41
AT94KAL Series FPSLIC
Rev. 1138G–FPSLI–11/03
XTAL2
Output from the inverting oscillator amplifier
TOSC1
Input to the inverting timer/counter oscillator amplifier
TOSC2
Output from the inverting timer/counter oscillator amplifier
SCL
2-wire serial input/output clock
SDA
2-wire serial input/output data
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 24. Either a quartz crystal or a
ceramic resonator may be used.
Figure 24.
Oscillator Connections
External Clock
To drive the device from an external clock source, XTAL2 should be left unconnected while
XTAL1 is driven as shown in Figure 25.
Figure 25.
External Clock Drive Configuration
XTAL2
XTAL1
GND
C2
C1
MAX 1 HC BUFFER
HC
R
BIAS
C1 = 33 pf
C2 = 27 pf
XTAL2
XTAL1
GND
NC
EXTERNAL
OSCILLATOR
SIGNAL