IS31LT3172/73
Integrated Silicon Solution, Inc. – www.issi.com 1
Rev. C, 07/01/2016
10-TO-200MA CONSTANT-CURRENT LED DRIVER
July 2016
GENERAL DESCRIPTION
The IS31LT3172 and IS31LT3173 are adjustable
linear current devices with excellent temperature
stability. A single resistor is all that is required to set
the operating current from 10mA to 200mA. The
devices can operate from an input voltage from 2.5V
to 42V with a minimal voltage headroom of 1V
(typical). Designed with a low dropout voltage; the
device can drive LED strings close to the supply
voltage without switch capacitors or inductors.
The IS31LT3172/73 simplifies designs by
providing a stable current without the additional
requirement of input or output capacitors,
inductors, FETs or diodes. The complete constant
current driver requires only a current set resistor
and a small PCB area making designs both
efficient and cost effective.
The EN pin (3) of the IS31LT3172 can be tied to
Vbat or BCM PWM signal for high side dimming.
The EN Pin (3) of the IS31LT3173 can function as
the PWM signal input used for low side dimming.
As a current sink it is ideal for LED lighting
applications or current limiter for power supplies.
The device is provided in a lead (Pb) free, SOP-8-EP
package.
FEATURES
Low-side current sink
- Current preset to 10mA
- Adjustable from 10mA to 200mA with external
resistor selection
Wide input voltage range from
- 2.5V to 42V (IS31LT3173)
- 5V to 42V (IS31LT3172)
with a low dropout of typical 1V
Up to 10kHz PWM input (IS31LT3173 only)
Protection features:
- 0.26%/K negative temperature coefficient at
high temp for thermal protection
Up to 1.8W power dissipation in a small SOP-8-
EP package
RoHS compliant (Pb-free) package
APPLICATIONS
Architectural LED lighting
Channel letters for advertising, LED strips for
decorative lighting
Retail lighting in fridge, freezer case and
vending machines
Emergency lighting (e.g. steps lighting, exit way
sign etc.)
TYPICAL APPLICATION CIRCUIT
Figure 1 Typical Application Circuit
