What is on the sillicon in the upper right corner of the nRF52832?

RE: What is on the sillicon in the upper right corner of the nRF52832?

Sigurd — Thu, 09 Nov 2017 15:21:05 GMT

From your description it sounds like something in the nRF52 IC have been broken, maybe caused by ESD damage. You should replace the IC with a new one.

RE: What is on the sillicon in the upper right corner of the nRF52832?

CurtisHx — Thu, 09 Nov 2017 13:52:49 GMT

I'm getting closer. On the good board, I can see the DC-DC converter switching nicely on pin 47 of the nRF52. On the bad board, pin 47 is stuck at a constant 2.35V. It's not switching even though the DC-DC converter has been enabled in firmware. Pin 47 snaps to 2.35V on power up and stays there. I can't see any attempt at switching happening.

RE: What is on the sillicon in the upper right corner of the nRF52832?

CurtisHx — Thu, 09 Nov 2017 13:40:05 GMT

It's a custom board. I have 2, but the other one is misbehaving in other ways. Current consumption is ~80mA into the nRF52832 with the LDO enabled. It's 100mA with the DC-DC converter. The inductors and cap for the DC-DC are on the board, just like the reference design. I loaded the same firmware onto a completely different (but still custom) board, and it draws 3mA. The firmware starts up the DC-DC converter, sets all of the GPIOs as disconnected inputs, and then falls into an infinite loop. It's just running the CPU. I've looked at the bad board under a microscope and under an xray machine. I cannot find any explanation for why the bad board is drawing so much current and why the nRF52 is getting hot. I'm looking at it with a thermal camera and there is a clear hot spot in the upper left corner of the nRF52

RE: What is on the sillicon in the upper right corner of the nRF52832?

Sigurd — Thu, 09 Nov 2017 13:18:36 GMT

Is this a custom board? Are you seeing this on several devices, or only one device? Could you measure the current consumption on this device?

RE: What is on the sillicon in the upper right corner of the nRF52832?

CurtisHx — Thu, 09 Nov 2017 12:26:23 GMT

I'm seeing a hot spot of about 115F. Everything I've checked (voltage / temperature) is within the operating conditions. All of the GPIOs are set as disconnected inputs, so they shouldn't be sourcing / sinking inputs.

RE: What is on the sillicon in the upper right corner of the nRF52832?

Sigurd — Thu, 09 Nov 2017 09:31:29 GMT

Hi,

Could you explain a bit more about what do mean by hot? What temperatures are you measuring?

Please make sure that you are not using the nRF52832 outside the Recommended operating conditions, and that you are within the electrical specification on the maximum current you can sink/source on the GPIO pins.