Our nRF52832 application PCB's battery level is dropped every 1024 secs

[Daewoong Kim]

Hi,

I've developed nRF52832 chip for our company's application,

and I found some weird phenomenon

we using nRF52832 chip with Nordic softdeivce and SDK v12,

BLE chip operates with DCDC converter (internally),

The power is supplied by 3V coin cell.

The above figure shows VDD voltage of BLE chip. Those values measured by SA-ADC module in BLE chip

every 1 second, and our custom hardware keep stored in refrigeration room (about -20 C).

As you could see, the VDD value have dropped every certain period. The period is about 1024 secs.

Anyone knows that? why this phenomenon is being observed..?

Thank you for your helps

- Daewoong Kim

[Turbo J]

Daewoong Kim said:

power is supplied by 3V coin cell

Those have high internal resistance...

Daewoong Kim said:

hardware keep stored in refrigeration room (about -20 C).

That makes this even worse - resistance is even higher at low tempereature.

Dumb question: How do you store the SAADC values? That might just happen every 1024 seconds and  would need some more power than usual.

In any case you need some more bulk capacitance in your design.

[Daewoong Kim]

ADC values is sent to BLE central device and the central device prints that value using UART terminal.

I understood that the ambient temperature may have an negative effect on the BLE chip.

However, It just weird the ADC value of BLE VDD (Battery) dropped per certain period...

If the problem is caused by the capacitance of coin cell, why the ADC dropped phenomenon

is observed intermittently, not continuously..?