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LM25118: Shorting of pins

Sonika .
Prodigy 180 points
Part Number: LM25118


Tool/software:

Hi,

Greetings,

I am Sonika, a Hardware Design Engineer. We are currently using the LM25118 IC in one of our designs, with an input voltage range of 10–40V and an output of 28V at 4A.

We are facing an issue where, under a load of just 100mA, the HB and HS pins of the IC become shorted, resulting in IC failure. The external components, including the MOSFETs and bootstrap capacitor (ranging from 100nF to 470nF), remain undamaged. However, the IC itself gets damaged due to the short.

For your reference, I have attached the schematic of our circuit.

Kindly advise on possible causes and how we can resolve this issue.

Best regards,
Sonika

  • 0
    TI__Guru 67225 points

    Hello Sonika,

    Please check if you are getting a lot undershoots on the switch node of the converter. These could lead to overcharging the HB capacitor and get out of the abs max rating of the HB to HS difference.

    You could check if the problem is becoming better when you add a Zener diode below 16V and above the maximum VCC voltage. Then the voltage between HB and HS would be clamped below the abs max rating.

    Best regards,
    Brigitte