
6
Operational Considerations
Electrical
These devices use a modified 4 x 7
dot matrix light emitting diode to
display decimal/hexadecimal
numeric information. The high
efficiency red and yellow LEDs
are GaAsP epitaxial layer on a
GaP transparent substrate. The
green LEDs are GaP epitaxial
layer on a GaP transparent
substrate. The LEDs are driven by
constant current drivers, BCD
information is accepted by the
display memory when the enable
line is at logic low and the data is
latched when the enable is at logic
high. Using the enable pulse width
and data setup and hold times
listed in the Recommended
Operating Conditions allows data
to be clocked into an array of
displays at a 6.7 MHz rate.
The decimal point input is active
low true and this data is latched
into the display memory in the
same fashion as the BCD data.
The decimal point LED is driven
by the on-board IC.
The blanking control input on the
hexadecimal displays blanks
(turns off) the displayed informa-
tion without disturbing the
contents of display memory. The
display is blanked at a minimum
threshold level of 2.0 volts. When
blanked, the display standby
power is nominally 250 mW at
TA = 25°C.
Mechanical
The primary thermal path for
power dissipation is through the
device leads. Therefore, to insure
reliable operation up to an
ambient temperature of +85°C, it
is important to maintain a case-to-
ambient thermal resistance of less
than 35°C watt/device as
measured on top of display pin 3.
For information on soldering and
post solder cleaning see Applica-
tion Note 1027, Soldering LED
Components.
Contrast Enhancement
These display devices are
designed to provide an optimum
ON/OFF contrast when placed
behind an appropriate contrast
enhancement filter. For further
information, please refer to
Application Note 1015, Contrast
Enhancement Techniques for
LED Displays.
Over Range Display
The over range devices display
“±1” and decimal point. The
character height and package
configuration are the same as the
numeric and hexadecimal devices.
Character selection is obtained
via external switching transistors
and current limiting resistors.
Package Dimensions
Pin
Character 1 2,3 4 8
+1XX1
-0XX1
1X1XX
Decimal Point X X 1 X
Blank 0 0 0 0
Notes:
0: Line switching transistor in Figure 7 cutoff.
1: Line switching transistor in Figure 7 saturated.
X: 'don't care'
13.5
(0.53)
3.3
(0.13)
10.2
(0.400)
1.9
(0.075)
1.5
(0.06)
4.8
(0.19)
4.8
(0.19)
7.4
(0.29)
87 6 5
5°
MAX. PIN
1
2
3
4
5
6
7
8
FUNCTION
Plus
Numeral One
Numeral One
DP
Open
Open
V
CC
Minus/Plus
NOTE: DIMENSIONS IN MILLIMETERS AND (INCHES).
D
FRONT VIEW
1 2 3 4