# Switching power supply simulation problem

I'm building a 5V power supply using MC34063 IC. Before I build a prototype, I want to simulate it in Proteus to see if everything works correctly. Here is the schematic:

It is done according to the datasheet for the IC (page 7), which can be found here: https://www.onsemi.com/pub/Collateral/MC34063A-D.PDF

Transformer is 10:1. However, when I start the simulation I cannot finish it (whole thing goes off after simulation of 100msec). Is there something wrong with the schematic? Thank you for help!

• what do you mean whole thing goes off? – jsotola Feb 11 '18 at 21:26
• Have you set your simulation to stop on steady state? – PlasmaHH Feb 12 '18 at 9:27
• This is a classic: you try to simulate a switching converter operating at a 100-kHz switching frequency while the input is a 60-Hz ac line. You can imagine how many high-frequency switching cycles of 10-µs duration it will take before you see a rectified dc voltage biasing the buck converter. The solution is to get rid of the front-end rectifier and replace $C_1$ with a dc source equal to the rectified voltage. It should be much faster now. If you truly want to simulate the whole thing, make sure first the dc-dc is ok and don't save data before several hundreds of ms. – Verbal Kint Feb 12 '18 at 12:03
• @VerbalKint Ok, when at the input there is dc source, everything works correctly. Anyway, the power supply part (meaning transofrmer+rectifier+filtering cap) seems to be fine regarding input for the MC34063? If not, how should it be designed? Unfortunately I couldn't find any reliable schematics on the internet (with switching power supply ICs)... – Em Ka Feb 12 '18 at 12:49
• @jsotola Proteus can't finidh the simulation (it stops at several msecs) – Em Ka Feb 12 '18 at 12:50