BQ32000 Back up battery problem

Tom Xu1

Prodigy 165 points

Other Parts Discussed in Thread: BQ32000

My BQ32000 circuit is as showed

I am using CR1220(35mAH) as back up battery for BQ32000.

When VCC is powered (+3.3V), BQ32000 is working fine.

During VCC powered off, the BQ32000 is powered by CR1220 battery, but the battery can only suport for

couple months(I guess 3 ~4 months), not all modules's battery is drained up, around 50% still working, 50% is drained up.

I measured Resistance between the BQ32000 BAT PIN(PIN3) to GND, the resistance is around 14MEG OHM.

Is there any need to configure BQ32000 register to lower the battery working current ?

or is there any sneak path from battery to GND ?

or probably the battery problem ?

Thanks !

over 10 years ago

0 Tom Xu1 over 10 years ago

Prodigy 165 points

I checked the BQ32000 datasheet, the battery working current is 1.5uA(max), so the CR1220(35mAH) should be working for more than 2 years.

0 Tom Xu1 over 10 years ago

Prodigy 165 points

Today, I measured the Battery working current when VCC is power off(never power on, only CR1220 battery is on position), the current is around 75uA, much higher than 1.5uA(max) in BQ32000 spec , I have measured 6 modules, 5 modules showed the Battery working current is 75uA, only one module showed 1.8uA.

I don't know the reason.

0 Tom Xu1 over 10 years ago in reply to Tom Xu1

Prodigy 165 points

Is there any experts give some suggestions to me?

0 Noel Fung over 10 years ago in reply to Tom Xu1

TI__Guru* 87930 points

Hi Tom,

This forum is not the right place for BQ parts, I have notified the right person to help you, stay tuned.

0 Noel Fung over 10 years ago in reply to Noel Fung

TI__Guru* 87930 points

resend with the right person copied.

0 Nicholas Oborny over 10 years ago in reply to Noel Fung

TI__Mastermind 21305 points

HI Tom,

Please check this post and see if it is related to your issue. Let me know if you have furthur questions. The BQ32000 requires a specific power sequence.

http://e2e.ti.com/support/applications/motor_drivers/f/38/t/295753.aspx

0 Tom Xu1 over 10 years ago in reply to Nicholas Oborny

Prodigy 165 points

Nicholas,

Thanks for your feedback, I have the same issue, after I power cycled the board, the BQ32000 enters low power mode(Battery working current is 1.12uA).

Anyway, I think this is an issue for BQ32000, Does TI has a plan to fix this issue ?

Tom

0 Nicholas Oborny over 10 years ago in reply to Tom Xu1

TI__Mastermind 21305 points

Tom,

Glad I could help.

I am unsure of any plan to change this at the moment. We are currently working to get it documented into the datasheet.

Clock & timing

Clock & timing forum

BQ32000 Back up battery problem