MC68HC912DG128 Datasheet, PDF (43/452 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
Pinout and Signal Descriptions
Signal Descriptions
NOTE:
The internal return path for the oscillator is the VSSPLL pin. Therefore it
is recommended to connect the common node of the resonator and the
capacitor directly to the VSSPLL pin.
EXTAL
MCU
XTAL
2 x E crystal or ceramic resonator
C1
C2
Figure 3-4. Common Crystal Connections
NOTE: When selecting a crystal, it is recommended to use one with the lowest
possible frequency in order to minimise EMC emissions.
EXTAL
MCU
XTAL _NC
2xE
CMOS-COMPATIBLE
EXTERNAL OSCILLATOR
Figure 3-5. External Oscillator Connections
XTAL is the crystal output.The XTAL pin must be left unterminated when
an external CMOS compatible clock input is connected to the EXTAL
pin. The XTAL output is normally intended to drive only a crystal. The
XTAL output can be buffered with a high-impedance buffer to drive the
EXTAL input of another device.
In all cases take extra care in the circuit board layout around the
oscillator pins. Load capacitances in the oscillator circuits include all
stray layout capacitances. Refer to Figure 3-4 and Figure 3-5 for
diagrams of oscillator circuits.
MC68HC912DG128 — Rev 3.0
MOTOROLA
Pinout and Signal Descriptions
For More Information On This Product,
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Technical Data
43