9160 rev B0 radio parts high current next reboot if resetting during radio active

[Johan]

We have a design where 9160 is always battery powered (, and only the RESET-pin is the way we have to shut it down (keep in reset).

Probably this design might not be the correct way, but we are stuck with it.

VDD = VBat (4.1V - 3.7V)

VEnable = 1.8V

SWD nReset is used to either reset the 9160 or to keep it in reset (active low).

What we have seen is, if we reset the 9160 during radio transmission, next time it boots, there is a +50mA draw, at boot.

We use modem fw 1.3.1.

Can this be fixed so 9160 will shut off radio parts at boot by default, if they were active and reset during connected state or transmission? 

It causes a faulty state for us now which doesn't resolve even with 9160 connect and disconnect.
Another reset is needed for it to resolve.

Best,

Johan

[Øyvind]

Hello, 

Our HW experts informs me that the enable pin is too low. From the nRF9160 HW design guidelines, Logic high (> 0.8 x VDD1) enables nRF9160.

Please note that nRF9160 B0 devices have been discontinued, more information can be found in PCN134. 

Kind regards,
Øyvind

[Johan]

Ok. we will look into that with ENABLE voltage range for B0.

We also have B1.
Where do we find the ENABLE voltage range for B1?

I remember our HW team mentioned finding different voltage rangers for ENABLE depending on chip revision.

[Johan]

We have both B0 and B1.

B0 is min 1.2V ENABLE we read in an old post. We have 1.8V here. 
devzone.nordicsemi.com/.../nrf9160-enable-minimum-voltage
Can you confirm in your old datasheets for B0 about ENABLE voltage for B0 ? We have a bunch of them and need to use them still.

B1 is min 0.8 x VDD as you say, and link.

[Øyvind]

Hi Johan, 

Sorry, my misunderstanding. I've talked to my colleague that had your previous case, and the VEnable = 1.8V should be correct. 

Do you have any log output showing what happens? My concern is now focused on the use of modem v1.3.1 on B0.

From the modem fw change log

Before applying this version:

• Note that this modem firmware is targeted nRF9160 SiP Revision 2 
• It can be used for nRF9160 SiP Revision 1, but only for testing and development
• It cannot be used for engineering samples of Revision 1 (e.g. DKs or Thingy:91 with version older than v0.9.0) 
• After you upgrade to MFW 1.3.x it is not recommended to downgrade to MFW 1.2.x or MFW 1.1.x.(potential file system issues)

Read out your revision by either AT command: AT%HWVERSION or look on the nRF9160 SIP for marking "B1".

"B1" = Revision 2

"B0" = Revision 1 

The AT command responses for Revision 1 and Revision 2 SiPs will be "nRF9160 SICA B0A" and "nRF9160 SICA B1A" respectively.

Early engineering Revision 2 (B1A) SiPs and Revision 1 (B0A) SiPs might produce AT command responses such as  "nRF9160 SICA BQA" and "nRFFFFFFFFF SICA FFFFFFFF" respectively.

What are the markings on your device?

[Johan]

Hi Öyvind,

Ok great for the 1.8V VEnable checkup. We are using 1.8V for B0 and VBat (4.1-3.6) for B1.

Ok we take note of MFW 1.3.1 is only for Rev 2. I was running a rev 2 board actually so I was lucky.
I guess we will have to use 1.2.3 for Rev 1 boards then, if ever used in production at customer. Probably not.

Markings on my Rev 2 is: SICA B1

Markings on my Rev 1 is SICA B0.

The current issue was due to an external wrongly configured fuel gauge IC so the 9160 seems to be not to blame this time.

Best,