Datasheet

Functional Description
MC68HC908QYA/QTA Family Data Sheet, Rev. 3
Freescale Semiconductor 97
The oscillator configuration uses five components:
•Crystal, X
1
• Fixed capacitor, C
1
• Tuning capacitor, C
2
(can also be a fixed capacitor)
• Feedback resistor, R
B
• Series resistor, R
S
(optional)
NOTE
The series resistor (R
S
) is included in the diagram to follow strict Pierce
oscillator guidelines and may not be required for all ranges of operation,
especially with high frequency crystals. Refer to the oscillator
characteristics table in the Electricals section for more information.
Figure 11-2. XTAL Oscillator External Connections
C
1
C
2
XTALCLK
R
B
X
1
R
S
MCU
OSC2OSC1
÷ 2
BUSCLKX2BUSCLKX4
See the electrical section for details.
SIMOSCEN (INTERNAL SIGNAL) OR
OSCENINSTOP (BIT LOCATED IN
CONFIGURATION REGISTER)