Analog Devices MAX77831 User manual

Evaluates: MAX77831 MAX77831 Evaluation Kit
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General Description
The MAX77831 evaluation kit (EV kit) provides a proven
design to evaluate the MAX77831, a 7A switching current,
high-e󰀩ciency, high-performance buck-boost regulator
that only operates in forced-PWM (FPWM) mode. The IC
is capable of 2.5V to 16V input and dynamically adjust-
able output between 4.5V to 15V when using internal
feedback resistors, or between 3V to 15V when using
external feedback resistors. The EV kit is factory-cong-
ured as internal feedback with the default startup output
voltage at 5V. Other startup voltage can be achieved
with external feedback resistors. Output voltage can be
adjusted dynamically through the I2C serial interface.
The I/O pins are available to support the I2C serial inter-
face, Enable function, and Interrupt/Power-OK indicator.
The I2C slave address, switching current limit, and feed-
back conguration can be adjusted by changing the RSEL
resistor value (R9). The MAXUSB_INTERFACE# allows
the use of Windows®-based software with a friendly
graphical user interface (GUI) as well as a detailed regis-
ter-based interface to exercise all the features of the IC.
The IC installed on the EV kit is the MAX77831BEWB+T.
Benets and Features
● Proven PCB Reference Design and Layout Benet
● Fully Assembled and Tested
● Sense Points for High-Accuracy Measurements
● Accessible Test Point Pins for EN, POKB/INTB, VIO,
and the I2C Serial Interface SCL, SDA
● MAXUSB_INTERFACE# Allows Easy Communication
with a Windows PC
● GUI Software that Drives the I2C Serial Interface for
Optional Software Control
● Startup Output Voltage Adjustable Through External
Feedback Resistors
● Output Voltage Dynamically Adjustable Through the
I2C Serial Interface
● I2C Slave Address, Switching Current Limit, and
Feedback Conguration Adjustable Using RSEL (R9)
319-100600; Rev 1; 9/21
Ordering Information appears at end of data sheet.
Windows is a registered trademark of Microsoft Corp.
SPECIFICATION TEST CONDITION MIN TYP MAX UNIT
Input Voltage 2.5 16 V
Output Voltage Internal Feedback 4.5 15 V
External Feedback 315 V
Default Output Voltage Internal Feedback 5 V
Switching Current Limit 7 A
Peak E󰀩ciency VIN = 4V, VOUT = 5V, 700mA Load 97.0 %
MAX77831 EV Kit Specications

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MAX77831 Evaluation Kit Evaluates: MAX77831
Figure 1. Application Circuit for MAX77831
Figure 2. MAX77831 EV Kit Photo
FB
C
OUT
2x
22μF
25V 0805
V
OUT
3.0 V TO 15V
OUT
USING EXTERNAL FEEDBACK RESISTORS
R
TOP
R
BOT
OPTIONAL
I
2
C INTERFACE
LX1
EN
IN
FB
AGND PGND
MAX77831
L
1.5 μH
DCSOURCE
2.5 V TO 16V
ENABLE
V
OUT
4.5 V TO 15V
R
SE L*
V
L
SEL
OUT
C
VL
2.2 μF
10V 0402
SCL
SDA
BST1 BST2LX2
C
BS T1
0.2 2μF
50V 0603
C
BS T2
0.2 2μF
50V 0603
C
IN
2x
10μF
25V 0805
C
OUT
2x 22 μF
25V 0805
V
IO
C
VIO
0.4 7μF
10V 0402
IO SUPPLY
1.0 8V TO 2.0 V
*CHOOSE R
SE L
VALUE
BASED ON TABLE 2
USING INTERNAL FEEDBACK RESI STORS
POKB/INTB
POK/
INTERRUPT
V
IO
R
PU
15kΩ
0402
C
FF
10pF
25V
0402

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MAX77831 Evaluation Kit Evaluates: MAX77831
EV Kit Default Conguration
With the default jumper settings listed in Table 1 and the
EV kit component values of RSEL (R9) = 0Ω, RTOP (R10)
= 0Ω, and RBOT (R11) = OPEN, the MAX77831 EV kit is
configured with the following settings:
● Internal Feedback
● Switching Current Limit = 7.0A
● I2C Slave Address (7-bit) = 0x66
● Switching Frequency = 1.8MHz (adjustable only
through the I2C)
● I2C Line Connected to MAXUSB_INTERFACE#
See the EV Kit Hardware section to change the EV kit
configuration.
Quick Start
Required Equipment
● MAX77831 EV Kit
● Adjustable DC Power Supply
● A 1.8V DC Power Supply
● Digital Multi-Meters
●Electronic Load
● MAXUSB_INTERFACE# for I2C Serial Interface
(Optional)
● USB Type-A to Micro-USB Cable (Optional)
● Windows-based PC with MAX77831 EV Kit GUI
(Optional)
Procedure
The EV kit is fully assembled and tested. Perform the
following steps to verify board operation. Use twisted
wires of appropriate gauge (20 AWG) that are as short as
possible to connect the load and power sources.
1) Ensure that the EV kit has the correct jumper settings,
as shown in Table 1.
2) Connect a DVM to the INS and PGND1S sense pins
to measure input voltage.
3) Connect a DVM to the OUTS and PGND2S sense
pins to measure output voltage.
4) Apply a power supply set to 1.8V (100mA current lim-
it) across VIO and GND terminals of the EV kit. Turn
on the power supply.
5) Apply a power supply set to 0V (1.5A current limit)
through an ammeter across the IN and PGND1 ter-
minals of the EV kit. Turn the supply on and increase
the voltage to 7.6V.
6) Conrm the DVM connected to OUTS and PGND2S
reads the default output voltage of the EV kit (5V).
Conrm the ammeter reads the expected input supply
current (about 12mA).
7) Now that the EV kit is conrmed working, short out
the series ammeter and increase the current limit on
the power supply connected across IN and PGND1.
Connect an electronic load across the OUT and
PGND2 terminals to evaluate the performance of the
MAX77831 buck-boost regulator.
The next steps of the procedure use the EV kit GUI and
MAXUSB_INTERFACE# to evaluate the MAX77831’s I2C
serial interface. If evaluation of the I2C serial interface is not
required, you may skip the following steps. The EV kit in-
cludes on-board 2.2kΩ pullup resistors (R4 and R7) to VIO.
8) Install GUI software. Visit the product webpage at
https://www.maximintegrated.com/products/
MAX77831WEVKIT and navigate to Design Re-
sources to download the latest version of the EV kit
software. Save the EV kit software installation file to
a temporary folder and decompress the ZIP file. Run
the .EXE file and follow the on-screen instructions to
complete installation.
Table 1. Default Shunt Positions and Jumper Description
*Default position
JUMPER NODE SHUNT
POSITION FUNCTION
J1 EN 1-2* Connects EN to VIO (logic-high, enables MAX77831).
2-3 Connects EN to AGND (logic-low, disables MAX77831).
J2 SDA 1-2* Pulls SDA up to VIO through R7 (2.2kΩ).
2-3 Connects SDA to AGND.
J3 MAXUSB_VIO 1-2* Connects MAXUSB_INTERFACE# VIO to EV kit VIO.
J4 MAXUSB_SDA 1-2* Connects MAXUSB_INTERFACE# SDA to EV kit SDA.
R3 MAXUSB_SCL 0Ω installed* Connects MAXUSB_INTERFACE# SCL to EV kit SCL.

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MAX77831 Evaluation Kit Evaluates: MAX77831
9) Turn off the 1.8V VIO power supply and input power
supply connected in step 4 and step 5.
10) Disconnect the 1.8V VIO power supply connected in
step 4 from the EV kit. The MAXUSB_INTERFACE#
has an on-board LDO to supply 1.8V to VIO.
11) Ensure the SW1 and SW2 switches on the
MAXUSB_INTERFACE# are set to the ON position.
This enables I2C mode on the MAXUSB_INTERFACE#.
12) Important: Ensure the VL Jumper on the MAX-
USB_INTERFACE# (J5) is set to 1.8V. This sets
the MAXUSB_INTERFACE# VIO voltage. Setting
this incorrectly to 3.3V could potentially damage the
MAX77831 IC.
13) Connect the MAXUSB_INTERFACE# to the
MAX77831 EV kit. Connect the MAXUSB_INTER-
FACE# to your PC’s USB port using a USB Type-A to
Micro-USB Cable.
14) Turn on the input power supply.
15) Open the GUI and click the Device button in the menu
bar. Click the Connect button in the Device button’s
drop-down list. Wait for the device to respond, and
in the Synchronize window, press the Connect and
Read button.
16) Drag the slide bar in the Output Voltage Configuration
section to change the output voltage and click Write.
17) Confirm with a DVM that the software instruction to
change output voltage was successful. If so, the I2C
serial interface is confirmed as working.
This concludes the Quick Start procedure. Users are now
encouraged to further explore the device and its register
settings with the GUI software. For more information on
the GUI, see the EV Kit Software section.
EV Kit Hardware
The MAX77831 EV kit demonstrates the MAX77831
buck-boost regulator. It regulates output from input voltage
ranges from 2.5V to 16V. The programmable output range
is from 4.5V to 15V with internal feedback resistors, or from
3V to 15V with external feedback resistors. The EV kit is
suited with a general DC input. Table 1 lists jumpers and
associated functions that are available on the EV kit.
RSEL Conguration Resistor
The MAX77831 includes an SEL pin to set the I2C slave
address, switching current limit, and feedback configura-
tion. A resistor with a tolerance of 1% (or better) should be
chosen for R9, which is the SEL pin configuration resistor
RSEL. The default RSEL value installed on the EV kit is
0Ω. See Table 2 for the nominal RSEL values and their
corresponding settings. The switching current limit is also
adjustable dynamically through the I2C serial interface
when the MAX77831 is enabled. See the EV Kit Software
section for more information.
Output Voltage Conguration
By default, the EV kit is configured to use internal feed-
back resistors, with 5V default startup output voltage and
an output voltage range from 4.5V to 15V. To achieve a
different default startup output voltage other than 5V, or to
achieve a lower minimum output voltage range down to
3V, external feedback resistors are required. To change
the EV kit to the external feedback configuration, replace
the feedback resistors RTOP (R10) and RBOT (R11) with
appropriate value resistors (use resistors with 1% toler-
ance or better) and adjust RSEL (R9) accordingly to select
the external feedback option. It is also recommended to
install a 10pF feed-forward capacitor on C9 when using
external feedback.
To select appropriate external feedback resistor values,
first choose RTOP (R10) to be between 150kΩ and
330kΩ. Then calculate the value of RBOT (R11) for a
desired startup output voltage with the following equation:
BOT REF
OUT
OUT REF
RV
VVV
×
−
=
where VREF is 0.333V and VOUT is the desired startup
output voltage. Note that the output voltage cannot
exceed the maximum output voltage 15V. The recom-
mended external feedback resistor values for common
output voltage are listed in Table 3.
After startup, the output voltage can be adjusted dynami-
cally using the I2C serial interface. See the EV Kit
Software section for more information. When using inter-
nal feedback, output voltage ranges between 4.5V and
15V in 73.5mV steps. When using external feedback,
output voltage range and step size vary based on the
external feedback resistor values. To calculate output
voltage range, use the following equation and plug in the
minimum VREF of 0.299V and maximum VREF of 1V:
REF
OUT BOT TOP
BOT
V
V (R R )
R+= ×
Output voltage step size can be calculated with the fol-
lowing equation:
BOT TOP
O
OUT_STEP BT
V (R R )
R
4.9mV
+= ×
Programmable output voltage ranges and output volt-
age step sizes for each recommended external feedback
resistor pairs are listed in Table 3.

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MAX77831 Evaluation Kit Evaluates: MAX77831
MAXUSB_INTERFACE#
The MAXUSB_INTERFACE# along with the companion
EV kit GUI software allows users to easily change the
MAX77831’s register settings with a Windows PC. Before
connecting the MAXUSB_INTERFACE# to the EV kit’s
MAXUSB_INTERFACE# connector (J5), make sure the
MAXUSB_INTERFACE# is configured with the following
settings:
● SW1, SW2 to ON Position (This enables I2C mode on
the MAXUSB_INTERFACE#.)
● VL Jumper (J5) to 1.8V (This sets the MAXUSB_
INTERFACE# VIO voltage.)
• Warning: Setting this incorrectly to 3.3V could
potentially damage the MAX77831 IC.
The MAXUSB_INTERFACE# also includes an on-board
LDO that can supply necessary voltage to VIO. If you are
using the MAXUSB_INTERFACE#, disconnect any exter-
nal VIO supply from the EV kit, and make sure header
jumpers J3, J4, and 0Ω jumper R3 are installed to connect
the MAXUSB_INTERFACE# to the EV kit.
Table 2. MAX77831 RSEL Selection Table
Table 3. Feedback Resistor Value Recommendations
*Default value installed on the EV kit
RSEL
(Ω)
FEEDBACK
RESISTOR
SELECTION
TYPICAL
ILIM (A)
I2C SLAVE
ADDRESS
(7-BIT)
RSEL
(Ω)
FEEDBACK
RESISTOR
SELECTION
TYPICAL
ILIM (A)
I2C SLAVE
ADDRESS
(7-BIT)
0*
Internal
Feedback
Resistors
7.0
110 0110 (0x66) 3740
External
Feedback
Resistors
7.0
110 0110 (0x66)
200 110 0111 (0x67) 8060 110 0111 (0x67)
309 110 1110 (0x6E) 12400 110 1110 (0x6E)
422 110 1111 (0x6F) 16900 110 1111 (0x6F)
536
5.6
110 0110 (0x66) 21500
5.6
110 0110 (0x66)
649 110 0111 (0x67) 26100 110 0111 (0x67)
768 110 1110 (0x6E) 30900 110 1110 (0x6E)
909 110 1111 (0x6F) 36500 110 1111 (0x6F)
1050
3.8
110 0110 (0x66) 42200
3.8
110 0110 (0x66)
1210 110 0111 (0x67) 48700 110 0111 (0x67)
1400 110 1110 (0x6E) 56200 110 1110 (0x6E)
1620 110 1111 (0x6F) 64900 110 1111 (0x6F)
1870
1.72
110 0110 (0x66) 75000
1.72
110 0110 (0x66)
2150 110 0111 (0x67) 86600 110 0111 (0x67)
2490 110 1110 (0x6E) 100000 110 1110 (0x6E)
2870 110 1111 (0x6F) OPEN 110 1111 (0x6F)
DEFAULT
VREF (V)
RTOP
R10 (kΩ)
RBOT
R11 (kΩ)
STARTUP
VOUT (V)
PROGRAMMABLE VOUT
RANGE (V)
VOUT STEP SIZE
(mV)
0.333
160 20 33.0 to 9.0 44.1
178 20 3.3 3.0 to 9.9 48.5
Internal Feedback Resistors 5 4.5 to 15 73.5
312 12 9 8.1 to 15 132.3
232 6.65 12 10.7 to 15 175.8
234 5.3 15 13.5 to 15 221.2

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MAX77831 Evaluation Kit Evaluates: MAX77831
External I2C Bus
To connect to the external I2C serial bus and not
use the MAXUSB_INTERFACE#, unplug the MAXUSB_
INTERFACE# from the MAX77831 EV kit’s MAXUSB_
INTERFACE# connector (J5), and remove header jump-
ers J3, J4, and 0Ω jumper R3 to isolate the MAXUSB_
INTERFACE# connector from the EV kit. Apply an exter-
nal I/O supply to VIO pin. Make sure the external I2C serial
bus’s logic voltage level is compatible to the MAX77831’s
I/O logic voltage level. Refer to the MAX77831 IC data
sheet for the appropriate I/O logic voltage level.
High Temperature Testing
The MAX77831 is rated for operation under junction
temperatures up to +125°C. Note that not all components
on the EV kit are rated for temperatures this high. Some
ceramic capacitors experience extra leakage when put
under temperatures higher than they are rated for, and
supply current readings for the IC might be larger than
expected. The MAXUSB_INTERFACE# is also not rated
for +125°C. Double check the components on the EV kit
if testing at +125°C ambient or junction temperatures.
Consider replacing these components if IC operation at
+125°C ambient or junction temperature is an important
use case.
List of capacitors not rated for +125°C:
● C10, C11 (OUT capacitors)
Critical Node Measurement (OUT and LX)
The EV kit comes with probe points for measuring critical
nodes OUT1, LX1, and LX2. See Figure 2 for their loca-
tions on the EV kit. Use these probe points to eliminate
as much noise as possible when measuring the critical
nodes. To ensure best results, use a very short ground
wire from the ground sleeve of the scope probe to the GND
side of the probe point, and use the bare tip of the probe
directly to the signal side of the probe point (Figure 3).
Following these guidelines gives the most accurate results
when measuring parameters such as output voltage
ripple, switching waveforms, and load transient response.
E󰀩ciency Measurement (INS, OUTS)
The EV kit also comes with sense pins for accurately
measuring input voltage (INS, PGND1S) and output volt-
age (OUTS, PGND2S). See Figure 2 for their locations on
the EV kit. For most accurate efficiency, load regulation,
and line regulation measurements, use these sense pins
to measure input and output voltages.
Warning: These sense pins are only for measuring volt-
ages. Do not connect input supply to input sense pins and
do not connect electronic load to output sense pins, as
these sense pins are not designed to have current run-
ning through them. Doing so damages the EV kit.
Use input supply terminals for connecting to input supply
and use output terminals for connecting to electronic load
as shown in Figure 2.
Figure 3. Probing Critical Nodes
Table 4. Usage of Critical Test Points
LOAD TRANSIENT,
OUTPUT RIPPLE
LOAD REGULATION,
LINE REGULATION,
VOUT ACCURACY
EFFICIENCY SWITCHING NODE
OUTPUT VOLTAGE INPUT VOLTAGE LX1 LX2
VOUT
(OUT1)
VOUT
(OUTS, PGND2S)
VOUT
(OUTS, PGND2S)
VIN
(INS, PGND1S)
LX1
(LX1)
LX2
(LX2)

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MAX77831 Evaluation Kit Evaluates: MAX77831
EV Kit Software
The graphical user interface (GUI) software allows for
quick, easy, and thorough evaluation of the MAX77831.
The GUI along with the MAXUSB_INTERFACE# drives
I2C communication with the EV kit. Every control in the
GUI corresponds directly to a register within MAX77831.
Refer to Register Map section of the MAX77831 IC data
sheet for a complete description of the registers. See
Figure 4 for a screenshot of the GUI upon first opening.
Installation
Visit the product webpage at https://www.maximinte-
grated.com/products/MAX77831WEVKIT and navigate
to Design Resources to download the latest version of the
EV kit software. Save the EV kit software installation file
to a temporary folder and decompress the ZIP file. Run
the .EXE installer and follow the on-screen instructions to
complete the installation.
Windows Driver
After plugging in the MAXUSB_INTERFACE# to the PC
with a Micro-USB cable for the first time, wait about 30
seconds for Windows to automatically install the neces-
sary drivers.
Connecting GUI to MAXUSB_INTERFACE#
After opening the GUI, click Device in the upper left corner
of the GUI window. Click Connect in the drop-down menu.
If you have multiple MAXUSB_INTERFACE# adapt-
ers or FTDI devices connected to your PC, the Port
Synchronization menu appears (Figure 5). Select
the port corresponding to the MAXUSB_INTERFACE#
attached to the MAX77831 EV kit and click Connect.
The Device Synchronization menu opens (Figure 6)
once the MAX77831 IC responds (voltages on IN pin
and VIO pin must be valid on the MAX77831 IC for it
to respond). The I2C address shown is the MAX77831
IC’s 7-bit slave address. The address shown changes
depending on the EV kit’s RSEL configuration. See the
EV Kit Hardware RSEL Configuration Resistor section
if you wish to change the address. Click Connect and
Read. The text at the bottom right of the GUI window
changes from “MAXUSB is Disconnected” to “MAXUSB
is Connected.”
Figure 4. MAX77831 EV Kit GUI Software Configuration Tab

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MAX77831 Evaluation Kit Evaluates: MAX77831
Conguration
The Configuration tab (Figure 4) displays information
and status of the IC on the EV Kit as well as all available
register settings. It is divided into different sections: Chip
Identification, POK Status and Fault Interrupts, Output
Voltage Configuration, and Miscellaneous Configuration.
Click Read Once located on the top of the GUI window
to obtain all setting values currently stored on all the
MAX77831’s registers. After changing the setting values
in the GUI software, click Write on the top of the GUI
window to apply all settings to the MAX77831’s registers.
Alternatively, click Read on each setting section to obtain
the setting values of that particular section currently
stored on the MAX77831’s registers. After changing the
setting values in the GUI software, click Write in the
corresponding setting section to apply the new settings
for that particular section to the MAX77831’s registers.
The Chip Identification section (Figure 7) displays the
revision and version information of the MAX77831 IC on
the EV Kit. Click Read to obtain information from the IC.
The POK Status and Fault Interrupt Source section
(Figure 8) displays the power-OK status and any fault
conditions detected on the MAX77831 IC, which are
stored in the INT_SRC register. Periodically check the
POK Status and Fault Interrupt Source section during
evaluation to monitor the status of power-OK (POK),
overvoltage protection (OVP), output hard-short, thermal
shutdown (THS), and overcurrent protection (OCP). Click
Read to obtain the latest status from the IC.
The POK Status and Fault Interrupt Masks section
(Figure 9) configures the reflection of the bits in INT_SRC
to the POKB/INTB pin. If a bit is masked, its status in
the INT_SRC register is not shown on the POKB/INTB
pin. Refer to the Power-OK Monitor and Fault Interrupts
section in the IC datasheet for more information about
the operation of the POKB/INTB pin. Click Read to obtain
the setting stored on the IC and click Write to apply new
settings to the IC.
Figure 5. Port Synchronization Menu Figure 6. Device Synchronization Menu

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MAX77831 Evaluation Kit Evaluates: MAX77831
Figure 7. Configuration Tab - Chip Identification Section
Figure 8. Configuration Tab - POK Status and Fault Interrupt Source Section
Figure 9. Configuration Tab - POK Status and Fault Interrupt Masks Section

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MAX77831 Evaluation Kit Evaluates: MAX77831
The Output Voltage Configuration section (Figure 10) con-
figures the EV kit IC’s output voltage. The output voltage
is changed by adjusting the internal reference voltage.
Drag the slider to the desired internal reference voltage
(or output voltage) and click Write to change the output
voltage. Clicking Read returns the programmed internal
reference voltage (or output voltage) to the GUI.
To make evaluation easier, the GUI software displays the
corresponding output voltage value in the Output Voltage
textbox based on the value in the Internal Reference
Voltage slider. To obtain the correct value, check the
Internal Feedback or External Feedback checkbox
corresponding to the EV kit configuration. For external
feedback configuration, enter the chosen feedback resis-
tor values in the Top Feedback Resistor and Bottom
Feedback Resistor textboxes to allow correct calculation
of the corresponding output voltage to be displayed on
the GUI software.
Note: Changing the Internal Feedback or External
Feedback checkboxes (Figure 10) does NOT change the
feedback configuration on the EV kit. It is only for calculat-
ing and displaying the correct output voltage value on the
GUI software. If you wish to change the EV kit’s feedback
configuration, see the EV Kit Hardware Output Voltage
Configuration section for details.
The Miscellaneous Configuration sections (Figure 11)
show the remaining register settings of the MAX77831.
Use these sections to control internal compensation resis-
tance, switching frequency, switching current limit, and
output voltage change slew rate (using the internal refer-
ence voltage DVS slew rate). Refer to the MAX77831 IC
data sheet for more information on each available setting.
Click Read to obtain the setting stored on the IC and click
Write to apply new settings to the IC.
Figure 10. Configuration Tab - Output Voltage Configuration Section
Figure 11. Configuration Tab - Miscellaneous Configuration Sections

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MAX77831 Evaluation Kit Evaluates: MAX77831
Register Map
The Register Map tab provides an overview of all the
MAX77831 registers and the values currently stored on
them. Clicking on an individual bit shows the name and
description of the specific bitfield.
Layout Guidelines
Careful circuit board layout is critical to achieve low
switching power losses and clean stable operation. The
EV kit also serves a Maxim recommended layout of the
MAX77831. If the POK or fault interrupt functionality
is desired, the high-density interconnect (HDI) PCB is
required to route to the POKB/INTB pin. Otherwise, the
HDI PCB is recommended but not required. Figure 13
and Figure 14 show example non-HDI and HDI PCB lay-
outs for the MAX77831 WLP package. Use the provided
layout files for guidance when designing with the IC. The
IC data sheet contains a list of useful tips and guidelines
for achieving the best possible layout. They are repeated
here for convenience:
● Place the input capacitors (CIN) and output capacitors
(COUT) immediately next to the IN pin and OUT pin of
the IC, respectively. Since the IC operates at a high
switching frequency, this placement is critical for mini-
mizing parasitic inductance within the input and output
current loops, which can cause high voltage spikes
and can damage the internal switching MOSFETs.
● Place the inductor next to the LX bumps (as close
as possible) and make the traces between the LX
bumps and the inductor short and wide to minimize
PCB trace impedance. Excessive PCB impedance
reduces converter efficiency. When routing LX traces
on a separate layer (as in the examples), make sure
to include enough vias to minimize trace impedance.
Routing LX traces on multiple layers is recommended
to further reduce trace impedance. Furthermore, do
not make LX traces take up an excessive amount of
area. The voltage on this node switches very quickly
and additional area creates more radiated emissions.
Figure 12. EV Kit GUI Software Register Map Tab

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MAX77831 Evaluation Kit Evaluates: MAX77831
●Route LX nodes to the corresponding bootstrap
capacitor (CBST) as short as possible. Prioritize CBST
placement to reduce trace length to the IC.
● Connect the inner PGND bumps to the low-impedance
ground plane on the PCB with vias placed next to
the bumps. Do not create PGND islands, as PGND
islands risk interrupting the hot loops. Connect AGND
and AGND island to the low-impedance ground plane
on the PCB (the same net as PGND).
● Keep the power traces and load connections short and
wide. This is essential for high converter efficiency.
● Do not neglect ceramic capacitor DC voltage derat-
ing. Choose capacitor values and case sizes carefully.
Refer to the Output Capacitor Selection section in the
MAX77831 IC datasheet and Tutorial 5527 for more
information.
Figure 13. Non-HDI PCB Layout Recommendation (with 4mm x 4mm inductor and without POKB/INTB)

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MAX77831 Evaluation Kit Evaluates: MAX77831
Figure 14. HDI PCB Layout Recommendation (with 2520 Inductor and POKB/INTB)
#Denotes a RoHS-compliant device that may include lead that is exempt under the RoHS requirements.
+Denotes a lead(Pb)-free/RoHS-compliant package.
PART U1 IC DEFAULT OUTPUT VOLTAGE TYPE
MAX77831WEVKIT# MAX77831BEWB+T 5V EV Kit
NOTE: PLACE CIN AND COUT CLOSE TO THE IC TO MINIMIZE PARASITIC INDUCTANCE WITHIN THE LOOP
+
IN
PGND
O UT
PGND
BST1
VLFBSEL
*USING INTERNAL
FEEDBACK RESISTORS
BST2
LX1 LX2
**LAYOUT BASED ON
3.8A ILI M CONFIGURATION
0603
0402
1008 (2520)
NON-HDI VIA
8mil HOLE, 16mil PAD
6mil HOLE, 12mil PAD
HDI µVIA
4mil HOLE, 8mil PAD
LEGEND
COMPONENT SIZES LISTED IN
IMPERIAL ( METRIC)
AGND
VIO
EN
SDA
SCL
POKB/INTB
L
1008 (2520)
C
IN
0603
C
IN
0603
C
OUT
0603
C
OUT
0603
C
BST2
0603
C
BST1
0603
R
SEL
0402
RPU
0402
CVIO
0402
CVL
0402
Ordering Information

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MAX77831 Evaluation Kit Evaluates: MAX77831
MAX77831 EV Kit Bill of Materials
REF_DES QTY MFG PART # MANUFACTURER VALUE DESCRIPTION
C1 1T491X107K025A KEMET 100µF CAPACITOR; SMT (7343-43); TANTALUM CHIP;
100µF; 25V; TOL = 10%
C2 1JMK105B7474KVHF TAIYO YUDEN 0.47µF CAP; SMT (0402); 0.47µF; 10%; 6.3V; X7R; CERAMIC CHIP
C4, C5 2GRM21BC71E106KE11 MURATA 10µF CAPACITOR; SMT (0805); CERAMIC CHIP; 10µF; 25V;
TOL = 10%; TG = -55°C TO +125°C; TC = X7S
C6 1C1005X7S0J225K050BC;
GRM155C70J225KE11 TDK;MURATA 2.2µF
CAPACITOR; SMT (0402); CERAMIC CHIP; 2.2µF; 6.3V;
TOL = 10%; MODEL = C SERIES;
TG = -55°C TO +125°C; TC = X7S
C7, C8 2GCJ188R71H224KA01 MURATA 0.22µF CAP; SMT (0603); 0.22µF; 10%; 50V; X7R; CERAMIC CHIP
C10, C11 2C2012X5R1E226M125AC;
CL21A226MAQNNN
TDK; SAMSUNG
ELECTRO-MECHANICS 22µF CAPACITOR; SMT (0805); CERAMIC CHIP; 22µF; 25V; TOL = 20%; TG = -55°C TO +85°C; TC = X5R
C13 1
GRM155R71E104KE14;
C1005X7R1E104K050BB;
TMK105B7104KVH;
CGJ2B3X7R1E104K050BB
MURATA;TDK;
TAIYO YUDEN;TDK 0.1µF CAP; SMT (0402); 0.1µF; 0.1; 25V; X7R; CERAMIC CHIP
EN, POKB/INTB,
POT1, POT2,
SCL, SDA
65002 KEYSTONE N/A
TEST POINT; PIN DIA = 0.1IN; TOTAL LENGTH = 0.3IN;
BOARD HOLE = 0.04IN; WHITE;
PHOSPHOR BRONZE WIRE SILVER;
GND, IN, OUT,
PGND1, PGND2 59020 BUSS WEICO WIRE MAXIMPAD EVK KIT PARTS; MAXIM PAD; WIRE; NATURAL; SOLID; WEICO WIRE; SOFT DRAWN BUS TYPE-S; 20AWG
GND3, GND4 25011 KEYSTONE N/A
TEST POINT; PIN DIA = 0.125IN; TOTAL LENGTH = 0.445IN;
BOARD HOLE = 0.063IN; BLACK;
PHOSPHOR BRONZE WIRE SILVER PLATE FINISH;
INS, OUTS,
VIO, VL 45000 KEYSTONE N/A
TEST POINT; PIN DIA = 0.1IN; TOTAL LENGTH = 0.3IN;
BOARD HOLE = 0.04IN; RED; PHOSPHOR BRONZE WIRE
SILVER PLATE FINISH;
J1, J2 2PEC03SAAN SULLINS
ELECTRONICS CORP.
PEC03SAAN EVKIT PART-CONNECTOR; MALE; THROUGH HOLE;
BREAKAWAY; STRAIGHT; 3PINS; -65°C TO +125°C;
J3, J4 2PBC02SAAN SULLINS
ELECTRONICS CORP. PBC02SAAN EVKIT PART-CONNECTOR; MALE; THROUGH HOLE; BREAKAWAY; STRAIGHT; 2PINS; -65°C TO +125°C;
J5 1PPPC092LJBN-RC SULLINS
ELECTRONICS CORP. PPPC092LJBN-RC CONNECTOR; FEMALE; THROUGH HOLE; PPP SERIES; RIGHT ANGLE; 18PINS
L1 1XEL4020-152ME COILCRAFT 1.5UH INDUCTOR; SMT; COMPOSITE; 1.5µH; 20%; 7.5A
MH1-MH4 49032 KEYSTONE 9032 MACHINE FABRICATED; ROUND-THRU HOLE SPACER;
NO THREAD; M3.5; 5/8IN; NYLON
PGND1S,
PGND2S 25001 KEYSTONE N/A
TEST POINT; PIN DIA = 0.1IN; TOTAL LENGTH = 0.3IN;
BOARD HOLE = 0.04IN; BLACK; PHOSPHOR BRONZE
WIRE SILVER PLATE FINISH;
R3, R9, R10, R12 4ERJ-2GE0R00 PANASONIC 0RESISTOR; 0402; 0Ω; 0%; JUMPER; 0.10W; THICK FILM
R4, R7 2CRCW04022K20FK;
RC0402FR-072K2L
VISHAY DALE;
YAGEO PHICOMP 2.2K RESISTOR, 0402, 2.2KΩ, 1%, 100PPM, 0.0625W, THICK FILM
R13 1ERJ-2RKF1502 PANASONIC 15K RESISTOR; 0402; 15KΩ; 1%; 100PPM; 0.1W; THICK FILM
U1 1MAX77831BEWB+ MAXIM MAX77831BEWB+ EVKIT PART - IC; MAX77831BEWB+; PACKAGE OUTLINE
DRAWING: 21-100367; PACKAGE CODE: W352A2+1; WLP35
PACK-OUT 1MAXUSB_
INTERFACE# MAXIM MAXUSB_ INTERFACE# ASSEMBLED BOARD
PCB 1MAX77831WLP MAXIM PCB PCB:MAX77831WLP
LX1, LX2,
OUT1 DNP SS-102-TT-2 SAMTEC SS-102-TT-2
IC-SOCKET; SIP; STRAIGHT; PRECISION MACHINED
SOCKET STRIP; OPEN FRAME; 2PINS; 100MIL
R2, R8 DNP 3296Y-1-204LF BOURNS 200K
RESISTOR; THROUGH HOLE-RADIAL LEAD; 3296 SERIES;
200KΩ; 10%; 100PPM; 0.5W
C3, C12 DNP N/A N/A OPEN CAPACITOR; SMT (0805); OPEN; FORMFACTOR
C9 DNP N/A N/A OPEN CAPACITOR; SMT (0402); OPEN; FORMFACTOR
R1, R5, R6, R11 DNP N/A N/A OPEN RESISTOR; 0402; OPEN; FORMFACTOR
48

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MAX77831 Evaluation Kit Evaluates: MAX77831
SHORT TWO GROUNDS NEAR C1
DNI
SS-102-TT-2
LX2
XEL4020-152ME
1.5UH
B6
SEL
0402RES
SCL
R5
POKB/INTB
R13
2
1
OUT1
SEL2
R3
R1
R9
R12
21
J3
21
J4
R4
R7
3 2 1
J2
VIO
GND GND4 GND3
PGND2S
OUTS C13C12 PGND2
OUT
C9
R11
R10
2
1
C8
BST2
C7
2
1
LX1
BST1
POT2
3
2
1
R2
R6
SDA
21
L1
SCL
POT1
3
2
1
R8
EN
VL
PGND1S
INS C3
2 1
C1
PGND1
IN
C11C10
C5
C4
3 2 1
J1
C6
C2
1817 1615 1413 1211 109 87 65 43 21
J5
E7
E6 E5 E4
E3
E2
E1
D7
D6
D5
D4
D3
D2
D1
C7
C6
C5
C4
C3
C2 C1
B7
B5
B4 B3 B2 B1
A7
A6 A5 A4
A3
A2 A1
U1
2.2K
VIN
25V
DNI
SS-102-TT-2
0.1UF 0402
OPEN
0603
0402_FF
SDA
0603
0805_FF
0.22UF
BST1
10UF 0805CAP
DNI
MAXUSB_VIO MAXUSB_SDA MAXUSB_SCL
DNI
DNI
0402CAP
15K
0402
MAXUSB_SCL
EN
6.3V
PEC03SAAN
0402RES
PEC03SAAN
200K
00402
0402_FF
PBC02SAAN
0
0402
MAXIMPAD
FB
0.47UF
MAXIMPAD MAXIMPAD
25V
50V
10UF
OPEN
SS-102-TT-2
OPEN
0402_FF
0402_FF
50V
6.3V
200K
VIO
OPEN
0402_FF
2.2K
25V
0805_FF
25V
22UF 0805CAP
22UF 0805CAP
25V
PPPC092LJBN-RC
MAXIMPAD
25V
100UF 7343CAP
MAXIMPAD 0805CAP
OPEN 0
0402
SDA
PBC02SAAN
SEL
0
OPEN
OPEN
2.2UF 0402
VIO
VL
BST2
OUT
VIO
POKB
0.22UF
LX1
LX2
MAX77831BEWB+
LX2
OUT OUT OUT
BST2
AGND
FB
LX2
LX2
LX2
OUT
PGND
PGND
SEL
PGND
PGND
PGND
PGND
PGND
POKB/INTB VL
LX1
LX1
LX1
IN EN EN SDA
LX1
IN IN IN
BST1
VIO SCL
3
2
1
3
2
1
+
1817
1615 1413
1211
109
87 65
1 3 4
2
MAX77831 EV Kit Schematic Diagram

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MAX77831 Evaluation Kit Evaluates: MAX77831
MAX77831 EV Kit Schematic Diagram
STAND OFF
MECHANICAL
MH4
MH3 MH2
MH1
02-SOM35016H-00
9032
9032
02-SOM35016H-0002-SOM35016H-00
9032
9032
02-SOM35016H-00
SPACER
SPACER SPACER
SPACER

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│ 17
MAX77831 Evaluation Kit Evaluates: MAX77831
MAX77831 EV Kit PCB Layout — Top Silkscreen
MAX77831 EV Kit PCB Layout — Top View
MAX77831 EV Kit PCB Layout — Internal 2
MAX77831 EV Kit PCB Layout — Internal 3
1.0”
1.0”
1.0”
1.0”
MAX77831 EV Kit PCB Layout Diagrams

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│ 18
MAX77831 Evaluation Kit Evaluates: MAX77831
MAX77831 EV Kit PCB Layout — Internal 4
MAX77831 EV Kit PCB Layout — Bottom View
MAX77831 EV Kit PCB Layout — Internal 5
1.0”
1.0”
1.0”
MAX77831 EV Kit PCB Layout Diagrams (continued)

MAX77831 Evaluation Kit Evaluates: MAX77831
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│ 19
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is
assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that
may result from its use.Specifications subject to change without notice. No license is granted by implicationor
otherwise under any patent or patent rights of Analog Devices. Trademarks andregistered trademarks are the
property of their respective owners.
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES CHANGED
0 9/20 Initial release —
19/21
Updated General Description and Benets and Features sections, MAX77831
EV Kit Specications table, Figure 2, updated EV Kit Default Conguration, Quick
Start, Table 1, Table 3, updated MAXUSB_INTERFACE#, External I2C Bus, High
Temperature Testing, Critical Node Measurement (OUT and LX), and EV Kit
Software, added Figure 3 and Table 4, updated Windows Driver and Connecting
GUI to MAXUSB_INTERFACE# sections
1–7
Revision History