3-109
High Performance CMOS 5 x 7
Alphanumeric Displays
Technical Data
HCMS-29XX Series
Features
• Easy to Use
• Interfaces Directly with
Microprocessors
• 0.15" Character Height in 4,
8, and 16 (2x8) Character
Packages
• 0.20" Character Height in 4
and 8 Character Packages
• Rugged X- and Y-Stackable
Package
• Serial Input
• Convenient Brightness
Controls
• Wave Solderable
• Offered in Five Colors
• Low Power CMOS
Technology
• TTL Compatible
Applications
Telecommunications
Equipment
Portable Data Entry Devices
Computer Peripherals
Medical Equipment
Test Equipment
Business Machines
Avionics
Industrial Controls
Device Selection Guide
AlGaAs HER Orange Yellow Green Package
Description HCMS- HCMS- HCMS- HCMS- HCMS- Drawing
1 x 4 0.15" Character 2905 2902 2904 2901 2903 A
1 x 8 0.15" Character 2915 2912 2914 2911 2913 B
2 x 8 0.15" Character 2925 2922 2924 2921 2923 C
1 x 4 0.20" Character 2965 2962 2964 2961 2963 D
1 x 8 0.20" Character 2975 2972 2974 2971 2973 E
Description
The HCMS-29XX series are high
performance, easy to use dot
matrix displays driven by on-board
CMOS ICs. Each display can be
directly interfaced with a
microprocessor, thus eliminating
the need for cumbersome interface
components. The serial IC
interface allows higher character
count information displays with a
minimum of data lines. A variety of
colors, font heights, and character
counts gives designers a wide
range of product choices for their
specific applications and the easy
to read 5 x 7 pixel format allows
the display of uppercase, lower
case, Katakana, and custom user-
defined characters. These displays
are stackable in the x- and y-
directions, making them ideal for
high character count displays.
H
ESD WARNING: STANDARD CMOS HANDLING PRECAUTIONS SHOULD BE OBSERVED TO
AVOID STATIC DISCHARGE.
5964-6376E
3-110
HCMS-291X
NOTES:
1. DIMENSIONS ARE IN mm (INCHES).
2. UNLESS OTHERWISE SPECIFIED, TOLERANCE ON DIMENSIONS IS ± 0.38 mm (0.015 INCH).
3. LEAD MATERIAL: SOLDER PLATED COPPER ALLOY.
2.54 ± 0.13
(0.100 ± 0.005)
(NON ACCUM.)
TYP.
35.56 (1.400) MAX.
76543210
0.25
(0.010)
7.62
(0.300)
PIN # 1 IDENTIFIER
XZ
COO
INTENSITY CATEGORY
DATE CODE (YEAR, WEEK)
COLOR BIN
COUNTRY OF ORIGIN
PART NUMBER
5.08 (0.200)
2.54
(0.100) SYM.
0.51
(0.020)
TYP.
0.51 ± 0.13
(0.020 ± 0.005)
2.22 (0.087) SYM.
10.16 (0.400) MAX.
2.11 (0.083) TYP.
4.32
(0.170)TYP.
1.27
(0.050)SYM.
4.45
(0.175)TYP.
3.71
(0.146)
TYP. NO PIN
NO PIN
V LED
NO PIN
NO PIN
NO PIN
GND LED
NO PIN
NO PIN
V LED
NO PIN
NO PIN
NO PIN
DATA IN
RS
NO PIN
CLOCK
CE
BLANK
GND LOGIC
SEL
V LOGIC
NO PIN
RESET
OSC
DATA OUT
PIN FUNCTION
ASSIGNMENT TABLE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
PIN # FUNCTION
3
26
HCMS-291X
YYWW
NOTES:
1. DIMENSIONS ARE IN mm (INCHES).
2. UNLESS OTHERWISE SPECIFIED, TOLERANCE ON DIMENSIONS IS ± 0.38 mm (0.015 INCH).
3. LEAD MATERIAL: SOLDER PLATED COPPER ALLOY.
X Z
COO
2.11 (0.083) TYP.
0.25
(0.010)
7.62
(0.300)
PIN # 1 IDENTIFIER
4321
17.78 (0.700) MAX.
3.71 (0.146) TYP.
4.45 (0.175) TYP.
2.22 (0.087) SYM.
10.16 (0.400) MAX.
PIN # 1
LIGHT INTENSITY CATEGORY
DATE CODE
COLOR BIN
COUNTRY OF ORIGIN
PART NUMBER
5.08
(0.200)
2.54
(0.100) SYM.
TYP.
0.51 ± 0.13
(0.020 ± 0.005)
2.54 ± 0.13
(0.100 ± 0.005)
(NON ACCUM.)
TYP.
4.32
(0.170)TYP.
1.27
(0.050)SYM.
1
12
0.51 (0.020)
DATA OUT
OSC
V LED
DATA IN
RS
CLK
CE
BLANK
GND
SEL
V LOGIC
RESET
PIN FUNCTION
ASSIGNMENT TABLE
1
2
3
4
5
6
7
8
9
10
11
12
PIN # FUNCTION
HCMS-290X
YYWW
HCMS-290X
3-111
HCMS-292X
NO PIN
NO PIN
V LED
NO PIN
NO PIN
NO PIN
GND LED
NO PIN
NO PIN
V LED
NO PIN
NO PIN
NO PIN
DATA IN
RS
NO PIN
CLOCK
CE
BLANK
GND LOGIC
SEL
V LOGIC
NO PIN
RESET
OSC
DATA OUT
PIN FUNCTION ASSIGNMENT TABLE
NO PIN
NO PIN
V LED
NO PIN
NO PIN
NO PIN
GND LED
NO PIN
NO PIN
V LED
NO PIN
NO PIN
NO PIN
DATA IN
RS
NO PIN
CLOCK
CE
BLANK
GND LOGIC
SEL
V LOGIC
NO PIN
RESET
OSC
DATA OUT
1A
2A
3A
4A
5A
6A
7A
8A
9A
10A
11A
12A
13A
14A
15A
16A
17A
18A
19A
20A
21A
22A
23A
24A
25A
26A
PIN # FUNCTION
NOTES:
1. DIMENSIONS ARE IN mm (INCHES).
2. UNLESS OTHERWISE SPECIFIED, TOLERANCE ON DIMENSIONS IS ± 0.38 mm (0.015 INCH).
3. LEAD MATERIAL: SOLDER PLATED COPPER ALLOY.
15141312111098
76543210
1.27
(0.050)
0.25
(0.010)
7.62
(0.300)
2.03
(0.080)
4.83
(0.190)
PIN # 1 IDENTIFIER
ROW A
ROW B
35.56 (1.400) MAX.
3.71 (0.146) TYP.
2.22 (0.088) SYM.
4.45 (0.175) MAX.
19.81 (0.780) MAX.
9.65 (0.380)
XZ
COO
INTENSITY CATEGORY
DATE CODE (YEAR, WEEK)
COLOR BIN
COUNTRY OF ORIGIN
PART NUMBER
5.08 (0.200)
2.54
(0.100) SYM.
0.51
(0.020)
0.51 ± 0.13
(0.020 ± 0.005)TYP.
2.54 ± 0.13
(0.100 ± 0.005)
(NON ACCUM.)
TYP.
3A
26A
3B
26B
2.11 (0.083) TYP.
1B
2B
3B
4B
5B
6B
7B
8B
9B
10B
11B
12B
13B
14B
15B
16B
17B
18B
19B
20B
21B
22B
23B
24B
25B
26B
PIN # FUNCTION
HCMS-292X
YYWW
HCMS-296X
NOTES:
1. DIMENSIONS ARE IN mm (INCHES).
2. UNLESS OTHERWISE SPECIFIED, THE TOLERANCE ON DIMENSIONS IS ± 0.38 mm (0.015 INCH).
3. LEAD MATERIAL: SOLDER PLATED COPPER ALLOY.
3210
PIN # 1 IDENTIFIER
PART NUMBER
5.31
(0.209)
0.169
(4.28) SYM.
TYP.
0.51 ± 0.13
(0.020 ± 0.005)
2.54 ± 0.13
(0.100 ± 0.005)TYP.
2.67 (0.105) SYM.
2.54 (0.100) TYP.
11.43 (0.450) MAX.
5.36 (0.211) TYP.
0.25
(0.010)
7.62
(0.300)
3.71
(0.146)TYP.
0.072
(1.83)SYM.
4.57
(0.180)TYP.
XZ
COO
INTENSITY CATEGORY
DATE CODE (YEAR, WEEK)
COLOR BIN
COUNTRY OF ORIGIN
21.46 (0.845) MAX.
0.50
(0.020)
DATA OUT
OSC
V LED
DATA IN
RS
CLK
CE
BLANK
GND
SEL
V LOGIC
RESET
1
2
3
4
5
6
7
8
9
10
11
12
PIN FUNCTION
ASSIGNMENT TABLE
PIN # FUNCTION
HCMS-296X
YYWW
3-112
Absolute Maximum Ratings
Logic Supply Voltage, VLOGIC to GNDLOGIC ....................... -0.3 V to 7.0 V
LED Supply Voltage, VLED to GNDLED .............................. -0.3 V to 5.5 V
Input Voltage, Any Pin to GND ......................... -0.3 V to VLOGIC +0.3 V
Free Air Operating Temperature Range T
A[1] ................. -40°C to +85°C
Relative Humidity (non-condensing)................................................ 85%
Storage Temperature, TS................................................. -55°C to 100°C
Maximum Solder Temperature
1.59 mm (0.063 in.) Below Seating Plane, t< 5 sec.................. 260°C
ESD Protection @ 1.5 k, 100 pF (each pin) ................................ 2 KV
TOTAL Package Power Dissipation at T
A = 25°C[2]
4 character ....................................................................... 1.2 W
8 character ....................................................................... 2.4 W
16 character....................................................................... 4.8 W
Notes:
1. For operation in high ambient temperatures, see Appendix A, Thermal Considerations.
HCMS-297X
NOTES:
1. DIMENSIONS ARE IN mm (INCHES).
2. UNLESS OTHERWISE SPECIFIED, TOLERANCE ON DIMENSIONS IS ± 0.38 mm (0.015 INCH).
3. LEAD MATERIAL: SOLDER PLATED COPPER ALLOY.
87654321
XZ
COO
PIN # 1 IDENTIFIER
INTENSITY CATEGORY
DATE CODE (YEAR, WEEK)
COLOR BIN
COUNTRY OF ORIGIN
PART NUMBER
5.31
(0.209)
6.22
(0.245)SYM.
0.51
(0.020)
TYP.
0.51 ± 0.13
(0.020 ± 0.005)
2.54 ± 0.13
(0.100 ± 0.005)
(NON ACCUM.)
TYP.
42.93 (1.690) MAX.
2.67 (0.105) SYM.
5.36 (0.211) TYP.
11.43 (0.450) MAX.
2.54 (0.100) TYP.
0.25
(0.010)
7.62
(0.300)
3.71
(0.146)TYP.
1.90
(0.075)SYM.
NO PIN
NO PIN
V LED
NO PIN
NO PIN
NO PIN
GND LED
NO PIN
NO PIN
V LED
NO PIN
NO PIN
NO PIN
DATA IN
RS
NO PIN
CLOCK
CE
BLANK
GND LOGIC
SEL
V LOGIC
NO PIN
RESET
OSC
DATA OUT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
PIN # FUNCTION
4.57
(0.180)TYP.
3
26
HCMS-297X
YYWW
Recommended Operating Conditions over Temperature Range
(-40°C to +85°C)
Parameter Symbol Min. Typ. Max. Units
Logic Supply Voltage VLOGIC 3.0 5.0 5.5 V
LED Supply Voltage VLED 4.0 5.0 5.5 V
GNDLED to GNDLOGIC -0.3 0 +0.3 V
3-113
Electrical Characteristics over Operating Temperature Range (-40°C to +85°C)
TA = 25°C -40°C < TA < 85°C
VLOGIC = 5.0 V 3.0 V < VLOGIC < 5.5 V
Parameter Symbol Typ. Max. Min. Max. Units Test Conditions
Input Leakage Current IIµAV
IN = 0 V to VLOGIC
HCMS-290X/296X (4 char) +7.5 -2.5 +50
HCMS-291X/297X (8 char) +15 -5.0 +100
HCMS-292X (16 char) +15 -5.0 +100
ILOGIC OPERATING ILOGIC(OPT) mA V
IN = V
LOGIC
HCMS-290X/296X (4 char) 0.4 2.5 5
HCMS-291X/297X (8 char) 0.8 5 10
HCMS-292X (16 char) 0.8 5 10
ILOGIC SLEEP[1] ILOGIC(SLP) µAV
IN = V
LOGIC
HCMS-290X/296X (4 char) 5 15 25
HCMS-291X/297X (8 char) 10 30 50
HCMS-292X (16 char) 10 30 50
ILED BLANK ILED(BL) mA BL = 0 V
HMCS-290X/296X (4 char) 0.4 1.8 2.5
HCMS-291X/297X (8 char) 0.8 3.5 5
HCMS-292X (16 char) 0.8 3.5 5
ILED SLEEP[1] ILED(SLP) µA
HCMS-290X/296X (4 char) 1 3 50
HCMS 291X/297X (8 char) 2 6 100
HCMS-292X (16 char) 2 6 100
Peak Pixel Current[2] IPIXEL VLED = 5.5 V
HCMS-29X5 (AlGaAs) 15.4 17.1 18.7 mA All pixels ON,
HCMS-29XX (Other Colors) 14.0 15.9 17.1 mA Average value per
pixel
HIGH level input voltage V
ih 2.0 V 4.5 V < VLOGIC < 5.5 V
0.8 VLOGIC V 3.0 V < VLOGIC < 4.5 V
LOW level input voltage V
il 1.1 V 4.5 V < VLOGIC < 5.5 V
0.2 VLOGIC V 3.0 V < VLOGIC < 4.5 V
HIGH level output voltage V
oh 2.4 V V
LOGIC = 4.5 V,
Ioh = -40 µA
0.8 VLOGIC V 3.0 V < VLOGIC < 4.5 V
LOW level output voltage V
ol 0.4 V V
LOGIC = 5.5 V,
Iol = 1.6 mA[3]
0.2 VLOGIC V 3.0 V < VLOGIC < 4.5 V
Thermal Resistance RθJ-P 70 °C/W IC junction to pin
Notes:
1. In SLEEP mode, the internal oscillator and reference current for LED drivers are off.
2. Average peak pixel current is measured at the maximum drive current set by Control Register 0. Individual pixels may exceed this
value.
3. For the Oscillator Output, Iol = 40 µA.
3-114
Optical Characteristics at 25°C[1]
VLED = 5.0 V, 50% Peak Current, 100% Pulse Width
Luminous Intensity Peak Dominant
per LED[2] Wavelength Wavelength
Character Average (µcd) λPeak (nm) λd[3] (nm)
Display Color Part Number Min. Typ. Typ. Typ.
AlGaAs Red HCMS-29X595 230 645 637
High Efficiency Red HCMS-29X229 64 635 626
Orange HCMS-29X429 64 600 602
Yellow HCMS-29X129 64 583 585
Green HCMS-29X357 114 568 574
Notes:
1. Refers to the initial case temperature of the device immediately prior to measurement.
2. Measured with all LEDs illuminated.
3. Dominant wavelength, λd, is derived from the CIE chromaticity diagram and represents the single wavelength which defines the
perceived LED color.
Electrical Description
Pin Function Description
RESET (RST) Sets Control Register bits to logic low. The Dot Register contents are
unaffected by the Reset pin. (logic low = reset; logic high = normal
operation).
DATA IN (DIN) Serial Data input for Dot or Control Register data. Data is entered on the
rising edge of the Clock input.
DATA OUT (DOUT) Serial Data output for Dot or Control Register data. This pin is used for
cascading multiple displays.
CLOCK (CLK) Clock input for writing Dot or Control Register data. When Chip Enable is
logic low, data is entered on the rising Clock edge.
REGISTER SELECT (RS) Selects Dot Register (RS = logic low) or Control Register (RS = logic high)
as the destination for serial data entry. The logic level of RS is latched on
the falling edge of the Chip Enable input.
CHIP ENABLE (CE) This input must be a logic low to write data to the display. When CE
returns to logic high and CLK is logic low, data is latched to either the LED
output drivers or a Control Register.
OSCILLATOR SELECT Selects either an internal or external display oscillator source.
(SEL) (logic low = External Display Oscillator; logic high = Internal Display
Oscillator).
OSCILLATOR (OSC) Output for the Internal Display Oscillator (SEL = logic high) or input for an
External Display Oscillator (SEL = logic low).
BLANK (BL) Blanks the display when logic high. May be modulated for brightness
control.
GNDLED Ground for LED drivers.
GNDLOGIC Ground for logic.
VLED Positive supply for LED drivers.
VLOGIC Positive supply for logic.
3-115
AC Timing Characteristics over Temperature Range (-40°C to +85°C)
Timing
Diagram
Ref. 4.5 V < VLOGIC <5.5 V VLOGIC = 3 V
Number Description Symbol Min. Max. Min. Max. Units
1 Register Select Setup Time to trss 10 10 ns
Chip Enable
2 Register Select Hold Time to trsh 10 10 ns
Chip Enable
3 Rising Clock Edge to Falling tclkce 20 20 ns
Chip Enable Edge
4 Chip Enable Setup Time to tces 35 55 ns
Rising Clock Edge
5 Chip Enable Hold Time to tceh 20 20 ns
Rising Clock Edge
6 Data Setup Time to Rising tds 10 10 ns
Clock Edge
7 Data Hold Time after Rising tdh 10 10 ns
Clock Edge
8 Rising Clock Edge to DOUT[1] tdout 10 40 10 65 ns
9 Propagation Delay DIN to DOUT tdoutp 18 30 ns
Simultaneous Mode for
one IC[1,2]
10 CE Falling Edge to DOUT Valid tcedo 25 45 ns
11 Clock High Time tclkh 80 100 ns
12 Clock Low Time tclkl 80 100 ns
Reset Low Time trstl 50 50 ns
Clock Frequency F
cyc 5 4 MHz
Internal Display Oscillator F
inosc 80 210 80 210 KHz
Frequency
Internal Refresh Frequency F
rf 150 410 150 400 Hz
External Display Oscillator F
exosc
Frequency
Prescaler = 1 51.2 1000 51.2 1000 KHz
Prescaler = 8 410 8000 410 8000 KHz
Notes:
1. Timing specifications increase 0.3 ns per pf of capacitive loading above 15 pF.
2. This parameter is valid for Simultaneous Mode data entry of the Control Register.
3-116
Reset
Reset initializes the Control
Registers (sets all Control
Register bits to logic low) and
places the display in the sleep
mode. The Reset pin should be
connected to the system power-on
reset circuit. The Dot Registers
are not cleared upon power-on or
by Reset. After power-on, the Dot
Register contents are random;
however, Reset will put the
display in sleep mode, thereby
blanking the LEDs. The Control
Register and the Control Words
are cleared to all zeros by Reset.
To operate the display after being
Reset, load the Dot Register with
logic lows. Then load Control
Word 0 with the desired bright-
ness level and set the sleep mode
bit to logic high.
Dot Register
The Dot Register holds the
pattern to be displayed by the
Display Overview
The HCMS-29XX series is a family
of LED displays driven by
on-board CMOS ICs. The LEDs
are configured as 5 x 7 font
characters and are driven in
groups of 4 characters per IC.
Each IC consists of a 160-bit shift
register (the Dot Register), two
7-bit Control Words, and refresh
circuitry. The Dot Register
contents are mapped on a
one-to-one basis to the display.
Thus, an individual Dot Register
bit uniquely controls a single
LED.
8-character displays have two ICs
that are cascaded. The Data Out
line of the first IC is internally
connected to the Data In line of
the second IC forming a 320-bit
Dot Register. The display’s other
control and power lines are
connected directly to both ICs. In
16-character displays, each row
functions as an independent
8-character display with its own
320-bit Dot Register.
LEDs. Data is loaded into the Dot
Register according to the
procedure shown in Table 1 and
the Write Cycle Timing Diagram.
First RS is brought low, then CE
is brought low. Next, each
successive rising CLK edge will
shift in the data at the DIN pin.
Loading a logic high will turn the
corresponding LED on; a logic
low turns the LED off. When all
160 bits have been loaded (or 320
bits in an 8-digit display), CE is
brought to logic high.
When CLK is next brought to
logic low, new data is latched into
the display dot drivers. Loading
data into the Dot Register takes
place while the previous data is
displayed and eliminates the need
to blank the display while loading
data.
Pixel Map
In a 4-character display, the
160-bits are arranged as 20
Table 1. Register Truth Table
Function CLK CE RS
Select Dot Register Not Rising L
Load Dot Register
DIN = HIGH LED = "ON" LX
D
IN = LOW LED = "OFF"
Copy Data from Dot Register to Dot Latch L H X
Select Control Register Not Rising H
Load Control Register[1] LX
Latch Data to Control Word 1[2] LHX
Notes:
1. BIT D0 of Control Word 1 must have been previously set to Low for serial mode or High for simultaneous mode.
2. Selection of Control Word 1 or Control Word 0 is set by D7 of the Control Shift Register. The unselected control word retains its
previous value.
3-117
and then CE is brought to logic
low. Next, each successive rising
CLK edge will shift in the data on
the DIN pin. Finally, when 8 bits
have been loaded, the CE line is
brought to logic high. When CLK
goes to logic low, new data is
copied into the selected control
word. Loading data into the
Control Register takes place while
the previous control word
configures the display.
Control Word 0
Loading the Control Register with
D7 = Logic low selects Control
Word 0 (see Table 2). Bits D0-D3
adjust the display brightness by
pulse width modulating the LED
on-time, while Bits D4-D5 adjust
the display brightness by
changing the peak pixel current.
Bit D6 selects normal operation or
sleep mode.
Control Register
The Control Register allows
software modification of the IC’s
operation and consists of two
independent 7-bit control words.
Bit D7 in the shift register selects
one of the two 7-bit control
words. Control Word 0 performs
pulse width modulation
brightness control, peak pixel
current brightness control, and
sleep mode. Control Word 1 sets
serial/simultaneous data out
mode, and external oscillator
prescaler. Each function is
independent of the others.
Control Register Data
Loading
Data is loaded into the Control
Register according to the proce-
dure shown in Table 1 and the
Write Cycle Timing Diagram.
First, RS is brought to logic high
columns by 8 rows. This array can
be conceptualized as four 5 x 8
dot matrix character locations,
but only 7 of the 8 rows have
LEDs (see Figures 1 & 2). The
bottom row (row 0) is not used.
Thus, latch location 0 is never
displayed. Column 0 controls the
left-most column. Data from Dot
Latch locations 0-7 determine
whether or not pixels in Column 0
are turned-on or turned-off.
Therefore, the lower left pixel is
turned-on when a logic high is
stored in Dot Latch location 1.
Characters are loaded in serially,
with the left-most character being
loaded first and the right-most
character being loaded last. By
loading one character at a time
and latching the data before
loading the next character, the
figures will appear to scroll from
right to left.
HCMS-29XX Write Cycle Diagram
NOTE:
1. DATA IS COPIED TO THE CONTROL REGISTER OR THE DOT LATCH AND LED OUTPUTS WHEN CE IS HIGH AND CLK IS LOW.
T
RSS RSH
T
T
CLKCE CES
T
CLKH
T
CLKL
T
CEH
T
DS
T
DH
T
CEDO
T
DOUT
T
DOUTP
T
PREVIOUS DATA NEW DATA
121143 5
1
6
2
7
10 8
9
NEW DATA LATCHED HERE
[1]
CE
RS
CLK
D
IN
LED OUTPUTS,
CONTROL
REGISTERS
(SIMULTANEOUS)
OUT
D
D (SERIAL)
OUT
3-118
Figure 2.
ROW 0
(NOT USED)
DATA TO
NEXT
CHARACTER
PIXEL
DATA FROM
PREVIOUS
CHARACTER
ROW 7
ROW 6
ROW 5
ROW 4
ROW 3
ROW 2
ROW 1
40 BIT
S.R.
DO
DI
DATA IN
OSCILLATOR
÷8
CLOCK
CHIP
ENABLE
REGISTER
SELECT
RESET
OSC
OSC
SELECT
BLANK
DATA IN
CLR DATA
OUT
CONTROL
REGISTER
REFRESH
CONTROL
RST
PRESCALE
VALUE
H
L
H
L
L
H
D Q RS
(LATCHED)
L
H
CURRENT
REFERENCE
PWM BRIGHT
CONTROL
LH
LH
RS (LATCHED)
SER/PAR
MODE
3:8 DECODER
CATHODE
FIELD DRIVERS
40 BIT
S.R.
DO
DI 40 BIT
S.R.
DO
DI 40 BIT
S.R.
DO
DI
ANODE CURRENT SOURCES
V LED +
GND (LED)
0
CHAR 0
COLUMN 0 COLUMN 19
CHAR 1 CHAR 2 CHAR 3
ROW 7
DOT
REGISTER
BIT # 159
ROW 1
ROW 0 (NO LEDS)
DOT
REGISTERS
AND
LATCHES
DATA OUT
Figure 1.
3-119
Registers are connected in series
to form a 320-bit dot shift
register. The location of pixel 0
has not changed. However, Dot
Shift Register bit 0 of IC2
becomes bit 160 of the 320-bit
dot shift register.
The Control Registers of the two
ICs are independent of each
other. This means that to adjust
the display brightness the same
control word must be entered into
both ICs, unless the Control
Registers are set to simultaneous
mode.
Longer character string systems
can be built by cascading multiple
displays together. This is
accomplished by creating a five
line bus. This bus consists of CE,
RS, BL, Reset, and CLK. The
display pins are connected to the
corresponding bus line. Thus, all
CE pins are connected to the CE
bus line. Similarly, bus lines for
RS, BL, Reset, and CLK are
created. Then DIN is connected to
the right-most display. DOUT from
this display is connected to the
next display. The left-most display
receives its DIN from the DOUT of
the display to its right. DOUT from
the left-most display is not used.
Each display may be set to use its
internal oscillator, or the displays
may be synchronized by setting
up one display as the master and
the others as slaves. The slaves
are set to receive their oscillator
input from the master’s oscillator
output.
Sleep mode (Control Word 0, bit
D6 = Low) turns off the Internal
Display Oscillator and the LED
pixel drivers. This mode is used
when the IC needs to be powered
up, but does not need to be
active. Current draw in sleep
mode is nearly zero. Data in the
Dot Register and Control Words
are retained during sleep mode.
Control Word 1
Loading the Control Register with
D7 = logic high selects Control
Word 1. This Control Word
performs two functions: serial/
simultaneous data out mode and
external oscillator prescale select
(see Table 2).
Serial/Simultaneous Data
Output D0
Bit D0 of control word 1 is used to
switch the mode of DOUT between
serial and simultaneous data entry
during Control Register writes.
The default mode (logic low) is
the serial DOUT mode. In serial
mode, DOUT is connected to the
last bit (D7) of the Control Shift
Register.
Storing a logic high to bit D0
changes DOUT to simultaneous
mode which affects the Control
Register only. In simultaneous
mode, DOUT is logically connected
to DIN. This arrangement allows
multiple ICs to have their Control
Registers written to simul-
taneously. For example, for N ICs
in the serial mode, N * 8 clock
pulses are needed to load the
same data in all Control Registers.
In the simultaneous mode, N ICs
only need 8 clock pulses to load
the same data in all Control
Registers. The propagation delay
from the first IC to the last is
N*t
DOUTP.
External Oscillator
Prescaler Bit D1
Bit D1 of Control Word 1 is used
to scale the frequency of an
external Display Oscillator. When
this bit is logic low, the external
Display Oscillator directly sets the
internal display clock rate. When
this bit is a logic high, the
external oscillator is divided by 8.
This scaled frequency then sets
the internal display clock rate. It
takes 512 cycles of the display
clock (or 8 x 512 = 4096 cycles
of an external clock with the
divide by 8 prescaler) to com-
pletely refresh the display once.
Using the prescaler bit allows the
designer to use a higher external
oscillator frequency without extra
circuitry.
This bit has no affect on the
internal Display Oscillator
Frequency.
Bits D2-D6
These bits must always be pro-
grammed to logic low.
Cascaded ICs
Figure 3 shows how two ICs are
connected within an HCMS-29XX
display. The first IC controls the
four left-most characters and the
second IC controls the four
right-most characters. The Dot
3-120
Bit D7On-Time Duty Relative
Set Low PWM Brightness Oscillator Factor Brightness
to Select Control Cycles (%) (%)
Control
Word 0 LLLL 0 0 0
L L L H 1 0.2 1.7
L L H L 2 0.4 3.3
L L H H 3 0.6 5.0
L H L L 4 0.8 6.7
L H L H 5 1.0 8.3
L H H L 7 1.4 11.7
LHHH 9 1.8 15
H L L L 11 2.1 18
H L L H 14 2.7 23
HLHL 18 3.5 30
H L H H 22 4.3 37
H H L L 28 5.5 47
H H L H 36 7.0 60
HHHL 48 9.4 80
HHHH 60 11.7 100
Table 2. Control Shift Register
CONTROL WORD 0
LD
6D
5D
4D
3D
2D
1D
0
Peak Current Typical Peak Relative Full
Brightness Pixel Current Scale Current
Control (mA) (Relative Brightness, %)
H L 4.0 31
L H 6.4 50
L L 9.3 73 (Default at Power Up)
H H 12.8 100
SLEEP MODE L – DISABLES INTERNAL OSCILLATOR-DISPLAY BLANK
H – NORMAL OPERATION
Serial/Simultaneous Data Out
L – Dout holds contents of Bit D7
H – Dout is functionally tied to Din
External Display Oscillator Prescaler
L – Oscillator Freq ÷ 1
H – Oscillator Freq ÷ 8
Bit D7
Set High
to Select
Control
Word 1
Reserved for Future
Use (Bits D2-D6
must be set Low)
CONTROL WORD 1
HLLLLLD
1D
0
3-121
Figure 3. Cascaded ICs.
CE
IC2
BITS 160-319
CHARACTERS 4-7
RS
BL
SEL
OSC
CLK
D
OUT
D
IN
IC1
BITS 0-159
CHARACTERS 0-3
D
IN
RS
BL
SEL
OSC
CLK
D
OUT
CE
RESET
RESET
RS
BL
SEL
OSC
CLK
D
OUT
CE
RESET
D
IN
3-122
PD can be calculated as Equation
2 below.
Figure 4 shows how to derate the
power of one IC versus ambient
temperature. Operation at high
ambient temperatures may
require the power per IC to be
reduced. The power consumption
can be reduced by changing
either the N, IPIXEL, Osc cyc or
VLED. Changing VLOGIC has very
little impact on the power
consumption.
Appendix A. Thermal
Considerations
The display IC has a maximum
junction temperature of 150°C.
The IC junction temperature can
be calculated with Equation 1
below.
A typical value for RθJA is 100°C/
W. This value is typical for a
display mounted in a socket and
covered with a plastic filter. The
socket is soldered to a .062 in.
thick PCB with .020 inch wide,
one ounce copper traces.
Equation 1:
TJMAX = TA + PD * RθJA
Where:
TJMAX = maximum IC junction temperature
TA= ambient temperature surrounding the display
RθJA = thermal resistance from the IC junction to ambient
PD= power dissipated by the IC
Equation 2:
PD = (N * IPIXEL * Duty Factor * VLED) + ILOGIC * VLOGIC
Where:
PD= total power dissipation
N = number of pixels on (maximum 4 char * 5 * 7 = 140)
IPIXEL = peak pixel current.
Duty Factor = 1/8 * Osccyc/64
Osc cyc = number of ON oscillator cycles per row
ILOGIC = IC logic current
VLOGIC = logic supply voltage
Equation 3:
IPEAK = M * 20 * IPIXEL
Where:
IPEAK = maximum instantaneous peak current for the display
M = number of ICs in the system
20 = maximum number of LEDs on per IC
IPIXEL = peak current for one LED
Equation 4:
ILED(AVG) = N * IPIXEL * 1/8 * (oscillator cycles)/64
(see Variable Definitions above)
Appendix B. Electrical
Considerations
Current Calculations
The peak and average display
current requirements have a
significant impact on power
supply selection. The maximum
peak current is calculated with
Equation 3 below.
The average current required by
the display can be calculated with
Equation 4 below.
The power supply has to be able
to supply IPEAK transients and
supply ILED(AVG) continuously.
The range on VLED allows noise on
this supply without significantly
changing the display brightness.
VLOGIC and VLED Considerations
The display uses two independent
electrical systems. One system is
used to power the display’s logic
and the other to power the
display’s LEDs. These two
systems keep the logic supply
clean.
Separate electrical systems allow
the voltage applied to VLED and
VLOGIC to be varied independently.
Thus, VLED can vary from 0 to 5.5
V without affecting either the Dot
or the Control Registers. VLED can
P MAX – MAXIMUM POWER
DISSIPATION PER IC – W
D
025
T – AMBIENT TEMPERATURE – °C
A
0.7
0.6
0.5
0.4
0.3
0.2
0.1
60555045403530
0.8
0.9
1.0
1.1
1.2
8580757065
R = 100°C/W
J-A
θ
90
1.3
Figure 4.
3-123
be varied between 4.0 to 5.5 V
without any noticeable variation
in light output. However, operat-
ing VLED below 4.0 V may cause
objectionable mismatch between
the pixels and is not
recommended. Dimming the
display by pulse width modulating
VLED is also not recommended.
VLOGIC can vary from 3.0 to 5.5 V
without affecting either the
displayed message or the display
intensity. However, operation
below 4.5 V will change the
timing and logic levels and
operation below 3 V may cause
the Dot and Control Registers to
be altered.
The logic ground is internally
connected to the LED ground by a
substrate diode. This diode
becomes forward biased and
conducts when the logic ground is
0.4 V greater then the LED
ground. The LED ground and the
logic ground should be connected
to a common ground which can
withstand the current introduced
by the switching LED drivers.
When separate ground
connections are used, the LED
ground can vary from -0.3 V to
+0.3 V with respect to the logic
ground. Voltages below -0.3 V can
cause all the dots to be ON.
Voltage above +0.3 V can cause
dimming and dot mismatch. The
LED ground for the LED drivers
can be routed separately from the
logic ground until an appropriate
ground plane is available. On long
interconnections between the
display and the host system,
voltage drops on the analog
ground can be kept from affecting
the display logic levels by
isolating the two grounds.
Electrostatic Discharge
The inputs to the ICs are pro-
tected against static discharge
and input current latchup. How-
ever, for best results, standard
CMOS handling precautions
should be used. Before use, the
HCMS-29XX should be stored in
antistatic tubes or in conductive
material. During assembly, a
grounded conductive work area
should be used and assembly
personnel should wear conductive
wrist straps. Lab coats made of
synthetic material should be
avoided since they are prone to
static buildup. Input current
latchup is caused when the CMOS
inputs are subjected to either a
voltage below ground (VIN <
ground) or to a voltage higher
then VLOGIC (VIN > VLOGIC) and
when a high current is forced into
the input. To prevent input
current latchup and ESD damage,
unused inputs should be con-
nected to either ground or VLOGIC.
Voltages should not be applied to
the inputs until VLOGIC has been
applied to the display.
Appendix C. Oscillator
The oscillator provides the
internal refresh circuitry with a
signal that is used to synchronize
the columns and rows. This
ensures that the right data is in
the dot drivers for that row. This
signal can be supplied from either
an external source or the internal
source.
A display refresh rate of 100 Hz
or faster ensures flicker-free
operation. Thus for an external
oscillator the frequency should be
greater than or equal to 512 x
100 Hz = 51.2 kHz. Operation
above 1 MHz without the
prescaler or 8 MHz with the
prescaler may cause noticeable
pixel to pixel mismatch.
Appendix D. Refresh
Circuitry
This display driver consists of 20
one-of-eight column decoders and
20 constant current sources, 1
one-of-eight row decoder and
eight row sinks, a pulse width
modulation control block, a peak
current control block, and the
circuit to refresh the LEDs. The
refresh counters and oscillator are
used to synchronize the columns
and rows.
The 160 bits are organized as 20
columns by 8 rows. The IC
illuminates the display by
sequentially turning ON each of
the 8 row drivers. To refresh the
display once takes 512 oscillator
cycles. Because there are eight
row drivers, each row driver is
selected for 64 (512/8) oscillator
cycles. Four cycles are used to
briefly blank the display before
the following row is switched on.
Thus, each row is ON for 60
oscillator cycles out of a possible
64. This corresponds to the
maximum LED on time.
Appendix E. Display
Brightness
Two ways have been shown to
control the brightness of this LED
display: setting the peak current
and setting the duty factor. Both
values are set in Control Word 0.
To compute the resulting display
brightness when both PWM and
peak current control are used,
simply multiply the two relative
brightness factors. For example,
if Control Register 0 holds the
word 1001101, the peak current
3-124
is 73% of full scale (BIT D5 = L,
BIT D4 = L) and the PWM is set
to 60% duty factor (BIT D3 = H,
BIT D2 = H, BIT D1 = L, BIT D0
= H). The resulting brightness is
44% (.73 x .60 = .44) of full
scale.
The temperature of the display
will also affect the LED brightness
as shown in Figure 5.
Appendix F. Reference
Material
Application Note 1027: Soldering
LED Components
Application Note 1015: Contrast
Enhancement Techniques for
LED Displays
Figure 5.
RELATIVE LUMINOUS INTENSITY
(NORMALIZED TO 1 AT 25°C)
YELLOW
HER/ORANGE
0.2-55
T – AMBIENT TEMPERATURE – °C
A
3.0
2.6
2.2
1.8
1.4
1.0
0.6
856545255-15-35
GREEN
AlGaAs