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BLDC H bridge considerations

My initial BLDC H-bridge design started with an IRS2104/2101 half bridge driver and IRLR3636 MOSFETs. They match perfectly.

All three half bridge drivers are driven by the same PWM signal. To turn the PWM signal individually on or off, I use a separate port to pull the input low.

This circuitry has no current protection. You would have to design it yourself. See current-shunt sensing part below.

The gate resistor of a few ohm determine of how “hard” you drive your FETs. The “harder (lower resistor value)” the shorter the rise time of faster the FETs do switch. That will reduce power-losses but significantly increase EMC noise. So you have to play around to find the optimum.

I also found, that the on the MOSFET “integrated” flyback (freewheeling) diode can hold the voltage peak driven from the motor coils when you turn off the current. No need for an extra external shottky diode (that would be different if you use an IGBT switch).

Currently I am using the BTN8962 device. The BTN8962TA is an integrated high current half bridge for motor drive applications. It is containing one p-channel highside MOSFET and one n-channel lowside MOSFET with an integrated driver IC in one package. Including current sensing and protection. Cool device I think.