CAT4008
© Catalyst Semiconductor, Inc. 1 Doc. No. MD-5034 Rev. A
Characteristics subject to change without notice
8-Channel Constant Current LED Driver
FEATURES
8 Constant current-sink channels
Serial interface up to 25MHz clock frequency
3V to 5.5V logic supply
LED current range from 2mA to 100mA
LED current set by external RSET resistor
300mV LED dropout at 30mA
Thermal shutdown protection
Available in RoHS-compliant 16-lead SOIC (150
and 300mil wide), and TSSOP packages
APPLICATIONS
Billboard Display
Marquee Display
Instrument Display
General Purpose Display
For Ordering Information details, see page 13.
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 0.4V
(for 2 to 100mA LED current) allows for more power
efficient designs.
A high-speed 4-wire serial interface of up to 25MHz
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.
TYPICAL APPLICATION CIRCUIT
LED1VDD
VIN
3V to
5.5V 1µF 20mA
3.09k
BLANK
LATCH
CONTROLLER
SIN
CLK
LED2
GND
CAT4008
LED8
SOUT to next
device
RSET
CAT4008
Doc. No. MD-5034 Rev. A 2 © Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
ORDERING INFORMATION
Part Number Package Quantity per Reel Package Marking
CAT4008W-T2 SOIC16 (N) (1) 2000 CAT4008W
CAT4008V-T1 SOIC16 (W)
(1)(2) 1000 CAT4008V
CAT4008Y-T2 TSSOP16
(1)(2) 2000 CAT4008Y
PIN CONFIGURATION
16-Lead SOIC (W, V), TSSOP (Y)
Notes:
(1) Matte-Tin Plated Finish (RoHS-compliant).
(2) Contact factory for package availability.
116
GND VDD
215
SIN RSET
314
SCLK SOUT
413
XLAT BLANK
512
LED1 LED8
611
LED2 LED7
710
LED3 LED6
89
LED4 LED5
CAT4008
© Catalyst Semiconductor, Inc. 3 Doc. No. MD-5034 Rev. A
Characteristics subject to change without notice
ABSOLUTE MAXIMUM RATINGS
Parameter Rating Units
VDD Supply Voltage 6 V
Logic input/output voltage (SIN, SOUT, CLK, BLANK, LATCH) -0.3V to VDD+0.3V 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 (10sec.) 300 °C
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
ELECTRICAL OPERATING CHARACTERISTICS
DC CHARACTERISTICS
VDD = 5.0V, TAMB = 25 ºC, over recommended operating conditions unless specified otherwise.
Symbol Name Conditions Min Typ Max Units
VLED = 1V, RSET = 3.08k 18 20 22
VLED = 1V, RSET = 1.54k 36 40 44
ILED-ACC LED Current (any channel)
VLED = 1V, RSET = 769 80
mA
VLED = 1V, RSET = 3.08k ±1.5
VLED = 1V, RSET = 1.54k -6.0 ±1.5 +6.0
ILED-MAT LED Current Matching
(ILED - ILEDAVR) / ILEDAVR
VLED = 1V, RSET = 769 ±2.0
%
ΔIVDD LED current regulation vs. VDD VDD within 4.5V and 5.5V
LED current 30mA ±0.1 % / V
ΔIVLED LED current regulation vs. VLED VLED within 1V and 3V
LED current 30mA ±0.05 % / V
RSET = 3.08k 2 8 mA
IDDOFF Supply Current (all outputs off) RSET = 769 5.5 mA
RSET = 3.08k 2.5 9 mA
IDDON Supply Current (all outputs on) RSET = 769 6.2 mA
ILKG LEDn output Leakage VLED = 5V, outputs off -1 1 µA
RLATCH LATCH Pull-down Resistance 100 180 300 k
RBLANK BLANK Pull-up Resistance 100 180 300 k
VIH
VIL
Logic high input voltage
Logic low input voltage 0.7xVDD
0.3xVDD
V
V
VHYS Logic input hysteresis voltage 0.1xVDD V
IIL Logic Input leakage current
(CLK, SIN) VI = VDD or GND -5 0 5 µA
VOH
VOL
SOUT logic high output voltage
SOUT logic low output voltage
IOH = -1mA
IOL = 1mA
VCC-0.3V
0.3 V
VRSET RSET Regulated Voltage BLANK high, outputs off 1.17 1.20 1.23 V
TSD Thermal Shutdown 160 ºC
THYST Thermal Hysteresis 20 ºC
CAT4008
Doc. No. MD-5034 Rev. A 4 © Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
TIMING CHARACTERISTICS
For 3.0V ≤ VDD ≤ 5.5V, TAMB = 25 ºC, unless specified otherwise.
Symbol Name Conditions Min(1) Typ(2) Max(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 to 3.0V 40 200 ns
tlf LED fall time (90% to 10%) Pull-up resistor = 50 to 3.0V 30 250 ns
SOUT
tor SOUT rise time (10% to 90%) CL = 15pF 5 ns
tof SOUT fall time (90% to 10%) CL = 15pF 5 ns
tod Propagation delay time SOUT CLK to SOUT 8 15 25 ns
TEST CIRCUIT FOR AC CHARACTERISTICS
Notes:
(1) All min and max values are guaranteed by design.
(2) VDD = 5V, LED current 30mA.
LED1
VDD
V
DD 1µF
BLANK
LATCH
CONTROLLER
SIN
CLK
GND
CAT4008
LED8
SOUT
RSET
RSET
15pF
Cl
V1
3
V
Rp 50
Rp 50
CAT4008
© Catalyst Semiconductor, Inc. 5 Doc. No. MD-5034 Rev. A
Characteristics subject to change without notice
CLK
SIN
SOUT
LATCH
1/f
clk
t
ssu
t
sh
t
cwl
t
cwh
t
lh
t
lsu
t
lwh
t
od
Figure 1. Serial Input Timing Diagram
LATCH
BLANK
LED1
LED2
LED8
t
ld
t
bd
t
ls
t
lst
= 7 t
ls
Figure 2. LED Output Timing Diagram
CAT4008
Doc. No. MD-5034 Rev. A 6 © Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
TYPICAL PERFORMANCE CHARACTERISTICS
VDD = 5.0V, LED current 30mA, all LEDs On, TAMB = 25°C unless otherwise specified.
LED Current vs. LED Pin Voltage
0
10
20
30
40
50
60
70
0.0 0.3 0.6 0.9 1.2 1.5
LED PIN [V]
LED CURRENT [mA]
Supply Current vs. VDD Pin Voltage
1.0
1.5
2.0
2.5
3.0
3.5
4.0
3.03.54.04.55.05.5
VDD [V]
SUPPLY CURRENT [mA]
All LED's OFF
All LED's ON
LED Current vs. VDD Pin Voltage
28.5
29.0
29.5
30.0
30.5
31.0
31.5
3.0 3.5 4.0 4.5 5.0 5.5
VDD [V]
LED CURRENT [ mA]
Supply Current vs. RSET Current
0
1
2
3
4
5
6
7
8
0.0 0.5 1.0 1.5 2.0
RSET CURRENT [mA]
SUPPLY CURRENT [mA]
All LED's ON
All LED's OFF
RSET Voltage vs. VDD Pin Voltage
1.10
1.15
1.20
1.25
1.30
3.0 3.5 4.0 4.5 5.0 5.5
VDD [V]
RSET PIN [V]
LED Current vs. RSET Resistor
0
20
40
60
80
100
0.1 1.0 10.0 100.0
RSET [kΩ]
LED CURRENT [mA]
CAT4008
© Catalyst Semiconductor, Inc. 7 Doc. No. MD-5034 Rev. A
Characteristics subject to change without notice
TYPICAL PERFORMANCE CHARACTERISTICS
VDD = 5.0V, LED current 30mA, all LEDs On, TAMB = 25°C unless otherwise specified.
RSET Voltage vs. Temperature
1.10
1.15
1.20
1.25
1.30
-50 0 50 100 150
TEMPERATURE [°C]
RSET PIN [V]
LED Current vs. Temperature
28.5
29.0
29.5
30.0
30.5
31.0
31.5
-50 0 50 100 150
TEMPERATURE [°C]
LED CURRENT [mA]
Internal Pull-Down Current (LATCH pin)
0
5
10
15
20
25
30
012345
LATCH VOLTAGE [V]
PULL-DOWN CURRENT [A] .
Internal Pull-Up Current (BLANK pin)
0
5
10
15
20
25
30
012345
BLANK VOLTAGE [V]
PULL-UP CURRENT [A] .
PWM Dimming on BLANK pin (f = 10kHz)
0
20
40
60
80
100
0 5 10 15 20 25 30
LED CURRENT [mA]
DUTY CYCLE [%]
BLANK Transient Response
CAT4008
Doc. No. MD-5034 Rev. A 8 © Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
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 0.4V.
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 1.2V.
VDD is the positive supply pin voltage for the entire
device. A small 1µF ceramic is recommended close
to pin.
CURRENT SETTING RESISTOR
Table 1 lists standard resistor values for various LED
current settings.
Table 1. LED Current and RSET resistor values
LED Current [mA] RSET [kΩ]
10 6.19
20 3.09
30 2.05
40 1.54
60 1.02
80 0.768
CAT4008
© Catalyst Semiconductor, Inc. 9 Doc. No. MD-5034 Rev. A
Characteristics subject to change without notice
BLOCK DIAGRAM
Figure 2. CAT4008 Functional Block Diagram
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.
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 0.4V 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 17ns (typical). Relative to
LED1, LED2 is delayed by 17ns, LED3 by 34ns and
LED8 by 120ns 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 then 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).
SET
R
2.1
51 current LED ×≅
Current
Setting
+
CURRENT
SINKS
LATCHES
SHIFT
REGISTER
1.2V Ref
GND
+
RSET
BLANK
VIN
VDD
LED1 LED2 LED3 LED8
CLK
SIN
LATCH L1 L2 L3 L8
S1 S2 S3 S8 SOUT
CAT4008
Doc. No. MD-5034 Rev. A 10 © Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
PACKAGE OUTLINE DRAWINGS
SOIC 16-Lead Narrow Body 150mils (W) (1)(2)
Notes:
(1) All dimensions in millimeters. Angle in degrees.
(2) Compiles with JEDEC MS-012
TOP VIEW
PIN#1 IDENTIFICATION
E
D
A
eb
A1 L
h
c
E1
SIDE VIEW END VIEW
SYMBOL MIN NOM MAX
A1.35 1.75
A1 0.10 0.25
b0.33 0.51
c0.19 0.25
D 9.80 9.90 10.00
E 5.80 6.00 6.20
E1 3.80 3.90 4.00
e 1.27 BSC
h0.25 0.50
L0.40 1.27
0º 8º
For current Tape and Reel information, download the PDF file from:
htt
p
://www.catsemi.com/documents/ta
p
eandreel.
p
df.
CAT4008
© Catalyst Semiconductor, Inc. 11 Doc. No. MD-5034 Rev. A
Characteristics subject to change without notice
SOIC 16-Lead Wide Body 300mils (V) (1)(2)
Notes:
(1) All dimensions in millimeters. Angle in degrees.
(2) Compiles with JEDEC MS-013.
L
h
EE1
PIN #1 IDENTIFICATION
D
A1
A
c
be
TOP VIEW
SIDE VIEW END VIEW
SYMBOL MIN NOM MAX
A 2.36 2.49 2.64
A1 0.10 0.30
b 0.33 0.41 0.51
c 0.18 0.23 0.28
D 10.08 10.31 10.49
E 10.01 10.31 10.64
E1 7.39 7.49 7.59
e 1.27 BSC
h 0.25 0.75
L 0.38 0.81 1.27
0º 8º
For current Tape and Reel information, download the PDF file from:
htt
p
://www.catsemi.com/documents/ta
p
eandreel.
p
df.
CAT4008
Doc. No. MD-5034 Rev. A 12 © Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
TSSOP 16-Lead 4.4mm (Y) (1)(2)
Notes:
(1) All dimensions in millimeters. Angle in degrees.
(2) Compiles with JEDEC MO-153.
PIN#1
IDENTIFICATION
1
A1
A2
D
TOP VIEW
SIDE VIEW END VIEW
e
E1 E
b
L1
c
L
A
SYMBOL MIN NOM MAX
A1.10
A1 0.05 0.15
A2 0.85 0.95
b 0.19 0.30
c 0.13 0.20
D 4.90 5.10
E 6.30 6.50
E1 4.30 4.50
e 0.65 BSC
L1.00 REF
L1 0.45 0.75
10° 8°
For current Tape and Reel information, download the PDF file from:
htt
p
://www.catsemi.com/documents/ta
p
eandreel.
p
df.
CAT4008
© Catalyst Semiconductor, Inc. 13 Doc. No. MD-5034 Rev. A
Characteristics subject to change without notice
EXAMPLE OF ORDERING INFORMATION
(1)
Notes:
(1) All packages are RoHS-compliant (Lead-free, Halogen-free).
(2) The standard lead finish is Matte-Tin.
(3) The device used in the above example is a CAT4008W–T2 (SOIC 16-Lead 150 mils, Matte-Tin, Tape & Reel 2000).
(4) Contact factory for package availability.
(5) For additional package and temperature options, please contact your nearest Catalyst Semiconductor Sales office.
Prefix Device # Suffix
CAT 4008 W – T2
Product Number
4008
Tape & Reel
T: Tape & Reel
1: 1000/Reel
2: 2000/Reel
Package
W: SOIC, 150mils
V: SOIC, 300mils
(4)
Y: TSSOP
(4)
Optional
Company ID
REVISION HISTORY
Date Rev. Reason
01/10/2008 A Initial Issue
Catalyst Semiconductor, Inc.
Corporate Headquarters
2975 Stender Way
Santa Clara, CA 95054
Phone: 408.542.1000 Document No: MD-5034
Fax: 408.542.1200 Revision: A
www.catsemi.com Issue date: 01
/
10
/
08
Copyrights, Trademarks and Pat ents
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ARISING OUT OF ANY SUCH USE OR APPLICATION, INCLUDING BUT NOT LIMITED TO, CONSEQUENTIAL OR INCIDENTAL DAMAGES.
Catalyst Semiconductor 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 Catalyst Semiconductor product could create a situation where
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Catalyst Semiconductor reserves the right to make changes to or discontinue any product or service described herein without notice. Products with data sheets labeled
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