MC68030 Datasheet, PDF (538/602 Pages) Motorola, Inc – ENHANCED 32-BIT MICROPROCESSOR

Applications Information
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Figure 12-24. PAL Pin Definition
To supply a solid power supply interface, 10 V_CC pins and 14 GND pins are provided. This
allows two V_CC and four GND pins to supply power for the address bus and two V_CC and
four GND pins to supply the data bus; the remaining V_CC and GND pins are used by the
internal logic and clock generation circuitry. Table 12-7 lists the V_CC and GND pin
assignments.
To reduce the amount of noise in the power supplied to the MC68030 and to provide for
instantaneous current requirements, common capacitive decoupling techniques should be
observed. While there is no recommended layout for this capacitive decoupling, it is
essential that the inductance between these devices and the MC68030 be minimized to
provide sufficiently fast response time to satisfy momentary current demands and to
maintain a constant supply voltage. It is suggested that a combination of low, middle, and
high frequency, high-quality capacitors be placed as close to the MC68030 as possible (e.g.,
a set of 10 µF, 0.1 µF, and 330 pF capacitors in parallel provides filtering for most
frequencies prevalent in a digital system). Similar decoupling techniques should also be
observed for other VLSI devices in the system.
12-42
MC68030 USER’S MANUAL
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