Standalone Operation - Analog Devices MAX77857 Manual

Evaluates: MAX77857 (WLP)
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.
Note: In the following sections, software-related items are identified by bolding. Text in bold refers to items directly from
the evaluation software. Text in bold and underlined refers to items from the Windows operating system.
1. Ensure the EV kit has the correct jumper settings, as shown in
2. Connect a voltmeter (DVM1) to INS and PGND1S sense pins to measure input voltage.
3. Connect a voltmeter (DVM2) to OUTS and PGND2S sense pins to measure the output voltage.
4. Apply a power supply set to 0V (1.5A current limit) through an ammeter across the IN and PGND1 terminals of the EV
kit. Turn the power supply on and increase the voltage to 7.6V.
5. Confirm the DVM2 reads the default output voltage of the EV kit (5V). Confirm the ammeter reads the expected input
supply current (about 12mA).
6. Now that the EV kit is confirmed working, short out the series ammeter and increase the power supply's current limit.
Connect an electronic load across OUT and PGND2 terminals to evaluate the performance of the MAX77857 buck-
boost regulator.
The next steps in the procedure use the EV kit GUI and MAXUSB_INTERFACE# to evaluate the MAX77857's I
interface. If such evaluation is not required, you may skip the following steps. The EV kit includes on-board 2.2kΩ pullup
resistors (R4 and R7) to V
7. Install GUI software. Visit the product webpage at
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.
8. Turn off the input power supply connected in step 4.
9. Remove jumper J2. V
2-3.
10. Ensure SW1 and SW2 switches on the MAXUSB_INTERFACE# are set to the ON position. This enables I
on the MAXUSB_INTERFACE#.
11. Important: Ensure the V
MAXUSB_INTERFACE#'s V
12. Connect the MAXUSB_INTERFACE# to the EV kit. Connect the MAXUSB_INTERFACE# to your PC's USB port using
a USB Type-A to Micro-USB cable.
13. Turn on the input power supply.
14. On the PC, 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.
15. Drag the slider bar in the
16. Confirm on DVM2 that the software command to change output voltage was successful. If so, the I
is confirmed 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 about the GUI, see the
EV Kit Hardware
The MAX77857 EV kit demonstrates the MAX77857 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.
functions that are available on the EV kit.

Standalone Operation

The MAX77857 is capable of standalone operation, in which the IC starts up whenever V
not require a separate supply for the V
the only power supply in the system. To configure the MAX77857 EV kit for standalone operation, install header jumper
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2
for I C serial interface signals SDA and SCL.
IO
is later powered from MAXUSB_INTERFACE#'s on-board LDO. Move jumper J1 to position
IO
jumper on the MAXUSB_INTERFACE# (J5) is set to 1.8V. This sets the
L
voltage. Setting this incorrectly to 3.3V could potentially damage the MAX77857 IC.
IO
Output Voltage Configuration
pin. This is useful for systems without a host controller or if the MAX77857 is
IO
MAX77857 Evaluation Kit
Table 1.
https://www.maximintegrated.com/products/MAX77857WEVKIT
section to change the output voltage and click Write.
EV Kit Software
2
C serial interface
section.
Table 1 lists jumpers and associated
and EN are valid, and it does
IN
Analog Devices | 5
2
C serial
2
C mode