Analog Devices LT3954

Description

The LT®3954 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 40V/5A. The LT3954 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 severalLED 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 LT3954 senses output current at the high side or at the low side of the load. The internal PWM generator 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.

Features

• 3000:1 True Color PWM™ Dimming for LEDs
• Wide VIN Range: 4.5V to 40V
• Rail-to-Rail Current Sense Range: 0V to 40V
• Internal 40V/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 applications

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

More information

• Datasheet
• IC product information