MP2731 ADC reading and VNTC during discharging

Battery Management
1

Dear experts,

We are using MP2731 in our design. We have 2 questions:

  1. During discharging, are the ADC reading (system voltage, battery voltage, NTC) available or not?
  2. During discharging, is it possible to have VNTC pin voltage remain ON? So far as we tested and it went off as soon as Input voltage was turned off. I have tried searching on this forum but it seems there are 2 different opinions about this.

Thank you.
Regards,
Tuan.

2

Hi tuanpm519,

I’m looking into your question, will get back to you asap.

Thanks,
Cindy

1 Like
3

Hi Cindy,

Thanks, we are looking forward to seeing your response.

Tuan.

4

Hi tuanpm519,

If you take a read on page 26, underneath “ADC”, it states the ADC is only available in charge mode and OTG mode.
It looks like VNTC is regulated by an LDO that is powered from VREF. If there is no voltage on VREF, then VNTC will not be on.

Thanks,
Cindy

5

Hi Cindy, thanks for your response.

Regarding the ADC, this means during discharge if we want ADC reading we have to turn on OTG mode which we don’t want as it consumes more battery current. Anyways I understand this.

About the VNTC, from my testing I see that when VIN is not present and battery is discharging, VREF is still ON but VNTC goes off. Is there any register setting which we can use to turn it on?

Thank you.

6

Unfortunately, I couldn’t find anything that allowed VNTC to turn on during discharge/no VIN. Reading closely at the specs on the datasheet, it looks like VNTC only works when battery is charging and in OTG mode.