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LM3445

ACTIVE

Triac dimmable offline LED driver

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Data sheet

LM3445

ACTIVE
Data sheet Order now

Product details

Input voltage type AC/DC Topology Buck, Flyback Vin (min) (V) 8 Vin (max) (V) 12 Vout (max) (V) 60 Vout (min) (V) 9 Iout (max) (A) 2 Iq (typ) (mA) 2 Features Adjustable Switch Frequency, Enable/Shutdown, Thermal shutdown Operating temperature range (°C) -40 to 125 Dimming method Forward Phase (Triac), PWM, Reverse Phase Number of channels 1 Rating Catalog
Input voltage type AC/DC Topology Buck, Flyback Vin (min) (V) 8 Vin (max) (V) 12 Vout (max) (V) 60 Vout (min) (V) 9 Iout (max) (A) 2 Iq (typ) (mA) 2 Features Adjustable Switch Frequency, Enable/Shutdown, Thermal shutdown Operating temperature range (°C) -40 to 125 Dimming method Forward Phase (Triac), PWM, Reverse Phase Number of channels 1 Rating Catalog
SOIC (D) 14 51.9 mm² 8.65 x 6 VSSOP (DGS) 10 14.7 mm² 3 x 4.9
  • TRIAC Dim Decoder Circuit for LED Dimming
  • Application Voltage Range 80 VAC to 277 VAC
  • Capable of Controlling LED Currents Greater
    Than 1 A
  • Adjustable Switching Frequency
  • Low Quiescent Current
  • Adaptive Programmable Off-Time Allows for
    Constant Ripple Current
  • Thermal Shutdown
  • No 120-Hz Flicker
  • Low Profile 10-Pin VSSOP Package or 14-Pin
    SOIC
  • Patented Drive Architecture
  • TRIAC Dim Decoder Circuit for LED Dimming
  • Application Voltage Range 80 VAC to 277 VAC
  • Capable of Controlling LED Currents Greater
    Than 1 A
  • Adjustable Switching Frequency
  • Low Quiescent Current
  • Adaptive Programmable Off-Time Allows for
    Constant Ripple Current
  • Thermal Shutdown
  • No 120-Hz Flicker
  • Low Profile 10-Pin VSSOP Package or 14-Pin
    SOIC
  • Patented Drive Architecture

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.

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.
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Technical documentation

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Type Title Date
* Data sheet LM3445 TRIAC Dimmable Offline LED Driver datasheet (Rev. M) PDF | HTML 30 Nov 2015
White paper Common LED Functions and LED Driver Design Considerations 21 Sep 2020
Selection guide Power Management Guide 2018 (Rev. R) 25 Jun 2018
User guide 120Vac Valley Fill Buck Triac Dimmable LED Driver 12 May 2015
Application note AN-1656 Design Challenges of Switching LED Drivers (Rev. A) 03 May 2013
EVM User's guide AN-1935 LM3445 Off-Line TRIAC Dimmer LED Driver Demo Board (Rev. I) 01 May 2013
EVM User's guide AN-1978 LM3445 120VAC Small Evaluation Board (Rev. G) 01 May 2013
User guide AN-1995 LM3445 208-277V AC Non-Isolated Evaluation PCB (Rev. B) 01 May 2013
Application note AN-2034 LM3445 -120VAC, 8W Isolated Flyback LED Driver (Rev. C) 01 May 2013
User guide AN-2061 LM3445 A19 Edison Retrofit Evaluation Board (Rev. C) 01 May 2013
Application note An Improved Line Regulation Solution Used in LM3444/5 Non-Isolated LED Lighting 25 Oct 2012
User guide 230 Vac Off-line Triac Dimmer Retrofit with 6 LEDs Reference Design User Guide 27 Jan 2012
Application note AN-2069 LM3445 - 230VAC, 6W- 15W Isolated Flyback LED Driver (Rev. B) 23 Nov 2010

Design & development

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Evaluation board

LM3445EVM-695 — LM3445 120Vac Valley Fill Buck Triac Dimmable LED Driver Evaluation Module

The LM3445EVM-695 implements a dimming solution using the LM3445 integrated circuit from Texas Instruments. The LM3445 is an adaptive constant off-time AC/DC buck constant current controller with built in phase dimming decoder. Line cycles are analyzed continuously by an internal low power digital (...)

User guide: PDF
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Simulation tool

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PSpice® for TI is a design and simulation environment that helps evaluate functionality of analog circuits. This full-featured, design and simulation suite uses an analog analysis engine from Cadence®. Available at no cost, PSpice for TI includes one of the largest model libraries in the (...)
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Reference designs

PMP30439 — 230 V in to 180 V out at 200 mA constant-current LED driver reference design

This reference design is a low-side Buck (the output voltage is referenced to the positive DC input (+Vin node), not to the GND node). The controller drives a LED string up to 180V with 200mA constant current. The low-side Buck topology simplifies the schematic thanks to direct-driving of the FET, (...)
Test report: PDF
Schematic: PDF
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SOIC (D) 14 Ultra Librarian
VSSOP (DGS) 10 Ultra Librarian
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