Offline switcher achieves 92% efficiency in classic flyback topology

February 5, 2026

The Power Integrations TinySwitch-5 family of integrated offline switcher ICs improves conversion efficiency in low- and mid-power flyback converters with an output of up to 175W.

The TinySwitch-5 dynamically adjusts its switching frequency to maintain high efficiency across varying loads, achieving up to 92% efficiency with standard diode rectification and optocoupler feedback across a wide load range.  

 

The fast switching capability of up to 150kHz, enables power-system designers to reduce transformer size. The TinySwitch-5 offline switchers also provide a highly integrated solution for flyback circuits, combining a 725V power MOSFET, control and protection circuitry into a single package.  

 

The TinySwitch-5 flyback controller can operate in continuous conduction mode (CCM) or discontinuous conduction mode (DCM). This control approach reduces switching losses during low-power operation while maintaining sufficient auxiliary output to support display, communication, or control functions.  

 

The IC supports up to 75W operation without a heat-sink due to improved thermal management in its enhanced package structure. No-load power consumption of less than 30mW at 230V ac helps product manufacturers to comply with strict standby power regulations.  

 

Built-in line under- and over-voltage protection stabilizes operation in regions with variable mains conditions, while frequency jittering reduces EMI without the need for external filtering.  

 

The TinySwitch-5 architecture allows designers to meet high efficiency targets without adopting more complex synchronous rectification or resonant converter topologies, retaining the simplicity of a traditional flyback design. 

Features

  • Integrated soft start 
  • Adjustable current limit 
  • Output short-circuit protection 
  • Thermal shutdown with large hysteresis 

Applications

  • Utility meters 
  • Industrial power supplies 
  • Appliance power supplies 
  • Consumer products 

Reference Design Board

RDK-1016

he RDR-1016 reference design board from Power Integrations implements a flyback converter which provides a dual isolated output voltage of 12V at 2A, and 5V at 500mA, from a wide input-voltage range of 85V to 265V ac. The power supply is based on the TNY5073K flyback converter, a member of the TinySwitch-5 family of ICs.  

 

The board achieves peak efficiency of at least 87% at full load with a 230V ac input. Average efficiency across the load range is at least 85%.  

 

The RDR-1016 conforms to the requirements of the CISPR22B/EN55022B standards for conducted EMI emissions. It is specified for operation at an ambient-temperature range of 0°C to 40°C with free-air convection cooling.  

 

Key features include: 

  • Up to 150kHz switching frequency  
  • <50mW no-load input power at 230V ac  
  • Protection features:  
  • Line under-voltage protection  
  • Line over-voltage protection  
  • Over-temperature protection  
  • Short-circuit protection  
  • Over-power protection 

 

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