
Electrical Characteristics
MC9S08LG32 Series Data Sheet, Rev. 9
Freescale Semiconductor
11
2.4
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 PI/O into account in power calculations, determine
the difference between actual pin voltage and VSS or VDD 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 VSS or VDD will be very small.
The average chip-junction temperature (TJ) in C can be obtained from:
TJ = TA + (PD JA)
Eqn. 1
Table 4. Absolute Maximum Ratings
Rating
Symbol
Value
Unit
Supply voltage
VDD
–0.3 to +5.8
V
Maximum current into VDD
IDD
120
mA
Digital input voltage
VIn
–0.3 to VDD +0.3
V
Instantaneous maximum current
Single pin limit (applies to all port pins)1, 2, 3
1
Input must be current limited to the value specified. To determine the value of the required
current-limiting resistor, calculate resistance values for positive (VDD) and negative (VSS) clamp
voltages and use the largest of the two resistance values.
2 All functional non-supply pins are internally clamped to V
SS and VDD.
3 Power supply must maintain regulation within operating V
DD range during instantaneous and
operating maximum current conditions. If positive injection current (VIn > VDD) is greater than
IDD, the injection current may flow out of VDD and could result in an external power supply going
out of regulation. Ensure that the external VDD load will shunt current greater than maximum
injection current, this will be of greater risk when the MCU is not consuming power. For instance,
if no system clock is present, or if the clock rate is very low (which would reduce overall power
consumption).
ID
25
2
mA
Storage temperature range
Tstg
–55 to 150
C
Table 5. Thermal Characteristics
Rating
Symbol
Value
Unit
Operating temperature range
(packaged)
TA
TL to TH
–40 to +105
C
Maximum junction temperature
TJ
125
C
Thermal resistance
Single-layer board
80-pin LQFP
64-pin LQFP
48-pin LQFP
JA
61
71
80
C/W
Thermal resistance
Four-layer board
80-pin LQFP
64-pin LQFP
48-pin LQFP
JA
48
52
56
C/W