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A5975D Blow on Power Up

rmaier9
Associate

Hello,

 

I am using the A5975 in an applicaiton that blows on power up. This sounds similar to the issue in the post below:

https://community.st.com/t5/power-management/st1s41-step-down-switching-regulator-destroys-itself-on-low/m-p/171683

 

I have been unable to fix this with the exception of adding a resistor (10 Ohm or more) between the power supply and the A5975 (VBAT to VCC). This failure appears to happen only at power ON with a low impedance source. That is: power supply ON and plug in the power to target. I believe that connector bouncing makes this worse. Plugging or switching the power does not consistently cause a failure, but it does occur too frequently. If I plug in the power connector and apply power from the power supply, the voltage is ramped up over a few milliseconds. It never fails under this condition. I have yet to see this cause a failure, so it's likely a low impedance power supply switched on suddenly.

The schematic is essentially the same as the reference design in the datasheet.

Here's the schematic.

rmaier9_0-1723159208709.png

Any ideas what I am doing wrong here?

 

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