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UCC37324: Driving FETs in High Side Configuration with low side gate driver

Mohammed Ibrahim Saqib
Prodigy 235 points
Part Number: UCC37324
Other Parts Discussed in Thread: UCC5390

Tool/software:

Hey TI Experts,
We are designing a circuit for Bidirectional current flow to and from a battery. The Mosfets are used in High Side Switching configuration arranged in back to back topology.

Hence, the Source terminals of both the Discharge and Charge FET are shorted.

To accomodate the above and for Isolation purpose we have an isolated supply giving 12V to the low side Gate driver and reference ground for the Source terminals.

Thus, we have the following queries:-

1) Will the FETs in high side configuration work with the low side gate driver as the Sources are shorted and always have a reference ground from the Isolated Power Supply.

2) The Isolated Power Supply is a 1:1 ratio power supply and has an output current of just 84mA. Is this sufficient for the Gate drivers current requirements.

3) Is the schematic fine interms of isolation or could be simplified/optimised more?

Would like your Valuable feedback on the same.

Thanks and Regards 

Ibrahim 

BMS-Gate_Driver.pdf

  • 0
    TI__Mastermind 20616 points

    Hi Ibrahim,

    1. Your input voltage will not follow the switch node. You can solve this problem by using an isolated gate driver like the UCC5390. The input side is low-voltage, and it sends a high frequency "on" signal across an isolation barrier to the high side, which is powered as you describe. 

    2. That is plenty of supply current, unless you plan on MHz switching speed.

    3.  The schematic looks pretty simple already. RP-2424 is a very simple isolated power supply, which I am using. You might even be able to use relays instead of gate drivers if your switching frequency can be very low.

    Best regards,

    Sean

  • 0 in reply to Sean Cashin
    Prodigy 235 points

    Hey Sean, 

    Thanks for your swift response.

    Understood the point you made regarding why isolated gate driver is necessary for source terminal to get referenced to ground.

    Based on your feedback we've attached the updated schematic.

    Please have a look and let us know if this approach will work and also let us know if there is a better part for this purpose.

    Thanks and Regards

    Ibrahim

    32'S_BMS-Gate_Driver_Current_Sense.pdf

  • 0 in reply to Mohammed Ibrahim Saqib
    TI__Mastermind 20616 points

    Hi Ibrahim,

    I think this will work. 

    Best regards,

    Sean