I know this is an old post, but I came across this problem yesterday, so the problem is still current.
I have been developing a project using a USB cable and yesterday, it was time to deploy the controller in it's final location.
I had checked
- the current carrying capacity of the schotky diode. 800 mA
- the input voltage of the AMS1117 voltage regulator 40V.
My assumption is/was that the 10uF decoupling capacitor has sufficient rating to handle say >16 V.
Anyway, I turned it on & immediately I saw smoke coming from the input diode (idiot diode) and the 12/14V connecting wire was un-soldered off the pin due to the created heat. Ie. it acted as a fuse. However the diode was now short circuited.
I then plugged the controlled back to my lap top via USB and this time the 10uF. decoupling capacitor lit up, so I quickly disconnected the controller.
This morning I removed the faulty diode & capacitor and I find that the controller works 100% OK.
So, my suspicion is that the voltage rating of the de-coupling capacitor is insufficient. I have no way of knowing what it is, but it might only be 6 Volt or so, which is typical for hi K ceramic capacitors.
With 14V supplied to Vin. this capacitor fails, becomes a short circuit and then causes the idiot diode to fail.
Solution. Replace this capacitor with a 10uF. capacitor with a voltage rating of at least 20V.
For what it is worth!