Connection method of optocoupler inisolated SMPS?

eem2am

New member
Hello,
Regarding opto-isolated flyback SMPS’s, which opto-coupler connection method is more conducive to facilitating a higher bandwidth in the feedback loop whilst maintaining stability?….is it the common emitter connection of the opto, or the common collecter connection?

An LTspice simulation (also schematic) showing both connection methods is attached. In the simulator, the “common emitter connection” version is far harder to make stable.
 

Attachments

  • Flyback _opto_CE_CC compare.pdf
    27.7 KB · Views: 25
  • Flyback _opto_CE_CC compare.txt
    16.1 KB · Views: 22
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