Perhaps you need to mention the load current. However ON semi's AN920 deals with many such converters adopting MC34063A. That is really a good chip. One such power supply design can be found on elektor UK magazine and / or EPE magazine of UK as an application for laptop power supply from 12V DC input.
hi,
thanks for reply......
i am trying to build my owm circuit ......
but i am confused.....
i am trying to build circuit using inductor(52uH), diode(1N5408), mosfet(IRFZ44N) & a capacitor of 4.7uF...... normal Boost circuit.......
feeding signal from atmega controller of 20KHz,50% duty cycle of 12V
@pushpa,
calculate the impedance offered by the 52uH, (unsaturated) at 20KHz. i fear you have to either increase frequency or the inductance. lower inductance would be like short circuit during the ON period of the pulse.