BQ25820: the timming of boost reverse power from the battery to the system

Hello Vincent,

Do you have auto_ reverse mode enabled?

What do you have ACUV set to? 

I assume you have auto reverse enabled. Reverse mode will only be enable when VAC falls below ACUV. In you waveform, you have the timing between VAC dropping and VSYS rising, but you actually need to measure timing of when VAC drop below ACUV and when VSYS rises. You can decrease this time by increasing ACUV.

Vincent Xu said:

on our design is about 250ms, which can't meet our design requirement.

What is your expected time requirement?

Best Regards,

Christian.

Hi Christian,

yes, we have auto_reverse mode enabled. the VAC is 26V, and ACUV is set to 22V. we have tried to increasing ACUV to decrease the time, for example( ACUV is set to around 24.5V), but it seem that not to much help. Mostly, based on the spec of BQ25820, what's the VSYS rise time when auto_reverse mode enabled? what we concern about is the audio drop when amplifier out in heavy load...

Hello Vincent,

Vincent Xu said:

Mostly, based on the spec of BQ25820,

we don't have a spec for the vsys rise time after VAC falls below ACUV. However I measured using our EVM, and the rise time was less than 1ms.

Can you confirm you followed the schematic checklist and PCB layout guidelines in section 10.1 layout guidelines in the datasheet:https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1397113/faq-bq25820evm-bq25820-schematic-and-layout-checklist/5396319?tisearch=e2e-sitesearch&keymatch=BQ25820%2520schematic%2520checklist#5396319

Best Regards,

Christian.