LCD Display Inverter

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PowerintLNK405EG15WPAR38TRIAC Dimming LED Driver Solution (DER-281)

Powerint’s DER-281 is a 15W PAR38 TRIAC dimming and flicker-free LED driver reference design using LNK405EG. The input voltage is 180VAC to 265VAC, the output voltage is 30V/0.5A, the full load efficiency reaches 83%, EMI and IEC 61000-4 -5 ringwave, IEC 61000-3-2 Class C and EN55015 B standards compliant. This article introduces the main specifications of the LED driver reference design, main board and daughter board circuit diagrams, bill of materials and PCB component layout diagrams.

The document describes a high power factor (PF) TRIAC dimmable LED driver designed to drive a nominal LED string voltage of 30 V at 0.5 A from an input voltage range of 180 VAC to 265 VAC. The LED driver utilizes the LNK405EG from the LinkSwitch- PH family of ICs.

LinkSwitch-PH ICs allow the implementation of cost effective and low component count LED drivers which both meet power factor, harmonic limits and offer enhanced end user experience. This includes ultra-wide dimming range, flicker-free operation (even with low cost with AC line TRIAC dimmers) and fast, clean turn on.

The topology used is an isolated flyback operating in continuous conduction mode. Output current regulation is sensed entirely from the primary side eliminating the need for secondary side feedback components. No external current sensing is required on the primary side either as this is performed inside the IC further reducing components and losses. The internal controller adjusts the MOSFET duty cycle to maintain a sinusoidal input current and therefore high power factor and low harmonic currents.

The LinkSwitch-PH ICs also provides a sophisticated range of protection features including auto-restart for open control loop and output short-circuit conditions. Line overvoltage provides extended line fault and surge withstand, output overvoltage protects the supply should the load be disconnected and accurate hysteretic thermal shutdown ensures safe average PCB temperatures under all conditions. In any LED luminaire the driver determines many of the performance attributes experienced by the end user. For this design a focus was given to compatibility with as wide a range of dimmers and as large of a dimming range as possible, at 230 VAC. This document contains the LED driver specification, schematic, PCB diagram, bill of materials, transformer documentation and typical performance characteristics.

15W LED Driver Specifications:

15W dimming LED driver main performance:

Focus of design was broad compatibility with standard TRIAC dimmers

o Compatibility includes 1000 W (vs. 600 W) rated models

o No output flicker

o No snap-on when starting from low phase angle

o Up to 1000:1 dimming range – limited only by connected dimmer

o Clean monotonic start-up – no output blinking

Highly energy efficient

o >84% at 230VAC

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

IEC 61000-4-5 ringwave, IEC 61000-3-2 Class C and EN55015 B conducted EMI compliant

Figure 1. 15W Dimmable LED Driver Outline Diagram

Figure 2. 15W dimming LED driver motherboard circuit diagram

Figure 3. 15W Dimmable LED Driver Daughter Board Circuit Diagram
Mainboard Bill of Materials (BOM):

Mainboard Mechanical Components List:

Daughter board bill of materials:

Figure 4. Transformer circuit diagram

Figure 5. Motherboard Component Layout (Top Layer)

Figure 6. Motherboard component layout (bottom layer)
For details, see: