Compensation Circuit [ using Electrolytic Capacitor ]
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I would like to ask if what is the disadvantage and advantage using Electrolytic capacitor compare to non-polarize capacitor in error amplifier compensation circuit at the output regulation circuit. Sometimes during design one must put a larger value of capcitance on the compensation circuit for better load dynamic response and Ecaps has that value.
When using an electrolytic, there are several problems.
One is DC polarization. Be sure that if there is DC voltage across the part, you have the polarity right. Also, there is usually some AC on the components in a compensation network, and if the polarity of the voltage on the cap. reverses under transient conditions, it will fail. In this case, a nonpolarized part is necessary, though these are larger, since they consist simply of two electrolytics back to back, doubling the volume, while halving the capacitance.
Secondly, the intial capacitance value of an electrolytic is not very accurate. Typically, these parts are -20%/+100% which means the corner in your compensating network will vary a lot in mass production.
Further, there is a considerable change in esr with temperature: about a factor of 1/2 when hot, and as much as 10X when cold! The rC corner is usually around 2-3 KHz, so this can be a problem, depending on how the part is used.
Options would be tantalums or stacked ceramics in the <100uF range; by raising the overall impedance level of your feedback, the R's go up, so your C's get smaller - another way to go! If you use this second approach, be careful of letting noise in as impedance rises: this is a design tradeoff.
