This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ76952: DSG path for Fets turn On/Off on Reference Design TIDA-010208

Part Number: BQ76952
Other Parts Discussed in Thread: TIDA-010208

Greetings from Canada TI Team.

I'm working on a design forLTO Batteries with the BQ76952 and I stumbled upon the reference design TIDA-010208. I would like to know how the circuitry works for the turn On/Off of the Fets on the DSG Path, Could you please clarify the role of circuitry involving Q28, D38, D37, R129, R135, R133, R132, R130 and D36? I know that the upper part of the circuitry is for Reverse Polarity protection but Im curious how the charge and discharge of the fets work in that design and the path of the current once the reverse connection has occured.

Best Regards.

  • Hi Bastian,

    Section 2 of this document explains the reverse charge part of the circuit in more detail: https://www.ti.com/lit/an/sluaa09/sluaa09.pdf And in Section 6 of the same document, it includes an example using a PNP to more quickly discharge the gate capacitance to improve the FET switching time. I believe the bottom portion of this circuit is using a similar idea. I think there may have also been a requirement on this reference design that it need to withstand a constant 120V on PACK+ when the FETs are disabled - I think the idea behind the R129/D37 is to increase the series resistance to reduce the current flow in one direction for this case.

    Best regards,

    Matt