Features • Triac dim decoder circuit for LED dimming • Application voltage range 80VAC – 270VAC • 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 VCC 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

Datasheet

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

More Application Notes

Title		Size	Date	Other Language
	AN-1679: Application Note 1679 LED Backlighting Solution with LM3430 and LM3432	2763 Kbytes	18-Sep-07
	AN-1907: Application Note 1907 LM3423 Buck-Boost Configuration Evaluation Board	879 Kbytes	8-Dec-08
	AN-1764: Application Note 1764 LM3431 Evaluation Board	588 Kbytes	10-Jan-08	中文
	AN-1529: Application Note 1529 LM3430 Evaluation Board	2770 Kbytes	21-Aug-07	中文

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

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.

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