I've been doing some research on how diodes fail, and to my understanding, diodes (specifically traditional and Schottky) fail open when their rated current is exceeded for an extended period of time, and fail short when their maximum reverse voltage rating is exceeded for an extended period of time.
I also understand that power supplies often have a diode placed in reverse bias in-between the power supply voltage output and GND to protect against reverse polarity from another voltage source. If a voltage source is applied to the power supply the wrong way, then the diode will short the external voltage source, which sometimes does damage the diode, causing it to fail short. I have read of some cases where this can happen, so now I'm trying to understand this:
- Do diodes usually fail open when their current rating is exceeded?
- If they do, then why do diodes in power supplies sometimes fail short?
Image of Power Supply Reverse Polarity Diode
