BQ76952: DCHG, DDSG pin status in SHUTDOWN mode

Kyungjae Lee

Part Number: BQ76952

Tool/software:

Hi,

I've noticed that when a BQ76952 transitions from NORMAL mode to SHUTDOWN mode by asserting RST/SHUT pin for >1sec, the DCHG/DDSG pins are keeping the previous states rather than being updated to HIGH. Is this an expected behavior?

For example, when the chip shuts down from the NORMAL state in which the CHG/DSG FETs were kept closed/enabled (i.e., DCHG/DDSG = LOW), the DCHG/DDSG pins were still keeping LOW state which does not properly represent the CHG/DSG FETs open/disbled status in SHUTDOWN mode.

I would appreciate the clarification here.

Thank you,

Kyungjae Lee

over 1 year ago

+1 Alexis_H over 1 year ago

TI__Genius 17845 points

Hello Kyungjae,

Thank you for your patience. I realized I misunderstood your question and have changed my response. Since by default, the DCHG/DDSG pins are configured to be active-high, i.e. they will be logic low(0) if the CHG/DSG is logic high (1), once the part enters shutdown mode, the DCHG/DDSG pins that were initially LOW, will still keep LOW.

Best Regards,
Alexis

0 Kyungjae Lee over 1 year ago in reply to Alexis_H

Intellectual 650 points

Hi Alexis,

Thank you for your response. So does that mean that it is not safe to fully rely on the readings of the DCHG/DDSG pins to determine the FET status from the host MCU since the DCHG/DDSG pins will keep their states LOW when the chip is in SHUTDOWN mode where it should be keeping all the FETs open/disabled (which translates to DCHG/DDSG = HIGH)?

Thank you,

Kyungjae Lee

+1 Alexis_H over 1 year ago in reply to Kyungjae Lee

TI__Genius 17845 points

Hello Kyungjae,

That is correct when the device is in SHUTDOWN mode. Once the part SHUTDOWNs, everything is off.

Best Regards,
Alexis

0 Kyungjae Lee over 1 year ago in reply to Alexis_H

Intellectual 650 points

Thanks Alexis, this is helpful. By the way, I was hoping to see the original response you left to my question before you erased it. I wanted to see if I can work around this situation by utilizing those parameters you mentioned there. Is there a way you can recover that response?

+1 Alexis_H over 1 year ago in reply to Kyungjae Lee

TI__Genius 17845 points

Glad I was able to help!

The parameters I mentioned previously are here:

More information about shutdown mode can be found in this BQ76952 Shutdown Mode FAQ including that paragraph I have shared as well.

Best Regards,
Alexis

0 Kyungjae Lee over 1 year ago in reply to Alexis_H

Intellectual 650 points

Thank you!

Power management

Power management forum

BQ76952: DCHG, DDSG pin status in SHUTDOWN mode