mc9s08qd4 Freescale Semiconductor, Inc, mc9s08qd4 Datasheet - Page 176

• Manufacturer Part Number: mc9s08qd4
• Description: Hcs08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Appendix A Electrical Characteristics
A.3
This section provides information about operating temperature range, power dissipation, and package
thermal resistance. Power dissipation on I/O pins is usually small compared to the power dissipation in
on-chip logic and voltage regulator circuits and it is user-determined rather than being controlled by the
MCU design. In order to take P
actual pin voltage and V
unusually high pin current (heavy loads), the difference between pin voltage and V
small.
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
176
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
Thermal Characteristics
int
DD
Operating temperature range
(packaged)
Thermal resistance (single-layer board)
Thermal resistance (four-layer board)
+ P
× V
8-pin PDIP
8-pin NB SOIC
8-pin PDIP
8-pin NB SOIC
I/O
DD
, Watts — chip internal power
and
and
I/O
SS
Equation A-2
Equation A-2
or V
<< P
Rating
K = P
I/O
DD
int
MC9S08QD4 Series MCU Data Sheet, Rev. 3
A
into account in power calculations, determine the difference between
and can be neglected. An approximate relationship between P
and multiply by the pin current for each I/O pin. Except in cases of
. Using this value of K, the values of P
Table A-2. Thermal Characteristics
D
P
T
× (T
D
J
iteratively for any value of T
for K gives:
= K ÷ (T
= T
J
A
) in °C can be obtained from:
+ 273°C) + θ
A
+ (P
J
D
+ 273°C)
× θ
JA
JA
Symbol
)
θ
θ
× (P
T
JA
JA
A
D
)
2
A
–40 to 125
.
T
Value
L
113
150
72
87
D
to T
and T
H
J
SS
can be obtained by
Freescale Semiconductor
or V
°C/W
°C/W
Unit
°C
DD
will be very
D
Eqn. A-1
Eqn. A-2
Eqn. A-3
and T
J