MC68340 datasheet(388/441 Pages) FREESCALE

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MOTOROLA

MC68340 USER’S MANUAL

10-1

SECTION 10

APPLICATIONS

This section provides guidelines for using the MC68340. Minimum system-configuration

requirements and memory interface information are discussed.

10.1 MINIMUM SYSTEM CONFIGURATION

One of the powerful features of the MC68340 is the small number of external components

needed to create an entire system. The information contained in the following paragraphs

details a simple high-performance MC68340 system (see Figure 10-1). This system

configuration features the following hardware:

• Processor Clock Circuitry

• Reset Circuitry

• SRAM Interface

• ROM Interface

• Serial Interface

CLOCK

CIRCUITRY

MC68340

SRAM

ROM

SERIAL

INTERFACE

Figure 10-1. Minimum System Configuration Block Diagram

10.1.1 Processor Clock Circuitry

The MC68340 has an on-chip clock synthesizer that can operate from an on-chip phase-

locked loop (PLL) and a voltage-controlled oscillator (VCO). The clock synthesizer uses

an external crystal connected between the EXTAL and XTAL pins as a reference

frequency source. Figure 10-2 shows a typical circuit using an inexpensive 32.768-kHz

watch crystal. The 20-M resistor connected between the EXTAL and XTAL pins provides

biasing for a faster oscillator startup time. The crystal manufacturer's documentation

should be consulted for specific recommendations on external component values.

Freescale Semiconductor, Inc.

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MC68340 Datasheet(PDF) 388 Page - Freescale Semiconductor, Inc