LT3956

PRODUCTION

80V_IN, 80V_OUT Constant-Current, Constant-Voltage Converter

Part Models: 4
1ku List Price: Starting From $4.19

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Overview

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

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.

Applications

High Power LED
Battery Charger
Accurate Current Limited Voltage Regulator

Part Models: 4
1ku List Price: Starting From $4.19

Documentation

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal. View our quality and reliability program and certifications for more information.

Part Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
LT3956EUHE#PBF	36-Lead QFN (5mm x 6mm x 0.75mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT3956EUHE#TRPBF	36-Lead QFN (5mm x 6mm x 0.75mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT3956IUHE#PBF	36-Lead QFN (5mm x 6mm x 0.75mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT3956IUHE#TRPBF	36-Lead QFN (5mm x 6mm x 0.75mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Hardware Ecosystem

Parts	Product Life Cycle	Description
Analog to Digital Converters (ADCs) 1
LTC2991	RECOMMENDED FOR NEW DESIGNS	Octal I²C Voltage, Current, and Temperature Monitor
Digital to Analog Converters (DACs) 1
LTC2657	PRODUCTION	Octal I²C 16-/12-Bit Rail-to-Rail DACs with 10ppm/°C Max Reference
Protection Switches & Controllers 1
LT4363	RECOMMENDED FOR NEW DESIGNS	High Voltage Surge Stopper with Current Limit
Pulse-Width Modulation (PWM) & Pulse Generators 1
LTC6992		TimerBlox: Voltage-Controlled Pulse Width Modulator (PWM)

Tools & Simulations

LTspice 1

LT3956 Demo Circuit - 94% Efficient 25W White LED Automotive Headlamp Driver (6-60V to 18x 3.6V LEDs @ 380mA)

Models for the following parts are available in LTspice:

LT3956

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.