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Power Integrations


Power Integrations InnoSwitch4-Pro Flyback Switcher ICs

Digitally Controllable Off-Line CV/CC Flyback Switcher IC with 750 V PowiGaN, Active Clamp Drive and Synchronous Rectification, Pairs With ClampZero Active Clamp IC for ZVS or Uses Stand-alone for Quasi-Resonant Mode

The InnoSwitch™4-Pro family of I²Cs substantially reduces the size of power adapters. Switching frequency of up to 140 kHz and a very high level of integration combine to reduce the component volume and PCB board area required by a typical adapter implementation.

InnoSwitch4-Pro interfaces seamlessly with the ClampZero family of active clamp ICs to achieve Zero Voltage Switching in both continuous and discontinuous conduction modes. Alternatively, InnoSwich4-Pro can operate in QR mode using an RCD clamp with the appropriated part number choice.

Overall system efficiency exceeds 95%, allowing designers to eliminate heat sinks, spreaders and potting materials for thermal management, further reducing size, component cost and manufacturing complexity. The integration of PowiGaN primary switch and controller, isolated feedback and secondary controller with an I²C interface simplifies the development and manufacturing of fully programmable, highly efficient power supplies.


Product Highlights

Highly Integrated, Compact Footprint

  • Quasi-Resonant (QR) or zero voltage switching (ZVS) flyback controller when paired with ClampZeroTM (active clamp IC)
  • Unique control algorithm to enable ZVS in both DCM and CCM
  • Robust 750 V PowiGaNTM primary switch
  • Steady-state switching frequency up to 140 kHz minimizes transformer size
  • Synchronous rectification driver and secondary-side sensing
  • Integrated FluxLinkTM, HIPOT-isolated, feedback link
  • Drives low-cost N-channel FET series load switch
  • Integrated 3.6 V supply for external MCU

Digitally Controlled via I2C Interface

  • Precise CV, CC, CP Control
  • Dynamic adjustment of power supply voltage and current
  • Selectable DCM-only operation to reduce SR FET voltage stress
  • Optimized command set to reduce I2C traffic
  • Telemetry for power supply status and fault monitoring

EcoSmart™ – Energy Efficient

  • Efficiency up to 95%
  • Less than 30 mW no-load including line sense and MCU

Advanced Protection / Safety Features

  • Series load switch short-circuit protection
  • Disable output fault response
  • Fast input line UV/OV protection
  • Programmable Output OV/UV fault detection and response
  • Open SR FET gate detection
  • Hysteretic thermal shutdown
  • Programmable watchdog timer for system faults

Full Safety and Regulatory Compliance

  • Reinforced isolation >4000 VAC
  • 100% production HIPOT testing
  • UL1577 isolation voltage 4000 VAC and TUV (EN62368) safety approved

Green Package

  • Halogen free and RoHS compliant


  • High density power adapters
  • Multiprotocol adapters including USB PD + PPS, QC, VOOC, VFC, SCP
  • Direct-charge mobile device chargers
  • Multi-chemistry tool and general purpose battery chargers
  • Adjustable CV and CC LED ballast

Block Diagram

Primary Controller Block Diagram

Power Integrations – InnoSwitch4-Pro Primary Controller Block Diagram

Secondary Controller Block Diagram

Power Integrations – InnoSwitch4-Pro Secondary Controller Block Diagram


Reference Design: RDR-961 60W Programmable Power Supply

60W programmable power supply with Zero Voltage Switching (ZVS) and 5-20 V variable output using PowiGaN-based Innoswitch4-Pro (INN4373F-H341), ClampZero (CPZ1075M) and Microchip™ microcontroller (PIC16F18325)

Power Integrations – RDR-961 60W Power Supply Using InnoSwitch4-Pro

InnoSwitch4-Pro Reference Design

RDR-961 Reference Design Report contains:

  • Power supply specification
  • Schematic diagram
  • Printed circuit board layout
  • Bill of materials
  • Transformer documentation
  • Performance data