Lumina
Newbie level 4
I am in the beginning stages of designing a circuit that will protect a low side FET when it sees a short circuited load. Currently I am contemplating using this FET and this driver . The FET is being driven with a PWM frequency of approx. 15 KHz . My load is some LED lights at 24 Volts and approx. 20 Amps . I would like to protect the FET from anything above about 25 Amps. I am considering using a .01 ohm sense resistor on the high side along with this current sense IC TSC101 followed by a comparator that would trigger an interrupt pin on my microcontroller which would then shut down PWM in the case of an overcurrent condition Does this seem like an ok solution? .I am also considering using a Hall effect sensor as the current sensing element. I like the simplicity of this circuit a user posted in another thread. Is this a better direction? I have also seen discussions on using Desaturation but not many examples using FETs, mostly IGBTs. I am however intrigued by this driver **broken link removed** which has a low Desat threshold of 250 mV as most drivers are up around 7 volts. While Desat detection looks like an elegant solution , I am concerned that going that route will lead me down a path of complications. I would really appreciate people's thoughts on the best way to detect a short circuited load so I can protect my FET in the case of a failure. I am also looking at putting a TVS from the Drain to Source to protect from large di/dt voltages in the case of a shorted load. Thanks a lot for your insights ;-)