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LM26003: 24V Output Burns the Regulator (28V Input)

Andrea Cresta
Prodigy 70 points
Part Number: LM26003

Hi support,

Input: 28V.

2 output parts:

The one that have to supply 24V output burns the regulator instantly.
After that the output provides a little resistance (just few ohms). 

The second one that supply 12V works fine and without any problems.

The tests were performed without any load.

The circuits were created with WEBENCH ®.

My question is:

Do you know why the first part burns the regulators ?

Here's the circuit.
Thanks in advance.

  • 0
    TI__Genius 11085 points
    This is a 38V part. It shouldn't be damaged by 24V input voltage. Could you capture the waveform of input voltage and input current when the part is powered up? Depends on the layout, there could be large current spikes at the input side when it is charging the 120uF output capacitor to 24V. You can try larger Css at the SS pin to reduce the soft start time and inrush current at the 24V design. Please also check the diode is ok or not. Output port low impedance can be a sign of damaged diode as well.

    Regards,

    Yang