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  1. #1
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    Suitable driver for a MOSFETs H Bridge

    Hi guys. I am sure this question has been asked before but when I search I get so many answers that don't really apply so I am confused.

    I have a 20V PSU which I want to power a 3 phase permanent magnet motor (brushless motor I guess).

    If I could, I would like to use 6 of TK40E06N1 (S N-channel MOSFET, 60 A, 60 V) for the high side and the low side switches of the H bridge.
    - Would I need to use a bootstrap capacitor driver?
    - If so, would I need a higher voltage than 20V to power the driver?

    My second option is to use IRF5305PBF P-channel MOSFET (31 A, 55 V) for the high side switching and the TK40E06N1 for the low side.
    - I would then have a positive 18V regulator (L7818) and a negative regulator for the MOSFET gates
    - MOSFET Vgs(max) is 20V. I think 18V will charge the gates very quickly. Is 18V too close to Vgs(max)?
    - Most of the driving circuits I have seen use a resistor (1KΩ to 10KΩ) between the MOSFET gate and source to discharge the gate and a transistor to charge it up. I feel this might be a bit slow. I want to switch the motor poles at 40kHz.
    - Can someone suggest a suitable driver chip to use in this case?
    - Or will I need to build one using 2 transistors for each MOSFET?

    Any guidance would be appreciated. Thanks.

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  2. #2
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    Re: Suitable driver for a MOSFETs H Bridge

    All NMOS bridge with bootstrap driver like IR2110 is the popular solution. It uses a single power supply of 12 - 15 V which determines Vgs,on value. 18V would be definitely too high for silicon MOSFET.

    IR2110 or similar drivers are driving the gate in push-pull mode, 1k resistor is effectively useless.


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  3. #3
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    Re: Suitable driver for a MOSFETs H Bridge

    Yes, half bridge gate driver IC's intended for driving nfets such as the IR2110 are incredibly common and cheap and designed for exactly your application. Find one with a good datasheet and application examples and follow them and you'll be in good shape.

    Many may have demo boards and other things that may be helpful for prototyping.



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