M68HC11F1EVS 查看數據表（PDF） - Freescale Semiconductor

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M68HC11F1EVS

MC68HC11F1 high-performance microcontroller unit (MCU)

Freescale Semiconductor 

Freescale Semiconductor, Inc.

The XTAL pin is normally left unterminated when an external CMOS compatible clock

is connected to the EXTAL pin. However, a 10 kΩ to 100 kΩ load resistor connected

from the XTAL output to ground can be used to reduce RFI noise emission.

The XTAL output is normally used to drive a crystal. The XTAL output can be buffered

with a high-impedance buffer, or it can be used to drive the EXTAL input of another

M68HC11 device. Refer to Figure 2-6.

In all cases, use caution when designing circuitry associated with the oscillator pins.

Load capacitances shown in the oscillator circuits include all stray layout capacitanc-

es. Refer to Figure 2-4, Figure 2-5, and Figure 2-6.

EXTAL

MCU

10M

XTAL

4xE

CRYSTAL

25 pF*

25 pF*

* Values include all stray capacitances.

Figure 2-4 Common Crystal Connections

EXTAL

MCU

XTAL

NC OR

10 k – 100 k

LOAD

CMOS-COMPATIBLE

EXTERNAL

OSCILLATOR

Figure 2-5 External Oscillator Connections

EXTAL

FIRST

MCU

10M

XTAL

4xE

CRYSTAL

25 pF*

25 pF*

220

NC OR

10 k – 100 k

LOAD

EXTAL

XTAL

SECOND

MCU

* Values include all stray capacitances.

Figure 2-6 One Crystal Driving Two MCUs

PIN DESCRIPTIONS

MC68HC11F1

2-4

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