LT1509 - Power Factor and PWM Controller


  • PFC and PWM Single Chip Solution
  • Synchronized Operation up to 300kHz
  • 99% Power Factor over 20:1 Load Current Range
  • Current Mode PWM
  • Instantaneous Overvoltage Protection
  • Dedicated Overvoltage Protection (OVP Pin)
  • Minimal Line Current Dead Zone
  • Typical 250µA Start-Up Supply Current
  • Line Switching Noise Filter
  • Low Quiescent Current: 13mA
  • Fast 2A Peak Current Gate Drivers
  • Separate Soft Start Controls

Typical Application

LT1509 Typical Application


The LT®1509 is a complete solution for universal off-line switching power supplies utilizing active power factor correction. The PFC section is identical to the LT1248 PFC controller except the EN/SYNC pin is removed because PFC and PWM are synchronized internally. The current mode PWM section (the LT1508 is the volt-age-mode counterpart) contains all the primary side functions to convert the PFC preregulated high voltage output to an isolated low voltage output. The PWM duty cycle is internally limited to 47% (maximum 50%) to prevent transformer saturation. PWM soft start begins when PFC output reaches the preset voltage. In the event of brief line loss,the PWM will be shut off when the PFC output voltage drops below 73% of the preset value.


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
LT1509CN#PBF N-20 N C 05-08-1510 (N20) Yes
LT1509CSW#PBF SW-20 SW C 05-08-1620 (SW20) Yes
LT1509CSW#TRPBF SW-20 SW C 05-08-1620 (SW20) Yes
LT1509IN#PBF N-20 N I 05-08-1510 (N20) Yes
LT1509ISW#PBF SW-20 SW I 05-08-1620 (SW20) Yes
LT1509ISW#TRPBF SW-20 SW I 05-08-1620 (SW20) Yes

LT1509 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
LT1509CN#PBF N-20 C $5.25 $3.95 Yes
LT1509CSW#PBF SW-20 C $5.25 $3.95 Yes
LT1509CSW#TRPBF SW-20 C $4.05 Yes
LT1509IN#PBF N-20 I $5.85 $4.35 Yes
LT1509ISW#PBF SW-20 I $5.85 $4.35 Yes
LT1509ISW#TRPBF SW-20 I $4.45 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


  • Universal Power Factor Corrected Power Supplies and Preregulators

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Design Tools


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

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