IS31LT3350-V1STLS2-TR

IS31LT3350 40V LED DRIVER WITH INTERNAL SWITCH October 2011 GENERAL DESCRIPTION FEATURES The IS31LT3350 is a continuous mode inductive step-down converter, designed for driving a single LED or multiple series connected LEDs efficiently from a voltage source higher than the LED voltage. The chip operates from an input supply between 6V and 40V and provides an externally adjustable output current of up to 750mA. Depending upon supply voltage and external components, this can provide up to 30 watts of output power.         The IS31LT3350 includes an integrated output switch and a high-side output current sensing circuit, which uses an external resistor to set the nominal average output current. Output current can be adjusted linearly by applying an external control signal to the ADJ pin. The ADJ pin will accept either a DC voltage or a PWM waveform. This will provide either a continuous or a gated output current. Applying a voltage of 0.2V or lower to the ADJ pin turns the output off and switches the chip into a low current standby state. The chip is assembled in SOT23-5 and SOT89-5 package. SOT23-5 is available for 350mA output current application. SOT89-5 is available for 750mA output current application.     Simple low parts count Internal 40V power switch Wide input voltage range: 6V to 40V Up to 750mA output current (SOT89-5 package) High efficiency (up to 95% ) Typical 1200：1 dimming ratio Typical 5% output current accuracy Single pin on/off and brightness control using DC voltage or PWM Up to 1MHz switching frequency Inherent open-circuit LED protection Thermal shutdown protection circuitry Two packages available for different current APPLICATIONS      Low voltage halogen replacement LEDs Automotive lighting Low voltage industrial lighting LED back-up lighting Illuminated sign TYPICAL APPLICATION CIRCUIT Figure 1 Lumissil Microsystems – www.lumissil.com Rev. A, 10/18/2011 Typical Application Circuit 1 IS31LT3350 PIN CONFIGURATION Package Pin Configuration SOT23-5 SOT89-5 LX 1 GND 2 ADJ 3 5 VIN Thermal Pad 4 ISENSE PIN DESCRIPTION No. Pin Description 1 LX Drain of power switch. 2 GND SOT23-5 SOT89-5 3 4 5 - Ground (0V). Multi-function On/Off and brightness control pin: * Leave floating for normal operation.(VADJ = VREF = 1.2V giving nominal average output current IOUT nom =0.1/RS) * Drive to voltage below 0.2V to turn off output current * Drive with DC voltage (0.3V