LT3955 - 60VIN LED Converter with Internal PWM Generator


  • 3000:1 True Color PWM™ Dimming for LEDs
  • Wide VIN Range: 4.5V to 60V
  • Rail-to-Rail Current Sense Range: 0V to 80V
  • Internal 80V/3.5A Switch
  • Programmable PWM Dimming Signal Generator
  • Constant Current (±3%) and Constant-Voltage (±2%) Regulation
  • Accurate Analog Dimming
  • Drives LEDs in Boost, SEPIC, CUK, Buck Mode,
  • Buck-Boost Mode, or Flyback Configuration
  • Output Short-Circuit Protected Boost
  • Open LED Protection and Reporting
  • Adjustable Switching Frequency: 100kHz to 1MHz
  • Programmable VIN UVLO with Hysteresis
  • C/10 Indication for Battery Chargers
  • Low Shutdown Current: <1μA
  • Thermally Enhanced 5mm × 6mm QFN Package

Typical Application

LT3955 Typical Application
LT3955 Typical Application


The LT®3955 is a DC/DC converter designed to operate as a constant-current source and constant-voltage regulator. It features an internal low side N-channel MOSFET rated for 80V/3.5A. The LT3955 is ideally suited for driving high current LEDs, but also has features to make it suitable for charging batteries and supercapacitors. The fixed frequency, current mode architecture results in stable operation over a wide range of supply and output voltages. A voltage feedback pin serves as the input for several LED protection features, and also makes it possible for the converter to operate as a constant-voltage source. A frequency adjust pin allows the user to program the frequency from 100kHz to 1MHz to optimize efficiency, performance or external component size.

The LT3955 senses output current at the high side or at the low side of the load. The PWM input can be configured to self-oscillate at fixed frequency with duty ratio programmable from 4% to 96%. When driven by an external signal, the PWM input provides LED dimming ratios of up to 3000:1. The CTRL input provides additional analog dimming capability.


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
LT3955EUHE#PBF 5x6 QFN-36 UHE E 05-08-1836 Yes
LT3955EUHE#TRPBF 5x6 QFN-36 UHE E 05-08-1836 Yes
LT3955IUHE#PBF 5x6 QFN-36 UHE I 05-08-1836 Yes
LT3955IUHE#TRPBF 5x6 QFN-36 UHE I 05-08-1836 Yes

LT3955 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
LT3955EUHE#PBF 5x6 QFN-36 E $5.36 $3.75 Yes
LT3955EUHE#TRPBF 5x6 QFN-36 E $3.81 Yes
LT3955IUHE#PBF 5x6 QFN-36 I $6.30 $4.41 Yes
LT3955IUHE#TRPBF 5x6 QFN-36 I $4.47 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.

Part Number Description Price Documentation
DC2020A LT3955EUHE Demo Board | Boost LED Driver; 5V to 60VIN, VOUT up to 67V@0.3A $175.00
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Click here to view our complete list of demo boards


  • High Power LEDs
  • Output Short-Circuit Protected Boost
  • Battery and SuperCap Chargers
  • Accurate Current Limited Voltage Regulators

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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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