ST2225A
Version
Issue Date
File Name
Total Pages
: A.025
: 2001/11/26
: SP-ST2225A-A.025.doc
: 12
LED Display Driver
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.
Fax：886-3-5645626
Tel：886-3-5645656
點晶科技股份有限公司
ST2225A
SILICON TOUCH TECHNOLOGY INC.
ST2225A
LED Display Driver
General Description
The ST2225A LED display driver is a monolithic CMOS IC. In order to achieve
continuous brightness control, the LED display brightness is controlled by setting a reference
current through a variable resistor connected between a supply and a single pin.
Features
n"
Continuous brightness control
n"
Serial data input
n"
No load signal required for data latch
n"
Wide power supply operation
n"
TTL compatibility
n"
35 outputs, 20mA capability
n"
Small package, SSOP48 and bare chip form
Applications
n"
Industrial control indicator
n"
Relay driver
n"
Digital clock, thermometer, counter, voltmeter
n"
Instrumentation readouts
Ordering Information
Part Number
Temp. Range
Package
ST2225A-SS3
-40 to +85℃
SSOP48
ST2225A-D
-40 to +85℃
Bare Chip
LED Display Driver
-1-
Version：A.025
點晶科技股份有限公司
ST2225A
SILICON TOUCH TECHNOLOGY INC.
Block Diagram
VDD
BRIGHTNESS
CONTROL
OUT35
OUT1
30
19
22
21
DATA ENABLE
SERIAL DATA
CLOCK
35 OUTPUT BUFFERS
LOAD
35 LATCHES
29
35-BIT SHIFT
REGISTERS
28
RESET
27
20
RESET
1,13,36
Figure 1
Connection Diagram : SSOP48 Package
1
48
OUTPUT BIT18
2
47
OUTPUT BIT19
OUTPUT BIT16
3
46
OUTPUT BIT20
OUTPUT BIT15
4
45
OUTPUT BIT21
OUTPUT BIT14
5
44
OUTPUT BIT22
OUTPUT BIT13
6
43
OUTPUT BIT23
OUTPUT BIT12
7
42
OUTPUT BIT24
OUTPUT BIT11
8
41
OUTPUT BIT25
OUTPUT BIT10
9
40
OUTPUT BIT26
OUTPUT BIT 9
10
39
OUTPUT BIT27
OUTPUT BIT 8
11
38
OUTPUT BIT28
OUTPUT BIT 7
12
37
OUTPUT BIT29
VSS
13
36
VSS
OUTPUT BIT 6
14
35
OUTPUT BIT30
OUTPUT BIT 5
15
34
OUTPUT BIT31
OUTPUT BIT 4
16
33
OUTPUT BIT32
OUTPUT BIT3
17
32
OUTPUT BIT33
OUTPUT BIT 2
18
31
OUTPUT BIT34
OUTPUT BIT 1
19
30
OUTPUT BIT35
RESET
20
29
DATA ENABLE
BRIGHTNESS CONTROL
21
28
DATA
VDD
22
27
CLOCK
N/A
23
26
N/A
N/A
24
25
N/A
ST2225A-SS3
VSS
OUTPUT BIT17
Figure 2
LED Display Driver
-2-
Version：A.025
點晶科技股份有限公司
ST2225A
SILICON TOUCH TECHNOLOGY INC.
OUTPUT BIT 22
OUTPUT BIT 21
OUTPUT BIT 20
OUTPUT BIT 19
OUTPUT BIT 18
OUTPUT BIT 23
OUTPUT BIT 24
OUTPUT BIT 11
OUTPUT BIT 25
OUTPUT BIT 10
OUTPUT BIT 26
ST2225A-D
OUTPUT BIT 13
OUTPUT BIT 12
OUTPUT BIT 9
OUTPUT BIT 8
OUTPUT BIT 7
VSS
OUTPUT BIT 6
OUTPUT BIT 27
OUTPUT BIT 28
OUTPUT BIT 29
VSS
OUTPUT BIT 30
OUTPUT BIT 5
OUTPUT BIT 31
OUTPUT BIT 4
OUTPUT BIT 32
OUTPUT BIT 3
OUTPUT BIT 33
OUTPUT BIT 2
OUTPUT BIT 34
OUTPUT BIT 1
OUTPUT BIT 35
DATA ENABLE
DATA
CLK
VDD
BRIGHTNESS CONTROL
RESET
(0, 0)
Die Size: 1449.6um * 2614um
Pad Size: 100um * 100um
VSS
OUTPUT BIT 17
OUTPUT BIT 16
OUTPUT BIT 15
OUTPUT BIT 14
Die Configuration
Figure 3
* Note: SiTI reserves the right to improve the device geometry and
manufacturing processes without prior notice. Though these improvements
may result in slight geometry changes, they will not affect die electrical
characteristics and pad layouts.
Wafer Information
Material： Silicon with P-Substrate
Diameter： 6 inches(≒15cm)
Thickness： 12 mils(≒300um)
Width of scribe line：100um
Malfunctioned die：Marked with red ink or equivalent marking
LED Display Driver
-3-
Version：A.025
點晶科技股份有限公司
ST2225A
SILICON TOUCH TECHNOLOGY INC.
Pad Allocation for the Bare Chip, ST2225A-D
VSS
OUTPUT17
OUTPUT16
OUTPUT15
Center Coordinate
(X,Y) um
666.2
2574.7
526.2
2574.7
381.2
2574.7
236.2
2574.7
OUTPUT14
OUTPUT13
OUTPUT12
OUTPUT11
OUTPUT10
OUTPUT9
OUTPUT8
OUTPUT7
VSS
OUTPUT6
OUTPUT5
OUTPUT4
OUTPUT3
OUTPUT2
OUTPUT1
RESET
IBRIGHT
VDD
91.2
100.1
100.1
100.1
100.1
100.1
100.1
100.1
100.1
100.1
100.1
100.1
100.1
100.1
100.1
168.6
385.7
520.7
PAD Name
LED Display Driver
2574.7
2225.2
2075.2
1925.2
1775.2
1625.2
1475.2
1325.2
1185.2
1045.2
895.2
745.2
595.2
446.6
306.6
109.7
109.7
109.7
PAD Name
CLK
DATA
DATAENZ
OUTPUT35
OUTPUT34
OUTPUT33
OUTPUT32
OUTPUT31
OUTPUT30
VSS
OUTPUT29
OUTPUT28
OUTPUT27
OUTPUT26
OUTPUT25
OUTPUT24
OUTPUT23
OUTPUT22
OUTPUT21
OUTPUT20
OUTPUT19
OUTPUT18
-4-
Center Coordinate
(X,Y) um
744
109.7
1033.2
109.7
1322.4
109.7
1375.9
295.2
1375.9
1375.9
1375.9
1375.9
1375.9
1375.9
1375.9
1375.9
1375.9
1375.9
1375.9
1375.9
1375.9
1375.9
1241.2
1096.1
951.2
806.2
Version：A.025
445.2
595.2
745.2
895.2
1045.2
1185.2
1325.2
1475.2
1625.2
1775.2
1925.2
2075.2
2225.2
2574.7
2574.7
2574.7
2574.7
2574.7
點晶科技股份有限公司
ST2225A
SILICON TOUCH TECHNOLOGY INC.
Absolute Maximum Ratings
Voltage (any pin)........................Vss to Vss +12V
Power Dissipation (PD)
+25℃......................................................1.52W
+85℃....................................................790mW
Junction Temperature (Tj)........................+150℃
Storage Temperature (Ts)..........-65℃ to +150℃
Lead Temperature (soldering, 10 sec.).....+300℃
Electrical Characteristics
4.5V≦VDD ≦11V, Vss=0V; TA=25℃, bold values indicate -40℃≦TA≦+85℃；unless noted
Symbol
IDD
VIL
VIH
IBC
IOUT OFF
IOUT ON
VBC
RMATCH
fC
tH
tL
tDS
tDH
tDES
Parameter
Condition
-25℃ to +85℃, excluding output loads
Power Supply Current
-40℃ to +85℃, excluding output loads
logic-0 level, ±10μA input bias
Low-level Data Input Voltage
logic-1 level, 4.75V≦VDD ≦5.25V
High-level Data Input Voltage
logic-1 level, VDD>5.25V
Brightness Control Input Current Note 2
Output Sink Current When “OFF” Segment off, VOUT=3.0V
Segment on, VOUT=1.0V, Note 3
Brightness input =0μA
Output Sink Current When “ON”
Brightness input =100μA
Brightness input =750μA
Brightness Control Input Voltage Input Current =750μA
Note 1
Output Matching
Notes 4, 5
Clock Input Frequency
Notes 4, 5
Clock Input High Time
Notes 4, 5
Clock Input Low Time
Data Input Setup Time
Data Input Hold Time
Data Enable Input Setup Time
Min
Typ
-0.3
2.2
VDD-2
0
0
2.0
15
3.0
2.7
20
Max
5
6
0.8
VDD
VDD
0.75
10
Units
mA
mA
V
V
V
mA
μA
10
4
25
μA
mA
mA
V
%
kHz
ns
ns
ns
ns
ns
4.3
±20
500
950
950
300
300
100
Note 1: Output matching is calculated as the percent variation (IMAX + IMIN) / 2
Note 2: With a fixed resistor on the brightness input pin, some variation in brightness will occur among devices.
Note 3: VOUT should be so regulated that power dissipation of the chip will not exceed its limit.
Note 4: AC input waveform specification for test purpose: tR≦20ns, tF≦20ns, t=500kHz, 50%±10% duty cycle.
Note 5: Clock input rise and fall times must not exceed 300ns.
LED Display Driver
-5-
Version：A.025
點晶科技股份有限公司
ST2225A
SILICON TOUCH TECHNOLOGY INC.
Operating Ratings
Supply Voltage (VDD – VSS) ..............................+4.75V to 11V
Ambient Temperature Range (TA)..................-40℃ to +85℃
Functional Description
The ST2225A display driver can drive either 4- or 5-digit alphanumeric LED displays. One of
its advantages is its minimal interface requirement with the display or data source.
Data transfer is accomplished by sending clock and serial data signals, without any need of an
external load signal. This method provides a non-multiplexed, direct drive to the LED display. The
data transfer format uses a leading “1” followed by 35 data bits. These 35 data bits are latched after
the 36th has been transferred. In this way, data output (refers to the currently displayed characters)
changes only if the serial data bits differ from those previously transferred.
Display brightness is controlled by the output current for LED displays. A 1nF capacitor should
be connected to brightness control pin to prevent oscillations.
Figure 1 shows the block diagram of this driver. The output current is set via an external
variable resistor, and is typically 27 times greater than the current in brightness control pin.
Input data format, as in Figure 4, shows a leading “1” followed by 35 data bits. When the 36th is
transferred, a LOAD signal is generated synchronously with the clock high state, thus, the 35 bits of
data are loaded into the latches. The low state of the clock is used to generate a RESET signal to
clear all shift registers for the next set of data. To allow continuous operation, all shift registers are
static master-slaves, with no clear for the master portion of the first register.
LED Display Driver
-6-
Version：A.025
點晶科技股份有限公司
ST2225A
SILICON TOUCH TECHNOLOGY INC.
Note that a complete set of 36 clocks must be sent in order to clear the shift registers. When
ST2225A is powered ON, reset signal is generated internally to reset all registers and all latches.
Then, the START bit and the first clock make it return to its normal operation.
Figure 2 shows the pin-out of the package for ST2225A. Figure 3 shows the pad-assignment of
the bare chip for ST2225A.The timing relationships between data, clock and DATA ENABLE is
shown in Figure 4, with maximum clock frequency of 0.5 MHz assumed.
When this driver is used for applications with lesser number of outputs, the current per output
can be increased, or the part can be operated at higher than 1V (Vout). The following equation can be
used for calculations.
Tj = (Vout) (ILED) (NO. of segments) (82℃/W)+TA
Where:
Tj = junction temperature (150℃ max)
Vout = the voltage at the LED driver outputs
ILED = the LED current
82℃/W = thermal resistance of the package
TA = ambient temperature
The above equation was used to plot Figure 6-8.
CLOCK
DATA
300 nS MIN
DATA ENABLE
100 nS MIN
Figure 4
LED Display Driver
-7-
Version：A.025
點晶科技股份有限公司
ST2225A
SILICON TOUCH TECHNOLOGY INC.
1
37
36
CLOCK
START BIT 1
BIT 34 BIT 35
DATA
LOAD
(INTERNAL)
RESET
Figure 5 Input Data Format
Vout v.s. ILED
Output Current v.s. Number of Segments
180
3.00
Ta = 85℃
Ta = 85℃
Tj = 150℃ (max.)
160
Vout = 1V
2.50
20 SEGM
Vout = 1.5V
2.00
Vout (Volt)
120
100
Vout = 2V
80
60
30 SEGM
1.50
35 SEGM
1.00
40
0.50
20
0
0.00
0
2
4
6
8
10 12 14 16 18 20 22 24 26 28 30 32 34
5
7
9
11
Figure 6 Number of Segments
13
15
17
19
Figure 7
21
23
25
27
29
31
ILED (mA)
Power dissipation v.s. Temperature
2.0
35 Segments
Vout = 1V
15 mA/Segment
1.8
1.6
1.4
1.2
Pdiss (W)
Output Current (mA)
140
1.0
0.8
Safe Operating
Area
0.6
0.4
0.2
0.0
0
5
10 15 20 25
30 35 40 45 50 55
60 65 70 75 80 85
Figure 8 Temp('C)
LED Display Driver
-8-
Version：A.025
33
35
點晶科技股份有限公司
ST2225A
SILICON TOUCH TECHNOLOGY INC.
Typical Applications
LED DISPLAY
AM
FM
35
ST2225A
DISPLAY DRIVER
ELECTRONIC
TUNING
CONTROLLER
KEYBOARD
PLL
SYNTHESIZER
STATION DETECT, ETC
Figure 9 Basic Electronically Tuned Radio System
VLED=3.0V
VLED=3.0V
VLED
VLED
9-12, 2-8, 48 40-47 31-35,
14-17
37-39
ST2225A
19
27
28 21
1, 13
36
CLOCK IN
DATA IN
BRIGHTNESS
CONTROL
100K
TYP
29 18
VDD
Figure 10 Duplexing 8 Digits with One ST2225A
LED Display Driver
-9-
Version：A.025
點晶科技股份有限公司
ST2225A
SILICON TOUCH TECHNOLOGY INC.
Package Outline ( SSOP48 ) for ST2225A-SS3
1
24
C
H×45。
E
25
E1
48
D
GAUGE PLANE
SYMBOL
A
A1
b
C
e
E
E1
H
L
θ
N
48
b
A1
e
DIMENSION IN MM
MIN.
NOM.
MAX.
2.413
2.591
2.794
0.203
0.305
0.406
0.203
0.343
0.127
0.254
0.635 BASIC
10.033
10.668
7.391
7.493
7.595
0.381
0.635
0.508
1.016
0
8
LED Display Driver
0.625
L
DIMENSION IN INCH
MIN.
NOM.
MAX.
0.095
0.102
0.110
0.008
0.012
0.016
0.008
0.0135
0.005
0.010
0.025 BASIC
0.395
0.420
0.291
0.295
0.299
0.015
0.025
0.020
0.040
0
8
D DIMENSION (IN INCH)
0.620
0.010 INCH
A
θ
JEDEC
0.630
MO-118(AA)
-10-
Version：A.025
點晶科技股份有限公司
ST2225A
SILICON TOUCH TECHNOLOGY INC.
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.
LED Display Driver
-11-
Version：A.025