nRF9160 DK PSM/System OFF current too high

[Oette]

Hi,

OS: Windows 10
Editor: SEGGER Embedded Studio for ARM (Nordic Edition) V5.68 (64-bit)
nrfjprog version: 10.15.1
JLinkARM.dll version: 7.52b
nRF Connect SDK version: 1.6.0
nRF9160 modem firmware version: 1.2.7
nRF9160 DK version: 1.0.2

I was testing our custom FW on a nRF9160 DK and I noticed a high PSM power consumption. The DK was consuming around 70µA while our custom board consumes ~15µA.

I then got 1452.sysoff.hex file from this guide to check if everything is right and I noticed it is consuming around 70µA even in system off mode (~5µA on custom board):

Do you have any idea what could be causing this? I am supplying power with PPK2 source mode through the VDD_nRF-pin (P22) like shown here. I have made sure the board controller FW is the original one provided here. I have no USB cable or anything else attached to the DK. I have also tried removing the SIM-card and disconnecting the interface MCU by moving the IFMCU DISCONN-switch to the right position. Neither of these helped with the consumption.

As far as I know the current should only be going to nRF9160 when supplied through the VDD_nRF-pin and therefore only be a few microamps in both cases. Is there anything I need to change/check in addition to the things I have already done? Or is my DK faulty?

Thanks in advance!

[JONATHAN LL]

Hi,

I recomed that you update to a newr modem fimrware if there is no spesific reson you have to stic to v1.2.7.

What modemfrimware are you using on the custom HW ?

Regards,
Jonathan

[Oette]

Our custom boards have the revision 1 of nRF9160. In your mfw changelog it is not recommended to use mfw1.3.X on rev 1 SIP and hence have sticked to 1.2.7.

[JONATHAN LL]

your DK seems to be Rev2 SiP so it could use a newer modem firmware, but you are correct on the custom HW stick to 1.2.7. But I se why you would want to use same modem firmware on the DK for development. 

I currently don't have a v1.0.2 DK but will test and see if I can replicate. 

Regards,
Jonathan

[Oette]

Hi,

Our DK has BWA version of the SiP:

AT%HWVERSION
%HWVERSION: nRF9160 SICA BWA
OK

I assume this is some early version of rev2?

Let me know how your testing goes.

[JONATHAN LL]

Hi,

After some testing i might have had a similar situation happen to one of my test DK's. After change in modem firmware, it had average current of 65uA.

I wiped the DK, flashed the AT client application, then wiped and reflash the system off hex file. Then the average current consumption was down to 2.10uA

DK v1.0.0
%HWVERSION: nRF9160 SICA BQA
%SHORTSWVER: nrf9160_1.3.1
avrg = 2.4uA

downgrade to mfw 1.2.7, avrg = 65uA

Cange application to AT client
%HWVERSION: nRF9160 SICA BQA
%SHORTSWVER: nrf9160_1.2.7
avrg = 2.10uA

Try to reprogram and reset the DK a couple of times, power cycle once or twice.

I did only see this once on one of my test DK's, tested 3 diffrent DK's. So the issue seems to be fixable.


Regards,
Jonathan

[Oette]

Hi,

I was able to get it down to 2.8µA @3.0V once by erasing the memory with nRF Connect Programmer and then flashing with the sysoff image. However, when I flashed our custom FW it went back to ~70µA in PSM. I then tried wiping the memory and flashing the sysoff image again multiple times but now it seems to be stuck at ~70µA again no matter what I do.

Do you have any idea what could be causing this? It doesn't make any sense to me that the same image on the same board suddenly consumes ~25 times more power.

[JONATHAN LL]

Thanks for keeping me posted, I will do some more testes and see if i can consistently reproduce the issue to figure out what could be the cause. 

Regards,
Jonathan

[JONATHAN LL]

Hi,

Running at 3V is on the low side of the operating conditions. So sometimes if not properly power cycling or if anything drops in voltage there can be some undefined states that cause trubel. I am not 100% sure that this is the issue, but runing at 3.3V dos not seem to cause the issue.

Do you experiance the same issues if you try at 3.3V ?

Regards,
Jonathan

[Oette]

Hi,

I tried with 3.3V and I have the same issue. The consumption is only slightly lower due to the higher voltage.

[JONATHAN LL]

Can you connect USB cable to the DK, when the debugger is not powered from USB it can draw the current form the SWD interface to the 9160, making the 9160 powering the debug chip.  
Regards,
Jonathan