Datasheet

MCF51AC256 ColdFire Microcontroller Data Sheet, Rev.7
Electrical Characteristics
Freescale Semiconductor18
2.3 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 it is user-determined rather than being controlled by the MCU design. In order 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 6. Absolute Maximum Ratings
Rating Symbol Value Unit
Supply voltage V
DD
–0.3 to 5.8 V
Input voltage V
In
–0.3 to V
DD
+ 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 (V
DD
) and negative (V
SS
) clamp
voltages, then use the larger of the two resistance values.
2
All functional non-supply pins are internally clamped to V
SS
and V
DD
.
3
Power supply must maintain regulation within operating V
DD
range during instantaneous and
operating maximum current conditions. If positive injection current (V
In
> V
DD
) is greater than
I
DD
, the injection current may flow out of V
DD
and could result in external power supply going
out of regulation. Ensure external V
DD
load will shunt current greater than maximum injection
current. This will be the greatest risk when the MCU is not consuming power. Examples are: if
no system clock is present, or if the clock rate is very low which would reduce overall power
consumption.
I
D
25 mA
Maximum current into V
DD
I
DD
120 mA
Storage temperature T
stg
–55 to 150 C
Table 7. Thermal Characteristics
Rating Symbol Value Unit
Operating temperature range (packaged) T
A
–40 to 105 C
Maximum junction temperature T
J
150 C
Thermal resistance
1,2,3,4
80-pin LQFP
1s
2s2p
64-pin LQFP
1s
2s2p
64-pin QFP
1s
2s2p
44-pin LQFP
1s
2s2p

JA
51
38
59
41
50
36
67
45
C/W