HDSP-2301 HP [Agilent(Hewlett-Packard)], HDSP-2301 Datasheet - Page 40

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

the one shown in Figure 27 typi-
cally exhibit a thermal resistance,
a 32 character display.
Copper or aluminum bars
mounted underneath the displays
can also be used to heat sink the
display assembly. Heat generated
within the displays is conducted
through the ceramic substrate
into the bar. The ends of the bar
are mounted to a heat sink or to a
metal front panel. The bar can be
insulated from the pins of the dis-
play and the printed circuit board
with a thermally conductive sili-
con rubber sheet. Figure 28 shows
a metal plate with slots milled in
the plate for each row of displays
such that each horizontal row of
displays straddles a bar.
A thermal resistance model for
this heat sinking technique is
shown in Figure 29. This model
assumes that all heat generated in
the display is generated in the
center of each display package
and that the ends of the bar are
connected to an ideal heat sink.
Then the temperature rise of the
centermost display in the bar can
be calculated as shown below:
For display strings of an even
number of n displays, the case
temperature of the centermost
displays can be calculated as
PIN-A
T
T
C
C
= 4 ( /2) P
= 8 P
= (n
, of 14 C/W per package for
+ 2 P
2
/8) P
D
+ T
D
+ P
D
A
D
+ 3 P
+ T
D
A
+ T
D
A
(25)
(26)
Figure 26. Maximum Metalized Printed Circuit for the Agilent HDSP-2000
Figure 27. Two-Part Heat Sink for the HDSP-2000
DISPLAY BEZEL AND
CONTRAST ENHANCEMENT
FILTER
HDSP-2000 DISPLAY
METAL CHASSIS
HDSP-2000
DISPLAY
PRINTED CIRCUIT BOARD
UTILIZING LARGE
METALIZATION PATTERN
THERMAL
CONDUCTIVE SILICONE
RUBBER SHEET
(ELECTRICALLY
INSULATING)
25 MIL INSULATING “TRACES” TO
SEPARATE METAL CONDUCTORS
32
THERMAL
CONDUCTING
COMPOUND
TWO PIECE
BLACK ANODIZED
HEAT SINK