nRF9160 not outputting 1.8V in "SIM_1V8" pin

[KN7702]

We have designed a custom board using the nRF9160. Most of the circuitry around nRF9160 is referencing the same as circuitry on the nRF9160 DK board. Upon flashing the modem firmware and the AT_Client sample application (with Bootloader), it seems that pin SIM_1V8 does not output 1.8V at all. 

I have noticed we have SIM_DET routed to our Sim Card Tray switch for switching between eSIM and SIM, but I have cut the trace since. The SIM_DET is now floating. 

The nRF9160 is powered from a 3.3V source and the ENABLE pin is at 3.3V (nRESET is also pulled high to 3.3V) and I can flash it with the Segger J-Link programmer, but the internal 1.8V regulator seems to be not operational. 

I understand there was a similar ticket before and it was resolved by reflowing the board. I could understand one or two boards might have reflow issue, but I have all of the boards exhibiting the same issue. 

Any help would be appreciated. 

[prega]

Hello, I do have the same issue. I have 18 boards having the same issue, no SIM_P1V8 present.

- the same FW has been used on a previous batch working OK

- all boards have been XRay, no soldering issue

- binocular inspection on a subset with not issue noted

- no short circuit between the SIM interface signals and GND/VCC, and between the signals themselves

- removed the eSIM, so basically the is one decoupling capacitor present

And still noP1V8. Is this a nRF9160 batch issue ?

[Håkon Alseth]

Hi,

 

I would recommend that you create a private ticket on this matter and share your schematic and other debug related information.

 

Kind regards,

Håkon

[prega]

For what it is worth: we finally nailed down the issue. The devices we bought has a date code 2226 and a modem fw version 1.1.6 pre-programmed

at AT+GCMR

mfw-pti_nrf9160_1.1.6

Updating the modem firmware to a version in line with our current SDK version fixed the issue. I guess the modem now gets the command sequence it expects to power on the SIM interface.

Pascal