SIPEX SP7615

®
Preliminary
SP7615
Four Channel Constant Current LED Driver
FEATURES
■ Cost Effective LED driver
VCC 1
8 LED1
■ Constant current output ideal for Driving LED strings
SP7615 7 LED2
EN 2
■ Four Channel LED Driver provides matched LED
6 LED3
GND 3
8 Pin DFN
current
ISET 4
5 LED4
■ Current adjusted via an external resistor
■ PWM dimming possible
Now Available in Lead Free Packaging
■ Small 2mm x 3mm DFN package
■ Outputs can be connected in parallel to
APPLICATIONS
increase drive
■ Constant current for wide cathode voltage range ■ Next Generation Mobile Phones
(1.0V to 16V)
■ PDA, DSC, MP3 Players
■ Highly integrated design, minimal components
■ Handheld Computers
■ LCD Display Modules
■ Thermal shutdown protects the driver
■ Keyboard Backlight
■ LED Displays
DESCRIPTION
The SP7615 is a linear constant current driver designed to drive multiple LEDs in series from
a high input voltage rail. The driver acts as a high current matched, four-channel current
source ensuring constant LED current for a range of input voltages. The SP7615 allows
implementing the lowest cost LED driver for a variety of applications. Internal circuitry
maintains the pre-set constant current output for a wide voltage range at the LED outputs
(LED1,2,3,4). LED current can be adjusted up to 125mA per string with an external resistor.
The dimming can be achieved by controlling the ISET input or by feeding a PWM signal to
the EN pin. Fast EN turn-on and turn-off time allows for very fast PWM dimming frequencies,
completely eliminating flicker. The built-in thermal protection automatically adjusts LED
current to prevent overheating.
TYPICAL APPLICATION SCHEMATIC
VCC
VCC
EN
EN
GND
C1
1n
R1
LED1
®
LED2
SP7615
LED3
ISET
LED4
GND
Date: 08/31/05
SP7615 Four Channel Constant Current LED Driver
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© Copyright 2005 Sipex Corporation
ABSOLUTE MAXIMUM RATINGS
Vcc, VLED1, VLED2, VLED3, VLED4 Voltage to GND 0.3V to 16V
ISET and EN Voltage to GND..................................... 6V
These are stress ratings only and functional operation
Output Current per LED (IOUT) ............................. 150mA
of the device at these ratings or any other above those
Power Dissipation per Package
indicated in the operation sections of the specifications
8-pin DFN at TA = 85ºC ......................… 1.1W
below is not implied. Exposure to absolute maximum
Junction Temperature ..........................................+150ºC
rating conditions for extended periods of time may affect
Storage Temperature ........................... -55ºC to +150ºC
reliability.
ESD Level. ....................................................... 2kV HBM
DFN Thermal Resistance......................................59ºC/W
ELECTRICAL CHARACTERISTICS
4.5V < VCC <16V , VEN = 5V, VLED1 =VLED2 =VLED3 =VLED4 =1.0V, RSET =10kΩ or ISET=126µA, -40 < TA < 85ºC,
Unless otherwise noted. Typical numbers are for TA = 25ºC.
PARAMETER
MIN.
TYP.
MAX.
UNITS
Supply Voltage
4.5
5
16
V
20
39
mA
1000
1200
Quiescent Supply Current
Output/I SET Current Multiplication Ratio
700
LED Current (per diode)
LED to LED Current Matching
126
-5
LED Current Line Voltage Regulation
LED Current Load Voltage Regulation
LED Current Thermal Regulation
ISET Pin Voltage
1.17
ILED1 = ILED2 = ILED3= ILED4 =126mA
mA
5
%
0.15
0.6
%/V
2
4
IOUT change per volt VCC change
%/V
0.4V < VLED < 5V, ILED = 25mA
9
%/V
1.0V < VLED < 5V, ILED = 126mA
0.1
%/ºC
ILED = 126mA
1.26
1.39
V
Thermal Shutdown Threshold
150
ºC
Thermal Shutdown Hysteresis
20
ºC
Current in OFF Mode
Min. ENABLE “ON Voltage”
(Note1)
Max. ENABLE “OFF Voltage”
(Note 2)
CONDITIONS
1
µA
1.6
V
0.4
ISET = 1µA
VEN = ZeroV
V
Note 1. ENABLE "ON" is VEN for which ILED > 80mA
Note 2. ENABLE "OFF" is VEN for which ILED < [email protected] VLED1 > 1.0V
Date: 08/31/05
SP7615 Four Channel Constant Current LED Driver
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© Copyright 2005 Sipex Corporation
BLOCK DIAGRAM
LED1
VCC
Thermal
Shutdown
GND
LED2
Bias
Driver
LED3
EN
V to I
Converter
Figure 1. SP7615 Block Diagram
LED4
ISET
THEORY OF OPERATION
Introduction
The SP7615 is a four channel constant current
source LED driver with programmable output
current level. The design consists of a regulator
bandgap, voltage to current converter, and
output mirror drivers. The bandgap ensures
good performance over voltage and
temperature. The four outputs are tightly
coupled allowing for excellent channel
matching.
acceptable. The enable pin can also be used to
control the LED brightness with a pulse width
modulated control signal. Duty Cycle or PWM
control of the LED current maintains constant
LED color while brightness is changing. The
SP7615 responds in less than 10µs to PWM
signals applied to this pin.
Thermal Shutdown
The ISET pin is the servo point of an amplifier
configured as a voltage to current converter.
The voltage at this pin trips servos to the
internal bandgap potential. A set resistor can
be connected from the ISET pin to ground to
generate a reference current for the following
current gain stages. A current could
alternately be applied to this pin in the form
of a current source or current output DAC.
This pin can also have a PWM signal applied
to control the LED brightness.
ISET Pin
The SP7615 uses a thermal comparator to
monitor the system temperature shutting the
device down if the internal temperature reaches
150ºC. The device will remain off until the
internal temperature drops below 130ºC.
Enable
The device has an enable function that is
designed for TTL level inputs. This input will
also track the VCC pin so levels up to VCC are
Date: 08/31/05
SP7615 Four Channel Constant Current LED Driver
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© Copyright 2005 Sipex Corporation
THEORY OF OPERATION
The RSET value may be determined as RSET =
1.26 * 1000/IOUT, kΩ where 1.26 is a typical
ISET pin voltage, 1000 is a typical current
multiplication ratio, and IOUT is a required
LED current in mA.
D1
LED
VCC
VCC
EN
EN
LED2
GND
C1
1n
R1
LED1
®
ISET
SP7615
LED3
LED4
GND
VCC
VCC
EN
EN
GND
C1
1n
LED1
®
LED2
SP7615
LED3
ISET
R1
LED4
VCC
LED1
®
EN
GND
GND
R2
LED2
SP7615
ISET
LED3
LED4
CATHODE VOLTAGE, SUPPLY VOLTAGE
AND POWER DISSIPATION
The voltage applied to the cathode of each
LED determines the overall efficiency of the
SP7615 circuit. The SP7615 is designed to
be able to sink 125mA at each of its four
outputs; LED1 - 4. The SP7615 is also
designed to be able to handle up to 16V on
these pins. This voltage handling capability
assumes the total power can be dissipated
by the SP7615. The power dissipation inside
the SP7615 will de directly related to the
voltage and current applied to these pins.
For example, the typical operating cathode
voltage is 500mV. At maximum current the
Date: 08/31/05
power dissipated by one LED driver output
is 125mA * 500mV = 62.5mW. The following
charts show the power dissipation of the
SP7615 under various conditions. The
power dissipation should be kept below
1.3W for safe operation and long term
reliability at room temperature and derates
to 530mW at 85 ºC. While the above
operating conditions are recommended, the
part cannot be damaged due to internal
temperature control as described above in
the thermal shutdown section.
SP7615 Four Channel Constant Current LED Driver
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© Copyright 2005 Sipex Corporation
PERFORMANCE GRAPHS
Figure 2 – Four Channel Total Power Dissipation versus Cathode Voltage at VCC = 5V
Figure 3 – Four Channel Total Power Dissipation versus Supply Voltage at Vcathode =
500mW
Date: 08/31/05
SP7615 Four Channel Constant Current LED Driver
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© Copyright 2005 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 4 – LED Current versus ISET Current and Cathode Voltage, Vcc=5V, T= 27°C
Figure 5 – LED Current versus RSET Value
Date: 08/31/05
SP7615 Four Channel Constant Current LED Driver
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© Copyright 2005 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 6 – LED Current versus Temperature with Thermal Shutdown
Figure 7 – ISET Voltage versus Temperature
Date: 08/31/05
SP7615 Four Channel Constant Current LED Driver
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© Copyright 2005 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 8 –PWM Signal Applied To The Enable Pin, Amplitude=5V, Duty Cycle=50%
Date: 08/31/05
SP7615 Four Channel Constant Current LED Driver
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© Copyright 2005 Sipex Corporation
PACKAGE: 8 PIN DFN
D2
D
D/2
D2/2
5
6
7
8
E/2
E2/2
E
E2
K
L
4
Pin1 Designator
to be within this
INDEX AREA
(D/2 x E/2)
3
2
e
TOP VIEW
1
b
INDEX AREA
(D/2 x E/2)
BOTTOM VIEW
ø
A
(A3)
A1
Seating Plane
SIDE VIEW
2x3 8 Pin DFN
SYMBOL
Dimensions in Millimeters:
Controlling Dimension
MIN
0.80
0.00
A
A1
A3
K
¿
b
D
D2
E
E2
e
L
JEDEC MO-229
0.20
0…
0.18
1.50
1.60
0.30
NOM
0.90
0.02
0.20 REF
0.25
2.00 BSC
3.00 BSC
0.50 BSC
0.40
Dimensions in Inches
Conversion Factor:
1 Inch = 25.40 mm
MAX
1.00
0.05
MIN
0.032
0.000
14…
0.30
0.008
0…
0.008
1.75
0.059
1.90
0.063
0.50
0.012
SIPEX Pkg Signoff Date/Rev:
Date: 08/31/05
VARIATION VCED-2
NOM
0.036
0.001
0.008 REF
0.010
0.079 BSC
0.118 BSC
0.020 BSC
0.016
MAX
0.039
0.002
14…
0.012
0.069
0.075
0.020
JL Aug18-05 / RevA
SP7615 Four Channel Constant Current LED Driver
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© Copyright 2005 Sipex Corporation
ORDERING INFORMATION
Part Number
Operating Temperature Range
Package Type
SP7615ER .................................................. -40°C to +85°C ............................................ 8 Pin DFN (2 x 3mm)
SP7615ER/TR ............................................ -40°C to +85°C ............................................ 8 Pin DFN (2 x 3mm)
Available in lead free packaging. To order add "-L" suffix to part number.
Example: SP7615ER/TR = standard; SP7615ER-L/TR = lead free
/TR = Tape and Reel
Pack quantity is 3000 for DFN.
Corporation
ANALOG EXCELLENCE
Sipex Corporation
Headquarters and
Sales Office
233 South Hillview Drive
Milpitas, CA 95035
TEL: (408) 934-7500
FAX: (408) 935-7600
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the
application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.
Date: 08/31/05
SP7615 Four Channel Constant Current LED Driver
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© Copyright 2005 Sipex Corporation