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Original question:

LMR51420: LMR51420XDDCR

LMR51420: IC is burning

Abhishek Kumar
Prodigy 50 points
Part Number: LMR51420

Tool/software:

Hi,

I am using this IC as a buck converter (24V to 5V). The circuit is already in mass production with a volume of over 15k units per month.

However, we are facing an issue that is rapidly increasing: the IC is either shorting to GND or burning out immediately when power is applied. In some cases, the IC even fails during the impedance check on the FCT tester, before any power is applied.

Could you please suggest the possible reasons for this failure and recommend any potential remedies?

Attaching my schematic for your reference.

  • 0
    TI__Guru 73335 points

    Hello

    Can you supply images of your PCB layout.

    Also, please give details on your impedance testing.

    Thanks

  • 0 in reply to Frank De Stasi
    Prodigy 50 points

    Here is the PCB layout.

    During impedance testing, the probe is connected to test points corresponding to different voltage levels with respect to ground (e.g., 24 V, 5 V w.r.t. GND). The readings are taken using a Gwinstek digital multimeter to verify that no short circuit exists before powering the IC. This is a precautionary step to ensure that no physical damage occurs.