LinkSwitch-PH LED Driver IC Family
Single-Stage PFC, Primary-Side Constant Current Control and TRIAC Dimming/Non-Dimming Options
The LinkSwitch-PH dramatically simplifies implementation of LED drivers requiring long lifetime, high efficiency, PF >0.9, and TRIAC dimming capability (LNK403-410). The single-stage combined power factor and constant-current controller eliminates a switching stage and the electrolytic bulk capacitor. The advanced primary-side control used by the LinkSwitch-PH device provides accurate constant current control while eliminating the need for an optocoupler and current sensing circuits.
LinkSwitch-PH incorporates a 725 V power FET, a continuous-mode PWM controller, a high-voltage switched current source for self biasing, frequency jittering, protection circuitry including cycle-by-cycle current limit and hysteretic thermal shutdown.
Dramatically Simplifies Off-line LED Drivers
• Single-stage combination of power factor correction and accurate constant-current (CC) output
• Enables very long lifetime designs (no electrolytic capacitors)
• Eliminates optocoupler and all secondary current control circuitry
• Eliminates control loop compensation circuitry
• Simple primary-side PWM dimming interface
• Universal input voltage range
• LNK403-410 optimized for flicker-free TRIAC dimming
EcoSmart™ – Energy Efficient
• Single-stage PFC combined with output CC control
• Greatly increases efficiency, >90% achievable
• Reduces component count
• No current sense resistors
• Low standby power remote ON/OFF feature (
Accurate and Consistent Performance
• Compensates for transformer inductance variations
• Compensates for line input voltage variation
• Frequency jittering greatly reduces EMI filter size and cost
Advanced Protection and Safety Features
• Auto-restart for short-circuit protection
• Open circuit fault detection mode
• Automatic thermal shutdown restart with hysteresis
• Meets high voltage creepage requirement between DRAIN and all other signal pins both on PCB and at package
• Halogen free and ROHS compliant package
• Off-line LED driver
Schematic of an Isolated, TRIAC Dimmable, High Power Factor, Universal Input, 14 W LED Driver.
Schematic of an Isolated, Non-Dimmable, High Power Factor, Universal Input, 7 W LED Driver.
Reference Design Report for a >92% Efficient 75 W Power Factor Corrected LED Driver Using LinkSwitchTM-PH LNK420EG
This document is an engineering report describing an isolated LED driver (power supply) utilizing a LNK420EG from the LinkSwitch-PH family of devices.
The RD-290 provides a single constant current output of 2.1 A over an LED string voltage of 29 V to 36 V in a highly efficient, simple and low component count design.
The board was optimized to operate over the high AC input voltage range (190 VAC to 300 VAC, 47 Hz to 63 Hz). LinkSwitch-PH based designs provide a high power factor(>0.95) with low harmonic current content, easily meeting international limits.
The form factor of the board was chosen to illustrate the simplicity of fitting into standard down light applications.
The document contains the power supply specification, schematic, bill of materials, transformer documentation, printed circuit layout, and performance data.
Summary and Features
Single-stage combined power factor correction and accurate constant current (CC) output
Low cost, low component count and small PCB footprint
Highly energy efficient, >92 % at 230 VAC input; 36 V LED
Fast start-up time (
Integrated protection features
Single shot no-load latching protection / output short-circuit protected with auto-recovery
Auto-recovering thermal shutdown with large hysteresis protects both components and printed circuit board
No damage during brown-out conditions
PF >0.95 at 230 VAC
Meet Class C Harmonics Limits EN61000-3-2
Meet EN55015 conducted EMI
Meets IEC ring wave (2.5 kV), differential line surge (2 kV), common mode line surge (4 kV) and EN55015 conducted EMI
Mechanical Bill of Materials
Transformer Electrical Diagram