nPM1100 configurations

[zuchang]

Hi ,

I want to use above PMIC for Gotek tracker. But I have below questions:

1. Due to the IO limitation, can I use static high or low to configure the chip with VOUTB = 2.7V, max. charging current 250mA?

2. The threshold of buck mode is 40 and 90 mA. If MODE connected to GND (automatic mode) and VOUTB supply nRF52833 & VDD_GPIO of nRF9160, the threshold of mode may never be crossover.

3. In the datasheet configuration 1 and 2 , can I enable buck regulator and 250mA charging current?

Hopefully I can get your answer soon.

Thanks...

[Martin Sivertsen]

Hello,

1. Due to the IO limitation, can I use static high or low to configure the chip with VOUTB = 2.7V, max. charging current 250mA?

Yes.

2. The threshold of buck mode is 40 and 90 mA. If MODE connected to GND (automatic mode) and VOUTB supply nRF52833 & VDD_GPIO of nRF9160, the threshold of mode may never be crossover.

Yes. Is there anything else you want to know regarding this?

3. In the datasheet configuration 1 and 2 , can I enable buck regulator and 250mA charging current?

Yes, you can mix and match configurations to suit your needs.

Best regards,

Martin S.

[zuchang]

Hi Martin,

Thanks for your quick reply.

For item2, since the total current of nRF52833 and VDD_GPIO is lower than the threshold of mode switching, so the automatic mode should not be applicable, right? That means I have to fix it in PWM mode.

Btw, what is max. current of VSYS when VBAT is on? In the design, VSYS will power up nRF9160. Is it OK? I didn't find the max. current of nRF9160's VDD.

Best Regards,

Zuchang

[Martin Sivertsen]

Hello,

If you tie the mode pin low it selects between the hysteretic and PWM mode automatically and you don't have to do anything, and it will likely stay in hysteretic mode because it will never reach the threshold as you mentioned. If you tie it high and force it into PWM mode the current draw will be higher and your battery won't last as long. If you tie the MODE pin high, you should wait 40 - 60 μs before applying any significant load.

Max current of VOUTB + VSYS is 500 mA, so if VOUTB is using 100 mA, VSYS can provide 400 mA, if VOUTB is 50 mA, VSYS can provide 450 mA etc.
VSYS uses the battery or VBUS. If VBUS is connected, VSYS voltage = VBUS voltage + LDO drop-out, if only the battery is connected VSYS = VBAT.

Here is a case that asked about the max current draw of nRF9160: https://devzone.nordicsemi.com/f/nordic-q-a/78915/nrf9160-max-current-draw
You can find the same information on page 67 of the product specification: https://infocenter.nordicsemi.com/pdf/nRF9160_PS_v2.1.pdf

I hope this answers your questions.

Best regards,

Martin S.

[zuchang]

Hi Martin,

Yes. I got it.

Thanks...