Rainbow Electronics AT90LS4433 - Manual (Page 6)

6
AT90S/LS4433
1042G–AVR–09/02
Clock Options
Crystal Oscillator XTAL1 and XTAL2 are input and output, respectively, of an inverting amplifier, which
can be configured for use as an On-chip Oscillator, as shown in Figure 2 and Figure 3.
Either a quartz crystal or a ceramic resonator may be used.
External Clock If the Oscillator is to be used as a clock for an external device, the clock signal from
XTAL2 may be routed to one HC buffer while reducing the load capacitor by 5 pF, as
shown in Figure 3. To drive the device from an external clock source, XTAL2 should be
left unconnected while XTAL1 is driven as shown in Figure 4.
Figure 2. Oscillator Connections
Figure 3. Using MCU Oscillator as a Clock for an External Device
Figure 4. External Clock Drive Configuration
XTAL1
REDUCE BY 5
P
F
MAX 1 HC BUFFER
XTAL2
HC