LM3450 Datasheet, PDF (1/28 Pages) National Semiconductor (TI) – LED Driver with Active Power Factor Correction and Phase Dimming Decoder

LM3450
November 18, 2010
LED Driver with Active Power Factor Correction and Phase
Dimming Decoder
General Description
The LM3450 is a power factor controller (PFC) with separate
phase dimming decoder. The PFC regulates an accurate out-
put voltage while maintaining excellent power factor at the
input. The phase dimming decoder interprets the phase angle
and remaps it to a 500Hz PWM output. This combination of
features is ideal for implementing a dimmable off-line LED
driver for 10-100W loads.
The phase dimming decoder has several unique features. A
programmable mapping from input to output increases design
flexibility, while a dynamic filter and variable sampling rate
provide a fast, smooth response to dimmer movement. A dy-
namic hold circuit ensures that the phase dimmer angle is
decoded properly while minimizing the extra power losses
associated with holding current.
Features
■ ^{Critical conduction mode PFC}
■ ^{Over-voltage protection}
■ ^{Feedback short circuit protection}
■ ^{70:1 PWM decoded from phase dimmer}
■ ^{Analog dimming}
■ ^{Programmable dimming range}
■ ^{Digital angle and dimmer detection}
■ ^{Dynamic holding current}
■ ^{Smooth dimming transitions}
■ ^{Low power operation}
■ ^{Start-up pre-regulator bias}
■ ^{Precision voltage reference}
Applications
■ ^{Dimmable downlights, troffers, and lowbays}
■ ^{Indoor and outdoor area SSL}
■ ^{Power supply PFC}
Typical Application
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