is31lt3117 53v, 350ma, 4-channel constant current regulator

IS31LT3117 53V, 350MA, 4-CHANNEL
CONSTANT CURRENT REGULATOR WITH OTP
DESCRIPTION
RECOMMENDED EQUIPMENT
The IS31LT3117 is a 4-channel, linear regulated,
constant current LED driver which can sink 4 equal
currents of up to 350mA per channel to drive high
brightness LEDs over an input voltage range of 6V to
53V, while maintaining an output leakage current of
less than 1uA. The sink current is easily programmed
using a single external resistor. The current sinks of
the IS31LT3117 may be connected in parallel to allow
greater than 350mA of LED current, ie, all four VLEDx
pins tied together for a maximum 1.4A sink available
for one LED string. See limitations in the LED
CURRENT SETTING section.
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

The IS31LT3117 also features a PWM input to enable
simple dimming control using a digital control signal.
FEATURES






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6V to 53V input supply voltage range
Up to 1.4A total sink current
Over temperature protections
Thermal current regulation above 130°C
Sink current matching 3% between channels
PWM dimming and Shutdown control input
Very few external components
QUICK START

6.0V~53V, 2A DC power supply
One digital voltmeter
Four series-connected HB LED strings rated no
less than 100mA
A current probe to measure the HB LED current
ABSOLUTE MAXIMUM RATINGS

≤ 53V power supply
Caution: Do not exceed the conditions listed above, otherwise
the board will be damaged.
EVALUATION BOARD OPERATION
The evaluation board is configured to operate each
HBLED string (CHx) at 100mA. The operating current
is set by the resistor value at IS31LT3117 pin 8. See
“LED CURRENT SETTING” section of the datasheet
for guidance in calculating resistor values for specific
currents.
PROCEDURE
The IS31LT3117 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.
1)
2)
Connect each HBLED string as follows:
CHx: Connect an HBLED strings cathode to the
CHx of CON3 and the anode to the CON2,
Where x is 1, 2, 3 and 4.
Unused CHx inputs should be connected to GND.
Calculate the VCC, recommended value is 0.5V
to 1V higher than the sum of the LED string’s total
forward voltage drop.
For example, if the LED string’s total forward
voltage is 9V@100mA, the recommended VCC is
10V.
Note: Selecting an input voltage much higher than the
LED string’s total forward voltage will cause a high
IS31LT3117 power dissipation which may lead to device
shutdown.
Figure 1: Photo of IS31LT3117 Evaluation Board
3)
4)
Insert the current probe between the CHx terminal
(CON3) and the cathode of the CHx LED string to
measure the HBLED current
JP1 is used to configure the PWM signal input
mode. When JP1 is “ON” the IS31LT3117 is
enabled and no external PWM signal should be
connected. When JP1 is “OFF” the IS31LT3117
must be driven by an external PWM signal source.
Caution: Always remove JP1 when driving the IS31LT3117
with an external PWM source. JP1 ON pulls up the TP1 pin
to a possibly high VCC voltage that may damage the PWM
signal source.
Integrated Silicon Solution, Inc. – www.issi.com
Rev.B, 07/16/2014
1
IS31LT3117 53V, 350MA, 4-CHANNEL
CONSTANT CURRENT REGULATOR WITH OTP
5)
6)
Verify that the VCC is 10V and connect the VCC
and GND to CON1.
Turn on the power supply (VCC) and measure the
HBLED current using the current probe and verify
all currents are equal.
ORDERING INFORMATION
Part No.
Temperature Range
Package
IS31LT3117-ZLS4-EB
-40°C ~ +125°C (Industrial Range)
eTSSOP-16, Lead-free
Table1: Ordering Information
For pricing, delivery, and ordering information, please contact ISSI’s analog marketing team at
[email protected] or (408) 969-6600
Integrated Silicon Solution, Inc. – www.issi.com
Rev.B, 07/16/2014
2
IS31LT3117 53V, 350MA, 4-CHANNEL
CONSTANT CURRENT REGULATOR WITH OTP
POWER SUPPLY AND POWER DISSIPATION
The dissipation is proportional to the voltage across
the LED and the sink current that can be defined as:
PLEDx  VLEDSx  I OUTx
Where x is 1, 2, 3 or 4. VLEDSx is the total forward
voltage of LEDs in series; IOUTx is the current of the
LED series. VVLEDx is the voltage of the IS31LT3117
VLEDx pin.
possible current is 350mA per VLEDx pin, however,
more than one VLEDx pin can be tied together to allow
for larger currents. Two combined VLEDx pins will
double the available sink current for the LED string,
while combining all four VLEDx pins will result in 4x the
sink current for one LED string. The VLEDx sink
current can be calculated by the following; VISET =
1.27V (typ):
I SINKx  1600 
The power of the IS31LT3117 can be defined as:
4
P3117   (VVLEDx
x 1

I OUTx )  VCC  I Q
4
  (VCC  V LEDS x )  I OUTx )  VCC  I Q
x 1
Assume VCC=10V, IOUTx =0.1A, VLEDSx=9V, IQ=5mA:
PLEDx=9V×0.1A=0.9W
P3117=(10V-9V)×0.1A×4+10V×0.005A
= 0.45W
The voltage at VLEDx pin of the IS31LT3117 will be the
remaining value of VCC-VOUTx, and if it is larger than
1.8V@350mA, the IC dissipation will be high which
may trigger the IC over temperature protection (OTP).
LED CURRENT SETTING
The maximum sink current of all four channels
(VLEDx) is set by resistor (RISET) connected from the
IS31LT3117 ISET pin (8) to ground. The maximum
Integrated Silicon Solution, Inc. – www.issi.com
Rev. B, 7/16/2014
V ISET
R ISET
From Figure 2, RISET=R1//R2, for accurate LED current,
resistors should be 1% or better tolerance. More
information please refers to the IS31LT3117 datasheet.
HBLED DIGITAL-DIMMING CONTROL
The JP1 connector is used for configuring the dimming
function as in the table below:
JP1
Configuration Description
ON
No external PWM signal
OFF
Connect external PWM signal source
The evaluation board features a PWM input terminal
for connecting an external digital PWM signal. JP1
connector is used to connect or disconnect a 100k
ohm pull up resistor (R3) to the PWM input. Apply a
digital PWM signal with a 0.8V logic-low (or less) and a
2.1V logic high (or greater) level, and frequencies from
4kHz to 100kHz. To adjust the HB LED brightness,
vary the signal duty cycle from 0 to 100.
Caution: If JP1 is “ON” the PWM pin will be pulled up to the
input VCC which can be up to 53V.
3
IS31LT3117 53V, 350MA, 4-CHANNEL
CONSTANT CURRENT REGULATOR WITH OTP
VCC
C3
VCC
33uF/100V
U1
VCC
GND
3
C1
10uF/100V
CON1
CON2
VCC
Vref
9
C2
1uF/10V
C4
0.1uF/100V R3
100K
VLED1
CH1
16
JP1
PWM
1
CH2
PWM
VLED2
TP1
8
R1
R2
20K
NC
CH3
Iset
VLED3
6
7
2
5
14
AGND
AGND
PGND
PGND
VLED4
12
CH4
10
CON3
IS31LT3117-EB
Figure 2: IS31LT3117 Application Schematic
BILL OF MATERIALS
Name
Symbol
LED Driver
U1
Resistor
Description
Qty
Supplier
Part No.
Constant current LED driver
1
ISSI
IS31LT3117
R1
RES,20k,1/10W,±1%,SMD
1
YAGEO
RC0805FR-0720KL
Resistor
R2
NC
1
Resistor
R3
RES,100k,1/10W,±5%,SMD
1
YAGEO
RC0805JR-07100KL
Capacitor
C1
CAP,10µF,100V,±20%,SMD
1
Capacitor
C2
CAP, 0.1µF,100V,±10%,SMD
1
YAGEO
CC1206DKX7R0BB104
Capacitor
C3
CAP,33µF,100V,±20%,SMD
1
Capacitor
C4
CAP, 1µF,10V,±10%,SMD
1
YAGEO
CC0805DKX7R6BB105
Jumper
JP1
2.54mm Jumper
1
Connector
CON1,CO
N2,CON3
DC connector
3
Bill of materials, refer to Figure 2 above.
Integrated Silicon Solution, Inc. – www.issi.com
Rev. B, 7/16/2014
4
IS31LT3117 53V, 350MA, 4-CHANNEL
CONSTANT CURRENT REGULATOR WITH OTP
Figure 3: Board Component Placement Guide -Top Layer
Figure 4: Board PCB Layout- Top Layer
Integrated Silicon Solution, Inc. – www.issi.com
Rev. B, 7/16/2014
5
IS31LT3117 53V, 350MA, 4-CHANNEL
CONSTANT CURRENT REGULATOR WITH OTP
Figure 5: Board Component Placement Guide -Bottom Layer
Figure 6: Board PCB Layout-Bottom Layer
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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.
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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;
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Integrated Silicon Solution, Inc. – www.issi.com
Rev. B, 7/16/2014
6