compensation cap in flyback smps

[saurav_sdpl]

Hii,

Generally compensation cap in error amplifier design of flyback smps is used for stability of power supply.

I want to know how excatly the value of cap is determined, should we use a low value cap or a high value cap in the design.

Regards
Saurabh

 

[Orson Cart]

there is a fair bit of learning involved for someone to calculate the feedback components for stable, fast operation, each situation is different - your question is too open ended.

 

[electrophysics]

in general compensation of capacitors and resistors in error amplifier is done so that at cross over frequency at which overall gain will be unity the phase angle does not come at 360 degree. i.e. there should be some phase margin plus at cross over frequency the resultant gain slope should be of -1 type (-20db/decade). of course you have to read a lot to understand it. also that at low frequency where bridge rectifier ripple may produce bad effects on loop there should be gain boost at low frequencies and similarly at very high frequencies where noise pick up may produce bad effects there should be decrease in gain. all this is done with compensation. also it depends on that either we are using output capacitors with or with out having any ESR.