IS31LT3135
V1,
IS31LT3135
V2
Dual
Ch.
(Main/Sub)
LED
Driver
Evaluation
Board
Guide
Integrated Silicon Solution, Inc. –
http://www.issi.com
1
V2, 4/23/2012
Description
The
IS31LT3135
is
a
dual
‐
channel
LED
driver
that
has
two
modes
of
operation;
it
can
function
as
the
main
‐
channel
driver
or
as
a
sub
‐
channel
source.
When
operating
in
main
mode,
the
device
functions
as
a
constant
current
source
that
outputs
an
adjustable
current,
via
an
external
resistor,
through
the
main
LED.
The
device
is
operable
with
a
dropout
voltage
of
0.1V
while
driving
a
200mA
current.
When
operating
as
a
sub
‐
channel
driver,
the
IC
grounds
the
LED’s
cathode.
The
device
normally
operates
with
a
single
channel
powered
on,
allowing
for
quick
switching
between
the
main
and
sub
channel
modes.
A
sweeping
power
supply
that
operates
between
high
and
low
voltages,
allows
for
simple
switching
between
sub/main
‐
channel
modes,
even
during
conditions
where
the
UV
pin
is
below
the
1.17V
(typical)
UV
threshold
IS31LT3135
‐
V1;
or
1.23V
(typical)
UV
threshold
for
IS31LT3135
‐
V2.
The
sweeping
power
supply
allows
sub
‐
channel
to
main
channel
switching
during
conditions
where
the
UV
pin
is
≥
80mV
than
the
UV
threshold.
In
addition,
the
main
channel
features
short
protection
via
switching
to
sub
‐
channel
if
any
abnormal
behaviors
occur
in
the
main
‐
channel
LED
circuitry.
Features
Power
supply
under
‐
voltage
detection
Main
‐
channel
LED
short
protection
Over
‐
temperature
protection
Input
voltage
range:
2.7V
to
5.5V
Main/sub
‐
channel
adjustable
output
current
(Set
via
user
‐
configurable
external
resistors)
Main
‐
channel
dropout
VDP=0.1V
Ultra
‐
low
quiescent
current
SOP
‐
8
Package,
small
PCB
footprint
size
Quick
Start
Figure
1:
Photo
of
IS31LT3135V1/V2
evaluation
board
Recommended
Equipment
5VDC
Power
supply
1W
LED
Multi
‐
meter
Recommended
I/O
Ratings
Power
supply
voltage:
3.8VDC
Output
of
I
MAIN
:
320mA
per
LED
Output
of
I
SUB
:
20mA
per
LED
Note:
When
the
power
supply
voltage
≥
LED
voltage
rating,
extra
voltage
is
dissipated
through
the
main
‐
channel,
causing
a
drop
in
system
efficiency
and
an
increase
in
wasted
energy.
Absolute
Maximum
Ratings
Input
voltage
≤
5VDC
Caution:
Do
not
exceed
the
input
voltage
conditions
listed
above
to
avoid
risking
permanent
damage
to
the
board.
Ordering
Information
Part
Number
Temperature
Range
IC
Package
IS31LT3135
‐
V1GRLS2
‐
EB
IS31LT3135
‐
V2GRLS2
‐
EB
−
40°C
to
+85°C
(Industrial
Grade)
SOP
‐
8
(5mm
x
4mm)
Table
1:
Ordering
Information
for
IS31LT3135
‐
V1/V2
evaluation
board.
Customers
with
inquiries
regarding
pricing,
delivery,
part
availability,
and
related
information,
can
reach
ISSI
Analog
marketing
via
either
of
the
following
methods:
Email:
/
Phone:
+1
(408)
969
‐
6600