I am trying to analyze a circuit where AOZ1014 buck converter is used to generate 7.5V and negative voltage(-5V) is generated with following arrangement.
As shown above Lx pin of AOZ1014 ( left sided pin of inductor L2 )is assigned to 7905 regulator with C33,D16 and D18 arrangement. Here, as per my consideration, D18 is for suppressing +ve peak to ground since we need -ve input to 7905 IC.
What is the purpose of D16, R57 and C33 here? How changing C33 will change my output voltage?
I used same concept with TP5430 Buck regulator as shown.
But I am getting random results in my case here. Sometimes it is regulating as per my requirement but randomly misbehaves with loading 7.5V to 1.5V and -5V to -2v. Am I correct in assigning C33 pin to in between of C31 and L2? Can someone guide me to make it work.
Thanks in advance.