I recently purchased a TB67H420FTG board to power a 24V DC gear motor. The board works well in my application but, as I am fairly new to electronics, I would like to understand more about the power circuit.
If I have reviewed the schematic properly, it seems to employ a p-channel MOSFET with a Zener diode for reverse polarity / battery protection. My question is whether or not this provides the same protection as a freewheel diode or whether I still need one across my motor.
The P-channel mosfet protect the board against reverse polarity, with lower losses than a common diode. This video explains it all.
The TB67H420FTG already has buildin back-EMF protection for the motor.
Look at the mosfet output stage of the chip (pin 13-24) on page 4 of the datasheet (the eight diodes).
Leo..
Power MOSFETs have built-in body diodes that's part of how they are made, so all MOSFET bridges are
already provided with free-wheel diodes.
BJTs and IGBTs need them as additional components, and even MOSFET circuits sometimes have additional
schottky diodes to reduce losses (lower forward voltage than body diodes).
