IS31LT3938 Datasheet, PDF (1/11 Pages) Integrated Silicon Solution, Inc – High Voltage LED Lighting Driver with Three Level Power Sequencing

IS31LT3938
Preliminary
High Voltage LED Lighting Driver with Three Level Power Sequencing
General Description
IS31LT3938 LED driver IC is a peak current detection
buck converter which operates in constant off time
mode. It operates over a very wide input voltage supply
range of 10VDC to 450VDC or 110VAC/220VAC.
IS31LT3938 incorporates the special feature of three
power sequencing levels by detecting OFF-ON cycles
of the main power switch. When the switch is cycled
within a 4 second period (typical) the device
automatically switches the power level to the next step.
As a result, the input and output power of the luminaire
may be adjusted depending on the desired amount of
illumination and/or power consumption. There are
multiple power levels that the engineer may configure,
2 steps or 3 steps, via the external pins DIM1 and
DIM2.
IS31LT3938 can also realize LED dimming using an
external PWM signal. It can accept a PWM signal from
0% to 100% duty cycle. The LED current may also be
adjusted linearly by applying an analog input voltage in
the range of 0.5V to 2.5V.
IS31LT3938 adopts a peak current mode control
architecture, which eliminates the need for any
additional loop compensation while maintaining a good
degree of constant output current regulation.
Features
 User configurable power sequencing levels
 3% output current accuracy
 Over current, temperature protection and short circuit
protection
 High efficiency (typical up to 95%)
 Higher MOS drive voltage
 Wide input voltage range: 10VDC~450VDC or
85Vac~ 265Vac
 Linear and PWM dimming
 Very few external components
Applications
 DC/DC or AC/DC constant current LED driver
 Signal and decorative lighting
 Backlight LED driver
Typical Application Circuit
Switch K ^D1
D2
R_IN
AC Input
Fuse
D3
C1
C_IN
D4
D5
C3
IS3938
VIN
DIM1
Gate
CS
DIM2
GND
ADJ
TOFF
R_EXT
L1
Q1
R_CS
LED+
LED-
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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R0.1, 04/25/2012