IS31LT3350 Datasheet, PDF (1/12 Pages) Integrated Silicon Solution, Inc – 40V LED DRIVER WITH INTERNAL SWITCH

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
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
1
Rev. A, 10/18/2011