BQ25601: Precharge current question

Bruce Lin_899

Part Number: BQ25601

Hi Expert

I am debuging a BQ25601 strange status. My customer battery protect VLO is 2.8V, and release voltage is 3.0V

hen battery is in protect status, and then plug in adapter ( PSEL = HIGH ), we have a big chance see the charge current to 500mA

But in that bat voltage, the charge current should be 180mA for precharge mode.( main control not work so reg is in default mode )

I also measure the power on voltage, BAT voltage seems not over 3V. So I have no idea why the charge current is 500mA.

Do you have and suggestion for me to check where would be the problem and how to debug.

Thank you so much!

Bruce

over 6 years ago

0 Hong Mao over 6 years ago

TI__Expert 5590 points

Hi Bruce, are you charging a battery emulator? did you measure the voltage right at BAT pin?

0 Bruce Lin_899 over 6 years ago in reply to Hong Mao

Intellectual 870 points

Hi Mao

1. battery is a real 18650 battery

2. Yes, we measure the IC bat pin

Bruce

0 Hong Mao over 6 years ago in reply to Bruce Lin_899

TI__Expert 5590 points

Bruce:

I am wondering why your battery voltage jumps from 0 to 2V above. Is that a dead battery? If the battery presents, VBAT should be always there high instead of being zero. Looks like there is BATshort regulation first.

0 Bruce Lin_899 over 6 years ago in reply to Hong Mao

Intellectual 870 points

Hi Hong Mao

Yes, as you think, my problem is when battery is lower then batery protect voltage 2.8V, at this situation we plug in power.

It will see the current not limit to 180mA but 500mA continuous. Can you help explan why this sympton?

Thank you so much

Bruce

0 Hong Mao over 6 years ago in reply to Bruce Lin_899

TI__Expert 5590 points

Hi Bruce:

This could be voltage tolerance. Have you tried slightly lower VBAT?

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BQ25601: Precharge current question