BQ76952: Reverse connection problem

Jiahui Gao

Part Number: BQ76952

Tool/software:

Hi team,

The BQ76952 chip currently in use was found to have its voltage pulled down after the charger was reversed, causing the PMOS enable pin level to be pulled down by about 2V. At this point, the PMOS is in the critical region of the switch.
After investigation, it was found that there was leakage in the PACK and LD pins of the chip. After adding diodes, there will be no leakage current, but it will cause damage to the MOSFET when the short-circuit protection is locked.
So how should the hardware circuit handle the reverse connection of this BQ76952 charger

Thanks & Best regards,

Jiahui

6 months ago

0 Alexis_H 6 months ago

TI__Genius 17755 points

Hello Jiahui,

Section 2 Reverse Charge Circuit from the Multiple FETs with the BQ769x2 Battery Monitors application note should help explain and show a reverse charge circuit we typically recommend.

Best Regards,
Alexis

0 Jiahui Gao 6 months ago in reply to Alexis_H

TI__Expert 6940 points

Hi Alexis，

The reverse connection circuit of the charger has been added, which can only ensure that the discharge MOS is quickly turned off, but cannot solve the problem of leakage current in the PACK and LD pins after the charger is reversed

There is still leakage current in the pins of the PACK and LD of the chip

0 Alexis_H 6 months ago in reply to Jiahui Gao

TI__Genius 17755 points

Hello Jiahui,

Do you also have the Schottky diodes D6 and D8 as shown in Figure 1-1. Typical 7S Series FET Schematic from the Multiple FETs application note? Section 3 Reverse Charge Component Selection from the application note, also discusses the reverse charge current paths and explains how those diodes help.

Best Regards,
Alexis

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BQ76952: Reverse connection problem