nPM1100 Operation

[fmighani]

We are using nPM1100 along with a STM CPU. When we put the CPU into deep sleep, it takes one minute for the current to go down to 20uA from 500uA.

We were expecting the nPM1100 goes down to low load mode right away not after 1 minute.

The question is, does nPM1100 need the 1 minute to detect low-load to drop the current?

Please advise.

Thanks.

Kind Regards,

Farhad Mighani 

[fmighani]

Thanks.

We have left NTC open. Therefore, there should not be any battery charging going on.

We feed nPM1100 from USB and there is no battery in the system. USB input is 5V. I suspect that VSYS is at 5.0 (we will measure). 

When we are in deep sleep, we draw only 10uA. so, we are in low load mode for sure. According to the datasheet, in low load mode, nPM1100 quiescent current can be as low as 800nA (.8uA). we expect the nPM1100 to detect the low load and drop to what is needed (around 10uA-17uA). Do we need to run this in PWM mode for low load detection to take effect right away?

This is very important to us. That is why we picked this device.

Is it time to have a conf call?

Thanks.

Kind Regards,

Farhad   

[runsiv]

Hi, So the nPM1100will have a quiescent of 800nA if it is supplied by VBAT and no voltage on VBUS. 

If a voltage is applied on VBUS then some features related to USB protection and VSYS regulation have to be enabled, so the quiescent cannot be as low. 

So the PMIC team has the following question:   Why do you supply the IC from VBUS if you do not plan to charge a battery? Can't it be supplied  from VBAT ? 

Regards

Runar

[fmighani]

Hi Runar,

Thank you. Our issue is resolved. Feeding the device form VBAT is the way to go. We tried it and the current goes down in low load mode.

Thanks a bunch.

Please close this ticket.

Kind Regards,

Farhad