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Schematic The goal is to control various Peltier modules using an H bridge and a PWM signal.

I've designed this schematic and made a PCB out of it.

It is an H-bridge using 4 IRLR7843TRPBF high power MOSFETs and 2 2ED21091S06FXUMA1 half bridge MOSFET drivers.

I have followed the data sheet of the MOSFET driver and everything seems ok, yet when I supply the circuit it shorts itself through the MOSFETs and I don't understand why.(I know that is through the MOSFETS because I checked it with a thermal camera)

In fact, the gate logic should prevent a short no matter what. Page 6 of the gate driver IC. Gate logic of the driver IC

So far I have changed the 10k gate resistors to 22 ohm ones and nothing. There is no physical short nor bad soldering. I'm running out of idea Is there something wrong with the schematic?

I'm starting to think that some components might be damaged.

EDIT: The schematic is right. The Source and Drain pin numbering in the schematic did not match the pin layout of the real componente, in fact what happend is that Source and Drain were inverted.

2ED21091S06F :datasheet

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I’d suggest taking one or more FETs out of circuit so you can see what the remaining ones are doing, or disconnect the 12V from the high side of the bridge and check the gate voltages

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  • \$\begingroup\$ 10k gate resistors seem extremely high. Should be more like 10 Ohms! Are C29 and 30 electrolytic caps? What is your pwm frequency and duty cycle? \$\endgroup\$
    – Kartman
    Commented Jan 31, 2022 at 3:26
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    \$\begingroup\$ Did you check your pcb footprints vs the datadheets? Mosfets could be wired backwards. \$\endgroup\$
    – Kartman
    Commented Jan 31, 2022 at 3:37
  • \$\begingroup\$ "Mosfets could be wired backwards" In the MOSFETS, S and D are inverted. The pin numbering of the symbol didn't match the footprints numbering. A wasted PCB. But even then I don't understand the short. The H-bridge should be off all the time not on. \$\endgroup\$
    – firemonkey
    Commented Jan 31, 2022 at 9:55
  • \$\begingroup\$ It’s the body diodes in the FETs, I think you’ll find that it’s not a dead short but you’ll see a diode drop across the FETs if they are ‘off’ and more or less no voltage drop if they are energised. \$\endgroup\$
    – Frog
    Commented Jan 31, 2022 at 19:09

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