CM68HC05C4ACFB Motorola / Freescale Semiconductor, CM68HC05C4ACFB Datasheet - Page 116

• Manufacturer Part Number: CM68HC05C4ACFB
• Description: Microcontroller
• Manufacturer: Motorola / Freescale Semiconductor

Electrical Specifications
13.6 Power Considerations
General Release Specification
116
The average chip-junction temperature, T
Where:
For most applications, P
Following is an approximate relationship between P
neglecting 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, C
= P
= Package thermal resistance, junction to ambient, C/W.
= Power dissipation on input and output pins (user-determined)
= I
A
. Using this value of K, the values of P
INT
DD
I/O
K = P
+ P
Electrical Specifications
:
V
DD
I/O
D
watts (chip internal power)
P
T
D
(T
J
I/O
= K
A
= T
+ 273 C) +
«
A
+ (P
P
(T
INT
J
+ 273 C)
D
and can be neglected.
JA
JA
J
)
, in C, can be obtained from:
(P
D
D
D
(at equilibrium) for a
and T
)
MC68HC05C4A
2
)
D
and T
J
can be obtained
J
A
MOTOROLA
.
—
Rev. 4.0
(1)
(2)
(3)