mc9s08qg8 Freescale Semiconductor, Inc, mc9s08qg8 Datasheet - Page 259

• Manufacturer Part Number: mc9s08qg8
• Description: Hcs08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

The average chip-junction temperature (T
where:
For most applications, P
(if P
Solving
where K is a constant pertaining to the particular part. K can be determined from equation 3 by measuring
P
solving
Freescale Semiconductor
D
(at equilibrium) for a known T
I/O
T
θ
P
P
P
JA
D
int
I/O
A
is neglected) is:
Equation A-1
= Ambient temperature, °C
= P
Equation A-1
= Package thermal resistance, junction-to-ambient, °C/W
= I
= Power dissipation on input and output pins — user determined
int
DD
+ P
× V
I/O
DD
, Watts — chip internal power
and
and
I/O
Equation A-2
Equation A-2
<< P
MC9S08QG8 and MC9S08QG4 Data Sheet, Rev. 1.01
K = P
int
A
and can be neglected. An approximate relationship between P
. Using this value of K, the values of P
D
P
T
× (T
D
J
iteratively for any value of T
for K gives:
= K ÷ (T
J
= T
A
) in °C can be obtained from:
+ 273°C) + θ
A
+ (P
J
D
+ 273°C)
× θ
JA
JA
)
× (P
D
)
2
A
.
D
Appendix A Electrical Characteristics
and T
J
can be obtained by
D
Eqn. A-1
Eqn. A-2
Eqn. A-3
and T
259
J