BQ76942: High-Side Driver for BQ76942

Jason Zhou

Part Number: BQ76942

What is the advantage of the high-side driver built into the BQ76942? If it is a low side driver, what are the implications?

over 3 years ago

0 Caleb Perez over 3 years ago

TI__Genius 11315 points

Hey Jason,

See this application note regarding the use cases for high side FET driving. The main benefit is that high side FETs allow for communication between the microcontroller and the AFE while the FETs are open. https://www.ti.com/lit/an/sluaa84a/sluaa84a.pdf?ts=1660578002545&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FBQ76952

Thanks,
Caleb

0 Jason Zhou over 3 years ago in reply to Caleb Perez

TI__Prodigy 190 points

I understand, thanks for your reply

0 Jason Zhou over 3 years ago in reply to Jason Zhou

TI__Prodigy 190 points

Hello, I would like to confirm with you again that when the high-side resistance sampling MOSFET is turned off, the battery can power the AFE and the microcontroller, right? If it is low-side resistance sampling, then after the switches are turned off, the battery can't power them, and they can't communicate, right? Looking forward to your reply, thank you very much.

0 Caleb Perez over 3 years ago in reply to Jason Zhou

TI__Genius 11315 points

Hey Jason,

High-side FET control allows communications between the BQ76942 and the Microcontroller to continue even if there is a fault since the ground connections do not separate. When implementing a low side FET configuration, during a fault, the ground connection between the BQ76942 and the Microcontroller becomes disconnected. This does not allow the two devices to communicate with each other.

Assuming you are using one of the regulator outputs on the BQ76942, the FETs being open in either configuration should not affect power delivery to your microcontroller or the BQ76942.

Hope this makes sense. Thanks!
Caleb

0 Jason Zhou over 3 years ago in reply to Caleb Perez

TI__Prodigy 190 points

Oh, thank you for your help, I basically understand, can I also understand that when the low-side switch is turned off, the BQ76942 can't supply power normally, because the battery may not supply power to it?

0 Caleb Perez over 3 years ago in reply to Jason Zhou

TI__Genius 11315 points

Hey Jason,

In both high and low side FET configurations, when the FETs are open, the load will not receive power from the battery. The BQ76942 will remain powered, however.

Thanks,
Caleb

0 Jason Zhou over 3 years ago in reply to Caleb Perez

TI__Prodigy 190 points

Thank you,I got it.

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BQ76942: High-Side Driver for BQ76942