Offline switcher achieves 92% efficiency in classic flyback topology
The Power Integrations TinySwitch-5 family of integrated offline switcher ICs improves the efficiency of power conversion in low- and mid-power flyback converters with an output of up to 175W.
The TinySwitch-5 from Power Integrations 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.
Power Integrations provides a blueprint for using the TinySwitch-5 to provide dual low-voltage outputs in its RDR-1016 reference design for an isolated flyback power supply for appliances. This reference design system produces an output of up to 26.5W, with a primary output rated for 12V/2A, and a secondary output of 5V/0.5A. The system supports a universal mains power input ranging from 85V to 265V ac.
The conversion circuit switches at a frequency of up to 150kHz to allow for the use of a small transformer. This achieves higher than 87% full-load efficiency with a 230V ac input. No-load power consumption is 50mW at 230V ac.