Fixed-Frequency, Flyback Regulator with Multi-Mode Control and Over-Power Line Compensation



The HF500-30 is a fixed-frequency, current-mode regulator with built-in slope compensation. The HF500-30 combines a 700V MOSFET and a full-featured controller into one chip for a low-power, offline, flyback, switch-mode power supply.
At medium and heavy loads, the regulator works in a fixed frequency with frequency jittering. Jitterring helps reduce EMI energy on the switching frequency and its harmonics. During a light-load condition, the regulator freezes the peak current and reduces its switching frequency to 25kHz to offer excellent efficiency. At very light loads, the regulator enters burst mode to achieve low standby power consumption.
Full protection features include brown-in and brown-out, VCC under-voltage lockout (UVLO), overload protection (OLP), short-circuit protection (SCP), input over-voltage protection (OVP), VCC over-voltage protection (OVP), and over-temperature protection (OTP).
The HF500-30 features over-power line compensation to ensure that the overload protection point is independent of the input voltage.
The HF500-30 is available in a PDIP8-7B package.


  • 700V/1.4Ω Integrated MOSFET
  • Fixed-Frequency, Current-Mode Control Operation with Built-In Slope Compensation
  • Frequency Foldback Down to 25kHz at Light Load
  • Burst Mode for Low Standby Power Consumption
  • Frequency Jittering for a Reduced EMI Signature
  • Over-Power Compensation
  • Internal High-Voltage Current Source
  • VCC Under-Voltage Lockout (UVLO) with Hysteresis
  • Programmable Input B/O and Over-Voltage Protection (OVP)
  • VCC Over-Voltage Protection (OVP)
  • Overload Protection (OLP) with Programmable Delay
  • Latch-Off Protection on TIMER
  • Over-Temperature Protection (OTP) (Auto-Restart with Hysteresis)
  • Short-Circuit Protection (SCP)
  • Programmable Soft Start (SS)
  • Available in a PDIP8-7B Package


  • Power Range DefinedNo
  • GradeCatalog
  • TypeRegulator
  • VCC (max) (V)30
  • Vac (max) (V)305
  • Vbr (V)700
  • PackagePDIP8-7B
  • Vac (min) (V)85