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LM5113: lm5113

Arun kumar N
Prodigy 15 points
Part Number: LM5113

Hi TI,

I am using LM5113 Gate driver for driving my Synchronous Buck Converter,I am using GaNFET's which we rated for 100V an 36A.But i am observinng a situation where both GaNFET's are shorting,though the PWM signal were good with enough dead time between them.After turning on setup for some time like 8 to 10 times ,these mosfet's are getting shorted.Could you please look into it,and any suggestions from your end is fine

  • 0
    TI__Genius 12990 points

    Hi Arun,

    Thanks for posting, welcome to e2e!

    There could be a few things happening that could be shorting the FETs. However if both FETs are shorting at the same time and the gate driver is ok and the system is running for 10-minutes its possible that there is some shoot through from high dv/dt on the switch node due to GaNs low threshold voltage which might be turning on the low-side FET through the miller turn on effect. After some time the shoot through could heat up and damage the FETs. To check what might be happening, can you probe 3 waveforms: High-side and low-side FET gate as well as the switch node? looking at these three waveforms we can tell if the gates are turning on properly with dead-time. You can also probe VDD of the driver to make sure the adequate drive voltage is being applied through out the switching cycle. If shoot through is happening there are a few things we can do to help with this. To fix this the first thing is to try a larger gate resistor on the high-side gate to slow down the dv/dt of the switch node preventing a larger rush of current through the miller charge of the low-side. 

    thanks,