Atmel AT89C2051 Manual page 4

4.7 XTAL2
5. Oscillator Characteristics
AT89C2051
4
Output from the inverting oscillator amplifier.
The XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier which can
be configured for use as an on-chip oscillator, as shown in
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
ments 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 5-1. Oscillator Connections
C1, C2 = 30 pF ± 10 pF for Crystals
Note:
= 40 pF ± 10 pF for Ceramic Resonators
Figure 5-2. External Clock Drive Configuration
Figure 5-1. Either a quartz crystal or
Figure 5-2. There are no require-
0368G–MICRO–6/05