ISSI IS31LT3918 Manual

IS31LT3918 T8 Lighting Evaluation Board Guide
Description
The IS31LT3918 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 6VDC to 450VDC or 110VAC/220VAC.
The IS31LT3918 incorporates the special feature of
switch dimming by detecting OFF-ON cycles of the main
power switch. When the switch is cycled within a 2
second period (typical) the device automatically switches
the dimming level to the next step. As a result, dimming
can be achieved without replacing any wiring in the
original system. There are multiple modes of switch
dimming that the user may configure, 2 steps or 3 steps,
as well as different levels of dimming via the external
pins DIM1 and DIM2.
Features

User configurable switch dimming levels

3% output current accuracy

Over current, voltage and temperature protection

High efficiency (typical up to 95%)

Wide input voltage range: 6VDC~450VDC or
85VAC~ 265VAC

Linear and PWM dimming

Very few external components
Applications

DC/DC or AC/DC LED driver applications

Signal and decorative LED lighting

Backlighting LED driver
For pricing, delivery, and ordering information, please contact ISSI at
or call +1-408-969-6600
Integrated Silicon Solution, Inc. – www.issi.com
R1.0, 18/12/2012

Quick Start

Recommended Equipment

85 ~ 265VAC 50~60Hz power supply

LED array (12 in series and 24 in parallel)

Main power switch
Absolute Maximum Ratings

≤ 265VAC power supply

≤ 42V Vout (Total Vf)
Caution: Do not exceed the conditions li
sted above, otherwise the board will be
damaged or the output will be limited
Procedure
The IS31LT3918 Evaluation Board is fully assembled
and tested. Follow the steps listed below to verify board
operation.
Caution: Do not turn on the power supply until all
connections are completed.
Switch
L
L
Input
85 – 265VAC
N
N
IS31LT3918
1) Connect the positive terminal of the LEDs to the
LED+ pin of the Evaluation Board and the negative
terminal of the LEDs to the LED- pin of the
Evaluation Board.
2) Connect the input pins (L and N) of the Evaluation
Board via the main power switch to AC power
supply.
3) Turn on the power supply.

Ordering Information

PART #
IS31LT3918_GRLS2_EBT8
LED+
LED
Array
LED-
Board
TEMP IC
RANGE PACKAGE
-40 °C to SO-8
85°C (5.0 x 6.0mm)
analog_mkt@issi.com
1