The cr4's H-Bridge is builded with MOSFET and BJT transistors and specialized low-side driver IC.
In my tests the bridge has worked at 32KHz PWM frequency with virtually no heat generated.
Two of these (one for each motor) are used in cr4.
The bridge prevents the shoot through conditions and allow the following operating modes:
- pwm cw rotation
- pwm ccw rotation
- pwm brake
Maximum supply voltage is around 18V and maximum current through the motors is limited by the IRF9540 MOSFET caracteristics.