nPM1100 voltage

RE: nPM1100 voltage

ketiljo — Mon, 30 May 2022 08:34:05 GMT

Hi Wes

If VBAT is connected to a GPIO, it's violating the spec if VBAT is higher than VDD + 0.3 V. In this case, the ESD protection diode will start to conduct and lift VDD, this should no happen.

So it can be something there that causes this. But VSYS at 7.7 V, no way! If nPM1100 VBUS=5.0V, VSYS can't be 4.2V.

Do you have the full schematic for this?

cheers,

Ketil

RE: nPM1100 voltage

WesC — Thu, 26 May 2022 18:50:11 GMT

IT turns out that the MODE pin was connected to VBAT and also to P1.00 of the NRF5340.

Apparently, connecting the battery when the entire system is already powered from VBUS caused both issues:

High (7V ) voltage issue.

Changing level of VDD from 1.8V to 3.3V

would you have any thoughts on why applying VBAT to P1.00 (and MODE pin on PMIC) might caused these issues?

RE: nPM1100 voltage

WesC — Thu, 26 May 2022 17:40:49 GMT

Only VBUS is connected:

VBUS = 5.0V

VBAT = 0

VSYS = 5.0 V

VOUTB = 1.8 V

VBUS is connected and battery (4.0V) is plugged:

VBUS = 5.0V

VBAT = 4.0

VSYS = 7.7 V

VOUTB = 2.0 V

one more question also:

No FW loaded into nRF5340.

When no battery connected and VDDH is applied (in the range 4.0 – 5.0 V) then VDD = 1.8 V.
When battery is connected (on PMIC VBUS = 5.0V, VSYS = 4.2V and VDDH = VSYS = 4.2 V, on nRF53 module VBUS pin is not powered or powered with 5.0 V – same effect) then VDD = 3.3 V. Why?
Is my understanding correct: if VREGH.DCDCEN, VERGMAIN.DCDCEN, VERGRADIO.DCDCEN are set to “DCDC” and UICR.VERGHVOUT is set to 1.8V – then GPIO, System Power Application Core and Radio Power Network Core all will be set to 1.8V?

RE: nPM1100 voltage

ketiljo — Wed, 25 May 2022 13:55:40 GMT

Hi Wes

This is very strange! There's no charge pump anywhere in the system, so I can't see how the voltage can be this high. Can you ask them to measure VBAT / VBUS / VOUTB level pin when they observe 7.4V on VSYS?

When the battery is disconnected, you have to cycle VBUS in order to charge the battery. But VSYS should follow what's highest of VBUS or VBAT.

cheers,

Ketil