LT3956 - 80VIN, 80VOUT Constant-Current, Constant-Voltage Converter

Features

  • 3000:1 True Color PWM™ Dimming
  • Wide Input Voltage Range: 4.5V to 80V
  • Output Voltage Up to 80V
  • Internal 3.3A/84V Switch
  • Constant-Current and Constant-Voltage Regulation
  • 250mV High Side Current Sense
  • Drives LEDs in Boost, Buck Mode, Buck-Boost Mode, SEPIC or Flyback Topology
  • Adjustable Frequency: 100kHz to 1MHz
  • Open LED Protection
  • Programmable Undervoltage Lockout with Hysteresis
  • Constant-Voltage Loop Status Pin
  • PWM Disconnect Switch Driver
  • CTRL Pin Adjusts High Side Current Sense Threshold
  • Low Shutdown Current: <1μA
  • Programmable Soft-Start
  • Available in the 36-Lead (5mm × 6mm) QFN Package

Typical Application

LT3956 Typical Application
LT3956 Typical Application

Description

The LT3956 is a DC/DC converter designed to operate as a constant-current source and constant-voltage regulator. It is ideally suited for driving high current LEDs. It features an internal low side N-channel power MOSFET rated for 84V at 3.3A and driven from an internal regulated 7.15V supply. The fixed frequency, current-mode architecture results in stable operation over a wide range of supply and output voltages. A ground referenced voltage FB 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 LT3956 senses output current at the high side of the LED string. High side current sensing is the most flexible scheme for driving LEDs, allowing boost, buck mode or buck-boost mode configuration. The PWM input provides LED dimming ratios of up to 3000:1, and the CTRL input provides additional analog dimming capability.

Packaging

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

QFN-36

LT3956 Package Drawing

Order Info

Package Variations and Pricing

Part Number Package Pins Temp Price (1-99) Price (1k)* RoHS Data
LT3956EUHE#PBF QFN 36 E $5.00 $3.50 View
LT3956EUHE#TRPBF QFN 36 E $3.56 View
LT3956IUHE#PBF QFN 36 I $5.89 $4.12 View
LT3956IUHE#TRPBF QFN 36 I $4.18 View
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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
DC1521A LT3956UHE Demo Board | 80Vin, 80Vout Constan-Current, Constant-Voltage Converter $175.00
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Click here to view our complete list of demo boards

Applications

  • High Power LED
  • Battery Charger
  • Accurate Current Limited Voltage Regulator

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Design Tools

LTspiceIV

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LT3956

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