ST2221A
Version
Issue Date
File Name
Total Pages
: A.036
: 2006/2/9
: SP-ST2221A-A.036
: 17
8-Bit CONSTANT CURRENT LED DRIVERS
新竹市科學園區展業一路 9 號 7 樓之 1
SILICON TOUCH TECHNOLOGY INC.
9-7F-1, Prosperity Road I, Science Based Industrial Park,
Hsin-Chu, Taiwan 300, R.O.C.
Tel：886-3-5645656
Fax：886-3-5645626
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
ST2221A
ST2221A
8-Bit CONSTANT CURRENT LED DRIVERS
General Description
The ST2221A is specifically designed for LED and LED DISPLAY constant current drivers.
The value of constant current can be varied using an external resistor (Iout = 5 ~90mA). The
devices include an 8-bit shift registers, latches, and constant current drivers on a single Silicon
CMOS chip.
Features
z
z
z
z
z
Constant Current Output :
Current with one resistor for 5mA to 90mA
Maximum Clock Frequency : 25MHz (Cascade Operation)
5V CMOS Compatible Input
Package :
PDIP16,SOP16,SSOP16
Constant Current Matching: (Ta = 25°C、VDD = 5.0V)
Bit-to-Bit : ± 6%、Chip-to-Chip : ± 10%、
@ IOUT = 5 ~ 40mA
Bit-to-Bit : ± 6%、Chip-to-Chip : ± 10%、
@ IOUT = 40 ~ 90mA
8-BIT CONSTANT CURRENT LED DRIVERS
Version:A.036
Page: 1
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
ST2221A
Pin Connection (Top view)
VDD
GND
SERIAL-IN
1
2
16
15
R-EXT
CLOCK
3
4
14
SERIAL-OUT
5
13
12
ENABLE
OUT7
OUT1
6
11
OUT6
OUT2
OUT3
7
10
9
OUT5
OUT4
LATCH
OUT0
8
Block Diagram
R-EXT
OUT7
OUT1
OUT0
I-REG.
ENABLE
Q
ST
Q
D
Q
ST
ST D
D
LATCH
SERIAL-IN
D
CK
Q
D
CK
Q
D
Q
CK
D
Q
SERIAL-OUT
CK
CLOCK
8-BIT CONSTANT CURRENT LED DRIVERS
Version:A.036
Page: 2
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
ST2221A
Timing Diagram
5V
CLOCK
0V
5V
SERIAL IN
0V
5V
LATCH
0V
5V
ENABLE
0V
OUT0
Off
On
OUT1
Off
Off
OUT2
On
OUT7
Off
SERIAL-OUT
5V
0V
(Note) Latches are level sensitive (not edge triggered).
LATCH-terminal = H level, latches become transparent; LATCH-terminal = L level, latches hold data.
ENABLE-terminal = H level, all outputs (OUT0~7) are off.
An external resistor is connected between R-EXT and GND for setting up the value of constant current.
SERIAL-OUT changes state on the falling edges of clock.
Pin Description
PIN No.
1
2
3
4
5~12
13
14
15
16
PIN NAME
GND
SERIAL-IN
CLOCK
LATCH
OUT0~7
ENABLE
SERIAL-OUT
R-EXT
VDD
FUNCTION
GND terminal
Input terminal of a data shift register
Input terminal of a clock for shift register
Input terminal for data strobe
Output terminals
Input terminal for output enable (active low)
Output terminal of a data shift register
Input terminal of an external resistor
5V Supply voltage terminal
8-BIT CONSTANT CURRENT LED DRIVERS
Version:A.036
Page: 3
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
ST2221A
Equivalent Circuit of Inputs and Outputs
1. ENABLE terminal
2. LATCH terminal
VDD
VDD
RIN(up)
ENABLE
LATCH
RIN(down)
GND
3. CLOCK, SERIAL-IN terminal
VDD
CLOCK,
SERIAL-IN
GND
8-BIT CONSTANT CURRENT LED DRIVERS
GND
4. SERIAL-OUT terminal
VDD
8th LATCH
SERIAL-OUT
DATA
GND
Version:A.036
Page: 4
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
ST2221A
Maximum Ratings (Ta=25°C, Tj(max) = 140°C)
CHARACTERISTIC
SYMBOL
RATING
UNIT
VDD
VIN
IOUT
VOUT
fCLK
IGND
0 ~ 7.0
-0.4 ~ VDD+0.4
90
-0.5 ~ 9.5
25
720
1.35 ( PDIP-16 : Ta=25°C)
1.03 ( SOP-16 : Ta=25°C)
0.99 ( SSOP-16 : Ta=25°C)
85 ( PDIP-16 )
110.9 ( SOP-16 )
115.9 ( SSOP-16 )
-55 ~ 150
V
V
mA
V
MHz
mA
Supply Voltage
Input Voltage
Output Current
Output Voltage
Clock Frequency
GND Terminal Current
Power Dissipation
PD
Thermal Resistance
Rth(j-a)
Storage Temperature
Tstg
W
°C/W
°C
Recommended Operating Condition
CHARACTERISTIC
Supply Voltage
Output Voltage
Operating temperature
Output Current
Input Voltage
LATCH Pulse Width
CLOCK Pulse Width
Set-up Time for DATA
Hold Time for DATA
Set-up Time for LATCH
Clock Frequency
Power Dissipation
SYMBOL
VDD
VOUT
TOPR
IO
IOH
IOL
VIH
VIL
tw LAT
tw CLK
tsetup(D)
thold(D)
tsetup(L)
fCLK
PD
CONDITION
⎯
⎯
⎯
OUTn
SERIAL-OUT
SERIAL-OUT
MIN.
4.5
TYP.
5.0
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
-40
5
⎯
⎯
⎯
⎯
0.7VDD
-0.3
VDD = 4.5 ~ 5.5 V
15
15
20
20
15
Cascade operation
Ta = 85°C(PDIP-16)
Ta = 85°C(SOP-16)
Ta = 85°C(SSOP-16)
⎯
⎯
⎯
⎯
8-BIT CONSTANT CURRENT LED DRIVERS
Version:A.036
MAX.
5.5
9
85
88
1.0
-1.0
VDD+0.3
0.3VDD
⎯
⎯
⎯
⎯
⎯
25
0.41
0.32
0.30
UNIT
V
V
℃
mA
V
ns
ns
ns
ns
ns
MHz
W
Page: 5
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
ST2221A
Electrical Characteristics (VDD = 5.0 V, Ta = 25°C unless otherwise noted)
CHARACTERISTIC
Input Voltage “H” Level
Input Voltage “L” Level
Output Leakage Current
Output Voltage ( S - OUT)
SYMBOL
CONDITION
VIH
⎯
VIL
⎯
IOH
VOH = 7.5 V
VOL
VOH
IOL1
Output Current (Bit-Bit)
IOL2
Output Current (Chip-Chip)
Supply Voltage Regulation
Pull-Up Resistor
Pull-Down Resistor
Supply Current “OFF”
Supply Current “ON”
IOL3
IOL4
% / VDD
RIN(up)
RIN(down)
IDD(off)1
IDD(0ff)2
IDD(off)3
IDD(on)1
IDD(on)2
IOL = 1.0 mA
IOH = -1.0 mA
VOUT = 0.7±0.25V
REXT = 910Ω
VOUT = 0.7±0.25V
REXT = 360Ω
VOUT = 0.7V REXT = 910Ω
VOUT = 0.7V REXT = 360Ω
REXT = 470Ω, Ta = -40 ~ 85°C
⎯
⎯
MIN.
0.7VDD
GND
4.6
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
150
100
REXT = OPEN, OUT0~7 = off
REXT = 470Ω, OUT0~7 = off
REXT = 250Ω, OUT0~7 = off
REXT = 470Ω, OUT0~7 = on
REXT = 250Ω, OUT0~7 = on
TYP.
⎯
4.0
7.3
4.0
7.3
MAX.
VDD
0.3VDD
1.0
UNIT
V
uA
0.4
⎯
V
3
6
%
3
6
%
5
5
1.5
300
200
0.3
5.6
10.2
5.6
10.2
10
10
5.0
600
400
0.6
7.8
14.3
7.8
14.3
%
%
%/V
KΩ
KΩ
mA
Switching Characteristics (Ta = 25 °C unless otherwise noted)
CHARACTERISTIC
SIN-OUTn
Propagation
LATCH-OUTn
Delay Time
ENABLE-OUTn
(“L” to “H”)
CLK-SOUT
SIN-OUTn
Propagation
LATCH-OUTn
Delay Time
ENABLE-OUTn
(“H” to “L”)
CLK-SOUT
Output Current Rise Time
Output Current Fall Time
1
SYMBOL
tpLH
tpHL
tor
tof
CONDITION
VDD=5.0V
VIH=VDD
VIL=GND
REXT=470Ω1
VL=3.0V
RL=65Ω
CL=13pF
MIN.
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
70
55
TYP.
115
115
115
15
120
120
120
15
140
110
MAX.
230
230
230
20
160
160
160
20
280
220
UNIT
ns
ns
ns
ns
Delay Time tpLH and Rise Time tor will both increase as the Rext value increased.
8-BIT CONSTANT CURRENT LED DRIVERS
Version:A.036
Page: 6
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
ST2221A
Test Circuit
DC characteristic
IDD
VDD
OUT0
ENABLE
IOL
CLOCK
IIL ,IIH
LATCH
OUT7
SERIAL-IN
VIL ,VIH
SERIAL-OUT
R-EXT GND
I ref
AC characteristic
RL
VDD
VIL ,VIH
OUT0
ENABLE
CL
SW-
CLOCK
MATRIX
LATCH
RL
OUT7
SERIAL-IN
SERIAL-OUT
R-EXT GND
CL
CL
8-BIT CONSTANT CURRENT LED DRIVERS
Version:A.036
VL
Page: 7
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
ST2221A
Timing Diagram
1. CLOCK-SERIAL OUT, OUTn
tr
tf
twCLK
CLOCK
90%
50%
10%
tsetup
90%
50%
10%
twCLK
50%
thold
50%
50%
SERIAL-IN
tof
tor
90%
50%
10%
OUTn (current)
90%
50%
10%
tpHL
tpLH
50%
50%
SERIAL-OUT
tpHL
tpLH
2. CLOCK-LATCH
50%
CLOCK
SERIAL-IN
“L” level = DATA HOLD
tw(LAT)
LATCH
50%
50%
tsetup(L)
3. ENABLE-OUTn
ENABLE
50%
50%
tpHL
tpLH
50%
50%
OUTn
8-BIT CONSTANT CURRENT LED DRIVERS
Version:A.036
Page: 8
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
ST2221A
Iout - Duty Cycle (SSOP)
Iout - Duty Cycle (SSOP)
100
100
80
Vo=0.45(V)
Vo=0.70(V)
Vo=0.95(V)
60
Iout (mA/bit)
Iout (mA/bit)
80
40
Vdd=5V
Tj=120°C(Max)
8bit Active
Ta=25°C
20
0
40
Vdd=5V
Tj=120°C(Max)
8bit Active
Ta=60°C
20
20
40
60
80
100
0
20
40
60
Duty Cycle (%)
Duty Cycle (%)
Iout - Duty Cycle (SSOP)
Iout - Duty Cycle (SOP)
100
80
100
80
100
100
Vo=0.45(V)
Vo=0.70(V)
60
40
Vo=0.95(V)
80
Iout (mA/bit)
80
Iout (mA/bit)
Vo=1.0(V)
60
0
0
20
60
40
Vdd=5v
Tj=140°C(Max)
8bit Active
Ta=25°C
0
0
0
Vo=0.45(V)
Vo=0.70(V)
Vo=0.95(V)
20
Vdd=5V
Tj=140°C(Max)
8bit Active
Ta=85°C
20
40
60
80
0
100
20
40
60
Duty Cycle (%)
Duty Cycle (%)
Iout - Duty Cycle (SOP)
Iout - Duty Cycle (SOP)
100
100
Vo=0.45(V)
Vo=0.70(V)
Vo=0.45(V)
80
Iout (mA/bit)
80
Iout (mA/bit)
Vo=0.45(V)
Vo=0.70(v)
Vo=0.95(V)
60
40
0
0
20
60
40
Vo=0.95(V)
Vdd=5V
Tj=140°C(Max)
8bit Active
Ta=85°C
20
Vdd=5V
Tj=140°C(Max)
8bit Active
Ta=60°C
20
Vo=0.70(V)
0
40
60
80
100
0
20
60
80
100
Duty Cycle (%)
Duty Cycle (%)
8-BIT CONSTANT CURRENT LED DRIVERS
40
Version:A.036
Page: 9
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
ST2221A
Iout - Duty Cycle (DIP)
Iout - Duty Cycle (DIP)
100
100
80
Vo=0.45(V)
Vo=0.70(V)
Vo=0.95(V)
60
Iout (mA/bit)
Iout (mA/bit)
80
40
Vdd=5V
Tj=140°C(Max)
8bit Active
Ta=25°C
20
Vo=0.45(V)
Vo=0.70(V)
Vo=0.95(V)
60
40
Vdd=5V
Tj=140°C(Max)
8bit Active
Ta=60°C
20
0
0
0
20
40
60
80
0
100
20
40
100
Vo=0.45(V)
Vo=0.70(V)
Iout (mA/bit)
Iout (mA/bit)
80
60
Vo=0.95(V)
40
Vdd=5V
Tj=140°C(Max)
8bit Active
Ta=85°C
0
20
40
60
100
Rext - Iout
Iout - Duty Cycle (DIP)
0
80
Duty Cycle (%)
Duty Cycle (%)
20
60
80
100
100
90
80
70
60
50
40
30
20
10
0
Iout = { 1.23 (V) / Rext (ohm) } * 14.45
Vo=0.70(V)
100
Duty Cycle (%)
1000
10000
Rext (Ohm)
Ta - Pd
1.6
Power dissipation Pd (W)
1.4
DIP
1.2
SOP
1
SSOP
0.8
0.6
0.4
0.2
0
0
50
100
150
Ambient Temperature Ta
8-BIT CONSTANT CURRENT LED DRIVERS
Version:A.036
Page: 10
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
ST2221A
Imax - Ta (SOP)
100
100
90
90
80
80
Iout max (mA/bit)
Iout max (mA/bit)
Imax
Ta (PDIP)
Iout –- Ta
(DIP)
70
Vo=0.7V
60
50
Vo=1.0V
40
30
70
Vo=0.7V
60
50
Vo=1.0V
40
30
20
20
Vdd=5V
Tj=140°C(Max)
8bit Active
10
0
0
Vdd=5V
Tj=140°C(Max)
8bit Active
10
0
50
100
150
0
50
100
150
Ambient Temperature Ta (°C)
Ambient Temperature Ta (°C)
Imax - Ta (SSOP)
100
90
Iout max (mA/bit)
80
70
Vo=0.7V
60
50
Vo=1.0V
40
30
20
Vdd=5V
Tj=140°C(Max)
8bit Active
10
0
0
50
100
150
Ambient Temperature Ta (°C)
Note
As the power dissipation of a semiconductor chip is limited its package and ambient temperature,
this device requires a maximum output current be calculated for a given operating condition. The
maximum allowable power consumption (Pd (max)) of this device is calculated as follows:
(Tj (junction temperature) (max) - Ta (ambient temperature) )(°C )
Pd (max)(Watt ) =
Rth (°C / Watt )
Based on the Pd (max), the maximum allowable current can be calculated as follows:
Iout = ( Pd – VDD‧IDD) / ( # outputs‧Vo‧Duty )
8-BIT CONSTANT CURRENT LED DRIVERS
Version:A.036
Page: 11
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
ST2221A
System Configuration Example
[1] Output current (IOUT)
Sink current is set by the external resistor as shown in figure (Iout vs. Rext).
[2] LED supply voltage (VLED) setup
VLED = VCE ( Tr Vsat ) + Vf ( LED forward voltage ) + VO ( IC supply voltage)
To prevent too much power dissipated by the device due to higher VLED , an additional R can
be used to reduce the Vout when the outputs consume current:
VLED − Vf − VO (min)
R=
IO (max) • Bit (max)
V L E D = 3 ~ 4 (V )
V DD
SCAN
Vf
+
VCE
—
OUT0
Vo
ENABLE
CLO CK
LATCH
S E R IA L -IN
R -E X T G N D
OUT7
R
S E R IA L -O U T
CPU
OUT0
ENABLE
CLO CK
LATCH
S E R IA L -IN
R -E X T G N D
OUT7
S E R IA L -O U T
Note
This device has only one ground pin shared by signal, output sink current, and power ground.
It is advisable to pattern the ground layout with minimized inductance such that the switching
noise induced by the input signals and the output sink current would not cause chip malfunction. To
prevent the drivers’ outputs from damage by overshoot stress, it is also advisable not to turn off the
drivers and scan transistors simultaneously.
8-BIT CONSTANT CURRENT LED DRIVERS
Version:A.036
Page: 12
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
ST2221A
Package Outline
Unit: mm
7.62
9.02±0508
9
6.35±0.13
16
0~15°
PDIP16 (ST2221A-1)
8
1
19.69MAX
1.524
0.635±0.254
5.33MAX
3.3±0.508
0.38MIN
3.3±0.1
19.18±0.51
0.4572
2.54
Weight : 1.11g(Typ.)
8-BIT CONSTANT CURRENT LED DRIVERS
Version:A.036
Page: 13
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
ST2221A
Package Outline
Unit: mm
9
1
8
4.0MAX
16
0.56
6.2MAX
SOP16 (ST2221A-3)
0.51
1.27
0.25
1.75
0.25
1.5
10
8-BIT CONSTANT CURRENT LED DRIVERS
1.27
Version:A.036
Page: 14
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
ST2221A
Package Outline
Unit: mm
SSOP16 (ST2221A-2)
3.91
5.99
9
16
8
1
0.229
0.3Max
0.254
0.635
0.15
1.5
4.9
1.63MAX
0.635
8-BIT CONSTANT CURRENT LED DRIVERS
Version:A.036
Page: 15
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
ST2221A
The products listed herein are designed for ordinary electronic applications, such as
electrical appliances, audio-visual equipment, communications devices and so on.
Hence, it is advisable that the devices should not be used in medical instruments,
surgical implants, aerospace machinery, nuclear power control systems,
disaster/crime-prevention equipment and the like. Misusing those products may
directly or indirectly endanger human life, or cause injury and property loss.
Silicon Touch Technology, Inc. will not take any responsibilities regarding the
misusage of the products mentioned above. Anyone who purchases any products
described herein with the above-mentioned intention or with such misused
applications should accept full responsibility and indemnify. Silicon Touch
Technology, Inc. and its distributors and all their officers and employees shall defend
jointly and severally against any and all claims and litigation and all damages, cost
and expenses associated with such intention and manipulation.
8-BIT CONSTANT CURRENT LED DRIVERS
Version:A.036
Page: 16