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LM46002: power supply stops working after 2 month

Part Number: LM46002

My lm46002 work great but one a while, the chip stop working. I have read a thread with the same title as this one that have exactly the same problem has mine. I wanted to know what was the issue. The Vcc doesn't raise to 3.2V it stay at 0.37V. if I supply a external 3.2V to the chip it start working properly even if I remove the external supply. In the other thread you asked if Vin could go below Vout, what happen if on a power down the Vout stay for a while while the capacitor discharge. My problem seam to begin when we cycle the power (not every time, it happen very rarely but it happen)

Vin = 36V

Vout = 5V

Iout = 50mA to 2000mA

Thank you.

  • If the output capacitors are allowed to discharge through the device, there may be a large current spike that can damage the 

    device.  If you believe that is a possibility, then using a Schottky diode from input to output will provide a path for the current 

    around the device.

    If you still have trouble, please gives us your schematic and an image of your PCB layout (or Altium) and we may be able to help further.

  • Hello

    I will close this post due to inactivity.

    Thanks

  • I tried to put a schotky between vin and vout. It help, but after one week it failed again. I then place a larger capacitor (100uF) on Vin and I program the UVLO to stop working at higher voltage. I am currently testing this solution on a bench with a PLC that cycle the power on many device in parallel. It seem to fix the problem but I want to do more tests to be absolutly sure that the problem is solved. I hope it will help somebody with the same problem.