This engineering report describes a low component count, TRIAC dimmable, non-isolated
buck LED driver, designed to drive a nominal LED voltage string of 52 V at 90 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.
LYTSwitch-7 is a SO-8 package LED driver controller IC designed for non-isolated buck
topology applications. The LYTSwitch-7 provides high efficiency, high power factor,
accurate LED current regulation, and inherent dimming capability. LYTSwitch-7
incorporates 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 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-540 is a single stage 4.68 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 Candelabra Lamp Bulb applications.
This document contains the power supply specification, schematic diagram, bill of
materials, printed circuit layout, and performance data.