LTspice simulation of MC34063 regulator.

[humvivz]

Yeah!!!!! finally!
Thank you so much 
By the way, what does it mean that MC34063 will give me feedback? Is it i have to put the probe on pin(gnd)?
Really thank you!

[c4757p]

The MC34063 will back off the output when the voltage at the Cinv pin hits 1.25V. You set the output voltage by using a voltage divider chosen so that when the output is what you want, the Cinv pin sees 1.25V and the MC34063 stops increasing the voltage.

[humvivz]

  i got it!
it means Cinv pin acts as sensor,which instructs the MC34063 to continue increase the voltage or stop increase it until i gain the desired output voltage.

Can i ask one more question?
I have to design a 220uH inductor. I know i need datasheet of the iron core to determine how many turns of the coil? Anything else i should consider?

By the way, thank you 

[c4757p]

I'm sure there is, but magnetics really isn't my thing, hopefully someone else can answer that! I usually just throw some wire on a core until the LCR meter reads 220uH...

[humvivz]

Good idea!!
Anyways, Thank you c4757p  ^^
I need to sleep now.
Good bye. And wish you have a great day! Thanks again