LM3445 - Triac Dimmable Offline LED Driver

LM3445

Triac Dimmable Offline LED Driver from the PowerWise® Family

Overview

Diagrams

Parametrics

Documents

Order

Boards

Packaging

Tools

Reliability

Videos

Features

• Triac dim decoder circuit for LED dimming

• Application voltage range 80V_AC – 270V_AC

• Capable of controlling LED currents greater than 1A

• Adjustable switching frequency

• Low quiescent current

• Adaptive programmable off-time allows for constant ripple current

• Thermal shutdown

• No 120Hz flicker

• Low profile 10 pin MSOP Package

• Patent pending drive architecture

Description
The LM3445 is an adaptive constant off-time AC/DC buck (step-down) constant current controller designed to be compatible with triac dimmers. The LM3445 provides a constant current for illuminating high power LEDs and includes a triac dim decoder. The dim decoder allows wide range LED dimming using standard triac dimmers. The high frequency capable architecture allows the use of small external passive components. The LM3445 includes a bleeder circuit to ensure proper triac operation by allowing current flow while the line voltage is low to enable proper firing of the triac. 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 V_CC under-voltage lockout.

Applications

• Retro Fit Triac Dimming

• Solid State Lighting

• Industrial and Commercial Lighting

• Residential Lighting

LM3445

AC Frequency 60 Hz 50 Hz

80.00 <= V in Lower
V
<= V in Upper
V
<= 260.00

Ambient Temperature °C <= 100

What are WEBENCH® tools?

MY BRIEFCASE

Click any "Briefcase" icon to add an item

Typical Application *click for larger image

Block Diagram *click for larger image

Typical Performance *click for larger image

Parameters Values

Topology Buck

Input Min Voltage 70 Volt

Input Max Voltage 277 Volt

Output Range 15-100

Output Current 1000 mA

Efficiency (peak) 85 %

Special Features Triac Decode

Adjustable Output Yes

On/Off Pin Yes

Adj Switch Frequency Yes

Sync Pin No

Step-Down Yes

Step-Up No

Inverting No

Flyback No

RegType Switching Controller

Temperature Min -40 deg C

Temperature Max 125 deg C

Feedback Voltage 0.75 Volt

Automotive No

PowerWise Yes

Datasheets
Title Size Date Other
Language

LM3445 Triac Dimmable Offline LED Driver 1201
Kbytes 9-Oct-09 日本語

Featured Application Notes
Title Size Date Other
Language

AN-1935: Application Note 1935 LM3445 Off-Line TRIAC Dimmer LED Driver Demo Board 1716
Kbytes 14-Apr-09 日本語

AN-1978: Application Note 1978 LM3445 120VAC Small Evaluation Board 1279
Kbytes 10-Nov-09

AN-1995: Application Note 1995 LM3445 208-277V AC Non-Isolated Evaluation PCB 1409
Kbytes 23-Oct-09

Part Number(s)
(NSID)

Top View

Availability

Current Reported Stock

Budgetary Pricing

Standard Pack Size

LM3445MM/NOPB

RoHS Status

MINI SOIC

Full production
Lead Time: 6 weeks

Distributor	Region	Qty
ARROW	Worldwide	9704
AVNET-EM	Worldwide	1000
DIGIKEY	Worldwide	5175
FUTURE	Worldwide	592
NEWARK	Americas	494
RSL MICRO	Asia Pacific	14080

$1.75 each at 1K+ pcs

reel
of
1000

LM3445MMX/NOPB

RoHS Status

MINI SOIC

Full production
Lead Time: 6 weeks

Distributor		Region	Qty
DIGIKEY		Worldwide	0

$1.75 each at 1K+ pcs

reel
of
3500

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/packaging/leadfree.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/quality/green.

National's certificate of product compliance is located at RoHS Status.

Part Number(s)
(NSID)

Description

Availability

Current Reported Stock

Budgetary Pricing

Standard Pack Size

LM3445-120VSMEV

Small Footprint/Most Efficient 110V Triac Dimmable Off-line LED Driver Evaluation Board

Full production
Lead Free (RoHS)

Distributor		Region	Qty
DIGIKEY		Worldwide	0
NATIONAL		Worldwide	0

$80.00 each

Description:

The LM3445-120VSMEV 110V Off-Line TRIAC Dimmer LED board converts 90V_AC to 135V_AC input, and drives seven, or eight series connected LEDs at 350 mA average current. The LM3445 switching frequency is set at a nominal 225 kHz. This is a four-layer board using the bottom and top layer for component placement. The demonstration board can be modified to adjust the LED forward current, the number of series connected LEDs and switching frequency.

LM3445 110V Evaluation Board Comparison

LM3445TRIACEVAL has extra pads for evaluating various AC input filter solutions. This board has a lower efficiency rating
LM3445-120VSMEV has been laid out to fit inside an Edison socket and uses a 0.031" thick PCB. It also has the most efficient design.

Contents:

LM3445 110V Small Footprint/High Efficiency Assembled Evaluation Board
Application Note 1978 for the LM3445-120SMEV Small Evaluation Board
LM3445 Datasheet

Part Number(s)
(NSID)

Description

Availability

Current Reported Stock

Budgetary Pricing

Standard Pack Size

LM3445-208277EV

208-277 Vac Triac Dimmable Off-line LED Driver Evaluation Board

Full production

Lead Free (RoHS)

Distributor		Region	Qty
DIGIKEY		Worldwide	8
NATIONAL		Worldwide	73

$80.00 each

The demonstration board included in this shipment is capable of converting a 176 V_AC to 305 V_AC input that has been phase dimmed to drive multiple LED`s at up to 500 mA average current. The evaluation board utilizing the LM3445 will automatically adjust the LED current and light output in relation to the triac firing angle.

The target solution for this design was 230 V_AC input driving 8 series connected white LEDs.? In this configuration the LM3445 will run at a nominal switching frequency of 80 kHz and supply a maximum of 350 mA.

Contents:

LM3445-208277VEV Assembled Evaluation Board
AN-1995: LM3445 208-277V AC Non-Isolated Evaluation Board
LM3445 Datasheet

Part Number(s) (NSID)	Top View	Type	Pins	MSL Rating	Peak Reflow	RoHS Status	CAD Symbols	Models	Package Marking Format
LM3445MM/NOPB		MINI SOIC	10	1	260	Detail	Download	N/A	ZXTT SULB
LM3445MMX/NOPB		MINI SOIC	10	1	260	Detail	Download	N/A	ZXTT SULB

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/packaging/leadfree.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/quality/green.

National's certificate of product compliance is located at RoHS Status.

Design Tools
Title Size Date

Article - #126: Dimming Techniques for Switched-Mode LED Drivers 386 Kbytes 30-Jul-2009

Reference Design

RD-172 - Off-Line TRIAC Dimmer LED Driver Reference Design

CAD Symbols and Models
Download LM3445 CAD Symbols

Models
N/A

LM3445

AC Frequency 60 Hz 50 Hz

80.00 <= V in Lower
V
<= V in Upper
V
<= 260.00

Ambient Temperature °C <= 100

What are WEBENCH® tools?

Reliability Metrics

Part Number Process EFR Reject EFR Sample Size PPM LTA Rejects LTA Device Hours FITS MTTF (Hours)

LM3445MM ABCD150XV1 0 3868 0 0 2595000 2 736338335

LM3445MMX ABCD150XV1 0 3868 0 0 2595000 2 736338335

Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.

For more information on Reliability Metrics, please click here.

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/packaging/leadfree.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/quality/green.

National's certificate of product compliance is located at RoHS Status.

Designing LED Driver Circuits Using WEBENCH LED Designer
Loading video...

LM3445 TRIAC Dimmable LED Driver LIGHTFAIR Demo
Loading video...

LED Driver Design for General Illumination
Loading video...

Arrow Electronics Evaluates National's LM3445 TRIAC Dimmable LED Driver
Loading video...

What's New in Power -- March 2009
Loading video...

Triac Dimming with the LM3445
Loading video...

Designing LED Driver Circuits Using WEBENCH LED Designer
Date: 12/2/2009
Length: 0:43:10

LM3445 TRIAC Dimmable LED Driver LIGHTFAIR Demo
Date: 9/1/2009
Length: 0:01:34

LED Driver Design for General Illumination
Date: 5/4/2009
Length: 0:36:55

Arrow Electronics Evaluates National's LM3445 TRIAC Dimmable LED Driver
Date: 03/10/2009
Length: 0:01:37

What's New in Power -- March 2009
Date: 3/4/2009
Length: 0:04:07

Triac Dimming with the LM3445
Date: 3/2/2009
Length: 0:4:12

[Information as of 9-Feb-2010]