MC68HC08JK1 Datasheet, PDF (90/198 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Oscillator (OSC)
Freescale Semiconductor, Inc.
8.3 X-tal Oscillator (MC68HC08xxx)
The X-tal oscillator circuit is designed for use with an external crystal or
ceramic resonator to provide accurate clock source.
In its typical configuration, the X-tal oscillator is connected in a Pierce
oscillator configuration, as shown in Figure 8-1. This figure shows only
the logical representation of the internal components and may not
represent actual circuitry. The oscillator configuration uses five
components:
• Crystal, X₁
• Fixed capacitor, C₁
• Tuning capacitor, C₂ (can also be a fixed capacitor)
• Feedback resistor, R_B
• Series resistor, R_S (optional)
From SIM
To SIM
2OSCOUT
To SIM
OSCOUT
SIMOSCEN
MCU
OSC1
XTALCLK
÷2
OSC2
R_B
X₁
C₁
R_S*
*R_S can be zero (shorted) when used with higher-frequency crystals.
Refer to manufacturer’s data.
See Section 18. for component value requirements.
C₂
Figure 8-1. X-tal Oscillator External Connections
Technical Data
90
Oscillator (OSC)
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MC68H(R)C08JL3 — Rev. 4
MOTOROLA