Freescale Semiconductor, Inc.
Electrical Specifications
Tables of Data
Table 20-2. Thermal Characteristics
Characteristic
Symbol
Value
T + (P × Θ )
Unit
T
Average junction temperature
Ambient temperature
°C
°C
J
A
D
JA
T
User-determined
A
Package thermal resistance (junction-to-ambient)
68HC912D60 80-pin quad flat pack (QFP)
112-pin thin quad flat pack (TQFP)
Θ
65
46
°C/W
°C/W
JA
Package thermal resistance (junction-to-ambient)
68HC12D60 80-pin quad flat pack (QFP)
112-pin thin quad flat pack (TQFP)
Θ
70
48
JA
P
+ P
or
INT
I/O
(1)
P
W
Total power dissipation
D
K
-------------------------
TJ + 273°C
P
I
× V
Device internal power dissipation
W
W
INT
DD DD
(2)
P
User-determined
I/O pin power dissipation
I/O
P × (T + 273°C) +
D
A
(3)
K
W · °C
A constant
2
Θ
× P
D
JA
1. This is an approximate value, neglecting PI/O
.
2. For most applications PI/O « PINT and can be neglected.
3. K is a constant pertaining to the device. Solve for K with a known TA and a measured PD (at equilibrium). Use this value of
K to solve for PD and TJ iteratively for any value of TA.
68HC(9)12D60 — Rev 4.0
MOTOROLA
Advance Information
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Electrical Specifications
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