C868 Datasheet, PDF (23/82 Pages) Infineon Technologies AG – 8-Bit Single-Chip Microcontroller

C868
Figure 12 shows the recommended oscillator circuitries for crystal and external clock
operation.
Crystal Oscillator Mode
XTAL2
6.67-10.67
MHz
C868
XTAL1
C = 20 pF ± 10 pF for crystal operation
(incl. StrayCapacitance)
Figure 12 Recommended Oscillator Circuit
Driving from External Source
External Oscillator
Signal
XTAL2
N.C.
XTAL1
In this application the on-chip oscillator is used as a crystal-controlled, positive-
reactance oscillator (a more detailed schematic is given in Figure 13). lt is operated in
its fundamental response mode as an inductive reactor in parallel resonance with a
capacitor external to the chip. The crystal specifications and capacitances are non-
critical. In this circuit tbd pF can be used as single capacitance at any frequency together
with a good quality crystal. A ceramic resonator can be used in place of the crystal in
cost-critical applications. If a ceramic resonator is used, the two capacitors normally
have different values depending on the oscillator frequency. We recommend consulting
the manufacturer of the ceramic resonator for value specifications of these capacitors.
Data Sheet
23
V 1.0, 2003-05