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
Rev. A, 10/18/2011
1
IS31LT3350
PIN CONFIGURATIONS
Package
Pin Configurations (Top View)
LX
1
2
3
4
5
V
IN
SOT23-5
GND
ADJ
I
SENSE
SOT89-5
PIN DESCRIPTION
Pin Name
NO. Description
LX
1
Drain of power switch
GND
2
Ground (0V)
Multi-function On/Off and brightness control pin:
* Leave floating for normal operation.(V
ADJ
= V
REF
= 1.2V giving nominal average output current
I
OUT nom
=0.1/R
S
)
* Drive to voltage below 0.2V to turn off output current
ADJ
3
* Drive with DC voltage (0.3V<V
ADJ
<1.2V) to adjust output current from 25% to 100% of I
OUTnom
* Drive with PWM signal to adjust output current.
* When driving the ADJ pin above 1.2V, the current will be clamped to 100% brightness
automatically.
I
SENSE
4
Connect resistor R
S
from this pin to V
IN
to define nominal average output current I
OUTnom
=0.1/R
S
Input voltage (6V to 40V). Decouple to ground with 1μF or higher X7R ceramic capacitor close to
V
IN
5
device
Integrated Silicon Solution, Inc. – www.issi.com
Rev. A, 10/18/2011
2
IS31LT3350
ORDERING INFORMATION
Industrial Range:
-40°C
to +85°C
Order Part No.
IS31LT3350-V1STLS2-TR
IS31LT3350-V2STLS2-TR
IS31LT3350-V1SDLS2-TR
IS31LT3350-V2SDLS2-TR
Package
SOT23-5, Lead-free
SOT23-5, Lead-free
SOT89-5, Lead-free
SOT89-5, Lead-free
QTY/Reel
3000
3000
2500
2500
V
SENSE
91mV~101mV
99mV~110mV
91mV~101mV
99mV~110mV
Integrated Silicon Solution, Inc. – www.issi.com
Rev. A, 10/18/2011
3
IS31LT3350
ABSOLUTE MAXIMUM RATINGS
(NOTE 1)
Symbol Parameter
V
IN
Input voltage
V
ISENSE
V
LX
V
ADJ
I
LX
P
tot
T
OP
T
ST
T
j MAX
R
θ
JA
I
SENSE
voltage
LX output voltage
Adjust pin input voltage
Switch output current
Power dissipation
Operating temperature
Storage temperature
Junction temperature
Junction to ambient
ESD Susceptibility(human body mode)
Rating
-0.3V to +50V
V
IN
+0.3V to V
IN
-5V ,V
IN
>5V
V
IN
+0.3V to -0.3V,V
IN
<5V
-0.3V to +50V
-0.3V to +6V
800mA@SOT89-5;400mA@ SOT23-5
1.2w @SOT89-5;600mw@SOT23-5
-40 to 85°C
-55 to 150°C
150°C
108°C/W @SOT23-5; 45°C/W @SOT89-5
2kV
ELECTRICAL CHARACTERISTICS
(V
IN
=12V, T
A
=25°C unless otherwise stated) (NOTE 2)
Symbol
V
IN
I
INQoff
I
INQon
V
SENSE
V
SENSEHYS
I
SENSE
V
REF
V
ADJ
V
ADJoff
V
ADJon
R
ADJ
I
LXmean
Parameter
Input voltage
Quiescent supply current with output off
Quiescent supply current with output
switching
Mean current sense threshold voltage
Sense threshold hysteresis
I
SENSE
pin input current
Internal reference voltage
External control voltage range on ADJ pin
for dc brightness control
DC voltage on ADJ pin to switch chip
from active (on) state to quiescent (off)
state
DC voltage on ADJ pin to switch chip
from quiescent (off) state to active (on)
state
Resistance between ADJ pin and V
REF
Continuous LX switch current
SOT23-5 package
SOT89-5 package
V
SENSE
= 0.1V
Measured on ADJ pin
with pin floating
0.3
V
ADJ
falling
V
ADJ
rising
0.15
0.2
0.2
0.25
500
0.35
0.65
ADJ pin grounded
ADJ pin floating
IS31LT3350-V1
IS31LT3350-V2
91
99
Conditions
Min.
6
40
60
450
95
105
±15
8
1.2
1.2
0.25
0.3
10
Typ.
Max.
40
80
600
101
110
mV
%
μA
V
V
V
V
KΩ
A
Unit
V
μA
μA
Integrated Silicon Solution, Inc. – www.issi.com
Rev. A, 10/18/2011
4
IS31LT3350
ELECTRICAL CHARACTERISTICS
(CONTINUED)
(V
IN
=12V, T
A
=25°C unless otherwise stated) (NOTE 2)
Symbol Parameter
Conditions
I
LX(leak)
LX switch leakage current
R
LX
LX Switch ‘On’ resistance
D
PWM(LF)
Brightness control range at low
frequency PWM signal
PWM frequency =100Hz PWM
amplitude=5V,Vin=15V,
L=27uH, Driving 1 LED
PWM frequency =10KHz PWM
amplitude=5V,Vin=15V,
L=27uH, Driving 1 LED
ADJ pin floating
L=100μH (0.82Ω) I
OUT
=350mA
@ V
LED
=3.4V Driving 1 LED
LX switch ‘ON’
LX switch ‘OFF’
Min.
Typ.
0.9
1200:1
Max.
1
1.5
Unit
μA
Ω
D
PWM(HF)
Brightness control range at low
frequency PWM signal
13:1
f
LX
T
ONmin
T
OFFmin
f
LXmax
D
LX
T
PD
T
SD
T
SD-HYS
Operating frequency
Minimum switch ‘ON’ time
Minimum switch ‘OFF’ time
Recommended maximum
operating frequency
Recommended duty cycle
range of output switch at f
LXmax
Internal comparator
propagation delay
Thermal shutdown
temperature
Thermal shutdown hysteresis
154
200
200
1
0.3
0.7
50
140
20
0.9
KHz
ns
ns
MHz
ns
°C
°C
NOTES:
1. Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under recommended operating conditions is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
2. All parts are production tested at T
A
=25°C. Other temperature limits are guaranteed by design.
