LY586 with LYTSwitch-7 Series TRIAC Dimming LED Driver Reference Design

PowerInt's LYTSwitchTM-7 series is a Phase-Cut dimmable single-stage LED driver with PFC and constant current output. The device integrates a 725V high voltage MOSFET with a variable on-state CrM controller. The factor is greater than 0.9, the efficiency is greater than 85%, the line input voltage is ±3% CC regulated, the input voltage is 90 VAC–308 VAC, mainly used in LED lighting. This article introduces the highlights of LYTSwitchTM-7 series, block diagram and 7.5 W, 60 V, 125 mA dimming non-isolated A19 LED driver circuit diagram, and LYTSwitch-7 series 10W 88% efficiency TRIAC dimming LED driver reference design for BR-30 dimming LED lamp DER586 main features and specifications, circuit diagram, bill of materials And PCB design drawings.

The LYTSwitchTM-7 family is ideal for single-stage, high PF, constant current LED dimmable applicaTIons.

The family incorporates a high-voltage MOSFET with a variable on-TIme CrM controller. Extensive protecTIon features with minimum external components provide industry leading power density and funcTIonality.

The CrM operation results in low turn-on losses and reduces cost of output diode (slower reverse-recovery type can be used).

LYTSwitch-7 peak current mode operation is suitable for TRIAC applications without the need for an active bleeder. LYTSwitch-7 devices are suitable for applications from 4 W to 22 W. For more information, see Application section.

Highlights of the LYTSwitchTM-7 series:

Single-Stage PFC + Accurate CC Output
±3% CC regulation in single line input voltage applications
Power factor >0.9
High efficiency >85%
Robust 725 V MOSFET for increased line voltage surge resistance
Critical Conduction Mode (CrM) buck
Low EMI
Excellent line noise and transient rejection
Dimming Highlights
Fast turn-on (<500 ms)
Low pop-on
Better than 10:1 dimming ratio
Simple passive RC damper
Monotonic dimming profile
Design Flexibility
Wide input (90 VAC – 308 VAC) and output voltage range operation
2 family members cover power range for optimum device selection
Requires no inductor bias winding
Small form factor package – SO-8
Highest Reliability
Industry's lowest component count dimming solution
Comprehensive protection features with auto-restart Input and output overvoltage protection (OVP)
Output short-circuit protection
Open-loop protection
Advanced thermal control Thermal foldback ensures that light continues to be delivered at elevated temperatures
Over-temperature shutdown provides protection during fault

Figure 1. LYTSwitchTM-7 Series Block Diagram

Figure 2. 7.5 W, 60 V, 125 mA dimming non-isolated A19 LED driver with LYT7503D

LYTSwitch-7 Series 10W 88% Efficiency TRIAC Dimming LED Driver Reference Design for BR-30 Dimming LED Lamps DER586

This engineering report describes a low component count, TRIAC dimmable, non-isolated buck LED driver, designed to drive a nominal LED voltage string of 60 V at 170 mA from an input voltage range of 90 VAC to 132 VAC. This LED driver utilizes the LYT7503D from the LYTSwitch-7 family of devices.

The LYTSwitch-7 device is an SO-8 package LED driver controller IC designed for non-isolated buck topology applications. The LYTSwitch-7 ICs provide high efficiency, high power factor, accurate LED current regulation, and inherent dimming capability. LYTSwitch-7 ICs incorporate a high-voltage power MOSFET and variable frequency / variable on-time, critical conduction mode control engine for accurate current regulation, high power factor and proprietary power MOSFET utilization for high efficiency. The controller also integrates protection features such as input and output Overvoltage protection, thermal fold-back, over temperature shutdown, output short-circuit and overcurrent protection.

DER-586 is a single stage 10 W TRIAC dimmable LED driver with constant current output. The key design goals were design simplicity, high efficiency, low component count, accurate constant current regulation, compact PCB and acceptable dimming compatibility. The design is intended for BR-30 dimmable LED bulb applications.

This document contains the power supply specification, schematic diagram, bill of materials, printed circuit layout, and performance data.

Reference design DER586 main features:

• Single-stage power factor corrected, PF >0.9
• Accurate constant LED current (CC) regulation, ±5%
• High efficiency, > 88% at 120 VAC
• Low cost and low component count for compact PCB solution
• TRIAC dimmable
• Works with a wide selection of TRIAC dimmers
• Fast start-up time (<500 ms) – no perceptible delay
• Minimum dead-band or visible pop-on effect.
• Integrated protection features
• Open load and output short-circuit protection
• Thermal fold-back protection
• No damage during line brown-out or brown-in conditions
• Meets IEC 2.5 kV ring wave, 1 kV differential surge and EN55015 conducted EMI

Figure 3. Reference design DER586 outline drawing (front)

Figure 4. Reference design DER586 outline drawing (back)
Reference design DER586 main indicators:

Figure 5. Reference design DER586 circuit diagram reference design DER586 material list:

Figure 6. Reference design DER586 PCB design (front)

Figure 7. Reference design DER586 PCB design (back)