I was trying to design a low power forward converter which convert 5V to 3v3. I used mc34063 for PWM at 100khz. But in datasheet the saturation voltage typical 1V, max 1.3V for output of 34063. ( it has two transistor as configure darlington in output). Therefore the number of two in transformer can not go zero. 34063 can not push it to ground.(In the photo blue waveform-probe 2). I need to create %50 duty cycle in 100khz. Can anybody help to me ?

 

You could use the Darlington output (pin 1) to drive an external transistor for switching the inductor.

 

That looks like a massive amount of work to go through just to drive a linear regulator at the output.

1. Is an isolated output required?

2. What is the required output current?

ak