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DRV8307: Help designing circuit

S S
Prodigy 10 points
Part Number: DRV8307
Other Parts Discussed in Thread: DRV8308EVM

Hi,

I am new to electronics and I am currently using the DRV8307 in a project. I have some basic questions that I couldn't find a clear answer of.

I am using IRF520's together with the DRV8307 to control a motor (12 V 3 A). When I tried testing the circuit, I found the voltages on the high side gate drives to be 0.7 V and the voltages on the low side gates to be 0 V, and FAULTn to be active. I believe this is because the MOSFETS overheated but I am not entirely sure. I recently bought a heatsink that is specified as follows: easy-to-use 23°C/W sink will let you burn about 4 Watts of power through a TO-220 (assuming an ambient temperature of 25°C and max die temp of 150°C). Would this be sufficient cooling for the transistors?

Also, are any gate resistors and/or any flyback diodes parallel to the MOSFETS required or is a circuit similar to the schematic provided in figure 13 of the datasheet of the DRV8307 sufficient to properly operate a motor?

Thanks in advance

  • 0
    TI__Guru** 114905 points

    Hi S S,

    May I recommend searching for FETs with lower VDS ratings (40V to 60V) and lower Rdson? There are some FETs that are <25mOhms, which will reduce the power by ~10x. This should be a bigger help than adding the heatsink.

    "Also, are any gate resistors and/or any flyback diodes parallel to the MOSFETS required or is a circuit similar to the schematic provided in figure 13 of the datasheet of the DRV8307 sufficient to properly operate a motor?"

    None are required, although adding 0 Ohm resistors or footprints fro diodes can be useful if you have the board space. Please refer to the schematic of the DRV8308EVM. The output section of this device is similar to the DRV8307.