Can 2 diodes and a capacitor be used to generate a negative voltage?

Thread Starter

Younes Thabet

Joined Jan 9, 2019
144
Hey!
I came across this circuit (see attached picture) which is used to create a -15V from a 15V rail then used as an input for a negative voltage regulator.
I couldn't understand quite how the circuit works! Can someone explain this for me please?

PS: the 2 diodes are in the same die, and i am not sure of the orientation of diodes.
But GND is connected on the top pin, -Vin on left pin, and VDD on right pin of the SOT-323 package.

IMG_20230121_202503.jpg

Thanks,
 

Thread Starter

Younes Thabet

Joined Jan 9, 2019
144
If the +15V input is DC then no, that circuit won't generate a negative voltage.

Where did you "come across" that circuit?
it's not a schematic It's an IGBT gate driver that I am trying to fix. I think this negative voltage regulator is used to generate a -15V rail for fast turn-off of IGBTs and to prevent miller injection phenomena.
The diodes are a SOT-323 package and might be in a different configuration. I thought it could be a BAV99 but I guess I was wrong.
 
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