BQ40Z50-R1: BQ40Z50-R1 bypass DMOS then do the short test find the CMOS does not turn off

Star Xu

Part Number: BQ40Z50-R1

I have a query need your help. I test with the BQ40Z50-R1 board, bypass DMOS(short the S and D of Q3) then do the short test.

Instantaneous short circuit, when P+P － , Q2(CMOS) gate pin only 8v, disconnected the short circuit Q2 gate pin recover to 27v, Q2 did not turn off, but ASCD and ASCDL was set.

CMOS did not turn off, does it normal?

Waiting for your reply.

Thanks

Star

over 2 years ago

0 Jackson DiGiovanna over 2 years ago

TI__Expert 8245 points

Hi Star,

This is expected behavior.

Since you are shorting Q3 (DSG_FET), only ASCD and ASCDL get set which results in XDSG being set as well, disabling the DSG_FET until the latch reset condition is met.

Best Regards,
Jackson

0 Star Xu over 2 years ago in reply to Jackson DiGiovanna

TI__Genius 9645 points

Hi Jackson

Thanks for your reply.

I have a query need your help. When shorting Q3(DSG_FET) and doing short test.

The CHG flag from register is set, but the gate of Q2(CHG_FET) only 8V.

The CHG FET did not turn on but the CHG flag was set. Why？

Thanks

Star

0 Jackson DiGiovanna over 2 years ago in reply to Star Xu

TI__Expert 8245 points

Hi Star,

What is the state of the XCHG FET when you are observing this behavior?

Best Regards,

Jackson

0 Star Xu over 2 years ago in reply to Jackson DiGiovanna

TI__Genius 9645 points

Hi Jackson

The XCHG is low, CHG is high

Thanks

Star

0 Jackson DiGiovanna over 2 years ago in reply to Star Xu

TI__Expert 8245 points

Star,

What is the voltage of the PACK+ pin when you observe this behavior? From the image you attached it appears like the gauge is trying to be in charge mode and no protections should be opening the CHG FET. However, BatteryStatus() DSG is still set. I am thinking there may not be enough current flowing for the device to exit relax mode.

Best Regards,

Jackson

Power management

Power management forum

BQ40Z50-R1: BQ40Z50-R1 bypass DMOS then do the short test find the CMOS does not turn off