Tool/software:
Applying 18VDC to the input of the enclosed circuit works. However, applying 28VDC fries the IC. This part is rated for Vin=36V (Abs.Max=40V), so I'm not sure what's causing the failure. There is no load on the 12V output. There is no overshoot on the 28VDC that is applied to the input.
Please advise ...
Thank you.
Hello Allen,
I am hoping to rule out ringing over the abs max of the part on the input, especially if you have some inductance on the input from the power supply connection to the ceramic input capacitors. Can you get an oscilloscope measurement of the input voltage across the input pin and GND pin of the module?
Another suggestion for troubleshooting: If you are getting consistent failure, can you please place a bulk Aluminum Electrolytic capacitor in parallel with C29 and do testing with the bulk cap and higher input voltage? Then remove the cap and see if you get a failure. If there is any input overshoot, the bulk capacitor with ESR will help provide some damping. If the part operates normally with the bulk cap it will give us a clue.
Regards,
Denislav
Hi Denislav,
So the overshoot is close to 35V (on my 200MHz o'scope). I will experiment with an aluminum electrolytic to the input to see what happens ...
