ZCD

GATE

LM3450/50A

GND

COMP

FB

HOLD

CS

DIM

FLT2

FLT1

PWM

BIAS

RETURN

SECONDARY

LED DRIVER

OPTICAL

ISOLATION

RETURN

EMI FILTER

PWM

AC

INPUT

LED

LOAD

VCC

VAC

ISEN

VREF

VADJ

HOLD

LM3450

www.ti.com

SNVS681D – NOVEMBER 2010 – REVISED MAY 2013

LED Drivers with Active Power Factor Correction and Phase Dimming Decoder

Check for Samples: LM3450

1

FEATURES

DESCRIPTION

The LM3450/50A is a power factor controller (PFC)

2

•

Critical Conduction Mode PFC

with separate phase dimming decoder. The PFC

•

Over-Voltage Protection

regulates

the

output

voltage

while

maintaining

•

Feedback Short Circuit Protection

excellent power factor. The phase dimming decoder

interprets the phase angle and remaps it to a 500Hz

•

70:1 PWM Decoded From Phase Dimmer

PWM output. This device is ideal for implementing a

•

Analog Dimming

dimmable off-line LED driver for 10-100W loads.

•

Programmable Dimming Range

The phase dimming decoder has several unique

•

Digital Angle and Dimmer Detection

features. The input-output mapping is programmable

•

Dynamic Holding Current

for design flexibility, while a dynamic filter and

variable

sampling

rate

provide

smooth

uniform

•

Smooth Dimming Transitions

dimming. A dynamic hold circuit ensures that the

•

Low Power Operation

phase dimmer angle is decoded properly while

•

Start-Up Pre-Regulator Bias

minimizing extra power loss.

•

Precision Voltage Reference

The LM3450A is identical to the LM3450 with the

exception of one circuit operation. The dynamic hold

APPLICATIONS

current

is

sampled

in

the

LM3450

while

it

continuously

operates

in

the

LM3450A.

This

•

Dimmable Downlights, Troffers, and Lowbays

difference between the two devices defines the

•

Large Form Factor Bulbs

suitable applications for each. The following is a

•

Indoor and Outdoor Area SSL

general guideline for choosing the correct device:

•

Power Supply PFC

•

Any 120V designs with POUT > 15W - LM3450A

•

Any 230V designs with POUT > 25W - LM3450A

•

120V 2-Stage designs with POUT < 15W - LM3450

•

230V 2-Stage designs with POUT < 25W - LM3450

Typical Application

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.

2

All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Copyright © 2010–2013, 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.