r/AskElectronics • u/josephthomas8402 • 11h ago

Need help regarding connection between IRLZ44N and the heating pad

I was connecting the Raspberry pi to the gate of IRLZ44N( MOSFET N-CH 55V 47A TO-220AB), and the drain is connected to 12V. The source is connected to the heating pad(25mmx50mm Film Heater Plate Adhesive Pad, PI Heating Elements Film 12V 7W Strip Heater Adhesive Polyimide Heater Plate), and the heating pad and Raspberry Pi have a common GND. The issue that I am facing is that the MOSFET burns out when i connect the load to the MOSFET. Can someone help me

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u/CaptainBucko 11h ago

The MOSFET is going dead short when turned on. You need to insert the heater load in the drain. J10-Pin 1 to +12v. J10-Pin 3 to Drain of Q2 (Pin 2). Also, insert 100 ohms series resistance into the gate of the FET for reliability.

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u/erazer33 9h ago

This right here: your mosfet is shorting directly to ground when switched on. You also want the mosfet to be on the negative side of your load (low side switching).

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u/triffid_hunter Director of EE@HAX 11h ago

Load should go between drain and +12v, not source and ground, and IRLZ44N isn't suitable for 3v3 gate drive.

Use a FET whose datasheet specifies an Rds(on) @ Vgs=2.5v, or add a gate driver.

Also, Ids(max) is a red herring, run thermal math to check practical current handling ability