Defined

NTC

Negative Temperature Coefficient

OEM

Original Equipment Manufacturer device: an application device integrating a u-blox cellular module

OTA

Over The Air

PA

Power Amplifier

PCM

Pulse Code Modulation

PFM

Pulse Frequency Modulation

PMU

Power Management Unit

PTCRB

PCS Type Certification Review Board

PWM

Pulse Width Modulation

QPSK

Quadrature Phase Shift Keying

RF

Radio Frequency

RSE

Radiated Spurious Emission

RTC

Real Time Clock

IC

UBX-16010573 - R12

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LARA-R2 series - System Integration Manual

SAR

Specific Absorption Rate

SAW

Surface Acoustic Wave

SDIO

Secure Digital Input Output

SDN / IN / PCN

Sample Delivery Note / Information Note / Product Change Notification

SIM

Subscriber Identification Module

SMD

Solder Mask Defined

SMS

Short Message Service

SMT

Surface-Mount Technology

SMTP

Simple Mail Transfer Protocol

SRF

Self Resonant Frequency

SSL

Secure Sockets Layer

STS

Smart Temperature Supervisor

TBD

To Be Defined

TCP

Transmission Control Protocol

TDMA

Time Division Multiple Access

THT

Through-Hole Technology

TI

Texas Instruments

TIS

Total Isotropic Sensitivity

TP

Test-Point

TRP

Total Radiated Power

TTFF

Time-To-First-Fix

UART

Universal Asynchronous Receiver-Transmitter

UDP

User Datagram Protocol

UICC

Universal Integrated Circuit Card

UL

Up-Link (Transmission)

UMTS

Universal Mobile Telecommunications System

USB

Universal Serial Bus

UTRA

UMTS Terrestrial Radio Access

VCC

Voltage Collector Collector

VCO

Voltage Controlled Oscillator

VoLTE

Voice over LTE

VSWR

Voltage Standing Wave Ratio

WCDMA

Wideband Code-Division Multiple Access

Wi-Fi

Wireless Local Area Network (IEEE 802.11 short range radio technology)

WLAN

Wireless Local Area Network (IEEE 802.11 short range radio technology)

WWAN

Wireless Wide Area Network (GSM / UMTS / LTE cellular radio technology)

UBX-16010573 - R12

Appendix
Page 154 of 157

LARA-R2 series - System Integration Manual

Related documents
[1]

u-blox LARA-R2 series Data Sheet, Docu No UBX-16005783

[2]

u-blox AT Commands Manual, Docu No UBX-13002752

[3]

u-blox EVK-R2xx User Guide, Docu No UBX-16016088

[4]

u-blox Windows Embedded OS USB Driver Installation Application Note, Docu No UBX-14003263

[5]

ITU-T Recommendation V.24 - 02-2000 - List of definitions for interchange circuits between the Data Terminal
Equipment (DTE) and the Data Circuit-terminating Equipment (DCE).
http://www.itu.int/rec/T-REC-V.24-200002-I/en

[6]

3GPP TS 27.007 – AT command set for User Equipment (UE) (Release 1999)

[7]

3GPP TS 27.005 – Use of Data Terminal Equipment – Data Circuit terminating; Equipment (DTE – DCE) interface
for Short Message Service (SMS) and Cell Broadcast Service (CBS) (Release 1999)

[8]

3GPP TS 27.010 – Terminal Equipment to User Equipment (TE-UE) multiplexer protocol (Release 1999)

[9]

Universal Serial Bus Revision 2.0 specification, http://www.usb.org/developers/docs/usb20_docs/

[10]

High-Speed Inter-Chip USB Specification, Ver. 1.0, http://www.usb.org/developers/docs/usb20_docs/

[11]

I2C-bus specification and user manual - Rev. 5 - 9 October 2012 - NXP Semiconductors,
http://www.nxp.com/documents/user_manual/UM10204.pdf

[12]

3GPP TS 51.010-2 – Technical Specification Group GSM/EDGE Radio Access Network; Mobile Station (MS)
conformance specification; Part 2: Protocol Implementation Conformance Statement (PICS)

[13]

3GPP TS 34.121-2 - Technical Specification Group Radio Access Network; User Equipment (UE) conformance
specification; Radio transmission and reception (FDD); Part 2: Implementation Conformance Statement (ICS)
3GPP TS 36.521-1 - Evolved Universal Terrestrial Radio Access; User Equipment conformance specification; Radio
transmission and reception; Part 1: Conformance Testing
3GPP TS 36.521-2 - Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment conformance
specification; Radio transmission and reception; Part 2: Implementation Conformance Statement (ICS)
3GPP TS 36.523-2 - Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Packet Core (EPC); User
Equipment conformance specification; Part 2: Implementation Conformance Statement (ICS)

[14]
[15]
[16]
[17]

GSM Association TS.09 - Battery Life Measurement and Current Consumption Technique
https://www.gsma.com/newsroom/wp-content/uploads//TS.09_v10.0.pdf

[18]

CENELEC EN 61000-4-2 (2001) – Electromagnetic compatibility (EMC); Part 4-2: Testing and measurement
techniques; Electrostatic discharge immunity test

[19]

ETSI EN 301 489-1 V1.8.1 – Electromagnetic compatibility and Radio spectrum Matters; EMC standard for radio
equipment and services; Part 1: Common technical requirements

[20]

ETSI EN 301 489-52 "Electromagnetic Compatibility (EMC) standard for radio equipment and services; Part 52:
Specific conditions for Cellular Communication Mobile and portable (UE) radio and ancillary equipment"

[21]

u-blox Multiplexer Implementation Application Note, Docu No UBX-13001887

[22]

u-blox GNSS Implementation Application Note, Docu No UBX-13001849

[23]

u-blox Firmware Update Application Note, Docu No UBX-13001845

[24]

u-blox End user test Application Note, Docu No UBX-13001922

[25]

u-blox Package Information Guide, Docu No UBX-14001652

[26]

u-blox Nested Design Application Note, Docu No UBX-16007243

[27]

u-blox SARA-U2 series Data Sheet, Docu No UBX-13005287

[28]

u-blox SARA-G3 and SARA-U2 series System Integration Manual, Docu No UBX-13000995

Some of the above documents can be downloaded from u-blox web-site (http://www.u-blox.com).

UBX-16010573 - R12

Related documents
Page 155 of 157

LARA-R2 series - System Integration Manual

Revision history
Revision

Date

Name

Status / Comments

R01

20-Sep-2016

sses

Initial release

R02

11-Oct-2016

lpah

Added LARA-R2 PTs information. PID of USB profile updated.

R03

25-Nov-2016

sses

Updated Power-on and Power-off sections.

R04

17-Mar-2017

sses

"Disclosure restriction" replaces "Document status" on page 2 and document footer
Updated GPRS / EDGE multi-slot class.
Added maximum antenna gain for LARA-R204.
Extended the document applicability to LARA-R202-02B and LARA-R203-02B.

R05

19-Apr-2017

sses

Updated LARA-R204-02B / LARA-R211-02B product status
Added maximum antenna gain for LARA-R211.

R06

29-May-2017

sses

Updated LARA-R203-02B product status to Engineering Samples

R07

30-Jun-2017

sses

Extended document applicability to LARA-R220 and LARA-R280.
Updated modem and application version for LARA-R202-02B.
Updated CE approval section.

R08

16-Aug-2017

sses

Updated LARA-R203-02B, LARA-R220-62B and LARA-R280-02B product status.

R09

22-Sep-2017

sses

Updated LARA-R202-02B product status.

R10

27-Oct-2017

sses

Updated LARA-R202-02B, LARA-R220-62B and LARA-R280-02B product status.

R11

18-Dec-2017

sses

Updated LARA-R280-02B product status.

R12

25-May-2018

sses

Extended
document
applicability
LARA-R204-02B-01, LARA-R280-02B-01

UBX-16010573 - R12

to

LARA-R202-02B-01,

LARA-R203-02B-01,

Revision history
Page 156 of 157

LARA-R2 series - System Integration Manual

Contact
For complete contact information, visit us at www.u-blox.com.
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info_tw@u-blox.com
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UBX-16010573 - R12

Contact
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