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LM5050-1: LM5050-1 OR-ing IC Failure Analysis

Noel Binny Abraham
Intellectual 570 points

Part Number: LM5050-1

Hi Team,

We have developed an OR-ing board based on the LM5050-1 ideal diode controller. The board was deployed at a client site, and during installation, the IC was damaged immediately upon connecting the battery to the input. Specifically, Pin 4 (VIN) of the LM5050-1 failed and showed visible burn damage.

The client is using a battery pack with a maximum voltage of 58.4 V, and at the time of connection, no load was connected at the output. This is the second occurrence of a similar failure at the client site, and we are currently investigating the root cause.
lm5050 damaged IC.jpeg

We suspect that a transient overvoltage or plug-in surge at the input may be stressing the VIN pin beyond its absolute maximum rating. We would like to better understand the possible mechanisms leading to this failure and identify suitable mitigation measures.

As a corrective action, we are evaluating the addition of input protection circuitry on the VIN pin—such as a series resistor combined with a Zener or TVS diode placed close to the IC—to clamp any potential voltage spikes during hot-plug events.

We would appreciate your guidance on:

-Possible causes for VIN pin failure under the described conditions

-Recommended protection strategies for hot-plug and transient suppression

-Any layout or component selection best practices specific to the LM5050-1

I can share the schematic and PCB layout files via private communication for a detailed review, if required.

Best regards,
Noel Binny Abraham

  • 0
    TI__Guru 58425 points

    Hi Abraham,

    Will get back to you early next week.

    Regards,

    Shiven Dhir

  • 0 in reply to Shiven Dhir
    TI__Guru 58425 points

    Hi Noel,

    Very high chance that the transient's voltage has damaged the IC.

    58.4V DC when hot plugged can have very high spike.

    Customer need to first probe and find out how high the input voltage is jumping and then passive components to clamp it well within recommended rating of the device.

    Regards,

    Shiven Dhir

  • 0 in reply to Shiven Dhir
    Intellectual 570 points

    Hi Shiven,

    Thanks for the update. I'll try and get the scope data for this. But meanwhile, do let me know if there are any recommended practices and passive components that TI suggests to pair up with the LM5050 to make sure that this situation of hot plugging in does not cause a transient spike on the IC. 

    We were thinking of adding a series resistor (10Ohm range) and a zener clamp near the IC to protect from transients. If you have any document or any suggestions from your end for a better system to protect the IC, then do let me know, we'll implement it on board. 

    Best Regards,
    Noel Binny Abraham

  • 0 in reply to Noel Binny Abraham
    TI__Guru 58425 points

    Hi Noel,

    Series resistor and Zener is one option.

    Or you can use a TVS which clamps under 75V and breaks down at 60V.

    Regards,

    Shiven Dhir