IS31LT3352 Datasheet, PDF (1/14 Pages) Integrated Silicon Solution, Inc – 40V LED DRIVER WITH TEMPERATURE COMPENSATION

IS31LT3352
40V LED DRIVER WITH TEMPERATURE COMPENSATION
OCTOBER 2011
GENERAL DESCRIPTION
The IS31LT3352 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 required 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 IS31LT3352 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.
The IS31LT3352 integrates temperature compensation
function in order to maintain LEDs’ stable and reliable
operation. The IS31LT3352 measures the thermistance
mounted close to LEDs. When ambient temperature near
LEDs goes too high and the Negative Temperature
Coefficient thermistors reach the value of threshold
resistance connected at R_TH pin, output current starts to
reduce automatically. After the ambient temperature falls
down to a safe temperature，the current will return to the
set value.
The IS31LT3352 can be connected as LED drivers’ chain
with the same temperature compensation percentage. In
this chain, every IS31LT3352’s ADJO output pin drives
next stage’s IS31LT3352 ADJI input pin with temperature
compensation information. So, only one thermistor is
needed in the whole IS31LT3352 system.
FEATURES
 Simple low parts count
 Internal 40V power switch
 Wide input voltage range: 6V to 40V
 Up to 750mA output current
 High efficiency (up to 95% )
 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 to protect IC itself
 Temperature compensation to protect LEDs
APPLICATIONS
 Low voltage halogen replacement LEDs
 Automotive lighting
 Low voltage industrial lighting
 LED back-up lighting
 Illuminated signs
APPLICATION CIRCUIT
IS31LT3352
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
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Rev. A, 09/01/2011