This engineering report describes a low component count, non-isolated, dimmable LED
driver in buck topology, designed to drive 52 V LED voltage string at 120 mA output
current from an input voltage range of 90 VAC to 132 VAC. The LED driver utilizes the
LYT7503D from the LYTSwitch-7 family of devices.
LYTSwitch-7 is a SO-8 package, TRIAC dimmable LED driver controller IC designed for
non-isolated buck topology applications. The LYTSwitch-7 provides high efficiency, high
power factor and accurate LED current regulation. LYTSwitch-7 ICs incorporate a high-
voltage power MOSFET and variable frequency / variable on-time, critical conduction
mode control engine for tight 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-539 offers a TRIAC dimmable, high power factor and low components count solution
for 6.2 W LED bulbs. The key design goals were low component count, high power factor
and excellent dimming compatibility.
The document contains the power supply specification, schematic, bill of materials,
transformer documentation, printed circuit layout, design spreadsheet, and performance