mc68hc705j2 Freescale Semiconductor, Inc, mc68hc705j2 Datasheet - Page 70

• Manufacturer Part Number: mc68hc705j2
• Description: 8-bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

10.3 Power Considerations
MOTOROLA
10-2
The average chip-junction temperature, T
where:
For most applications P
The following is an approximate relationship between P
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
value of K, the values of P
and (2) iteratively for any value of T
I
/
O
T
P
P
P
):
JA
A
D
INT
I
/
O
= Ambient temperature, C
= P
= Package thermal resistance, junction to ambient, C/W
= Power dissipation on input and output pins (user-determined)
= I
INT
DD
+ P
V
I
/
DD
O
ELECTRICAL SPECIFICATIONS
watts (chip internal power)
K = P
I
/
O
« P
D
D
P
and T
T
INT
D
(T
J
= K
= T
A
and can be neglected.
D
+ 273 C) +
J
A
A
(at equilibrium) for a known T
.
can be obtained by solving equations (1)
+ (P
(T
J
J
+ 273 C)
D
, in C, can be obtained from:
JA
JA
)
(P
D
) 2
D
and T
A
J
MC68HC705J2
. Using this
(neglecting
(1)
(2)
(3)