Analog Devices LT3950

Description

The LT®3950 is a multitopology DC/DC converter designed specifically to drive high current LEDs. It contains a 1.5A,60V DMOS switch and supports an external PWM dimming PMOS. The LT3950 has an internal PWM generator for dimming that maps an analog control signal to anexponential scale used to define PWM dimming duty ratio. Using an exponential scale to define duty ratio preservesdimming resolution across a wide range of LED current. In addition to operating as a constant current source, the LT3950 also provides output voltage regulation. This canbe used to prevent damage to the part in case of open LED events. A programmable switching frequency offers flexibilityin design for higher efficiency or reduced component size. Enabling spread spectrum frequency modulation reduces EMI. The switching frequency can also easily be synchronized by driving the SYNC/SPRD pin with an external clock. LED current is programmed with a single external sense resistor and can be adjusted from zero tofull-scale by an analog signal at the CTRL pin.

Features

• Operates in Boost, SEPIC, Buck Mode and Buck-Boost Mode
• 128:1 Internal Exponential Scale PWM Dimming
• Wide Input Voltage Range (3V to 60V)
• 1.5A, 60V Internal Switch
• 20000:1 External PWM Dimming at 100Hz
• ±2% LED Current and Output Voltage Regulation
• PMOS Switch Driver for PWM Dimming
• LED Short/Open Protection and Indication
• Constant Voltage and Constant Current Regulation
• Adjustable 300kHz to 2MHz Switching Frequency
• Adjustable 100Hz to 1kHz PWM Generator Frequency
• Internal Spread Spectrum Frequency Modulation
• Easy Synchronization to External Clock
• Programmable VIN UVLO with Hysteresis
• Available in 16-Lead MSOP Package

Typical applications

• Display Backlighting, Automotive and Avionic Lighting

More information

• Datasheet
• IC product information