nrf52832 device DEC1 pin is not in 0.9v range, but at 0.73v

[Goale Jian]

Hi,

I made a PCB with nrf52832. In the intial bring up, I noticed its 32MHz XTAL is not up. Then I debugged the PCB and measured the voltages at different points in the circuit.

DEC1 - 0.73V

VDD - 3.18V

DEC4 - 1.21V

DEC3 - 3.18V

DEC2 - 1.21V

RESET PIN - 3.18V

Is the 0.73v at DEC1 shows something wrong since it should be 0.9V? 

I tried on 3 boards and saw similar, i.e, about 0.7v on DEC1 pin.

My nrf52832 device is a rev1 device which has code QFAAB0 as device marking code.

Any comments? Thank you very much!

[Håkon Alseth]

Hi,

 

This is the digital power supply for the nRF52832, and is nom. 0.9V (can be higher in run mode), but if it is in ULP (ultra low power) mode, it will be duty cycled by the "refresh mode" in hardware. In the latter mode, the voltage is lower than in run mode.

 

Note that the softdevice only starts up the external 32M HFCLK if it is required (by the radio), and for power optimizing reasons; its turned off afterwards.

Do you have a 32kHz external LFCLK? If not, you have to set the LFCLK source to 32k RC oscillator in your sdk_config  (define NRF_SDH_CLOCK_LF_SRC). See for instance this thread on how to configure the RC oscillator: https://devzone.nordicsemi.com/f/nordic-q-a/29792/internal-rc-slow-clock-problems-with-sdk12-and-sdk14/118193#118193

  

Kind regards,

Håkon

[Goale Jian]

Hi Håkon, thanks for your infomation. 

I just replaced these boards with new parts and the issue is fixed. I guess the issue is due to broken parts or bad soldering.

Regards,

Goale