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SECTION 3 - CONFIGURING A TYPICAL SYSTEM
The three card spacing arrangements below show three possible system configurations
to distribute power dissipation and heat.
The first two correspond to the cal-
culations in example 2 which follows.
An improvement of 6°C in the calculated T A ' was
attained by the addition of a space near the cODponent side of the 7701 RAM card.
The
third configured system may not be optimal.
The additional space may give better result
if it is also on the component side of the RAM card.
This depends on the power
dissipated on the card adjacent to the circuit side of the
RA~
card and other
system characteristics.
First attempt for
power distribution
Example 2 (See sample
calculation
T
A
, = 52
0
C)
Second attempt for
power distribution
(~ee
example 2 sample
calculation T
A
,=56 O C)
Third attempt for
power distribution
(no sample calculations
included in text)
s...
s...
Ql
Ql
-0 -0
""
N
N
rt\
..:t
-0 -0
s...
C
0
0
0
0
0
0
s...
c
ro
Ql
00
.........
'-'>
'"'
~
'-'>
ro
Q)
O~
'"'
'"'
r-....
r-....
"' " '"'
O~
x
x
Ql
Ql
r
w
0
i
lW
I
2
3W
I
1 J75W
I
t-- 7W---i
1-10.85W1
. ..- 8.
1 W
-I
I-
1
2.0 5W-I
t-
1
o.
1 W
- i
I:-
4.
05\01
-+
s...
Ql
L
-0
Q}
-0
C
""
N
N
Q)
rt\
..:::r-
"'0 -0
L
Q)
0
0
0
U
0
0
0
1-
C
ro~
co
'"'
~
ro
'"'
'-'>
'-0
ro
Q}
U
x
'"' '"' '"'
0-
r-....
'"'
........
U+J
Q)
(/)
x
Q}
[]
~
m
&
75
W ;
!
i
I
lW
8\~
i
OW
j
I
2.i3W
I
I
t-- 7W
- 1
1-=
9. 1 W
--f
....
4. 05W
-4
~
8.
1 W
-t
f-
9. 7 5W
~
1-2. lW
- I
t-l2.05W-i
s...
Ql
-0
-0
C
""
N
N
Ql
Q.)
CV"\
..:::t
L
Q.)
0
0
0
U
0
U
0
0
I'O~
00
'"'
~
ro
'"'
1'0
'-D
'-'>
u x
'"' '"' '"'
0-
r-....
0-
........
r-....
Q.)
(/)
(/)
+
+
11
I'
r
,~\
[J
ill
I
I
OW
i
8\~
1
~
75W
1.
1W
I
OW
I
j
!
2.J~J
1--7W
----4
'-9.1W~
t-
4. 05W-4
A 11
cards on 1/2"
centers.
Power distribution .
in groups of
3
card
slots
As above excep t 111
spacing on component
side of 7701 RAM card.
s...
Q)
-0
""0
L
C
As above except
1'0
Q.)
u~
1" space on both
x
Q)
sides of 7701
~
RA'1
card
I
t-8.1W""1
I-
8. 05W--l
t--4.05'tH
l -
2.
l\.J-i
I-
9. 75W-{
~
Primary consideration should be given to the space provided on the component side
for the high power dissipating card.
106257
21
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