AOZ1237QI 02 Datasheet. Www.s Manuals.com. Ao

User Manual: Marking of electronic components, SMD Codes Z1, Z1-, Z11, Z11 *, Z12, Z1237QI2, Z13, Z14, Z15, Z16, Z17, Z19, Z1AAG, Z1AAL, Z1ABG, Z1ABL, Z1ACG, Z1ACL, Z1ADG, Z1ADL, Z1AEG, Z1AEL, Z1AFG, Z1AFL, Z1AGG, Z1AGL, Z1AHG, Z1AHL, Z1AIG, Z1AIL, Z1W, Z1Z, Z1p, Z1t. Datasheets 2N7002PT, AOZ1237QI-02, BZV49C4V7, BZX84-C2V4, BZX84-C2V7, BZX84-C3V0, BZX84-C3V3, BZX84-C3V6, BZX84-C3V9, BZX84-C4V3, BZX84-C4V7, BZX84C2V4, BZX84C2V4-V, BZX84C2V4LT1G, BZX84C2V7, BZX84C2V7-V, BZX84C2V7LT1G, BZX84C3V0, BZX84C3V0-V, BZX84C3V0LT1

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AOZ1237QI-02

24V/8A Synchronous EZBuckTM Regulator

General Description

Features

The AOZ1237 is a high-efficiency, easy-to-use DC/DC
synchronous buck regulator that operates up to 24V.
The device is capable of supplying 8A of continuous
output current with an output voltage adjustable down to
0.8V (±1.0%).

 Wide input voltage range

A proprietary constant on-time PWM control with input
feed-forward results in ultra-fast transient response while
maintaining relatively constant switching frequency over
the entire input voltage range. The switching frequency
can be externally programmed up to 1MHz.

– 2.7V to 24V
 8A continuous output current
 Output voltage adjustable down to 0.8V (±1.0%)
 Low RDS(ON) internal NFETs

– 35m high-side
– 8m low-side SRFET™
 Constant On-Time with input feed-forward
 Programmable frequency up to 1MHz

The device features multiple protection functions such as
VCC under-voltage lockout, cycle-by-cycle current limit,
output over-voltage protection, short-circuit protection, as
well as thermal shutdown.

 Selectable PFM light load operation

The AOZ1237 is available in a 4mm x 4mm QFN-23L
package and is rated over a -40°C to +85°C ambient
temperature range.

 Integrated bootstrap diode

 Ceramic capacitor stable
 Adjustable soft start
 Power Good output
 Cycle-by-cycle current limit
 Short-circuit protection
 Over voltage protection
 Thermal shutdown
 Thermally enhanced 4mm x 4mm QFN-23L package

Applications
 Portable computers
 Compact desktop PCs
 Servers
 Graphics cards
 Set-top boxes
 LCD TVs
 Cable modems
 Point-of-load DC/DC converters
 Telecom/Networking/Datacom equipment

Rev. 2.0 April 2013

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Page 1 of 15

AOZ1237QI-02
Typical Application
RTON
TON

IN
C2
33μF

BST

C5
0.1μF

VCC

5V
R3
100kΩ

C4
1μF

Input
2.7V to 24V

AOZ1237

Power Good

PGOOD

Off On

R1
2.65kΩ
1%

L1
1μH

EN
FB

R2
8.06kΩ
1%

PFM
AGND

SS
CSS

Output
1.05V, 8A
C3
44μF

PGND
Power Ground
Analog Ground

Ordering Information
Part Number

Ambient Temperature Range

Package

Environmental

AOZ1237QI-02

-40°C to +85°C

23-Pin 4mm x 4mm QFN

Green Product

AOS Green Products use reduced levels of Halogens, and are also RoHS compliant.
Please visit www.aosmd.com/media/AOSGreenPolicy.pdf for additional information.

VCC

BST

PGND

Pin Configuration

PGOOD

PFM

PGND

IN
5

PGND

TON

PGND

AGND

23-Pin 4mm x 4mm QFN
(Top View)

Rev. 2.0 April 2013

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Page 2 of 15

AOZ1237QI-02
Pin Description
Pin Number

Pin Name

Pin Function

PGOOD

Power Good Signal Output. PGOOD is an open-drain output used to indicate the status
of the output voltage. It is internally pulled low when the output voltage is 10% lower than
the nominal regulation voltage for 50µs (typical time) or 15% higher than the nominal
regulation voltage. PGOOD is pulled low during soft-start and shut down.

Enable Input. The AOZ1237 is enabled when EN is pulled high. The device shuts down
when EN is pulled low.

PFM

PFM Selection Input. Connect PFM pin to VCC/VIN for forced PWM operation. Connect
PFM pin to ground for PFM operation to improve light load efficiency.

AGND

TON

Analog Ground.
Feedback Input. Adjust the output voltage with a resistive voltage-divider between the
regulator’s output and AGND.
On-Time Setting Input. Connect a resistor between VIN and TON to set the on time.
Not Connected. Connect to IN pins (8 and 9) to help with heat dissipation.

8, 9, 22

12, 13, 14, 15, 19

PGND

Power Ground.

10, 11, 16, 17, 18

Switching Node.

BST

Bootstrap Capacitor Connection. The AOZ1237 includes an internal bootstrap diode.
Connect an external capacitor between BST and LX as shown in the Typical Application
diagram.

VCC

Supply Input for analog functions. Bypass VCC to AGND with a 1µF ceramic capacitor.
Place the capacitor close to VCC pin.

Rev. 2.0 April 2013

Supply Input. IN is the regulator input. All IN pins must be connected together.

Soft-Start Time Setting Pin. Connect a capacitor between SS and AGND to set the
soft-start time.

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AOZ1237QI-02
Absolute Maximum Ratings

Maximum Operating Ratings

Exceeding the Absolute Maximum Ratings may damage the
device.

Parameter

The device is not guaranteed to operate beyond the
Maximum Operating ratings.

Rating

IN, TON to AGND

Parameter

-0.3V to 30V

LX to AGND

Output Voltage Range

-0.3V to 36V

SS, PGOOD, FB, EN, VCC, PFM to
AGND
PGND to AGND
Storage Temperature (TS)

-65°C to +150°C

ESD Rating(1)

2kV

-40°C to +85°C

Package Thermal Resistance

-0.3V to +0.3V
+150°C

0.8V to 0.85*VIN

Ambient Temperature (TA)

-0.3V to 6V

Junction Temperature (TJ)

2.7V(3) to 24V

Supply Voltage (VIN)

-2V to 30V

BST to AGND

Rating

(θJA)

40°C/W

(θJC)

4.5°C/W

Note:
3. Connect VCC to external 5V for VIN = 2.7V ~ 6.5V application.

Note:
1. Devices are inherently ESD sensitive, handling precautions are
required. Human body model rating: 1.5k in series with 100pF.
2. LX to PGND Transient (t<20ns) ------ -7V to VIN + 7V.

Electrical Characteristics
TA = 25°C, VIN = 12V, VCC = 5V, EN = 5V, unless otherwise specified. Specifications in BOLD indicate a temperature range of
-40°C to +85°C.

Symbol
VIN

Parameter

Conditions

IN Supply Voltage

Min.

Typ.

Max

Units

4.0
3.7

4.4

2.7

Under-Voltage Lockout Threshold of VCC

VCC rising
VCC falling

Quiescent Supply Current of VCC

IOUT = 0, VFB = 1V, VEN > 2V

1.5

IOFF

Shutdown Supply Current

VEN = 0V

A

VFB

Feedback Voltage

TA = 25°C
TA = 0°C to 85°C

0.800
0.800

0.808
0.812

VUVLO
Iq

IFB

3.2

0.792
0.788

Load Regulation

0.5

Line Regulation

FB Input Bias Current

200

Enable
VEN

EN Input Threshold

VEN_HYS

EN Input Hysteresis

Off threshold
On threshold

0.5
2.5
100

V
mV

PFM Control
VPFM

PFM Input Threshold

VPFMHYS

PFM Input Hysteresis

PFM Mode threshold
Force PWM threshold

0.5
2.5
100

V
mV

Modulator
TON

On Time

RTON = 100k, VIN = 12V
RTON = 100k, VIN = 24V

200

250
150

TON_MIN

Minimum On Time

100

TOFF_MIN

Minimum Off Time

250

Rev. 2.0 April 2013

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300

ns
ns

400

Page 4 of 15

AOZ1237QI-02
Electrical Characteristics (Continued)
TA = 25°C, VIN = 12V, VCC = 5V, EN = 5V, unless otherwise specified. Specifications in BOLD indicate a temperature range of
-40°C to +85°C.

Symbol

Parameter

Conditions

Min.

Typ.

Max

Units

A

0.5

±1

A

Soft-Start
ISS_OUT

SS Source Current

VSS = 0
CSS = 0.001F to 0.1F

Power Good Signal
VPG_LOW

PGOOD Low Voltage

IOL = 1mA

PGOOD Leakage Current
VPGH

VPGL

TPG_L

PGOOD Threshold
(Low level to High level)
PGOOD Threshold
(High level to Low level)

FB rising (AOZ1237-02)
FB rising (AOZ1237-04)
FB falling (AOZ1237-04 only)

80
85
114

85
90
117

90
95
120

FB rising (AOZ1237-02/04)
FB falling (AOZ1237-02)
FB falling (AOZ1237-04)

117
77
82

120
82
87

123
87
92

PGOOD Threshold Hysteresis

PGOOD Fault Delay Time (FB falling)

s

Under Voltage and Over Voltage Protection
VPL

Under Voltage Threshold

TPL

Under Voltage Delay Time

VPH

Over Voltage Threshold

FB rising

Under Voltage Shutdown Blanking Time

VIN = 12V, VEN = 0V, VCC = 5V

High-Side NFET On-Resistance

VIN = 12V, VCC = 5V

High-Side NFET Leakage

VEN = 0V, VLX = 0V

Low-Side NFET On-Resistance

VLX = 12V, VCC = 5V

Low-Side NFET Leakage

VEN = 0V

TUV_LX

FB falling

-30

-25

-20

%
s

128
23

%
ms

Power Stage Output
RDS(ON)
RDS(ON)

m

A

m

A

Over-current and Thermal Protection
ILIM

Valley Current Limit

VCC = 5V

Thermal Shutdown Threshold

TJ rising
TJ falling

Rev. 2.0 April 2013

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A
145
100

°C

Page 5 of 15

AOZ1237QI-02
Functional Block Diagram
BST

PGood

VCC
EN

UVLO
Reference
& Bias

TOFF_MIN
Q
Timer

Error Comp

0.8V
SS
ISENCE
(AC)
FB

PG Logic

S
Q
R
FB
Decode

ILIM Comp
ILIM_VALLEY
Current
Information
Processing

ISENSE
OTP

ISENSE (DC)
ISENSE (AC)

Vcc
TON
Q

Timer

PFM
TON

TON
Generator

Light Load
Threshold

Light Load
Comp

ISENSE

PGND

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AGND

Page 6 of 15

AOZ1237QI-02
Typical Performance Characteristics
Circuit of Typical Application. TA = 25°C, VIN = 19V, VOUT = 1.05V, fs = 400kHz unless otherwise specified.

Normal Operation

Load Transient 0.8A (10%) to 7.2A (90%)
VLX
20V/div

VLX
10V/div
Io
2A/div

ILX
5A/div

Vo ripple
20mV/div
Vo ripple
50mV/div

1ms/div

5μs/div

Full Load Start-up

Full Load Short

LX
10V/div

VLX
20V/div

Ven
2V/div
ILX
5A/div

ILX
5A/div
Vo
500mV/div

50μs/div

Rev. 2.0 April 2013

Vo ripple
500mV/div

50μs/div

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Page 7 of 15

AOZ1237QI-02
The simplified control schematic is shown in Figure 1.

Detailed Description
The AOZ1237 is a high-efficiency, easy-to-use,
synchronous buck regulator optimized for notebook
computers. The regulator is capable of supplying 8A of
continuous output current with an output voltage
adjustable down to 0.8V. The programmable operating
frequency range of 100kHz to 1MHz enables optimizing
the configuration for PCB area and efficiency.
The input voltage of AOZ1237 can be as low as 4.5V.
The highest input voltage of AOZ1237 can be 24V.
Constant on-time PWM with input feed-forward control
scheme results in ultra-fast transient response while
maintaining relatively constant switching frequency over
the entire input range. True AC current mode control
scheme guarantees the regulator can be stable with a
ceramic output capacitor. The switching frequency can
be externally programmed up to 1MHz. Protection
features include VCC under-voltage lockout, valley
current limit, output over voltage and under voltage
protection, short-circuit protection, and thermal
shutdown.
The AOZ1237 is available in 23-pin 4mm x 4mm QFN
package.
Input Power Architecture
The AOZ1237 integrates an internal linear regulator to
generate 5.3V VCC from input. If input voltage is lower
than 5.3V, the linear regulator operates at low dropoutput mode; the VCC voltage is equal to input voltage
minus the drop-output voltage of internal linear regulator.
Enable and Soft Start
The AOZ1237 has external soft start feature to limit
in-rush current and ensure the output voltage ramps up
smoothly to regulation voltage. A soft start process
begins when VCC rises to 4.1V and voltage on EN pin is
HIGH. An internal current source charges the external
soft-start capacitor; the FB voltage follows the voltage of
soft-start pin (VSS) when it is lower than 0.8V. When VSS
is higher than 0.8V, the FB voltage is regulated by
internal precise band-gap voltage (0.8V). The soft-start
time can be calculated by the following formula:
TSS(s) = 330 x CSS(nF)
If CSS is 1nF, the soft-start time will be 330µs; if CSS is
10nF, the soft-start time will be 3.3ms.
Constant-On-Time PWM Control with Input
Feed-Forward

IN
PWM

–
Programmable
One-Shot

FB Voltage/
AC Current
Information

Comp
+

0.8V

Figure 1. Simplified Control Schematic of AOZ1237

The high-side switch on-time is determined solely by a
one-shot whose pulse width can be programmed by one
external resistor and is inversely proportional to input
voltage (IN). The one-shot is triggered when the internal
0.8V is lower than the combined information of FB
voltage and the AC current information of inductor, which
is processed and obtained through the sensed lower-side
MOSFET current once it turns on. The added AC current
information can help the stability of constant-on time
control even with pure ceramic output capacitors, which
have very low ESR. The AC current information has no
DC offset, which does not cause offset with output load
change, which is fundamentally different from other V2
constant-on time control schemes.
The constant-on-time PWM control architecture is a
pseudo-fixed frequency with input voltage feed-forward.
The internal circuit of AOZ1237 sets the on-time of highside switch inversely proportional to the IN.
– 12

26.3  10
 R TON   
T ON = ---------------------------------------------------------------V IN  V 

(1)

To achieve the flux balance of inductor, the buck
converter has the equation:

V OUT
F SW = --------------------------V IN  T ON

(2)

Once the product of VIN x TON is constant, the switching
frequency keeps constant and is independent with input
voltage.
An external resistor between the IN and TON pin sets the
switching frequency according to the following equation:
12

V OUT  10
F SW = --------------------------------26.3  R TON

(3)

The control algorithm of AOZ1237 is constant-on-time
PWM Control with input feed-forward.

Rev. 2.0 April 2013

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Page 8 of 15

AOZ1237QI-02
A further simplified equation will be:

38000  V OUT  V 
F SW  kHz  = ----------------------------------------------R TON  k 

(4)
Inductor
Current

Ilim

If VOUT is 1.8V, RTON is 137k, the switching frequency
will be 500kHz.
This algorithm results in a nearly constant switching
frequency despite the lack of a fixed-frequency clock
generator.
True Current Mode Control
The constant-on-time control scheme is intrinsically
unstable if output capacitor’s ESR is not large enough as
an effective current-sense resistor. Ceramic capacitors
usually cannot be used as output capacitor.
The AOZ1237 senses the low-side MOSFET current and
processes it into DC and AC current information using
AOS proprietary technique. The AC current information is
decoded and added on the FB pin on phase. With AC
current information, the stability of constant-on-time
control is significantly improved even without the help of
output capacitor’s ESR, and thus the pure ceramic
capacitor solution can be applicable. The pure ceramic
capacitor solution can significantly reduce the output
ripple (no ESR caused overshoot and undershoot) and
less board area design.
Valley Current-Limit Protection
The AOZ1237 uses the valley current-limit protection by
using RDSON of the lower MOSFET current sensing. To
detect real current information, a minimum constant-off
(250ns typical) is implemented after a constant-on time. If
the current exceeds the valley current-limit threshold, the
PWM controller is not allowed to initiate a new cycle. The
actual peak current is greater than the valley current-limit
threshold by an amount equal to the inductor ripple
current. Therefore, the exact current-limit characteristic
and maximum load capability are a function of the
inductor value as well as input and output voltages. The
current limit will keep the low-side MOSFET ON and will
not allow another high-side on-time, until the current in
the low-side MOSFET reduces below the current limit.
Figure 2 shows the inductor current during the current
limit.

Rev. 2.0 April 2013

Time

Figure 2. Inductor Current

After 128s (typical), the AOZ1237 considers this is a
true failed condition and therefore, turns-off both highside and low-side MOSFETs and latches off. When
triggered, only the enable can restart the AOZ1237
again.
Output Voltage Under-Voltage Protection
If the output voltage is lower than 25% by over-current or
short circuit, the AOZ1237 will wait for 128s (typical)
and turns-off both high-side and low-side MOSFETs and
latches off. When triggered, only the enable can restart
the AOZ1237 again.
Output Voltage Over-Voltage Protection
The threshold of OVP is set 20% higher than 800mV.
When the VFB voltage exceeds the OVP threshold,
AOZ1237-02 will shutdown.
Power Good Output
The power good (PGOOD) output, which is an open
drain output, requires the pull-up resistor. When the
output voltage is 15% below than the nominal regulation
voltage for 50s (typical), the PGOOD is pulled low.
When the output voltage is 20% higher than the nominal
regulation voltage, the PGOOD is also pulled low.

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AOZ1237QI-02
Application Information
The basic AOZ1237 application circuit is shown in page
2. Component selection is explained below.
Input Capacitor
The input capacitor must be connected to the IN pins and
PGND pin of the AOZ1237 to maintain steady input
voltage and filter out the pulsing input current. A small
decoupling capacitor, usually 1F, should be connected
to the VCC pin and AGND pin for stable operation of the
AOZ1237. The voltage rating of input capacitor must be
greater than maximum input voltage plus ripple voltage.
The input ripple voltage can be approximated by
equation below:

For reliable operation and best performance, the input
capacitors must have current rating higher than ICIN-RMS
at worst operating conditions. Ceramic capacitors are
preferred for input capacitors because of their low ESR
and high ripple current rating. Depending on the
application circuits, other low ESR tantalum capacitor or
aluminum electrolytic capacitor may also be used. When
selecting ceramic capacitors, X5R or X7R type dielectric
ceramic capacitors are preferred for their better
temperature and voltage characteristics. Note that the
ripple current rating from capacitor manufactures is
based on certain amount of life time. Further de-rating
may be necessary for practical design requirement.
Inductor

VO  VO
IO

V IN = -----------------   1 – ---------  --------V IN V IN
f  C IN 
Since the input current is discontinuous in a buck
converter, the current stress on the input capacitor is
another concern when selecting the capacitor. For a buck
circuit, the RMS value of input capacitor current can be
calculated by:

The inductor is used to supply constant current to output
when it is driven by a switching voltage. For given input
and output voltage, inductance and switching frequency
together decide the inductor ripple current, which is:

VO 
VO 
I L = -----------   1 – ---------
V IN
fL 
The peak inductor current is:

VO 
VO 
I CIN_RMS = I O  ---------  1 – ---------
V IN 
V IN

I L
I Lpeak = I O + -------2

if let m equal the conversion ratio:

VO
-------- = m
V IN
The relation between the input capacitor RMS current
and voltage conversion ratio is calculated and shown in
Figure 3. It can be seen that when VO is half of VIN, CIN it
is under the worst current stress. The worst current
stress on CIN is 0.5 x IO.

High inductance gives low inductor ripple current but
requires a larger size inductor to avoid saturation. Low
ripple current reduces inductor core losses. It also
reduces RMS current through inductor and switches,
which results in less conduction loss. Usually, peak to
peak ripple current on inductor is designed to be 30% to
50% of output current.
When selecting the inductor, make sure it is able to
handle the peak current without saturation even at the
highest operating temperature.

0.5

The inductor takes the highest current in a buck circuit.
The conduction loss on the inductor needs to be checked
for thermal and efficiency requirements.

0.4
ICIN_RMS(m) 0.3
IO
0.2

Surface mount inductors in different shapes and styles
are available from Coilcraft, Elytone and Murata.
Shielded inductors are small and radiate less EMI noise,
but they do cost more than unshielded inductors. The
choice depends on EMI requirement, price and size.

0.1
0

0.5
m

Figure 3. ICIN vs. Voltage Conversion Ratio

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Page 10 of 15

AOZ1237QI-02
Output Capacitor
The output capacitor is selected based on the DC output
voltage rating, output ripple voltage specification and
ripple current rating.
The selected output capacitor must have a higher rated
voltage specification than the maximum desired output
voltage including ripple. De-rating needs to be
considered for long term reliability.
Output ripple voltage specification is another important
factor for selecting the output capacitor. In a buck converter circuit, output ripple voltage is determined by
inductor value, switching frequency, output capacitor
value and ESR. It can be calculated by the equation
below:

1
V O = I L   ESR CO + -------------------------

8fC 
O

where,
CO is output capacitor value and
ESRCO is the Equivalent Series Resistor of output capacitor.

When a low ESR ceramic capacitor is used as output
capacitor, the impedance of the capacitor at the
switching frequency dominates. Output ripple is mainly
caused by capacitor value and inductor ripple current.
The output ripple voltage calculation can be simplified to:

1
V O = I L  ------------------------8fC
O

If the impedance of ESR at switching frequency
dominates, the output ripple voltage is mainly decided by
capacitor ESR and inductor ripple current. The output
ripple voltage calculation can be further simplified to:

V O = I L  ESR CO

Thermal Management and Layout
Consideration
In the AOZ1237 buck regulator circuit, high pulsing
current flows through two circuit loops. The first loop
starts from the input capacitors, to the VIN pin, to the LX
pins, to the filter inductor, to the output capacitor and
load, and then returns to the input capacitor through
ground. Current flows in the first loop when the high side
switch is on. The second loop starts from the inductor, to
the output capacitors and load, to the low side switch.
Current flows in the second loop when the low side
switch is on.
In PCB layout, minimizing the two loops area reduces the
noise of this circuit and improves efficiency. A ground
plane is strongly recommended to connect the input
capacitor, output capacitor and PGND pin of the
AOZ1237.
In the AOZ1237 buck regulator circuit, the major power
dissipating components are the AOZ1237 and output
inductor. The total power dissipation of the converter
circuit can be measured by input power minus output
power.

P total_loss = V IN  I IN – V O  I O
The power dissipation of inductor can be approximately
calculated by output current and DCR of inductor and
output current.

P inductor_loss = IO2  R inductor  1.1
The actual junction temperature can be calculated with
power dissipation in the AOZ1237 and thermal
impedance from junction to ambient.

T junction =  P total_loss – P inductor_loss    JA

For lower output ripple voltage across the entire
operating temperature range, X5R or X7R dielectric type
of ceramic, or other low ESR tantalum are recommended
to be used as output capacitors.
In a buck converter, output capacitor current is
continuous. The RMS current of output capacitor is
decided by the peak to peak inductor ripple current.
It can be calculated by:

The maximum junction temperature of AOZ1237 is
150ºC, which limits the maximum load current capability.
The thermal performance of the AOZ1237 is strongly
affected by the PCB layout. Extra care should be taken
by users during design process to ensure that the IC will
operate under the recommended environmental
conditions.

I L
I CO_RMS = ---------12
Usually, the ripple current rating of the output capacitor is
a smaller issue because of the low current stress. When
the buck inductor is selected to be very small and
inductor ripple current is high, the output capacitor could
be overstressed.
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AOZ1237QI-02
Layout Considerations
Several layout tips are listed below for the best electric
and thermal performance.
1. The LX pins and pad are connected to internal low
side switch drain. They are low resistance thermal
conduction path and most noisy switching node.
Connect a large copper plane to LX pin to help
thermal dissipation.

5. Voltage divider R1 and R2 should be placed as close
as possible to FB and AGND.
6. RTON should be placed on PCB on the opposite side
of feedback network or away from FB pin and FB
feedback resistors in order to avoid unwanted touch,
which will short TON pin and FB together to ground
and cause improper operation.

2. The IN pins and pad are connected to internal high
side switch drain. They are also low resistance
thermal conduction path. Connect a large copper
plane to IN pins to help thermal dissipation.

7. A ground plane is preferred; Pin 19 (PGND) must be
connected to the ground plane through via.

3. Input capacitors should be connected to the IN pin
and the PGND pin as close as possible to reduce the
switching spikes.

8. Keep sensitive signal traces such as feedback trace
far away from the LX pins.
9. Pour copper plane on all unused board area and
connect it to stable DC nodes, like VIN, GND or
VOUT.

4. Decoupling capacitor CVCC should be connected to
VCC and AGND as close as possible.

9RXW

3*22'

3*1'

3)0

3*1'

9&&

%67

3*1'

ġġġġġġġġġġġġġġġġġġġġ3*1'

3*1'

$*1'

721

9LQ

9RXW

3*1'

9RXW

Rev. 2.0 April 2013

www.aosmd.com

9RXW

Page 12 of 15

AOZ1237QI-02
Package Dimensions, QFN 4x4, 23 Lead EP2_S
D

D3
L1

Pin #1 Dot
By Marking
L

e
E

L3
L2

TOP VIEW

BOTTOM VIEW
A1
A

SIDE VIEW

RECOMMENDED LAND PATTERN
0.37
0.25

0.50

0.25

0.22

0.45

2.71
3.10
3.43

3.10

0.26
0.75
1.34

0.37
0.75
0.95

UNIT: MM

Dimensions in inches

Dimensions in millimeters
Symbols

Min.

Typ.

Max.

Symbols

Min.

Typ.

Max.

A
A1
A2
E
E1
D
D1
D2
D3
L
L1
L2
L3
b
e

0.80
0.00

0.90
—
0.2 REF
4.00
3.05
4.00
0.75
0.95
1.34
0.40
0.62
0.28
0.62
0.25
0.50 BSC

1.00
0.05

A
A1
A2
E
E1
D
D1
D2
D3
L
L1
L2
L3
b
e

0.031
0.000

0.035
—
0.008 REF
0.157
0.120
0.157
0.030
0.037
0.053
0.016
0.024
0.011
0.024
0.010
0.020 BSC

0.039
0.002

3.90
2.95
3.90
0.65
0.85
1.24
0.35
0.57
0.23
0.57
0.20

4.10
3.15
4.10
0.85
1.05
1.44
0.45
0.67
0.33
0.67
0.30

0.154
0.116
0.154
0.026
0.033
0.049
0.014
0.022
0.009
0.022
0.008

0.141
0.124
0.141
0.033
0.041
0.057
0.018
0.026
0.013
0.026
0.012

Notes:
1. Controlling dimensions are in millimeters. Converted inch dimensions are not necessarily exact.
2. Tolerance: ± 0.05 unless otherwise specified.
3. Radius on all corners is 0.152 max., unless otherwise specified.
4. Package wrapage: 0.012 max.
5. No plastic flash allowed on the top and bottom lead surface.
6. Pad planarity: ± 0.102
7. Crack between plastic body and lead is not allowed.

Rev. 2.0 April 2013

www.aosmd.com

Page 13 of 15

AOZ1237QI-02
Tape and Reel Dimensions, QFN 4x4, 23 Lead EP2_S
Carrier Tape
P1
P2

E2
E

Feeding Direction

UNIT: mm

Package

QFN 4x4
(12mm)

4.35
±0.10

1.10
±0.10

1.50
Min.

1.50
+0.10/-0

12.00
±0.30

Reel

1.75
±0.10

5.50
±0.05

8.00
±0.10

4.00
±0.10

2.00
±0.05

0.30
±0.05

S
G
N

V
R
H
W
UNIT: mm
Tape Size Reel Size
12mm
ø330

M
ø330.0
±2.0

N
ø79.0
±1.0

W
12.4
+2.0/-0.0

W1
17.0
+2.6/-1.2

H
ø13.0
±0.5

K
10.5
±0.2

S
2.0
±0.5

G
—

R
—

V
—

Leader/Trailer and Orientation

Trailer Tape
300mm min.
or 75 Empty Pockets

Rev. 2.0 April 2013

Components Tape
Orientation in Pocket

www.aosmd.com

Leader Tape
500mm min.
or 125 Empty Pockets

Page 14 of 15

AOZ1237QI-02
Part Marking
AOZ1237QI-02
(QFN4x4)

Z1237QI2

Part Number Code

FAYWLT

Assembly Lot Code

Fab & Assembly Location
Year & Week Code

LEGAL DISCLAIMER
Alpha and Omega Semiconductor makes no representations or warranties with respect to the accuracy or
completeness of the information provided herein and takes no liabilities for the consequences of use of such
information or any product described herein. Alpha and Omega Semiconductor reserves the right to make changes
to such information at any time without further notice. This document does not constitute the grant of any intellectual
property rights or representation of non-infringement of any third party’s intellectual property rights.
LIFE SUPPORT POLICY
ALPHA AND OMEGA SEMICONDUCTOR PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL
COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS.
As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant into
the body or (b) support or sustain life, and (c) whose
failure to perform when properly used in accordance
with instructions for use provided in the labeling, can be
reasonably expected to result in a significant injury of
the user.

Rev. 2.0 April 2013

2. A critical component in any component of a life
support, device, or system whose failure to perform can
be reasonably expected to cause the failure of the life
support device or system, or to affect its safety or
effectiveness.

www.aosmd.com

Page 15 of 15

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