Micrel MIC4605

I’ve been lately searching for the best half bridge driver IC’s for my reference.

A good, fast, and cheap half bridge driver for DC main voltages up to 85V is the Micrel MIC4605-2YM-TR.  This device requires only two additional capacitors to work, and is triggered by a convenient single PWM input.  The device ratings indicate that it should still be somewhat functional at PWM frequencies up to 1Mhz for driving power mosfets with gate capacitance of 1000pf or less, but no doubt operates with much easier to insure (easier to design a pcb for) reliability in the 50-200kHz range.

I still need to find the best IC for DC mains up to 300V, if such can be found.

The search has been educational.  For one thing, I’ve learned that the shoot-through protection on the output of these chips affects the output timing of every HO and LO cycle, basically holding HO low until LO is low which affects the usable PWM input frequencies and duty cycles by adding some dead delay time.

The gate drivers circuits and microcontroller of my inverter don’t need that shoot through protection on every PWM_IN cycle.  Rather, the shoot-through protection is only necessary when switching the FOR_!REV output.  Therefore, in the programming of the controller, the PWM_IN output has to be disabled for a few clock cycles while switching the FOR_!REV output from high to low or low to high.  This is a much smaller effect than on the MIC4605 for an inverter or VFD application because the 50% duty cycle PWM output for FOR_!REV is equivalent to the output frequency which will typically be between 50 and 2000Hz.



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