BQ24075T: BQ24075TRGTT

Glen Robinson1

Part Number: BQ24075T

Hi all,

I’m using the BQ24075TRGTT and all appears to be working correctly except that CHG pin is always low (charging). I have confirmed that the CHG pin / tracking is not shorted to any other signal.

My circuit is a below and any suggestions would be as appreciated.

IN = 4.7V CE = 0V

R1 = 24k (3 hours) SYSOFF = 0V

R2 = 3.9k (0.4A) EN1 = 0V

R3 = 5.76k (0.155A) EN2 = 3.3V

R6 = 20k TS = 0.92V

R7 = 8.45k VBat = 4.12v (battery connected)

The disconnected battery voltage is 4.11V

Many thanks...

over 4 years ago

0 Raheem over 4 years ago

TI__Mastermind 21590 points

Hello,

The battery voltage is not at VBATREG which is 4.2V so /CHG will be low.

0 Glen Robinson1 over 4 years ago in reply to Raheem

Prodigy 60 points

Do you have any suggestions why the battery voltage does not reach 4.2v even after 12 hours?

Regards

0 Glen Robinson1 over 4 years ago in reply to Glen Robinson1

Prodigy 60 points

Raheem,

I have an ultra low quesent LDO connected across the battery to provide 3.3v to a RTC, approximately 2uA total.

Is it probably that this current draw causing my problem.

RegardsG

0 Glen Robinson1 over 4 years ago in reply to Glen Robinson1

Prodigy 60 points

Raheem,

Is the BQ24075T capable of charging a battery with a built in protection circuit?

Regards

0 Raheem over 4 years ago in reply to Glen Robinson1

TI__Mastermind 21590 points

Hello,

I'll suggest you power the LDO through the VOUT pin.

The BQ24075T can work with battery PCM. Do you have any load on VOUT during charging?

0 Glen Robinson1 over 4 years ago in reply to Raheem

Prodigy 60 points

Hi,

I can't use VOUT to power the LDO as I use SYSOFF to shut down the system and I require the LDO to power the RTC.

When charging I gave a 100mA load on VOUT.

Regards

0 Glen Robinson1 over 4 years ago in reply to Glen Robinson1

Prodigy 60 points

Thanks for all the help

Power management

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BQ24075T: BQ24075TRGTT