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Topic: Freewheel diode with reverse polarity protection (Read 119 times) previous topic - next topic

seanlyons318

Hello,

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.

Thanks in advance for any guidance.

Wawa

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..

MarkT

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).
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

seanlyons318

Thank you, both, for sharing your insight.  Very helpful information.

Cheers,
Sean

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