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Power Integrations


LinkSwitch-TNZ Energy Efficient Off-Line Switcher IC

With Best-in-Class Light Load Efficiency and Lossless AC Zero-Cross Detection

The Power Integrations LinkSwitch-TNZ family of ICs combine power conversion with lossless generation of AC zero crossing signal used typically for system clock and timing functions. Designs using the highly integrated LinkSwitch-TNZ ICs are more flexible than discrete implementations reducing component count by 40% or higher. Besides enabling 80+ efficiencies in low power Flyback designs, very low consumption at light loads enabled by On/Off control allow for more functions (display, wireless connectivity, sensors etc.) to be active during system standby. The device family supports buck, buck-boost and flyback converter topologies.

Each device incorporates a 725 V power MOSFET, oscillator, a high-voltage switched current source for self-biasing, frequency jittering, fast (cycle-by-cycle) current limit, hysteretic thermal shutdown, and output and input overvoltage protection circuitry onto a monolithic IC.

LinkSwitch-TNZ ICs consume <100 µA current in standby resulting in power supply designs that can meet no-load and standby regulations worldwide. MOSFET current limit modes can be selected through the BYPASS pin capacitor value. The high current limit level provides maximum continuous output current while the low level permits using very low-cost and small surface mount inductors. A full suite of protection features enables safe and reliable power supplies protecting the device and the system against input and output overvoltage faults, device over-temperature faults, lost regulation, and power supply output overload or short-circuit faults.


Product Highlights

◊ Highest Performance and Design Flexibility

  • Lossless zero cross signal generation
  • Supports buck, buck-boost and flyback topologies
  • Enables ±3% regulation across line and load
  • Selectable device current limit
  • 66 kHz operation with accurate current limit
    • Allows the use of low-cost off-the-shelf inductors
    • Reduces size and cost of magnetics and output capacitor
  • Frequency jittering reduces EMI filter complexity
  • X capacitor discharge function (LNK331x only)

◊ Enhanced Safety and Reliability Features

  • Soft-start limits system component stress at start-up
  • Auto-restart for short-circuit and open loop faults
  • Output overvoltage protection (OVP)
  • Line input overvoltage protection (OVL)
  • Hysteretic over-temperature protection (OTP)
  • Extended creepage between DRAIN pin and all other pins improves field reliability
  • 725 V MOSFET rating for excellent surge withstand
  • Nemko (EN62368-1) and CB (IEC62368-1) certifications

◊ EcoSmart– Extremely Energy Efficient

  • IC standby supply current <100 µA
  • On/Off control provides constant efficiency over a wide load range
  • Easily meets all global energy efficiency regulations
  • No-load consumption <30 mW with external bias

◊ Applications

  • Home and building automation
  • Dimmers, switches and sensors with and w/o Neutral wire
  • Appliances
  • IoT and industrial controls


LinkSwitch-TNZ Functional Block Diagram

LinkSwitch-TNZ Typical Buck Converter Application

Introduction to LinkSwitch TNZ with Power Integrations


Reference Design Kit for LinkSwitch-TNZ

Reference Design Kit for a 6 W Isolated Flyback Power Supply with Lossless Generation of AC Zero Cross Signal Using LinkSwitchTM-TNZ LNK3306D

Specification: 90 VAC – 305 VAC Input, 12 V, 0.5 A Output

Application: Home Appliance and Industrial Power

Power Integrations — RDK-877

Summary and Features

  • Meets all existing and proposed energy efficiency standards including ErP
  • No-load consumption <30 mW across AC line
  • More than 350 mW available in stand-by while meeting 500 mW max input power
  • Active mode efficiency meets DOE6 and EC CoC (v5)
  • Highly integrated solution with LNK3306D
  • Low-component count with integrated 725 V power MOSFET, current sensing and protection
  • Wide-range AC input
  • Isolated Zero-crossing signal output synchronized to AC line
  • >80% full-load efficiency at nominal lines
  • Meets EN550022 and CISPR-22 Class B conducted EMI


Reference Design Kit for a 2.5 W Universal Input, Non-Isolated Buck Converter with Zero Crossing Detection Using LinkSwitchTM -TNZ LNK3307D

Specification: 90 VAC – 300 VAC Input; 5 V / 500 mA Output

Application: Home Building Automation & IoT

Power Integrations — RDK-866

Summary and Features

  • 5 V / 500 mA output for wireless (WiFi, NBIoT etc.) and relay power
  • Low cost and component count buck converter using off-the-shelf inductor
  • Compact solution 1.25" x 1.25" x 0.6"
  • AC zero crossing signal output
  • Optimized for <10 dB audible noise performance
  • No-load input power <50 mW
  • Excellent output voltage line regulation (<2% 5 VTYP)
  • Reduced dissipation during output short-circuit fault
  • Low output voltage ripple <100 mVPK-PK
  • >6 dB conducted EMI margin