MC68306 Motorola, MC68306 Datasheet - Page 166

• Manufacturer Part Number: MC68306
• Description: Integrated EC000 Processor
• Manufacturer: Motorola

8.3 POWER CONSIDERATIONS
The average chip-junction temperature, T J , in C can be obtained from:
where:
For most applications, P I/O < P INT and can be neglected.
An approximate relationship between P D and T J (if P I/O is neglected) is:
Solving Equations (1) and (2) for K gives:
where K is a constant pertaining to the particular part. K can be determined from equation
(3) by measuring P D (at thermal equilibrium) for a known T A . Using this value of K, the
values of P D and T J can be obtained by solving Equations (1) and (2) iteratively for any
value of T A .
8.4 AC ELECTRICAL SPECIFICATION DEFINITIONS
The AC specifications presented consist of output delays, input setup and hold times, and
signal skew times. All signals are specified relative to an appropriate edge of the clock and
possibly to one or more other signals.
The measurement of the AC specifications is defined by the waveforms shown in Figure
8-1. To test the parameters guaranteed by Motorola, inputs must be driven to the voltage
levels specified in that figure. Outputs are specified with minimum and/or maximum limits,
as appropriate, and are measured as shown in Figure 8-1. Inputs are specified with
minimum setup and hold times and are measured as shown. Finally, the measurement for
signal-to-signal specifications is also shown.
8-2
T A
P D
P INT
P I/O
JA
= Ambient Temperature, C
= Package Thermal Resistance, Junction-to-Ambient, C/W
= P INT + P I/O
= I C
= Power Dissipation on Input and Output Pins—User Determined
The testing levels used to verify conformance to the AC
specifications do not affect the guaranteed DC operation of the
device as specified in the DC electrical specifications.
C x V CC , Watts—Chip Internal Power
K = P D • (T A + 273 C) + JA • P D
T J = T A + (P D • JA )
MC68306 USER'S MANUAL
P D = K
NOTE
(T J + 273 C)
(1)
2
MOTOROLA