BQ24780S: Some question about BQ24780S

Lumina Gui

Part Number: BQ24780S
Other Parts Discussed in Thread: BQ24780

Hi TI Teams,

Our new notebook project using BQ24780S for 3-cell batteries charging. The voltage of ACDRV, ACDET and +VCHG_REGN are all normal when the adapter (19V) was inserted in. The measured data are as follows: ACDRV: 23.6V, ACDET: 2.8V, +VCHG_REGN: 5.95V. At this time, the voltage of BATPRES is low and ACOK output is high,the BATDRV is high, which causing the Q13 MOSFET abnormal working . When remove the Q13 MOSFET, the MOSFET drive signal does not work. But the Q13 MOSFET works fine with only battery for power supply.

The schematic is as below:

BQ24780_Schematic.pdf

Can u help to analyze the cause of this problem and give us some suggestion for the design?

Thanks,

Kind Regards

over 1 year ago

0 Pengzhao Zhu over 1 year ago

TI__Genius 11385 points

Hi Lumina,

BATDRV should not be high relative to BATSRC when the adaptor is present. Both ACDRV (relative to CMSRC) and BATDRV (relative to BATSRC) should not be high at the same time.

I would recommend double checking the schematic + check for any manufacturing issues.

Please refer to the following schematic checklist.

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1064617/faq-bq24780s-faq-how-do-i-ensure-the-charger-schematic-is-satisfactory-is-there-a-schematic-checklist-for-bq24780s

Thanks,

Peng

0 Jeffic Chang over 1 year ago

Prodigy 50 points

Mount the Q11 MOS and remove R632 might solve the problem.

Power management

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BQ24780S: Some question about BQ24780S