BQ25505: BQ25505 not allowing battery current

Mike SABBAGH

Part Number: BQ25505

Tool/software:

Hi
I've been struggling with this since 2 prototypes.

I am using the BQ25505RGRR to charge li battery at 3.6v max. When i connect a 3.3v on vbat_sec, I do not see any voltage on VSTOR.

I also changed the applied voltage to 2.5 to 4v with nothing on vstor.

I already tested on 2 different runs and each time 3 boards.

I dont know why this is happening.
I am not using OK_HYST
and not using OK_PROG

can this be it?

2 months ago

0 Michael Emanuel35 2 months ago

TI__Mastermind 40535 points

Hello,

Can you confirm the voltage on VBAT_SEC pin itself as opposed the to suspected applied voltage?

Regards,

Mike Emanuel

0 Mike SABBAGH 2 months ago in reply to Michael Emanuel35

Prodigy 30 points

2.5 to 4v

0 Mike SABBAGH 2 months ago

Prodigy 30 points

it seems I need to apply a voltage on vstor for a second or so and then vstor stays on at the correct voltage. if i turn the battery vbat_sec off then on, vstor goes close to zero. i need to reapply a voltage of 3.3 v on vstor for a second only, then vstor is close to vbat_sec.
This is not what the datasheet describes
is there something i am missing?

+1 Michael Emanuel35 2 months ago in reply to Mike SABBAGH

TI__Mastermind 40535 points

Hello,

Please read Section 7.4.3 about attaching a partially charged storage element. It needs to be done in the correct sequence.

Regards,

Mike Emanuel

Power management

Power management forum

BQ25505: BQ25505 not allowing battery current