1 Features

1• Application Voltage Range: 80 VAC to 277 VAC • Capable of Controlling LED Currents

Greater than 1 A

• Adjustable Switching Frequency

• Low Quiescent Current

• Adaptive Programmable Off-Time Allows for

Constant Ripple Current

• Thermal Shutdown

• No Flicker at 120 Hz

• Low-Profile 10-Pin VSSOP Package

or 8-Lead SOIC Package

• Patented Drive Architecture

2 Applications

• Solid State Lighting

• Industrial and Commercial Lighting

• Residential Lighting

3 Description

The LM3444 is an adaptive constant off-time AC/DC

buck (step-down) constant current controller that provides a constant current for illuminating high

power LEDs. The high-frequency capable

architecture allows the use of small external passive

components. A passive PFC circuit ensures good

power factor by drawing current directly from the line

for most of the cycle, and provides a constant positive

voltage to the buck regulator. Additional features

include thermal shutdown, current limit and VCC

undervoltage lockout. The LM3444 is available in a

low profile 10-pin VSSOP package or an 8-lead SOIC package.