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| MC68HC11PH8 Datasheet, PDF (226/264 Pages) Motorola, Inc – High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit | |||
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TJ = TA + (PD ⢠θJA)
[1]
where:
TA = Ambient temperature (°C)
θJA = Package thermal resistance, junction-to-ambient (°C/W)
PD = Total power dissipation = PINT + PI/O (W)
PINT = Internal chip power = IDD ⢠VDD (W)
PI/O = Power dissipation on input and output pins (user determined)
An approximate relationship between PD and TJ (if PI/O is neglected) is:
PD = -T---J----+-K----2---7---3--
[2]
Solving equations [1] and [2] for K gives:
K = PD ⢠(TA + 273) + θJA ⢠PD2
[3]
where K is a constant for a particular part. K can be determined by measuring PD (at equilibrium)
for a known TA. Using this value of K, the values of PD and TJ can be obtained for any value of TA,
by solving the above equations. The package thermal characteristics are shown below:
Characteristics
Thermal resistance
à 84-pin PLCC package
à 84-pin CERQUAD package (EPROM)
à 112-pin QFP package
Symbol
θJA
Value
50
50
TBD
Unit
°C/W
12
MOTOROLA
A-2
ELECTRICAL SPECIFICATIONS (STANDARD)
TPG
MC68HC11PH8
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