Datasheet

Table Of Contents
Appendix A Electrical Characteristics
MC9S08SH8 MCU Series Data Sheet, Rev. 3
Freescale Semiconductor 291
A.4 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.
Table A-3. Thermal Characteristics
Num C Rating Symbol Value Unit
1 Operating temperature range (packaged)
C
M
T
A
T
L
to T
H
–40 to 85
–40 to 125
°C
2 Maximum junction temperature T
J
135 °C
Thermal resistance
1,2
Single-layer board
1
Junction temperature is a function of die size, on-chip power dissipation, package thermal resistance, mounting
site (board) temperature, ambient temperature, air flow, power dissipation of other components on the board,
and board thermal resistance.
2
Junction to Ambient Natural Convection
3 D 8-pin NB SOIC
θ
JA
167
°C/W
16-pin TSSOP 123
20-pin PDIP 68
20-pin TSSOP 115
24-pin QFN 110
Thermal resistance
1,2
Four-layer board
8-pin NB SOIC 115
°C/W
4 D 16-pin TSSOP 75
20-pin PDIP θ
JA
49
20-pin TSSOP 76
24-pin QFN 42