AT89S8252
Oscillator
Characteristics
XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier that
can be configured for use as an on-chip oscillator, as shown in Figure 11. Either a
quartz crystal or ceramic resonator may be used. To drive the device from an external
clock source, XTAL2 should be left unconnected while XTAL1 is driven, as shown in
Figure 12. There are no requirements on the duty cycle of the external clock signal,
since the input to the internal clocking circuitry is through a divide-by-two flip-flop, but
minimum and maximum voltage high and low time specifications must be observed.
Figure 11. Oscillator Connections
Note:
C1, C2
=
=
30 pF 10 pF for Crystals
40 pF 10 pF for Ceramic Resonators
Figure 12. External Clock Drive Configuration
21
0401G–MICRO–3/06
ATMEL [ ATMEL ]
