BQ25750EVM: VSYS is OFF when the adapter power is removed

HI Sam,

What is the voltage from BATDRV pin to GND?

Regards,

Jeff

Hi Jeff,

Please see the waveform below. 

Regards,
Sam Ting

Hello Sam,

Just to make sure, the battery voltage is staying the same at 24V?

Can you use a multimeter's diode/resistance function to check that the BATFETs are functional?

Best Regards,
Ethan Galloway

Hi Ethan,

Yes, VBAT is staying the same at 24V. The adapter-only and battery-only operations are fine. The DC to AC transition is also fine.

Regards,
Sam Ting  

Hello Sam,

Can you send me a screenshot/file of the registers?

Let me know if checking the resistance of the FETs confirms the FETs are still in good working order.

Best Regards,
Ethan Galloway

Hi Ethan,

We have confirmed that the BATFETs are functional.

Registers:

Add more waveforms:

- BATDRV retry after adapter power is removed @ system 5A load

- System no load condition

Regards,
Sam Ting

Hi Ethan,

We found that if we increase the VIN to 30V (from 20V) and short Q8 on the EVM, the operations are fine. FYI. But the project needs the 20V input.

Regards,
Sam Ting

Hello Sam,

I see you are using the BQ25756 bqz file. Here's a link to the BQ25750 bqz file: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1357451/faq-bq25750-bqz-file-for-bqstudio

The BATFETs are supposed to turn on once VAC go outside the ACUV/ACOV window. Can you measure the voltage on VAC when the load is removed?

For the registers you sent me, are those registers form the BQ25756 while the charger has VIN plugged in or has VIN been removed?

Best Regards,
Ethan Galloway