nRF52840 DK not starting when nPM1300 VBAT = 2.7 V

[Sagar Patel]

Hello,

I have connected the nRF52840 DK to the nPM1300 EVK, with the DK powered from BUCK1 output of the nPM1300.

When I supply 3 V or higher to the VBAT pin of the nPM1300 (using an external supply), the nRF52840 DK powers up correctly and I can see the serial logs.

However, our requirement is for the firmware to operate down to 2.7 V. When I apply 2.7 V to VBAT, the DK does not start and no logs appear.

Could anyone please guide me on how to achieve operation at 2.7 V?
Is there any register configuration needed in the nPM1300 for this, or should I debug elsewhere?

Let me know if required more info.

Thank you for your support.

[Menon]

Hello,

I don't think this issue is related to any register configuration. Might be that 2.7 V is not sufficient for the DK to function properly. While that voltage range is acceptable for the nRF52840 SoC itself, the Development Kit especially with the onboard debugger requires a higher voltage to operate correctly.

If you're using 2.7 V only as a test for your custom hardware, it may work for your design, but I doubt it will work reliably on the DK.

Kind regards,
Abhijith

[Sagar Patel]

I initially tested this behavior on our custom board, in that nrf52840 with npm1300,  where the setup did not work as expected.
To isolate the issue, we are now testing the same configuration on the nRF52840 DK connected to the nPM1300 EVK.

Could you please advise if there are any specific checks required on the hardware side?
Additionally, if any software configurations or register settings need to be modified, your guidance would be appreciated.

We are currently using a battery profile with a voltage range of 2.9 V (minimum) to 4.5 V (maximum).
As part of troubleshooting, I also modified the minimum voltage setting from 2.9 V to 2.7 V to verify whether this would affect the operation, but the device still does not start at 2.7 V.

Thank you for your assistance and any further recommendations.

Best regards,

Sagar Patel

[Ressa]

Hi,

Thanks for contacting us. 
If you would like, we can review your schematic in case there might be some hardware issue. For that you just need to upload the schematic here. I make the ticket private so that the schematic will be visible to just me (and Nordic employees). 
* Just wondering what is the resistor values used for VSET pins on nPM1300 (VSET1 and VSET2)? If VBAT voltage gets closer to the voltage set by resistors, you might not get exact value you would expect, there will be some voltage drop.




Best regards,
Ressa

[Sagar Patel]

Sorry for late reply, Due to medical issue.

Can send me your mail id so that i can sent you the schematic for review ?

 

For VSET we have used 47K register, please check the screenshot attached.

[Ressa]

Hi, 

No problem. Based on the table I shared in previous message, to get 1.8 V on VOUT2 you should use resistor value of 4.7 K Ohm not 47 K ohm on VSET2.

Best regards,
Ressa