HC705CT4GRSSLASHD datasheet(21/152 Pages) NXP

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General Description

Signal Description

MC68HC705CT4 — Rev. 2.0

General Release Specification

MOTOROLA

General Description

The IRQ pin contains an internal Schmitt trigger as part of its input to

improve noise immunity.

NOTE:

The voltage on the IRQ pin affects the mode of operation. See Section

6. Operating Modes.

CAUTION:

Port C interrupt is an external interrupt provided by port C that is

generated when the part comes out of reset. Therefore, an interrupt is

pending that is not being serviced until the CLI instruction is executed.

This interrupt is produced because the state of mask option register

(MOR) is not known until a few clock cycles after the part comes out of

reset. After this interrupt occurs, normal operation resumes, unless the

part is put in reset again.

1.4.4 OSC1 and OSC2

These pins provide control input for an on-chip clock oscillator circuit that

drives the PLL reference source. A crystal resonator, a ceramic

resonator, or an external signal connects to these pins providing a

system clock. The oscillator frequency is selectable between 5 or 40

times the internal bus rate. Typical oscillator configurations and

component values are shown in Figure 1-4. The manufacturer of the

crystal should be consulted, since actual component values are

dependent on the type of crystal used.

Figure 1-4. Oscillator Connections

OSC1

OSC2

OSC1

OSC2

MCU

EXTERNAL CLOCK

UNCONNECTED

(a) Crystal/Ceramic Resonator

(b) External Clock Source

10 M

Ω

10.24 MHz

Oscillator Connections

Connections

15 pF

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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