24V 36W AC-DC Reference Design with a Quasi-Resonant Controller

January 10, 2019 by Paul Shepard

The EVHFC0100HS-00A evaluation board from Monolithic Power Systems provides a reference design for a universal offline power supply with 24V, 1.5A output. It contains the complete specification of the power supply, a detailed circuit diagram, the entire bill of materials required to build the power supply, drawing of the power inductors and transformers, and test data of the most important performance.

Possible applications include: Battery chargers for cellular phones, digital cameras, video cameras, etc.; Standby power supplies for televisions, desktop PCs, audio systems, etc.; Power supplies for printers, DVD/VCR/CD players, set-top boxes, etc.; and Adapters for notebook/tablet computers, and so on.

The EVHFC0100HS-00A evaluation board features the HFC0100, a peak current mode controller with Green Mode Operation. Its high efficiency over the entire line and load range meets the stringent world-wide energy efficiency requirements.

(click on schematic to enlarge)

The HFC0100 integrated with a high-voltage current source, its valley detector ensures minimum Drain-Source voltage switching (Quasi-Resonant operation). When the output power falls below a given level, the controller enters the burst mode.

The HFC0100 provides various protections, such as Thermal Shutdown (TSD), Vcc Under Voltage Lockout (UVLO), Over Load Protection (OLP), Over Voltage Protection (OVP) and so on.

The HFC0100 is available in the 8-pin SOIC8 package.

EVHFC0100HS-00A evaluation board

Summary of features and specifications:

  • Universal Main Input Voltage (85- to 265-Vac)
  • Quasi-Resonant Operation
  • Valley Switching for high efficiency and EMI
  • Burst Mode for low standby consumption
  • Internal High Voltage Current Source
  • High level of integration, allows a very low number external component count
  • Maximum Frequency Limited
  • Internal Soft Start
  • Internal 250nS Leading Edge Blanking
  • Thermal shutdown
  • Vcc UVLO with Hysteresis
  • Over Voltage Protection
  • Over Load Protection