is32lt3117 60v, 350ma, 4-channel constant current regulator

IS32LT3117 60V, 350MA, 4-CHANNEL CONSTANT CURRENT
REGULATOR WITH OTP FOR AUTOMOTIVE LIGHT
DESCRIPTION
RECOMMENDED EQUIPMENT
The IS32LT3117 is designed for automotive lighting
applications such as map light, dome light, tail light and
daytime running lights. This device 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 60V, while maintaining an output leakage
current of less than 1µA. The sink current is easily
programmed using a single external resistor. The
current sinks of the IS32LT3117 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 IS32LT3117 also features a PWM input to enable
simple dimming control using a digital control signal.
FEATURES
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6V to 60V 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
IC is AEC-Q100 qualified (pending)
QUICK START

6.0V~60V, 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

≤ 60V 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 IS32LT3117 pin 8. See
“LED CURRENT SETTING” section of the datasheet
for guidance in calculating resistor values for specific
currents.
PROCEDURE
The IS32LT3117 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
IS32LT3117 power dissipation which may lead to device
shutdown.
3)
Figure 1: Photo of IS32LT3117 Evaluation Board
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 IS32LT3117 is
enabled and no external PWM signal should be
connected. When JP1 is “OFF” the IS32LT3117
must be driven by an external PWM signal source.
Caution: Always remove JP1 when driving the IS32LT3117
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. A, 03/10/2014
1
IS32LT3117 60V, 350MA, 4-CHANNEL CONSTANT CURRENT
REGULATOR WITH OTP FOR AUTOMOTIVE LIGHT
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.
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 IS32LT3117
VLEDx pin.
The power of the IS32LT3117 can be defined as:
4
P3117   (VVLEDx  I OUTx )  VCC  I Q
x 1
4
  (VCC  VLEDS x )  I OUTx )  VCC  I Q
x 1
LED CURRENT SETTING
The maximum sink current of all four channels
(VLEDx) is set by resistor (RISET) connected from the
IS32LT3117 ISET pin (8) to ground. The maximum
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 
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 IS32LT3117 datasheet.
HB LED Digital-Dimming Control
The JP1 connector is used for configuring the dimming
function as in the table below:
JP1
Configuration Description
Assume VCC=10V, IOUTx =0.1A, VLEDSx=9V, IQ=5mA:
ON
No external PWM signal
PLEDx=9V×0.1A=0.9W
OFF
Connect external PWM signal source
P3117=(10V-9V)×0.1A×4+10V×0.005A
= 0.45W
The voltage at VLEDx pin of the IS32LT3117 will be the
remaining value of VCC-VOUTx, and if it is larger than
2V@350mA (VVLEDx, recommended max headroom
voltage), the IC dissipation will be high which may
trigger the IC over temperature protection (OVP).
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 60V.
ORDERING INFORMATION
Part No.
Temperature Range
Package
IS32LT3117-ZLA3-EB
-40°C ~ +125°C (Automotive 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. A, 03/10/2014
2
IS32LT3117 60V, 350MA, 4-CHANNEL CONSTANT CURRENT
REGULATOR WITH OTP FOR AUTOMOTIVE LIGHT
VCC
C3
VCC
33uF/100V
U1
VCC
3
C1
GND
10uF/100V
CON2
VCC
Vref
9
C2
C4
0.1uF/10V
0.1uF/100V
CON1
100K
R3
VLED1
PWM
1
CH2
VLED2
8
R2
20K
NC
14
CH3
Iset
VLED3
6
7
2
5
CH1
PWM
TP1
R1
16
AGND
AGND
PGND
PGND
VLED4
12
CH4
10
CON3
IS32LT3117-EB
Figure 2: IS32LT3117 Application Schematic
BILL OF MATERIALS
Name
Symbol
LED Driver
U1
Resistor
Description
Qty
Supplier
Part No.
Constant current LED driver
1
ISSI
IS32LT3117
R1
RES,20k,1/10W,±1%,SMD
1
YAGEO
Resistor
R2
NC
1
Resistor
R3
RES,100k,1/10W,±5%,SMD
1
YAGEO
Capacitor
C1
CAP,10µF,100V,±20%,SMD
1
YAGEO
Capacitor
C2
CAP, 0.1µF,100V,±20%,SMD
1
YAGEO
Capacitor
C3
CAP,33µF,100V,±20%,SMD
1
YAGEO
Jumper
JP1
2.54mm Jumper
1
connectors
CON1~CON3
3
Bill of materials, refer to Figure 2 above.
Integrated Silicon Solution, Inc. – www.issi.com
Rev. A, 3/10/2014
3
IS32LT3117 60V, 350MA, 4-CHANNEL CONSTANT CURRENT
REGULATOR WITH OTP FOR AUTOMOTIVE LIGHT
Figure 3: Board Component Placement Guide -Top Layer
Figure 4: Board PCB Layout- Top Layer
Integrated Silicon Solution, Inc. – www.issi.com
Rev. A, 3/10/2014
4
IS32LT3117 60V, 350MA, 4-CHANNEL CONSTANT CURRENT
REGULATOR WITH OTP FOR AUTOMOTIVE LIGHT
Figure 5: Board Component Placement Guide -Bottom Layer
Figure 6: Board PCB Layout-Bottom Layer
Copyright © 2014 Integrated Silicon Solution, Inc. All rights reserved. ISSI reserves the right to make changes to this specification and its
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.
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, 3/10/2014
5