Hello,
I am doing an isolated, offline flyback SMPS.
I must have low standby power, and also, very little current (less than 30uA) in the opto-diode during heavy load.
so i must use this circuit
http://i54.tinypic.com/295r18x.jpg
.....but do you know of problems with this?....will the feedback loop gain be too high due to the PNP amplfier?
The PWM controller IC on the primary side has a feedback pin which is connected to the opto collector...........just 90uA COMPLETELY stops switching.
i cannot use this circuit, as the parallel resistor invokes current in the opto-diode http://i53.tinypic.com/300qt8l.jpg
...due to the volt drop across the opto diode
I am doing an isolated, offline flyback SMPS.
I must have low standby power, and also, very little current (less than 30uA) in the opto-diode during heavy load.
so i must use this circuit
http://i54.tinypic.com/295r18x.jpg
.....but do you know of problems with this?....will the feedback loop gain be too high due to the PNP amplfier?
The PWM controller IC on the primary side has a feedback pin which is connected to the opto collector...........just 90uA COMPLETELY stops switching.
i cannot use this circuit, as the parallel resistor invokes current in the opto-diode http://i53.tinypic.com/300qt8l.jpg
...due to the volt drop across the opto diode
