MC68HC12 Datasheet, PDF (209/478 Pages) Motorola, Inc – The MC68HC912DT128A microcontroller unit (MCU) is a 16-bit device composed of standard on-chip peripherals including a 16-bit central processing unit

Oscillator
MC68HC912Dx128C Colpitts Oscillator Specification
13.4.4 MC68HC912Dx128C DC Blocking Capacitor Guidelines
Due to the placement of the resonator from EXTAL to VSS and the
nature of the microcontroller’s inputs, there will be a DC bias voltage of
approximately (VDD–2V) across the pins of the resonator. For some
resonators, this can have long-term reliability issues. To remedy this
situation, a DC-blocking capacitor can be placed in series with the
crystal, as shown in Figure 13-3.
The value of the DC-blocking capacitor should be between 0.1 and
10nF, with a preferred value of 1nF. This capacitor must be connected
as shown in Figure 13-3. If connected thus, all other oscillator
specifications and guidelines continue to apply.
MC68HC912DT128A — Rev 4.0
MOTOROLA
Oscillator
Technical Data
209