LT1249 - Power Factor Controller

Features

  • Standard 8-Pin Packages
  • High Power Factor Over Wide Load Range with Line Current Averaging
  • International Operation Without Switches
  • Instantaneous Overvoltage Protection
  • Minimal Line Current Dead Zone
  • Typical 250µA Start-Up Supply Current
  • Rejects Line Switching Noise
  • Synchronization Capability
  • Low Quiescent Current: 9mA
  • Fast 1.5A Peak Current Gate Driver

Typical Application

LT1249 Typical Application

Description

The 8-pin LT®1249 provides active power factor correction for universal offline power systems with very few external parts. By using fixed high frequency PWM current averaging without the need for slope compensation, the LT1249 achieves far lower line current distortion, with a smaller magnetic element than systems that use either peak current detection or zero current switching approach, in both continuous and discontinuous modes of operation.

The LT1249 uses a multiplier containing a square gain function from the voltage amplifier to reduce the AC gain at light output load and thus maintains low line current distortion and high system stability. The LT1249 also provides filtering capability to reject line switching noise which can cause instability when fed into the multiplier. Line current dead zone is minimized with low bias voltage at the current input to the multiplier.

The LT1249 provides many protection features including peak current limiting and overvoltage protection. The switching frequency is internally set at 100kHz.

While the LT1249 simplifies PFC design with minimal parts count, the LT1248 provides flexibilities in switching frequency, overvoltage and current limit.

Packaging

CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
Drawing
RoHS
LT1249CN8#PBF N-8 N C 05-08-1510 (N8) Yes
LT1249CS8#PBF SO-8 S8 C 05-08-1610 (S8) Yes
LT1249CS8#TRPBF SO-8 S8 C 05-08-1610 (S8) Yes
LT1249IN8#PBF N-8 N I 05-08-1510 (N8) Yes
LT1249IS8#PBF SO-8 S8 I 05-08-1610 (S8) Yes
LT1249IS8#TRPBF SO-8 S8 I 05-08-1610 (S8) Yes


LT1249 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LT1249CN8#PBF N-8 C $4.17 $3.25 Yes
LT1249CS8#PBF SO-8 C $4.50 $3.50 Yes
LT1249CS8#TRPBF SO-8 C $3.56 Yes
LT1249IN8#PBF N-8 I $4.75 $3.70 Yes
LT1249IS8#PBF SO-8 I $5.56 $4.00 Yes
LT1249IS8#TRPBF SO-8 I $4.06 Yes
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Click here to view our complete list of demo boards

Applications

  • Universal Power Factor Corrected Power Supplies
  • Preregulators up to 1500W

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Design Tools

LTspice

LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice

To launch a ready to run LTspice demonstration circuit for this part:

  • Step 1: If you have not installed LTspice on this computer, download and install LTspice
  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
  • Step 3: If LTspice does not automatically open after clicking the link above, you can instead run the simulation by right clicking on the link and selecting "Save Target As." After saving the file to your computer, start LTspice and open the demonstration circuit by selecting 'Open' from the 'File' menu

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Models for the following parts are available in LTspice:
LT1249

Technical Support