# MC68HC705J1A

Manufacturer Part NumberMC68HC705J1A
ManufacturerMotorola
MC68HC705J1A datasheet

CaseDIP-20L
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Page 120/162:

## Power Considerations

PrevNext
Electrical Specifications
10.6 Power Considerations
The average chip junction temperature, T
Where:
T
P
P
P
For most applications, P
Ignoring P
Solving equations (1) and (2) for K gives:
where K is a constant pertaining to the particular part. K can be
determined from equation (3) by measuring P
known T
by solving equations (1) and (2) iteratively for any value of T
Technical Data
120
T
= T
+ (P
J
A
D
= ambient temperature in C
A
= package thermal resistance, junction to ambient in C/W
JA
= P
+ P
D
INT
I/O
= I
V
= chip internal power dissipation
INT
CC
CC
= power dissipation on input and output pins (user-determined)
I/O
< P
I/O
INT
, the relationship between P
I/O
K
P
=
D
T
+ 273 C
J
= P
x (T
+ 273 C) +
D
A
. Using this value of K, the values of P
A
Electrical Specifications
, in C can be obtained from:
J
x
)
JA
and can be neglected.
and T
is approximately:
D
J
2
x (P
)
JA
D
(at equilibrium) for a
D
and T
can be obtained
D
J
.
A
MC68HC705J1A — Rev. 4.0
MOTOROLA
(1)
(2)
(3)