HF500A-30 EMI Optimized Flyback Regulator Monolithic Power Systems (MPS) HF500A-30 EMI Optimized Flyback Regulator is a fixed-frequency, current-mode regulator with built-in slope compensation. With EMI optimization, the device combines a 700V MOSFET and a full-featured controller into one chip for a low-power, offline, flyback, switch-mode power supply.