Datasheet

Appendix A Electrical Characteristics
MC9S08QG8 and MC9S08QG4 Data Sheet, Rev. 5
266 Freescale Semiconductor
A.3 Thermal Characteristics
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. To take P
I/O
into account in power calculations, determine the difference between actual pin
voltage and V
SS
or V
DD
and multiply by the pin current for each I/O pin. Except in cases of unusually high
pin current (heavy loads), the difference between pin voltage and V
SS
or V
DD
will be very small.
The average chip-junction temperature (T
J
) in °C can be obtained from:
T
J
= T
A
+ (P
D
× θ
JA
) Eqn. A-1
where:
T
A
= Ambient temperature, °C
θ
JA
= Package thermal resistance, junction-to-ambient, °C/W
P
D
= P
int
+ P
I/O
Table A-2. Thermal Characteristics
Rating Symbol Value Unit
Operating temperature range (packaged)
T
A
T
L
to T
H
°CC –40 to 85
M –40 to 125
Thermal resistance
Single-layer board
8-pin PDIP
θ
JA
113
°C/W
8-pin NB SOIC 150
8-pin DFN 179
16-pin PDIP 78
16-pin TSSOP 133
16-pin QFN 132
24-pin QFN 125
Thermal resistance
Four-layer board
8-pin PDIP
θ
JA
72
°C/W
8-pin NB SOIC 87
8-pin DFN 41
16-pin PDIP 53
16-pin TSSOP 86
16-pin QFN 36
24-pin QFN 44