BQ77915: Enquiry about circuit for MOSFET at charging side and discharging side

Po Yang Khor

Part Number: BQ77915

Tool/software:

Hi,

I would like to ask about circuit for MOSFET at charging side and discharging side. Sense resistor(2mR) is implemented to ensure max 30A Load. Due to the Heat dissipation issue. Hence, I have decided to put 2 mosfet, but I am not so sure which circuit is more reliable? Circuit 1 or Circuit 2. Please provide suggestion and explanation. Thanks in advanced.

Circuit 1

Remarks: Duplicate the whole circuit & parallel for charging and discharging side respectively.

Circuit 2

Remarks: Only parallel the MOSFET.

10 months ago

0 Luis H. S. 10 months ago

TI__Mastermind 42060 points

Hello Po,

Circuit 2 is what I would recommend and what most designs would do. However, I also would recommend to add an individual gate resistance to each of the gates of the MOSFETs. This resistance helps prevent parasitic oscillations between parallel FETs.

Best Regards,

Luis Hernandez Salomon

0 Po Yang Khor 10 months ago in reply to Luis H. S.

Prodigy 110 points

Hi Luis Hernandez Salomon,

Thanks for your advice. For charging side(circle in green), duplicate side(circle in red) is it need to include extra zener diode(Z1) or just only gate resistor will do, the gate resistor don't need change the value right?

0 Luis H. S. 10 months ago in reply to Po Yang Khor

TI__Mastermind 42060 points

Hello Po,

A single Zener is okay! For the individual gate resistor, I would recommend a value such as 10-Ohm or 20-Ohm.

Best Regards,

Luis Hernandez Salomon

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BQ77915: Enquiry about circuit for MOSFET at charging side and discharging side