Powerint’s LinkSwitch-PH series greatly simplifies the design of LED drivers that achieve power factor greater than 0.9, TRIAC dimming and high efficiency. The device integrates 725V power MOSFET, continuous mode PWM controller, high voltage switch for self bias Current sources, frequency jittering, cycle-by-cycle current limiting and hysteretic thermal shutdown circuits, ideal for offline LED drivers. This article presents the LinkSwitch-PH family of product highlights, functional block diagrams, 14W and 7W LED driver circuit diagrams, and electroless using the LNK417EG High-efficiency capacitor (≥90%) 15W LED driver with PFC greater than 0.9 reference design circuit diagram, main specifications and bill of materials and PCB layout.

LinkSwitch-PH dramatically simplifies implementation of LED drivers requiring Power Factors greater than 0.9, TRIAC dimming, and high efficiency. This highly integrated controller introduces a new control technique that provides very high power factor and accurate output current control, and eliminates passive circuitry required for power factor correction, optocoupler and secondary current control circuitry.

Each device incorporates a 725V power MOSFET, a continuous-mode PWM controller, a high voltage switched current source for self biasing, frequency jittering, cycle-by-cycle current limit and hysteretic thermal shutdown circuitry into a monolithic IC.

LinkSwitch-PH Series Product Highlights:

Dramatically Simplifies Off-line LED Drivers

Single-stage power factor correction and accurate constant current (CC) output

Flicker-free, phase-controlled TRIAC dimming

Eliminates optocoupler and all secondary current control circuitry

Eliminates all control loop compensation circuitry

Simple primary-side PWM dimming interface

Universal input voltage range

Enables designs that are electrolytic-free

Accurate and Consistent Performance

Fast start-up time

Compensates for transformer inductance tolerances

Compensates for line input voltage variations

Frequency jittering greatly reduces EMI filter size and costs

Advanced Protection and Safety Features

Auto-restart for short circuit protection

Open circuit fault detection mode

Automatic thermal shutdown or restart with hysteresis

Meets high voltage creepage requirement between DRAIN and all other signal pins both on PCB and at package

EcoSmart – Energy-Efficiency Technology

Low standby power remote ON/OFF feature (< 50 mW at 230 VAC)

No current sense resistors – maximizes efficiency

High efficiency operation, >85% achievable

Green Package

Halogen free and RoHS compliant package

LinkSwitch-PH Application:

• Off-line LED driver

Figure 1. LinkSwitch-PH Series Functional Block Diagram

Figure 2. LinkSwitch-PH Series Insulated TRIAC Dimmable High Power Factor Universal Input 14W LED Driver Circuit Diagram

Figure 3. LinkSwitch-PH Series Isolated Non-Dimming High Power Factor Universal Input 7W LED Driver Circuit Diagram Using LNK417EG Electrolytic Capacitor-Free High Efficiency (≥90%) 15W LED Driver Reference Design with PFC Greater than 0.9

This document describes an isolated, power factor corrected, very high efficiency LED driver designed to drive a 30 V LED string at a current of 500 mA (nominal). The input voltage range is 90 VAC to 265 VAC.

The LED driver uses a LNK417EG device from the LinkSwitch-PH family of ICs. This integrated controller and 725 V MOSFET dramatically reduces the complexity and component count of the solution.

The key design goals were to achieve the highest possible efficiency and eliminate electrolytic capacitors. Both are key factors for increasing the lifetime and reliability of LED drivers making this solution ideal for industrial and commercial applications.

15W LED Driver Reference Design Key Features:

No electrolytic capacitors

Clean monotonic start-up – no output blinking

Fast start-up (<100 ms) – no perceptible delay

Highly energy efficient

o ≥90% at 115 VAC and 230 VAC input Low cost, low component count and small printed circuit board footprint solution

o No current sensing required

o Frequency jitter for smaller, lower cost EMI filter components Integrated protection and reliability features

o Output open-circuit / output short-circuit protected with auto-recovery

o Line input overvoltage shutdown extends voltage withstand during line faults.

o Auto-recovering thermal shutdown with large hysteresis protects both components and printed circuit board

o No damage during brown-out or brown-in conditions

Meets IEC 61000-4-5 ring wave, IEC 61000-3-2 Class C harmonics and EN55015 B conducted EMI

Figure 4. 15W LED Driver Reference Design Outline Drawing: 3.115” L x 1.525” W.
Power Specifications:


Figure 5. 15W LED Driver Reference Design Circuit Diagram


Figure 6. Transformer circuit diagram
Transformer main indicators:

Figure 7. PCB Layout (Top Layer)
For details, see:
http://www.powerint.com/sites/default/files/product-docs/linkswitch-ph_family_datasheet.pdf
and
http://www.powerint.com/sites/default/files/PDFFiles/der284.pdf