Datasheet

Electrical Specifications
M68HC12B Family Data Sheet, Rev. 9.1
308 Freescale Semiconductor
19.3 Functional Operating Range
19.4 Thermal Characteristics
Rating Symbol Value Unit
All devices in this document meet these operating temperature ranges:
“C” temperature range
“V” temperature range
“M” temperature range
T
A
T
L
to T
H
−40 to +85
−40 to +105
−40 to +125
°C
Operating voltage range
V
DD
5.0 ± 10% V
Characteristic Symbol Value Unit
Average junction temperature
T
J
T
A
+ (P
D
× Θ
JA
)
°C
Ambient temperature
T
A
User-determined °C
Package thermal resistance (junction-to-ambient)
80-pin quad flat pack (QFP)
Θ
JA
76 °C/W
Total power dissipation
(1)
1. This is an approximate value, neglecting P
I/O
.
P
D
P
INT
+ P
I/O
or
W
Device internal power dissipation
P
INT
I
DD
× V
DD
W
I/O pin power dissipation
(2)
2. For most applications, P
I/O
« P
INT
and can be neglected.
P
I/O
User-determined W
A constant
(3)
3. K is a constant pertaining to the device. Solve for K with a known T
A
and a measured P
D
(at equilibrium). Use this value
of K to solve for P
D
and T
J
iteratively for any value of T
A
.
K
P
D
× (T
A
+ 273 °C) +
Θ
JA
× P
D
2
W/°C
K
T
J
273°C+
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