June 15, 2011
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.
Here is the schematic (click to enlarge):
The thruth table is:
I choosed this solution because I have upgraded some previous designs and wantd to keep the components used.
I like how the bridge works but if I will need to upgrade the design I will use only N-channel MOSFETs with specialized driver ICs.