HDLX-3461 HP [Agilent(Hewlett-Packard)], HDLX-3461 Datasheet - Page 11

• Manufacturer Part Number: HDLX-3461
• Description: Four Character 6.9 mm (0.27 inch) Smart 5 x 7 Alphanumeric Displays
• Manufacturer: HP [Agilent(Hewlett-Packard)]

+ V
250 k
Figure 4. Intensity Modulation Control
Using an Astable Multivibrator
(reprinted with permission from
Electronics magazine, Sept. 19, 1974,
VNU Business pub. Inc.).
Figure 4 shows a circuit designed
to dim the display from 98% to
2% by pulse width modulating
the BL input. A logarithmic or a
linear potentiometer may be used
to adjust the display intensity.
However, a logarithmic potentio-
meter matches the response of
the human eye and therefore
provides better resolution at low
intensities. The circuit frequency
should be designed to operate
at 10 kHz or higher. Lower fre-
quencies may cause the display
to flicker.
Extended Function
Disable
Extended Function Disable (bit
D
disables the extended blanking
and dimming functions in the
HDLX-3416. If the Extended
Function Disable is a logic 1, the
internal brightness control,
Master Blank, and Digit Blank
Disable bits are ignored.
However, the BL input and
Cursor control are still active.
LOG
6
DD
of the Control Register)
1 k
1N914
400 pF
1 k
7
6
8
2
555
1
4
3
BL
(PIN 18)
10 kHz
OUTPUT
Mechanical and Electrical
Considerations
The HDLX-3416 is a 22 pin DIP
package that can be stacked
horizontally and vertically to
create arrays of any size. The
display is designed to operate
continuously from -40 C to
+85 C for all possible input
conditions.
The HDLX-3416 is assembled by
die attaching and wire bonding
140 LEDs and a CMOS IC to a
high temperature printed circuit
board. A polycarbonate lens is
placed over the PC board creating
an air gap environment for the
LED wire bonds. Backfill epoxy
environmentally seals the display
package. This package construc-
tion makes the display highly
tolerant to temperature cycling
and allows wave soldering.
The inputs to the CMOS IC are
protected against static discharge
and input current latchup. How-
ever, for best results standard
CMOS handling precautions
should be used. Prior to use, the
HDLX-3416 should be stored in
anti-static tubes or 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 charge build-up.
Input current latchup is caused
when the CMOS inputs are sub-
jected either to a voltage below
ground (V in < ground) or to a
voltage higher than V
V
forced into the input. To prevent
input current latchup and ESD
damage, unused inputs should
DD
) and when a high current is
DD
(V in >
11
be connected either to ground or
to V
applied to the inputs until V
has been applied to the display.
Transient input voltages should
be eliminated.
Soldering and Post Solder
Cleaning Instructions for
the HDLX-3416
The HDLX-3416 may be hand
soldered or wave soldered with
SN63 solder. When hand solder-
ing it is recommended that an
electronically temperature con-
trolled and securely grounded
soldering iron be used. For best
results, the iron tip temperature
should be set at 315 C (600 F).
For wave soldering, a rosin-based
RMA flux can be used. The solder
wave temperature should be set at
245 C
dwell in the wave should be set
between 1
optimum soldering. The preheat
temperature should not exceed
110 C (230 F) as measured on
the solder side of the PC board.
For further information on solder-
ing and post solder cleaning, see
Application Note 1027, Soldering
LED Components.
Contrast Enhancement
The objective of contrast enhance-
ment is to provide good readabil-
ity in the end user’s ambient
lighting conditions. The concept
is to employ both luminance and
chrominance contrast techniques.
These enhance readability by
having the OFF-dots blend into
the display background and the
ON-dots vividly stand out against
the same background. For addi-
tional information on contrast
enhancement, see Application
Note 1015.
DD
. Voltages should not be
5 C (473 F
1
/
2
to 3 seconds for
9 F), and
DD