Hello,
I have a DC-DC converter that starting failing recently when enabled. Normally, the parts sits under full potential with output turned off. On Enable from processor I generate +5V for USB host port. Input varies from 6.5V high to 4.0V low. The input inductor is 22uH. Output capacitors are three 68uF to get past the 150uF spec of USB. I suspect the high end of the voltage being the problem. The part is ok under bias, when disabled. When enabled, it immediately fails short (SW-PGND) and eventually blows the input power protection fuse. Replace the fuse and the chip, and normal operation returns. We are now observing about 3% fall out at the factory, used to be 0%. Any insight how is the part failing? Is there a similar part with higher input voltage rating. Any other ideas? I can increase the input inductor from 22uH to 27uH or even 33uH, trying to slow down the inrush through the main switch. Thank you.
