mc68hc908lj24 Freescale Semiconductor, Inc, mc68hc908lj24 Datasheet - Page 105

• Manufacturer Part Number: mc68hc908lj24
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

7.3 Internal Oscillator
7.4 X-tal Oscillator
7.5 I/O Signals
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
The internal RC oscillator clock (ICLK) is a free running 64kHz clock (at
V
input to the computer operating properly (COP) module.
The ICLK can be turned off in stop mode by setting the STOP_IRCDIS
bit in CONFIG2. After reset, the bit is clear by default and ICLK is
enabled during stop mode.
The crystal (x-tal) oscillator circuit is designed for use with an external
32.768kHz crystal or ceramic resonator to provide an accurate clock
source.
In its typical configuration, the X-tal oscillator is connected in a Pierce
oscillator configuration, as shown in
the logical representation of the internal components and may not
represent actual circuitry. The oscillator configuration uses five
components:
The series resistor (R
oscillator guidelines and may not be required for all ranges of operation,
especially with high frequency crystals. Refer to the crystal
manufacturer’s data for more information.
The following paragraphs describe the oscillator I/O signals.
DD
•
•
•
•
•
= 5V) that requires no external components. It is the reference clock
Crystal, X
Fixed capacitor, C
Tuning capacitor, C
Feedback resistor, R
Series resistor, R
1
Oscillator (OSC)
(32.768kHz)
S
) is included in the diagram to follow strict Pierce
S
1
(optional)
2
B
(can also be a fixed capacitor)
Figure
7-1. This figure shows only
Internal Oscillator
Oscillator (OSC)
Data Sheet
105