XC68HC05P18A Motorola, XC68HC05P18A Datasheet - Page 117

• Manufacturer Part Number: XC68HC05P18A
• Description: HCMOS Microcontroller Unit
• Manufacturer: Motorola

13.5 Power Considerations
MC68HC05P18A
MOTOROLA
The average chip junction temperature, T
Where:
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
T
P
P
P
JA
A
D
INT
I/O
= ambient temperature in C
= P
= package thermal resistance, junction to ambient in C/W
= power dissipation on input and output pins (user-determined)
A
= I
. Using this value of K, the values of P
INT
I/O
CC
, the relationship between P
= P
+ P
Electrical Specifications
V
D
I/O
CC
x (T
T
= chip internal power dissipation
P
J
D
A
= T
I/O
+ 273 C) +
=
A
T
+ (P
J
P
+ 273 C
INT
D
K
x
and can be neglected.
JA
JA
)
x (P
D
J
, in C can be obtained from:
and T
D
D
)
D
2
(at equilibrium) for a
and T
J
is approximately:
Electrical Specifications
Power Considerations
J
can be obtained
Technical Data
A
.
117
(1)
(2)
(3)