BQ25750EVM: Switchover timing clarification for switch from VAC to VBAT output?

Andrew Edwards

Part Number: BQ25750EVM
Other Parts Discussed in Thread: BQ25750

Tool/software:

Can you provide some clarification on the switchover timing for this device? How long from when the UV threshold for the VAC supply is reached until the BATFETs are activated? For UPS type behaviour, is it best to use Auto_rev functionality?

A previous question mentioned 1.3s for this switchover to occur. The datasheet implies this happens very quickly in auto_rev mode.
Is Auto reverse mode on by default or can it only be enabled in host mode?

over 1 year ago

0 Ethan Galloway over 1 year ago

TI__Mastermind 30615 points

Hello Andrew,

Thanks for being patient with the wait. We will get to your question early next week.

Best Regards,
Ethan Galloway

0 Andrew Edwards over 1 year ago in reply to Ethan Galloway

Prodigy 31 points

Thanks Ethan! Appreciate it!

0 Ethan Galloway over 1 year ago in reply to Andrew Edwards

TI__Mastermind 30615 points

Hello Andrew,

The switchover time is certainly less than 1.3 seconds. I'll get back to you tomorrow with the exact data.

Auto reverse mode is off by default and has to be enabled by the host.

Best Regards,
Ethan Galloway

0 Ethan Galloway over 1 year ago in reply to Ethan Galloway

TI__Mastermind 30615 points

Hello Andrew,

Once again, thanks for being patient with the wait. We've been swamped lately.

When VAC is removed, it takes under 500µs for the BATFET to respond and switch over. For auto reverse mode, it takes about 50µs for the charger's converter to activate and start switching.

For your application, what's your input voltage, system voltage/current, and battery voltage/charge current?

To help with calculating ACUV, ACOV, and the battery charge voltage, we have a design calculator for the BQ2575X family: https://www.ti.com/tool/download/BQ25756-DESIGN-CALC/

We also have a schematic and design checklist for the BQ25750: e2e.ti.com/.../faq-bq25750-schematic-and-layout-checklist

Let me know if you have any other questions.

Best Regards,
Ethan Galloway

Power management

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BQ25750EVM: Switchover timing clarification for switch from VAC to VBAT output?