HDSP-2301 HP [Agilent(Hewlett-Packard)], HDSP-2301 Datasheet - Page 38

• Manufacturer Part Number: HDSP-2301
• Description: Four Character 5.0 mm (0.20 inch) 5 x 7 Alphanumeric Displays
• Manufacturer: HP [Agilent(Hewlett-Packard)]

Figure 24. External Circuitry to Load
a Control Word into the HDSP-2470/-
2471/-2472 Alphanumeric System
upon Request
maximum power dissipation can
be reduced to under 1.0 W, while
the typical power dissipation can
be reduced to 0.60 W. In most in-
door ambients, the D.F. can be
reduced to 10% for standard red
and 5% for GaP displays. Under
these conditions the maximum
power dissipation is 0.72 W or
0.52 W and the typical power dis-
sipation is 0.43 W or 0.34 W. Thus,
in power sensitive applications,
GaP displays can be used to con-
serve power. Turning off V
during the time the display is
blanked can further reduce the
power dissipation. In this manner
the maximum power dissipation
DESIRED
LENGTH,
YYYY*
DESIRED
MODE, XX*
*SEE HDSP-2470/1/2 DATA SHEET
READY
DI 7
DI 6
DI 5
DI 4
DI 3
DI 2
DI 1
DI 0
CS
V CC
14
11
13
10
15
14
11
13
10
15
5
2
6
3
1
5
2
6
3
1
74LS157
74LS157
4A
3A
2A
1A
4B
3B
2B
1B
SEL
ST
4A
3A
2A
1A
4B
3B
2B
1B
SEL
ST
4Y
3Y
2Y
1Y
4Y
2Y
3Y
1Y
12
9
7
4
12
9
7
4
(23)
(21)
(19)
(17)
(15)
(13)
(11)
(22)
(4)
(1)
CC
2470/1/2
DI 7
DI 6
DI 5
DI 4
DI 3
DI 2
DI 1
DI 0
CS
READY
HDSP-
AN1016.24
can be reduced .32 W and the
typical power dissipation can be
reduced to 0.20 W for the
GaP displays.
Heat Sinking
Considerations
For operation at the maximum
temperature of 85 C, it is impor-
tant that the following criteria
be met:
where T
hottest pin
The thermal resistance IC junc-
tion to case,
pin,
Using these factors, it is possible
to determine the required heat
sink power dissipation capability
and associated power derating
through the following equations:
where
Table 2. Device Thermal Resistance
For example, given
35 C/W an ambient temperature
of 60 C, and the operating condi-
tions shown in equations (13),
(14), and (16) the T
the HDSP-2000 family can be
calculated as shown below:
Device
HDSP-2000 Series
HDSP-2300 Series
HDSP-2490 Series
a. T
b. T
T* = *
T
* = Pin or Case
T
J
PIN
= T* +
PIN
J
J-PIN
PIN
125 C
A
= (35 C/W) (1.12 W)
= 99 C
, is shown in Table 2.
100 C
P
= temperature of
+ 60 C
D
J
* P
+ T
JC
, or IC junction to
D
A
7.5 C/W
7.5 C/W
20 C/W
PIN
JC
PIN-A
and T
25 C/W
10 C/W
13 C/W
of
J-PIN
J
for
(21)
(22)
(23)
Heat sink design for the
HDSP-2000 family of displays can
be accomplished in a variety of
ways. For single line applications,
a maximum metalized printed cir-
cuit board such as shown in
Figure 26 can be used. For ex-
ample, the HDSP-2416/-2424/
-2432/-2440 display boards consist
of 16, 24, 32 or 40 characters of
HDSP-2000 displays mounted on a
maximum metalized printed cir-
cuit board. The HDSP-2432
printed circuit board is 2.3" x 6.4"
and has a
per package for a 1/2 ounce cop-
per clad printed circuit. These
display boards are designed for
free air operation of 55 C and
operation to 70 C with forced air
cooling of 150 fpm normal to the
rear side of the board, for displays
operating at a P
or less.
Heat Sink Design
for Operation Above 70 C
A free air operating temperature
of 85 C can be achieved by heat
sinking the display. Figure 27 de-
picts a two part heat sink which
can be assembled using two differ-
ent extruded parts. In this design,
the vertical fins promote heat
transfer due to naturally induced
convection. Care should be taken
to insure a good thermal path be-
tween the two portions of the heat
sink. To optimize power handling
capability, the heat transfer con-
tact area between the printed
circuit board metallization and the
heat sink should be maximized.
A thermally conductive silicon
rubber sheet can be used to insu-
late the printed circuit board.
Heat sink assemblies similar to
30
T
J
= 99 C + (25 C/W)
= 99 C + 28 C
= 127 C
PIN-A
(1.12 W)
D
of about 45 C/W
of 1.00 watt
(24)