Reference Design for a 10W Dual-Output (5V / 12V) AC-DC Flyback Converter

February 07, 2018 by Paul Shepard

Power Integrations offers the RDR-611 reference design for a 10W dual-output power supply using the company's InnoSwitch3-EP (INN3672C-H602). The InnoSwitch™3-EP family of ICs dramatically simplifies the design and manufacture of flyback power converters, particularly those requiring high efficiency and/or compact size.

The RDR-611 reference design has an input voltage range of 90- to 265-Vac and delivers outputs of 5Vdc at 0.3A and 12Vdc at 0.7A. The resulting flyback converter has a full-load efficiency of over 85% and a no-load power consumption of 30mW. The InnoSwitch3-EP features an isolation voltage >4000Vac.

The InnoSwitch3-EP family incorporates primary and secondary controllers and safety-rated feedback into a single IC. InnoSwitch3-EP family devices incorporate multiple protection features including line over and under-voltage protection, output over-voltage and over-current limiting, and over-temperature shutdown.

RDR-611 reference design (click on schematic to enlarge)

RDR-611 reference design summary and features

  • InnoSwitch3-EP - industry first ac-dc ICs with isolated, safety rated integrated feedback
  • Built in synchronous rectification for >85% efficiency at nominal ac input
  • All the benefits of secondary side control with the simplicity of primary side regulation
  • Insensitive to transformer variation
  • Extremely fast transient response independent of load timing
  • Meets output cross regulation requirements without linear regulators
  • Primary sensed output overvoltage protection (OVP) eliminates optocoupler for fault protection
  • Accurate thermal protection with hysteretic shutdown
  • Input voltage monitor with accurate brown-in / brown-out and overvoltage protection

RDR-611 board top

RDR-611 board bottom

The InnoSwitch3-EP family includes devices that support the common combinations of latching and auto-restart behaviors required by applications such as appliance, server standby, industrial, utility meter, smart grid, solar inverters and smart lighting.

InnoSwitch3-EP product highlights

  • Highly-integrated, compact footprint
    • Up to 94% efficiency across full load range
    • Incorporates a multi-mode Quasi-Resonant (QR) / CCM flyback controller, 725 V MOSFET, secondary-side sensing and synchronous rectification driver
    • Integrated FluxLink™, HIPOT-isolated, feedback link
    • Exceptional CV accuracy, independent of external components
    • Adjustable accurate output current sense using external output sense
    • Excellent multi-output cross regulation with weighted SSR feedback and synch FETs
  • EcoSmart™ - energy efficient
    • Less than 15mW no-load including line sense
    • Easily meets all global energy efficiency regulations
    • Low heat dissipation
  • Advanced protection / safety features
    • Secondary MOSFET or diode short-circuit protection
    • Open SR FET-gate detection
    • Fast input line UV/OV protection
  • Optional features
    • Auto-restart or latching fault response for output OVP
  • Full safety and regulatory compliance
    • Reinforced isolation
    • Isolation voltage >4000Vac
    • 100% production HIPOT testing
    • UL1577 and TUV (EN60950) safety approved
    • Excellent noise immunity enables designs that achieve class "A" performance criteria for EN61000-4 suite; EN61000-4-2, 4-3 (30 V/m), 4-4, 4-5, 4-6, 4-8 (100 A/m) and 4-9 (1000 A/m) and Ford FMC1278 (RI-115)