Hi sir.
Is LM5001 a chance that it could latch up?
Best regards
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Hello user1567465,
Thanks for reaching out with your question and for considering the LM5001 in your design.
Can you please describe what is happening in our circuit. I have not seen any latch up issues in the LM5001.
Thanks,
Garrett
Hi sir
Thank you for your reply.
LM5001 is used to our product.
The products circuit board tarnish in the area of LM5001's circuit.
Picture of tarnished circuit board is below.
Our circuit is below.
The circuit operates correctly, but a few products occurred this issue during operation.
LM5001 has thermal shutdown function.
Why does the issue occurs?
Hello,
What are the operating conditions when this issue occurs? VIN, IOUT...
Is there a certain pin that is tarnished? I cannot make it out from the provided picture.
Let me know if you have any questions.
Thanks,
Garrett
Hi sir.
Thank you for your reply.
Operating conditions are below.
VIN:24V
VOUT:24V
IOUT:20 to 50mA
LM5001's pins was not tarnished.
Best Regards
Hello,
Have you only seen this issue when VIN is 24V? Also if you try to power up the LM5001 that have been on a tarnished board does it still work?
Based on the operating conditions and the schematic I don't see any reason to think this is a latch up issue.
Thanks,
Garrett
Hi, sir
This issue did not occur at our evaluation test.
The test voltage range is 21.5V to 26.5V.
Our customer continued to use about 4 months.
Capacitor(C8) is short-circuit on the tarnished board.
The LM5001 is still work after the capacitor(C8) was removed.
Best Regards
Hello,
What is the voltage rating on C8? To me it sounds like the component might have been damaged causing the output to be shorted. Once this is removed the LM5001 will be able to operate again.
Thanks,
Garrett
Hi, sir
Thank you for your reply.
The voltage rating on C8 is 35V.
Attached is the file of the waveform measured on the board mounted with normal C8.
Best regards,Waveform of output voltage.pdf
Hello,
After C8 is replaced is it damaged again? How many boards have you seen this on?
Thanks,
Garrett
Hi sir.
Thank you for your reply.
No it did not.
Replaced capacitor (C8) was not broken.
Broken capacitor was 4 boards.
We shipped about 200 boards.
Best regards,
Hello,
To me this sounds like the issue is that C8 is getting cracked, this can be due to the PCB flexing. If C8 is cracked this would cause the capacitor so short to ground. This is effectively shorting the output which would be why the output voltage doesn't rise.
-Garrett
Hi sir,
Thank you for your reply.
We concluded that the cause of this issue is the PCB flexing.
Thank you for your support.
Best regards,