STMicroelectronicsS R3911BD1 NFC card reader board User Manual Manual

STMicroelectronics NFC card reader board Manual

Manual

July 2017 DocID029132 Rev 2 1/251UM2042User manualDiscovery kit for the ST25R3911B high performance HF reader / NFC initiatorIntroductionThe ST25R3911B-DISCO is a ready-to-use development kit to evaluate the functions of the high performance HF reader / NFC initiator ST25R3911B in Reader mode for contactless applications.The ST25R3911B-DISCO kit supports•ISO 18092 (NFCIP-1) active P2P•ISO 14443A and ISO14443B•ISO 15693•FeliCa™•VHBR, with 6.8 Mbit/s PCD to PICC framing and 3.4 Mbit/s PICC to PCD framing•Up to 1.4 W output power with differential antenna•Possibility of driving two antennas in single ended mode, with automatic antenna tuning (AAT) system•Inductive and capacitive Wake-up•User selectable and automatic gain control•Transparent and Stream modes to implement MIFARE® Classic compliant or other custom protocolsThe evaluation kit includes•the STM32L476RET6, a 32-bit microcontroller with 512 KB of Flash memory•a 105 mm x 52 mm, two turns antenna etched on the PCB, and its VHBR tuning circuit•a Micro-USB connector for communication with the host PC and board powering•six LEDs indicating the presence of the RF field and of the protocol used to communicate.Figure 1. ST25R3911B-DISCO PCB (top view)www.st.com
Contents UM20422/25 DocID029132 Rev 2Contents1 Quick start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.1 Getting started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.2 System requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.2 Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.2.1 USB connectivity and power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.2.2 STM32L4 MCU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.2.3 ST25R3911B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.2.4 Antenna and matching network components . . . . . . . . . . . . . . . . . . . . . . 82.3 PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142.3.1 PCB overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142.3.2 PCB layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Antenna matching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 Federal Communications Commission (FCC) and Industry Canada (IC) compliance statements . . . . . . . . . . . . . . . . 224.1 FCC Compliance Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.1.1 Part 15.19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.1.2 Part 15.21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.1.3 Part 15.105 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.1.4 FCC ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.2 Formal notices required by the Industry Canada (“IC”) . . . . . . . . . . . . . . 224.2.1 Compliance Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.2.2 Declaration de Conformité . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234.2.3 IC ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
DocID029132 Rev 2 3/25UM2042 List of tables3List of tablesTable 1. NFC Forum matching alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Table 2. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
List of figures UM20424/25 DocID029132 Rev 2List of figuresFigure 1. ST25R3911B-DISCO PCB (top view). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Figure 2. Functional block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Figure 3. Schematics overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Figure 4. USB interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Figure 5. STM32L476 schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Figure 6. ST25R3911B schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Figure 7. Antenna and matching network schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Figure 8. PCB overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Figure 9. PCB layout, top layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Figure 10. PCB layout, mid layer 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Figure 11. PCB layout, mid layer 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Figure 12. PCB layout, bottom layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Figure 13. VHBR matching with an AAT setting of 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Figure 14. NFC Forum matching with an AAT setting of 11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
DocID029132 Rev 2 5/25UM2042 Quick start241 Quick startThe ST25R3911B-DISCO is connected to a PC via USB to show the features of the ST25R3911B chip. To do so, use the software STSW-ST25R001 to control all the functions of the discovery kit.1.1 Getting startedConnect the discovery kit to a PC using a micro USB cable. The USB port of the PC must be capable of delivering at least 250 mA at 5 Volt supply.To control the board, download the software STSW-ST25R001 from www.st.com and install it. Further information on how to operate the software can be found in the user manual UM2177 “PC software for the ST25R3911B-DISCO kit”, available on www.st.com.1.2 System requirements•Windows® PC (Windows 7 recommended)•USB port, capable of delivering at least 250 mA at 5 V supply (1.25 W)•Unit must be supplied by a Safety Extra Low Voltage (SELV) limited power source through the USB port, the source should not exceed 60 Vdc / 8 A / 100 VA•Micro-USB cable
Hardware UM20426/25 DocID029132 Rev 22 Hardware The PCB (Printed Circuit Board) is connected via USB to the PC. The STSW-ST25R001 PC software controls the STM32 MCU located on the PCB. The STM32 MCU then operates the ST25R3911B via SPI.The ST25R3911B is connected directly to the 5 V supply of the USB bus. An LDO converts this voltage down to 3.3 V, to supply the microcontroller.A green LED close to the USB plug indicates if the board is powered. Six blue LEDs indicate the mode of operation (transmit / receive) and which technologies are in use.The antenna runs along the PCB perimeter.2.1 Block diagramFigure 2 shows the functional block diagram of the board.Figure 2. Functional block diagram2.2 SchematicsAs indicated in Figure 3, the schematics can be split into four main parts•USB connectivity and power supply (Figure 4)•STM32 MCU (Figure 5)•ST25R3911B (Figure 6) •Antenna and matching network components (Figure 7)069+RVW3& (&0)&0;/'385N+]FU\VWDO0+]FU\VWDO670/5( 675% 3&%DQWHQQD63, 0DWFKLQJQHWZRUN9 986%675%',6&2
DocID029132 Rev 2 7/25UM2042 Hardware242.2.1 USB connectivity and power supplyThe ST25R3911B-DISCO board can be connected via USB to a host device. Right behind the Micro-USB plug, an ECMF02 common mode filter with ESD protection for USB 2.0 interface is placed. The common mode filter is connected to VBUS and to the D+/D- data lines of the USB. All the USB terminals are ESD-protected by the built-in ESD diodes of the ECMF02. Additionally, the power supply filter for the 5 V supplies the 3.3 V LDO, that, in turn, supplies the microcontroller.A green LED is connected to the USB VBUS supply and shows the USB-power status.2.2.2 STM32L4 MCUThis schematic includes the microcontroller needed to operate the NFC reader IC.The MCU is clocked by a 32.768 kHz crystal. The MCU uses an internal PLL to generate the 48 MHz USB clock and the 80 MHz core clock from the provided 32.768 kHz.Connector P201 is a JTAG/SWD interface to assist in software development. It can be connected to an external ST-LINK/V2 device using a 9-pin Cortex®-M adapter.The six blue LEDs (LED201 to LED206) show the current mode of communication. If multiple protocols are active at the same time, then all corresponding LEDs are turned on.The five resistors (R218 to R222) can be used to disconnect the MCU from SPI interface header P204. This SPI cross-connect mode can be used to operate the ST25R3911B with a different MCU PCB by cross connecting the ST25R3911B SPI to the second MCU PCB.Connectors P202 and P203 can be used to connect an external UART or I2C host device to the MCU.2.2.3 ST25R3911BThe ST25R3911B is directly connected to the filtered 5 V USB supply, and there are additional supply filtering components placed close to it. The jumper JP301 can be used to measure the supply current of the chip. If this measurement is performed, the ferrite bead L301 has to be removed.Capacitors C301 to C304 provide additional filtering. All decoupling capacitors have been placed as close as possible to the ST25R3911B. Special care has been taken for C310, C302, C314 and C301, as they are the decoupling capacitors for the high power driver stage.In order to demonstrate the capacitive wake-up feature, two capacitive electrodes are placed on the PCB. Additional electrodes can be connected using UFL connectors on P301 and P302.For SPI cross-connecting to another reader PCB, the resistors R301 to R305 can be removed. Then the STM32L4 MCU SPI can be connected to the ST25R3911B on any customer PCB via header P204.Thanks to J303 it is possible to bypass the internal VSP_RF regulator, this is required in case output currents higher than 200 mA need to be supplied.
Hardware UM20428/25 DocID029132 Rev 22.2.4 Antenna and matching network componentsThis schematic contains the matching network and the automatic antenna tuning capacitors, as well as the alternative NFC Forum matching components. In the default configuration, the ST25R3911B-DISCO is populated with a VHBR matching, with communication speeds up to 3.4 Mbps.To support VHBR, the antenna is matched to a system Q-Factor of 8. By switching to the NFC Forum matching components the system Q-Factor is increased to 16. This can increase the read range up to 20%, depending on the used communication technology, but limits the maximum supported communication bit rate to 848 kbps. Additional details about antenna matching can be found on www.st.com/st25r.
UM2042 HardwareDocID029132 Rev 2 9/25Figure 3. Schematics overview11223344D DC CB BA A373B131.05.2017 10:09:36Project Overview.SchDocTitleSize: Number:Date:File:Revision:Sheet ofTime:A4ST25R3911B-DISCOMDG NFC & Reader Competence CenterPM/USB_conU_Power ManagementPower Management.SchDocAntenna_ConU_AntennaAntenna.SchDocSPI/Power_ConPM/USB_conU_MicrocontrollerMicrocontroller.SchDocAntenna_ConSPI/Power_ConU_ST25R3911BST25R3911B.SchDoc
Hardware UM204210/25 DocID029132 Rev 2Figure 4. USB interface11223344D DC CB BA A474B131.05.2017 10:09:36Power Management.SchDocTitleSize: Number:Date:File:Revision:Sheet ofTime:A4ST25R3911B-DISCOMDG NFC & Reader Competence Center3V3GND3V3 LDOGNDGNDUSB InterfaceUSBD_PUSBD_NV_RF3_3VPM/USB_conGNDEN1GND2VO 4NC 5GND0VI6PG 3U102 LD39050PU33RGNDESDG101Logo_ESDRoHSG102Logo_RoHSST25G103Logo_ST25ST MicroelectronicsG104Logo_STML102FB_0603_0RL101FB_0603C104C_1μ_0603_X5RC103C_1μ_0603_X5RC106C_2μ2_0402_X5RC105C_10n_0402_X7RC102C_10μ_0603_X5RC101C_10μ_0603_X5RR101LED101PWR 1D- 2D+ 3ID 4Shield6GND 5P101μUSBVBUS1D-2D+3ID4GND 5D- 6D+ 7GND 8U101ECMF02-4CMX8V_RFV_RFV_RF3V3J101closed 0RL103FB_0603_0RPM/USB_conUSBD_NUSBD_PUSBD_PUSBD_N
UM2042 HardwareDocID029132 Rev 2 11/25Figure 5. STM32L476 schematics11223344D DC CB BA A575B131.05.2017 10:09:36Microcontroller.SchDocTitleSize: Number:Date:File:Revision:Sheet ofTime:A4ST25R3911B-DISCOMDG NFC & Reader Competence CenterMicrocontrollerSENINTRMISOMOSISCLKMCU_CLKV_RF3_3VSPI/Power_ConSPI/Power_ConUSBD_NUSBD_PV_RF3_3VPM/USB_conPM/USB_conInterfaceLP_UART_RXLP_UART_TXUART_TXUART_RX3V3GND12345678P204 d.n.p.SWD3V3PC13 2PC14 - OSC32_IN 3PC15 - OSC32_OUT 4PC08PC19PC210PC311PA014PA115PA216PA3/SAR_VREF+17PA420PA521PA622PA723PC424PC525PB0 26PB1/VREF+ 27PB2 28PB10/PE8 29PB11/VCAP1 30PB12/SD_VREF+ 33PB13/PB14 34PB14/PB15 35PB15/PD8 36PC637PC738PC8 39PC9 40PA841PA942PA1043PA1144PA1245PA1346PA1449PA1550PC10 51PC11 52PC12 53PB3 55PB4 56PB5 57PB6 58PB7 59PB8 61PB9 62497-15872-NDU201ASTM32L476RESCLK_MCUMISO_MCUMOSI_MCULP_UART_RXLP_UART_TXUART_TXUART_RXIRQ_MCULED1LED2VBAT/VLCD1PF0/PD0/PH0 - OSC_IN5PF1/PD1/PH1 - OSC_OUT6NRST 7VSSA 12VDDA/VREF+13VSS/PF4/PA3 18VDD/PF519VSS/VCAP1 31VDD32VSS/VCAP2/PF6 47VDD/VUSB/VSA/PF748BOOT0 60VSS 63VDD64PD2 54U201BSTM32L476RE3V3T_NRSTCaseS201CaseS202 3V31234P203d.n.p.3V31234P202d.n.p.LP_UART_RXLP_UART_TXT_NRSTT_JTDIT_SWOT_JTCKT_JTMSLED1LED2LED3LED4LED5LED6SENMISOINTRMOSISCLKSCLK_MCUMOSI_MCUIRQ_MCUMISO_MCU/SS_MCUSDASCL3V3C206d.n.p.C205d.n.p.Y201d.n.p.USBD_NUSBD_PJ201openJ202openPin 18+19 Pin 47+48 Pin 63+64 Pin 12+13Pin 31+32 Pin 13V3Pin 18+19Pin 47+48Pin 63+64Pin 31+32Pin 1V_RF3V3R202R203R205R206R208R209R201R204R207R210R211R214R215R216R217R218R219R220R221R222C203C_4p3_0402C204C_4p3_0402X20132.768 kHz12345678910P201Header 10C209C_4μ7_0402_X5RC211C_4μ7_0402_X5RC210C_100n_0402_X7RC212C_100n_0402_X7RC213C_100n_0402_X7RC214C_100n_0402_X7RC216C_100n_0402_X7RC215C_1μ_0402_X5RC207C_100n_0402_X7RC208C_100n_0402_X7RR223L201FB_0603AVDDAVDDLED201LED202LED203LED204LED205LED206INTRMISOMOSISCLKSENV_RF3V3V_RFLED6C201C_56p_0402C202C_56p_0402R212R213USBD_PUSBD_N MCU_D_NMCU_D_PT_JTMST_JTCKT_JTDIMCU_D_PMCU_D_NAVDDSDASCL/SS_MCULED5LED4T_SWOAVDDLED3Pin 12+13C216555X5RAVDD5X
Hardware UM204212/25 DocID029132 Rev 2Figure 6. ST25R3911B schematics11223344D DC CB BA A676B131.05.2017 10:09:36ST25R3911B.SchDocTitleSize: Number:Date:File:Revision:Sheet ofTime:A4ST25R3911B-DISCOMDG NFC & Reader Competence CenterGNDGNDGNDGNDCSOCSITRIM1_0TRIM1_1TRIM1_2TRIM1_3TRIM2_0TRIM2_1TRIM2_2TRIM2_3RFO1RFO2RFI1RFI2SEN_11MISO_11MOSI_11SCLK_11INTR_11VSP_RFVSP_RFJ301C303d.n.p.GNDCSO_outGND GNDGNDGNDGND1GND32P301d.n.p.GND1GND32P302d.n.p.V_RF_3911RFI1RFI2RFO1RFO2TRIM1_0TRIM1_1TRIM1_2TRIM1_3TRIM2_0TRIM2_1TRIM2_2TRIM2_3Antenna_ConAntenna_ConTRIM2_0TRIM2_1TRIM2_2TRIM2_3TRIM1_0TRIM1_1TRIM1_2TRIM1_3RFO1RFO2RFI2RFI1INTR_11MISO_11MOSI_11SCLK_11SEN_11ST25R3911 NFC Initiator / HF Reader Controller InterfaceAntenna ConnectionVSP_AVSP_DAGDV_RFGNDGNDGNDSENINTRMISOMOSISCLKV_RF3_3VMCU_CLKSPI/Power_Con3V3JP301d.n.p.J303openJ302d.n.p.GNDV_RF3V3C302C_100n_0402_X7RC301C_1μ_0402_X5RC304C_100n_0402_X7RY301C308C_8p2_0402C307C_8p2_0402C309C_10n_0402_X7RC310C_10n_0402_X7RC311C_10n_0402_X7RC312C_10n_0402_X7RC313C_2μ2_0402_X5RC314C_2μ2_0402_X5RC315C_2μ2_0402_X5RC316C_1μ_0402_X5RR306C305C_12p_0402R307C306C_12p_0402CSI_outGNDR301R302 R303R304 R305SPI/Power_ConL301FB_0603V_RF_3911ST25R3911VDD_IO 1CSO2VSP_D3XTO4XTI5VSN_D6VSP_RF9RFO1 10RFO2 11VSN_RF12TRIM1_3 13TRIM2_3 14TRIM1_0 19TRIM2_0 20VSS21RFI1 22RFI2 23AGD24IRQ27MCU_CLK28MISO29MOSI30SCLK31/SS32VSP_A7VDD 8TRIM1_2 15TRIM2_2 16TRIM1_1 17TRIM2_1 18CSI25VSN_A26EP VSUB33NFC Initiator / HF Reader ICU301ST25R3911B
UM2042 HardwareDocID029132 Rev 2 13/25Figure 7. Antenna and matching network schematics11223344D DC CB BA A777B131.05.2017 10:09:36Antenna.SchDocTitleSize: Number:Date:File:Revision:Sheet ofTime:A4ST25R3911B-DISCOMDG NFC & Reader Competence CenterTRIM1_0TRIM1_1TRIM1_2TRIM1_3TRIM2_0TRIM2_1TRIM2_2TRIM2_3RFO1RFO2GNDGNDTRIM1TRIM2GNDTRIM1TRIM2Trim Capacitor BanksGNDRFI1RFI2RFO1RFO2TRIM1_0TRIM1_1TRIM1_2TRIM1_3TRIM2_0TRIM2_1TRIM2_2TRIM2_3Antenna_ConAntenna_ConAntenna Connection12J403123J402C407d.n.p.C404d.n.p.NFC Forum matchingGND GNDRFI1RFI2RFI1RFO1RFO2TRIM1_0TRIM1_1TRIM1_2TRIM1_3TRIM2_0TRIM2_1TRIM2_2TRIM2_3RFI2C401C_82p_0603C412C_82p_0603C402C_10p_0603C411C_10p_0603C403C_180p_0603C410C_180p_0603C405C_680p_0603C409C_680p_0603L401270nL402270nC415C_5p6_0402C416C_5p6_0402C417C_12p_0402 C418C_12p_0402C419C_27p_0402C420C_27p_0402C421C_56p_0402C422C_56p_0402C403_NFCFC_120p_0603C410_NFCFC_120p_0603C406C_120p_0603C408C_120p_0603Antenna LoopR401R402R401_NFCFR402_NFCFJ405closed 0RJ404closed 0RJ401closed 0RJ406closed 0RJ407closed 0RAntenna Circuit incl. EMI Filter and Matching
Hardware UM204214/25 DocID029132 Rev 22.3 PCB layout2.3.1 PCB overviewThe PCB (see Figure 8) is organized in two halves•Left side: the SPI header P204 and the digital / MCU sections•Right side: the analog parts and the ST25R3911B.The whole PCB is surrounded by a two turns NFC antenna.Figure 8. PCB overviewThe boot button can be found right above the I2C header. If this button is pressed during the powering or the resetting of the board, the STM32L4 will enter the boot loader mode. The reset button is positioned between the JTAG/SWD header and the I2C header.2.3.2 PCB layersThe PCB layout is designed considering that the ST25R3911B is a high power RF transmitter, hence the decoupling capacitors are located as close as possible to the positive and negative power supply pins, for example VSP_RF and VSN_RF. Since the chip is using a differential output driver stage, the antenna matching network is treated as a differential network. The space between the components is kept as small as possible and the whole network is routed in a completely symmetrical way.Via stitching and via shielding is used to maintain a low impedance and prevent short return current loops. The RF traces are protected by via stitching in combination with guard rings to create a via wall. This keeps the PCB electromagnetically “quiet”.A via shield is used to create a vertical copper barrier through the PCB. This helps to reduce crosstalk and electromagnetic interference in any route carrying an RF signal. The RFI traces and AAT lanes are routed as close as possible to each other.670/8$57-7$*6:' ,&63, 675%1)&)RUXPPDWFKLQJ86%/'29 0DWFKLQJFRPSRQHQWV069
DocID029132 Rev 2 15/25UM2042 Hardware24Top layerThe top layer (Figure 9) contains most of the components and PCB traces. The unused areas around the ICs are filled with GND planes, guarded using via stitching. Furthermore, important analog traces are surrounded by GND vias.Mid layer 1This layer (Figure 10) is a pure GND plane, providing a low ohmic DC path for the GND connection.Mid layer 2Mid layer 2 (Figure 11) is used for the power distribution. It contains the power planes for the 5 V supply of the ST25R3911B and the 3.3 V supply of the microcontroller.Bottom layerThe bottom layer (Figure 12) is mainly a GND plane, but some traces are routed through it.
Hardware UM204216/25 DocID029132 Rev 2Figure 9. PCB layout, top layer
UM2042 HardwareDocID029132 Rev 2 17/25Figure 10. PCB layout, mid layer 1
Hardware UM204218/25 DocID029132 Rev 2Figure 11. PCB layout, mid layer 2
UM2042 HardwareDocID029132 Rev 2 19/25Figure 12. PCB layout, bottom layer
Antenna matching UM204220/25 DocID029132 Rev 23 Antenna matchingThe default matching network assembled enables VHBR operation up to 3.4 Mbps.Components for an optional NFC Forum matching are placed on the board. Exchanging the components as indicated in Table 1 will increase the Q factor of the antenna system. VHBR communication at 3.4 Mbps and 1.7 Mbps bit rate will not be supported anymore, but the read range for lower data rate applications will increase, up to 20%.The matching impedance will remain the same when switching between the two matchings.VHBR matchingThe VHBR matching is designed with a target Q-Factor of 8. The matching impedance is around 12.8 + j5 . The HW based AAT algorithm will typically adjust to an AAT value of 8 (see Figure 13).Figure 13. VHBR matching with an AAT setting of 8NFC Forum matchingThe NFC Forum matching is designed with a target Q-Factor of 16.To switch to the NFC Forum matching the user needs to change the components listed in Table 1.
DocID029132 Rev 2 21/25UM2042 Antenna matching24 With the new assembled values, the matching impedance looks as in Figure 14, with a value close to 11 + j6 .Figure 14. NFC Forum matching with an AAT setting of 11The HW based AAT algorithm will typically adjust to an AAT value of 11. Due to the higher Q-Factor the voltage on the antenna is also increasing. To have the receiver in an optimum signal level range, the capacitors C401 and C412 can be increased to 100 pF.Table 1. NFC Forum matching alternativesDefault assembly Value NFC Forum replacement ValueC403 80 pF C403_NFCF 120 pFC410 180 pF C410_NFCF 120 pFR401 3R9 R401_NFCF 1R96R402 3R9 R402_NFCF 1R96
Federal Communications Commission (FCC) and Industry Canada (IC) compliance statements22/25 DocID029132 Rev 24 Federal Communications Commission (FCC) and Industry Canada (IC) compliance statements4.1 FCC Compliance Statement4.1.1 Part 15.19This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.4.1.2 Part 15.21Any changes or modifications to this equipment not expressly approved by STMicroelectronics may cause harmful interference and void the user’s authority to operate this equipment.4.1.3 Part 15.105This 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:•Reorient or relocate the receiving antenna.•Increase the separation between the equipment and receiver.•Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.•Consult the dealer or an experienced radio/ TV technician for help.4.1.4 FCC IDFCC ID: YCPR3911BD14.2 Formal notices required by the Industry Canada (“IC”)4.2.1 Compliance StatementThis device complies with Industry Canada license-exempt RSS standard(s). Operation is subject to the following two conditions: (1) this device may not cause interference, and (2) this device must accept any interference, including interference that may cause undesired operation.
DocID029132 Rev 2 23/25UM2042Federal Communications Commission (FCC) and Industry Canada (IC) compliance state-244.2.2 Declaration de ConformitéLe présent appareil est conforme aux CNR d’Industrie Canada applicables aux appareils radio exempts de licence. L’exploitation est autorisée aux deux conditions suivantes: (1) l’appareil ne doit pas produire de brouillage, et (2) l’utilisateur de l’appareil doit accepter tout brouillage radioélectrique subi, même si le brouillage est susceptible d’en compromettre le fonctionnement.4.2.3 IC IDIC ID: 8976B-R3911BD1
Revision history UM204224/25 DocID029132 Rev 25 Revision historyTable 2. Document revision history Date Revision Changes23-Jun-2017 1 Initial release.25-Jul-2017 2Added Section 4.1.3: Part 15.105.Updated Section 4.1.4: FCC ID and Section 4.2.3: IC ID.Updated Figure 8: PCB overview, Figure 9: PCB layout, top layer and Figure 12: PCB layout, bottom layer.
DocID029132 Rev 2 25/25UM204225 IMPORTANT NOTICE – PLEASE READ CAREFULLYSTMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, enhancements, modifications, and improvements to ST products and/or to this document at any time without notice. Purchasers should obtain the latest relevant information on ST products before placing orders. ST products are sold pursuant to ST’s terms and conditions of sale in place at the time of order acknowledgement.Purchasers are solely responsible for the choice, selection, and use of ST products and ST assumes no liability for application assistance or the design of Purchasers’ products.No license, express or implied, to any intellectual property right is granted by ST herein.Resale of ST products with provisions different from the information set forth herein shall void any warranty granted by ST for such product.ST and the ST logo are trademarks of ST. All other product or service names are the property of their respective owners.Information in this document supersedes and replaces information previously supplied in any prior versions of this document.© 2017 STMicroelectronics – All rights reserved

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