VAC

TSNS

LM3447

FLT1

FLT2

BIAS

HOLD

AUX

VCC

FF

INV

COMP

GATE

ISNS

GND

+

–

+

–

LM3447

www.ti.com

SNOSC65 A – APRIL 2012 – REVISED MAY 2012

Phase Dimmable, Primary Side Power Regulated PFC Flyback Controller for LED Lighting

Check for Samples: LM3447

1

FEATURES

DESCRIPTION

The LM3447 is a versatile power factor correction

•

Integrated Phase Angle Decode

(PFC) controller designed to meet the performance

–

Leading and Trailing Edge Compatible

requirements of residential and commercial phase-cut

–

Over 50:1 Dimming Range

dimmer compatible LED lamp drivers. The device

incorporates

a

phase

decoder

circuit

and

an

•

Power Factor Correction with Low Total

adjustable hold current circuit to provide smooth,

Harmonic Distortion

flicker free dimming operation. A proprietary primary

•

Primary Side Control Using Input Voltage

side

control

technique

based

on

input

voltage

Feedforward Technique

feedforward is used to regulate the input power

•

Input Power Regulation Scheme with Improved

drawn by the LED driver and to achieve line

regulation over a wide range of input voltage. Valley

Line Regulation

switching operation is implemented to minimize

•

Constant Power Operation of LEDs to

switching loss and reduce EMI. An internal thermal

Compensate for Forward Voltage Variations

foldback circuit is provided to protects the LEDs from

Over Temperature and Lifetime

damage based on the temperature sensed by a

•

Fixed Frequency Discontinuous Conduction

single external NTC resistor. Additional features

Mode Operation

include LED open circuit and short circuit protection,

cycle-by-cycle FET over-current protection, burst

•

Valley Switching Operation to Achieve High

mode fault operation using an internal 812ms fault

Efficiency and Low EMI

timer and internal thermal shutdown.

•

Efficient TRIAC Hold Current Management

The LM3447 is ideal for implementing dimmable,

•

Thermal Foldback Function for LED Protection

isolated

single

stage

LED

lamp

drivers

where

•

LED Open Circuit and Short Circuit Protection

simplicity, low-component count and small solution

size are of primary importance. This device is

APPLICATIONS

currently available in a TSSOP 14-pin package.

•

Dimmable A19, R20, PAR30/38 LED Lamps

•

Recessed LED Downlights and Pendant Lights

•

Industrial and Commercial Solid State Lighting

TYPICAL APPLICATION DIAGRAM

1

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

PRODUCTION DATA information is current as of publication date.

Copyright © 2012, Texas Instruments Incorporated

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.