© Semiconductor Components Industries, LLC, 2010
March, 2010 − Rev. 2
1Publication Order Number:
CAT4008/D
CAT4008
8-Channel Constant Current
LED Driver
Description
The CAT4008 is an 8 channel constant current driver for LED
billboard and other general display applications. LED channel
currents are programmed together via an external RSET resistor. Low
output voltage operation on the LED channels as low as 0.4 V (for 2 to
100 mA LED current) allows for more power efficient designs.
A high−speed 4−wire serial interface of up to 25 MHz clock
frequency controls each individual channel using a shift register and
latch configuration. A serial output data pin (SOUT) allows multiple
devices to be cascaded and programmed via one serial interface. The
device also includes a blanking control pin (BLANK) that can be used
to disable all channels independently of the interface.
Thermal shutdown protection is incorporated in the device to
disable the LED outputs if the die temperature exceeds a set limit.
The device is available in the 16−lead SOIC (narrow and wide), and
TSSOP packages.
Features
•8 Constant Current−sink Channels
•Serial Interface up to 25 MHz Clock Frequency
•3 V to 5.5 V Logic Supply
•LED Current Range from 2 mA to 100 mA
•LED Current set by External RSET Resistor
•300 mV LED Dropout at 30 mA
•Thermal Shutdown Protection
•Available in 16−lead SOIC (150 and 300 mil wide), and TSSOP
Packages
•These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS
Compliant
Applications
•Billboard Display
•Marquee Display
•Instrument Display
•General Purpose Display
CAT4008W−T2
A3B
CAT4008WZ
YMXXXX
A3B
CAT4008VZ
YMXXXX
CAT4008V−T1
AB
4008YZZ
3YMXXX
CAT4008Y−T2 or
CAT4008Y−GT2
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SOIC−16
W SUFFIX
CASE 751BG
PIN CONNECTIONS
16−Lead SOIC (W, V), TSSOP (Y)
(Top View)
1
GND
SIN
SCLK
LED1
XLAT
VDD
RSET
SOUT
BLANK
LED8
LED7
LED6
LED5
LED2
LED3
LED4
SOIC−16
V SUFFIX
CASE 751BH
TSSOP−16
Y SUFFIX
CASE 948AN
1
11
See detailed ordering and shipping information in the package
dimensions section on page 13 of this data sheet.
ORDERING INFORMATION
A = Assembly Location
3 = Lead Finish − Matte−Tin
B = Product Revision (Fixed as “B”)
CAT4008W, CAT4008V, 4008Y = Device Code
Z or ZZ = Leave Blank
Y = Production Year (Last Digit)
M = Production Month (1-9, A, B, C)
XXX or XXXX = Last Three of Four Digits of
XXX or XXXX = Assembly Lot Number
MARKING DIAGRAMS
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Figure 1. Typical Application Circuit
LED1VDD
VIN
3 V to
5.5 V 1 mF20 mA
3.09 kW
BLANK
LATCH
CONTROLLER
SIN
CLK
LED2
GND
CAT4008
LED8
SOUT to next
device
RSET
Table 1. ABSOLUTE MAXIMUM RATINGS
Parameter Rating Units
VDD Supply Voltage 6 V
Logic input/output voltage (SIN, SOUT, CLK, BLANK, LATCH) −0.3 V to VDD+0.3 V V
LEDn voltage 6 V
DC output current on LED1 to LED8 150 mA
Storage Temperature Range −55 to +160 _C
Junction Temperature Range −40 to +150 _C
Lead Soldering Temperature (10 sec.) 300 _C
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
Table 2. RECOMMENDED OPERATING CONDITIONS
Parameter Range Units
VDD 3.0 to 5.5 V
Voltage applied to LED1 to LED8 0.4 to 5.5 V
LED current RSET control range up to 100 mA
Ambient Temperature Range −40 to +85 _C
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Table 3. ELECTRICAL OPERATING CHARACTERISTICS
(VDD = 5.0 V, TAMB = 25°C, over recommended operating conditions unless specified otherwise.)
Symbol Name Conditions Min Typ Max Units
DC CHARACTERISTICS
ILED−ACC LED Current (any channel) VLED = 1 V, RSET = 3.08 kW18 20 22 mA
VLED = 1 V, RSET = 1.54 kW36 40 44
VLED = 1 V, RSET = 769 W80
ILED−MAT LED Current Matching
(ILED − ILEDAVR) / ILEDAVR
VLED = 1 V, RSET = 3.08 kW±1.5 %
VLED = 1 V, RSET = 1.54 kW−6.0 ±1.5 +6.0
VLED = 1 V, RSET = 769 W±2.0
ΔIVDD LED current regulation vs. VDD VDD within 4.5 V and 5.5 V
LED current 30 mA
±0.1 % / V
ΔIVLED LED current regulation vs. VLED VLED within 1 V and 3 V
LED current 30 mA
±0.05 % / V
IDDOFF Supply Current (all outputs off) RSET = 3.08 kW2 8 mA
RSET = 769 W5.5
IDDON Supply Current (all outputs on) RSET = 3.08 kW2.5 9 mA
RSET = 769 W6.2
ILKG LEDn output Leakage VLED = 5 V, outputs off −1 1 mA
RLATCH LATCH Pull−down Resistance 100 180 300 kW
RBLANK BLANK Pull−up Resistance 100 180 300 kW
VIH
VIL
Logic high input voltage
Logic low input voltage
0.7xVDD
0.3xVDD
V
VHYS Logic input hysteresis voltage 0.1xVDD V
IIL Logic Input leakage current
(CLK, SIN)
VI = VDD or GND −5 0 5 mA
VOH
VOL
SOUT logic high output voltage
SOUT logic low output voltage
IOH = −1 mA
IOL = 1 mA
VCC−0.3 V
0.3
V
VRSET RSET Regulated Voltage BLANK high, outputs off 1.17 1.20 1.23 V
TSD Thermal Shutdown 160 °C
THYST Thermal Hysteresis 20 °C
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Table 4. TIMING CHARACTERISTICS
(For 3.0 V ≤ VDD ≤ 5.5 V, TAMB = 25°C, unless specified otherwise.)
Symbol Name Conditions
Min
(Note 1)
Typ
(Note 2)
Max
(Note 1) Units
CLK
fclk CLK Clock Frequency 25 MHz
tcwh CLK Pulse Width High 20 ns
tcwl CLK Pulse Width Low 20 ns
SIN
tssu Setup time SIN to CLK 4 ns
tsh Hold time SIN to CLK 4 ns
LATCH
tlwh LATCH Pulse width 20 ns
Tlh Hold time LATCH to CLK 4 ns
Tlsu Setup time LATCH to CLK Channel Stagger Delay 400 ns
LEDn
tld LED1 Propagation delay LATCH to LED1 off/on 40 300 ns
tls LED Propagation delay stagger LED(n) to LED(n+1) 17 40 ns
tlst LED Propagation delay stagger total LED1 to LED8 120 ns
tbd BLANK Propagation delay BLANK to LED(n) off/on 60 300 ns
tlr LED rise time (10% to 90%) Pull−up resistor = 50 W to 3.0 V 40 200 ns
tlf LED fall time (90% to 10%) Pull−up resistor = 50 W to 3.0 V 30 250 ns
SOUT
tor SOUT rise time (10% to 90%) CL = 15 pF 5 ns
tof SOUT fall time (90% to 10%) CL = 15 pF 5 ns
tod Propagation delay time SOUT CLK to SOUT 8 15 25 ns
1. All min and max values are guaranteed by design.
2. VDD = 5 V, LED current 30 mA.
Figure 2. Test Circuit for AC Characteristics
LED1
VDD
VDD 1 mF
BLANK
LATCH
CONTROLLER
SIN
CLK
GND
CAT4008 LED8
SOUT
RSET
RSET
15 pF
Cl
V1
3 V
Rp 50 W
Rp 50 W
CAT4008
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Figure 3. Serial Input Timing Diagram
CLK
SIN
SOUT
LATCH
tod
tsh
tssu tcwl tcwh
1/fclk
tlwh
tlsu
tlh
Figure 4. LED Output Timing Diagram
LATCH
BLANK
LED1
LED2
LED8
tld
tls
tbd
tlst = 7 tls
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TYPICAL PERFORMANCE CHARACTERISTICS
(VDD = 5.0 V, LED current 30 mA, all LEDs On, TAMB = 25°C unless otherwise specified.)
Figure 5. LED Current vs. LED Pin Voltage Figure 6. Supply Current vs. VDD Pin Voltage
LED PIN (V) VDD (V)
1.51.20.90.60.30
0
10
20
30
40
50
60
70
5.55.04.54.03.53.0
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Figure 7. LED Current vs. VDD Pin Voltage Figure 8. Supply Current vs. RSET Current
VDD (V) RSET CURRENT (mA)
5.55.04.54.03.53.0
28.5
29.0
29.5
30.0
30.5
31.0
31.5
2.01.51.00.50
0
1
2
3
4
5
6
8
Figure 9. RSET Voltage vs. VDD Pin Voltage Figure 10. LED Current vs. RSET Resistor
VDD (V) RSET (kW)
5.55.04.54.03.53.0
1.10
1.15
1.20
1.25
1.30
1001010.1
0
20
40
60
80
100
LED CURRENT (mA)
SUPPLY CURRENT (mA)
LED CURRENT (mA)
SUPPLY CURRENT (mA)
RSET PIN (V)
LED CURRENT (mA)
ALL LED’s OFF
ALL LED’s ON
7
ALL LED’s OFF
ALL LED’s ON
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TYPICAL PERFORMANCE CHARACTERISTICS
(VDD = 5.0 V, LED current 30 mA, all LEDs On, TAMB = 25°C unless otherwise specified.)
Figure 11. RSET Voltage vs. Temperature Figure 12. LED Current vs. Temperature
TEMPERATURE (°C) TEMPERATURE (°C)
150100500−50
1.10
1.15
1.20
1.25
1.30
150100500−50
28.5
29.0
29.5
30.0
30.5
31.0
31.5
Figure 13. Internal Pull−Down Current
(LATCH Pin)
Figure 14. Internal Pull−Up Current
(BLANK Pin)
LATCH VOLTAGE (V) BLANK VOLTAGE (V)
543210
0
5
10
15
20
25
30
543210
0
5
10
15
20
25
30
Figure 15. PWM Dimming on BLANK Pin
(f = 10 kHz)
Figure 16. BLANK Transient Response
LED CURRENT (mA)
302520151050
0
20
40
60
80
100
RSET PIN (V)
LED CURRENT (mA)
PULL−DOWN CURRENT (mA)
PULL−UP CURRENT (mA)
DUTY CYCLE (%)
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Table 5. PIN DESCRIPTION
Name Function
GND Ground
SIN Serial data input pin
CLK Serial clock input pin
LATCH Latch serial data to output registers
LED1−LED8 LED channel 1 to 8 cathode terminals
BLANK Enable / disable all channels
SOUT Serial data output pin.
RSET LED current set pin
VDD Positive supply Voltage
Pin Function
GND is the ground reference pin for the device. This pin
must be connected to the ground plane on the PCB.
SIN is the serial data input. Data is loaded into the internal
register on each rising edge of CLK.
CLK is the serial clock input. On each rising CLK edge, data
is transferred from SIN to the internal 8−bit serial shift
register.
LATCH is the latch data input. On the rising edge of
LATCH, data is loaded from the 8−bit serial shift register
into the output register latch. On the falling edge, this data
is latched in the output register and isolated from the state of
the serial shift register.
LED1 – LED8 are the LED current sink channels. These
pins are connected to the LED cathodes. The current sinks
drive the LEDs with a current equal to about 51 times RSET
pin current. For the LED sink to operate correctly, the
voltage on the LED pin must be above 0.4 V.
BLANK is the LED channel enable and disable input pin.
When low, LEDs are enabled according to the output latch
register content. When high, all LEDs are off, while
preserving the data in the output latch register.
SOUT is the serial data output of the 8−bit serial shift
register. This pin is used to cascade several devices on the
serial bus. The SOUT pin is then connected to the SIN input
of the next device on the serial bus to cascade.
RSET is the LED current setting pin. A resistor is connected
between this pin and ground. Each LED channel current is
set to about 51 times the current pulled out of the pin. The
RSET pin voltage is regulated to 1.2 V.
VDD is the positive supply pin voltage for the entire device.
A small 1 mF ceramic is recommended close to pin.
Current Setting Resistor
Table 6 lists standard resistor values for various LED
current settings.
Table 6. LED CURRENT
AND RSET RESISTOR VALUES
LED Current [mA] RSET [kW]
10 6.19
20 3.09
30 2.05
40 1.54
60 1.02
80 0.768
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Block Diagram
Figure 17. CAT4008 Functional Block Diagram
Current
Setting
+
CURRENT
SINKS
LATCHES
SHIFT
REGISTER
1.2 V Ref
GND
+
RSET
BLANK
VIN
VDD
LED1 LED2 LED3 LED8
CLK
SIN
LATCH L1 L2 L3 L8
S1 S2 S3 S8 SOUT
Basic Operation
The CAT4008 uses 8 tightly matched current sinks to
accurately regulate the LED current in each channel. The
external resistor, RSET, is used to set the LED channel
current to about 51 times the current in RSET.
LED current ^51 1.2
RSET
Tight current regulation for all channels is possible over
a wide range of input and LED voltages due to independent
current sensing circuitry on each channel. The LED
channels have a maximum dropout of 0.4 V for most current
and supply voltage conditions. This helps improve the heat
dissipation and efficiency of the LED driver.
Upon power−up, an under−voltage lockout circuit clears
all latches and shift registers and sets all outputs to off. Once
the under−voltage lockout threshold has been reached the
device can be programmed.
The driver delays the activation of each consecutive LED
output channel by 17 ns (typical). Relative to LED1, LED2
is delayed by 17 ns, LED3 by 34 ns and LED8 by 120 ns
typical. The delay is introduced when LATCH is activated.
The delay minimizes the inrush current on the LED supply
by staggering the turn on and off current spikes over a period
of time and therefore allowing usage of smaller bypass
capacitors.
Pull−up and pull−down resistors are internally provided to
set the state of the BLANK and LATCH pins to the off−state
when not externally driven.
Serial Interface
A high−speed serial 4−wire interface is provided to
program the state of each LED on or off. The interface
contains an 8−bit serial to parallel shift register (S1−S8) and
an 8−bit latch (L1−L8). Programming the serial to parallel
register is accomplished via SIN and CLK input pins. On
each rising edge of the CLK signal, the data from SIN is
moved through the shift register serially. Data is also moved
out of SOUT which can be connected to a next device if
programming more than one device on the same interface.
On the rising edge of LATCH, the data contents of the
serial to parallel shift register is reflected in the latches. On
the falling edge of LATCH, the state of the serial to parallel
register at that particular time is saved in the latches and does
not change irrespective of the contents of the serial to
parallel register.
BLANK is used to disable all LEDs (turn off)
simultaneously while maintaining the same data in the latch
register. When low, the LED outputs reflect the data in the
latches. When high, all outputs are high impedance (zero
current).
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PACKAGE DIMENSIONS
SOIC−16, 150 mils
CASE 751BG−01
ISSUE O
TOP VIEW
PIN#1 IDENTIFICATION
E
D
A
ebA1 L
h
c
E1
SIDE VIEW END VIEW
Notes:
(1) All dimensions are in millimeters. Angles in degrees.
(2) Complies with JEDEC MS-012.
q
SYMBOL MIN NOM MAX
θ
A
A1
b
c
D
E
E1
e
h
0º 8º
0.10
0.33
0.19
0.25
9.80
5.80
3.80
1.27 BSC
1.75
0.25
0.51
0.25
0.50
10.00
6.20
4.00
L0.40 1.27
1.35
9.90
6.00
3.90
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PACKAGE DIMENSIONS
SOIC−16, 300 mils
CASE 751BH−01
ISSUE A
L
h
EE1
PIN #1 IDENTIFICATION
D
A1
A
c
be
TOP VIEW
SIDE VIEW END VIEW
Notes:
(1) All dimensions are in millimeters. Angles in degrees.
(2) Complies with JEDEC MS-013.
q
SYMBOL MIN NOM MAX
θ
A
A1
b
c
D
E
E1
e
h
0º 8º
0.10
0.33
0.18
0.25
10.08
10.01
7.39
1.27 BSC
2.64
0.30
0.51
0.28
0.75
10.49
10.64
7.59
L0.38 1.27
2.36
10.31
10.31
7.49
0.41
0.23
0.81
2.49
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PACKAGE DIMENSIONS
TSSOP16, 4.4x5
CASE 948AN−01
ISSUE O
PIN#1
IDENTIFICATION
θ1
A1
A2
D
TOP VIEW
SIDE VIEW END VIEW
e
E1
b
L1
c
L
A
SYMBOL
θ
MIN NOM MAX
A
A1
A2
b
c
D
E
E1
e
L1
0º 8º
L
0.05
0.85
0.19
0.13
0.45
4.90
6.30
4.30
0.65 BSC
1.00 REF
1.10
0.15
0.95
0.30
0.20
0.75
5.10
6.50
4.50
Notes:
(1) All dimensions are in millimeters. Angles in degrees.
(2) Complies with JEDEC MO-153.
E
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Example of Ordering Information (Note 5)
Prefix Device # Suffix
Company ID
CAT 4008
Product Number
4008
T2
T: Tape & Reel
1: 1,000 / Reel
2: 2,000 / Reel
Tape & Reel (Note 8)
(Optional)
Y
Package
− G
G: NiPdAu
Blank: Matte−Tin (Note 6)
Lead Finish
W: SOIC, 150 mils
V: SOIC, 300 mils (Note 6)
Y: TSSOP (Note 6)
Table 7. ORDERING INFORMATION
Part Number Package Quantity per Reel Package Marking
CAT4008W-T2 SOIC16 (N) (Note 9) 2,000 CAT4008W
CAT4008V-T1 SOIC16 (W) (Notes 6, 9) 1,000 CAT4008V
CAT4008Y-T2 TSSOP16 (Notes 6, 9) 2,000 CAT4008Y
CAT4008Y-GT2 TSSOP16 (Note 10) 2,000 CAT4008Y
3. All packages are RoHS−compliant (Lead−free, Halogen−free).
4. The standard lead finish is Matte−Tin.
5. The device used in the above example is a CAT4008Y−GT2 (TSSOP, NiPdAu, Tape & Reel, 2,000/Reel).
6. Contact factory for package availability.
7. For additional package and temperature options, please contact your nearest ON Semiconductor Sales office.
8. For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging
Specifications Brochure, BRD8011/D.
9. Matte−Tin Plated Finish (RoHS−compliant).
10.NiPdAu Plated Finish (RoHS−compliant).
ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice
to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability
arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages.
“Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All
operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights
nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications
intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should
Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates,
and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death
associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal
Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner.
CAT4008/D
PUBLICATION ORDERING INFORMATION
N. American Technical Support: 800−282−9855 Toll Free
USA/Canada
Europe, Middle East and Africa Technical Support:
Phone: 421 33 790 2910
Japan Customer Focus Center
Phone: 81−3−5773−3850
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