8 months ago.

Operation with battery power without USB

Hi, Many thanks for all the nice demo codes. That's very helpful. I tried the "MAX32620FTHR_Pmic" and the "FuelGauge" demos. Both are working well as long as the USB power is connected. When I connect a charged LIPO battery and disconnect the USB power to the board, the board stops working. Then I press the Power button and the device starts up, but after 3 seconds, the board shuts down. Is this a kind of default mode or something? Should I configure the MAX77650 so that the board keeps running?

Thanks again, Hans-Günther

Question relating to:

MAX32620FTHR Rapid Development Platform
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2 Answers

8 months ago.


Take a look at the MAX32620FTHR's datasheet and the MAX77650's datasheet page 40. You can see there is a pin assigned from the MAX32620 to the Power Hold pin of the MAX77650, therefore a Digital output needs to be assign and set to ON for the PMIC to stay on. something like this:

DigitalOut pw_Hold(P2_2, POWER_HOLD_ON);

Let me know if that makes sense.

Hi Felippe, Thanks a lot. Yes that helps. It is working now. Here is the code I called at the beginning of the code:

  1. define POWER_HOLD_OFF 0
  2. define POWER_HOLD_ON 1 DigitalOut pw_Hold(P2_2, POWER_HOLD_ON);

inside my program, I can switch off the PMIC with this code (if running from Battery):


posted by Hans-Günther Nusseck 20 May 2018
8 months ago.

Hi there,

I would make sure that your USB power and battery power are providing the board with the same voltage. You can check these values using a low cost device such as a USB voltage meter.

Please let me know if you have any questions!

- Jenny, team Mbed

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