LMZ14202H: Short circuit problems

user6356451

Part Number: LMZ14202H

Hi I have a problem with LMZ14202HTZE/NOPB. I test my circuit on lab bench with power supply and works great. But when I connect 24V with a simple manual switch it turns out to burn with smoke. I measured why is that so and only explanation is a rise time for 24V. Its no spike and so on. When I hit the switch immedaitely appear 24V on input, but when i used my lab power supply it slowly rise to 24V. Schematic below. Why its happening this? I burn a 14 LMZ converters because of it!!!

over 4 years ago

0 iAlejandro over 4 years ago

TI__Expert 8130 points

Hello,

Can you provide a waveform of VIN and VOUT when using the switch?

Thanks,
Alejandro

0 user6356451 over 4 years ago in reply to iAlejandro

Prodigy 20 points

I only have VIN (see below). LMZ was burned to smoke in instant and i didnt have opportunity to measure vout.

0 iAlejandro over 4 years ago in reply to user6356451

TI__Expert 8130 points

Thanks for the waveform, this helps!

Well, VIN is not spiking above the abs max limit, so let's try something:
Take a working device and disable it (short pin 3 to GND) prior to hitting the switch. Once VIN has reached regulation (~400uS, according to the waveform provided), release the short to enable the device. Please capture results, VIN, VOUT, and input current.

Thanks,
Alejandro

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LMZ14202H: Short circuit problems