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debugging_gate_driver.md

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    Debugging Gate Drivers

    It seems like the bootstrap portion of the gate drivers is not working.

    I disconnected the gate drivers from the mosfets and noticed that they wouldn't boost over ~12V (which is their supply voltage).

    With a 100ohm resistor as the load and 20V applied to V+, these are the curves I'm seeing (with ~15mA average current draw from the supply):

    Pulse output:

    The gate of the bottom discharge FET:

    The bootstrap pin of the discharge gate driver:

    The drain of the discharge FET:

    The bootstrap pin of the charge gate driver:

    I figured this out… I overlooked the fact that this half-bridge driver doesn't include a charge pump and relies on the HS pin (between the low and high mosfet being grounded routinely to charge):

    With the VHB capacitor connected to HB and the HS pins, the VHB capacitor charge is refreshed every switching cycle when HS transitions to ground.