IS31LT3350
40V LED DRIVER WITH INTERNAL SWITCH
GENERAL DESCRIPTION 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. APPLICATION CIRCUIT
http://www.DataSheet4U.net/
OCTOBER 2011
FEATURES 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
Copyright © 2011 Integrated Silicon Solution, Inc. All rights reserved. ISSI reserves the right to make changes to this specification and its products at any time without notice. ISSI assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to obtain the latest version of this device specification before relying on any published information and before placing orders for products. Integrated Silicon Solution, Inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless Integrated Silicon Solution, Inc. receives written assurance to its satisfaction, that: a.) the risk of injury or damage has been minimized; b.) the user assume all such risks; and c.) potential liability of Integrated Silicon Solution, Inc is adequately protected under the circumstances
Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 10/18/2011
1
datasheet pdf - http://www.DataSheet4U.net/
IS31LT3350
PIN CONFIGURATIONS Package Pin Configurations (Top View)
LX 1 2 3 4 5 VIN
SOT23-5
GND ADJ
ISENSE
SOT89-5
PIN DESCRIPTION Pin Name NO. Description LX 1 Drain of power switch GND 2 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 ADJ 3 * Drive with DC voltage (0.3V