Reset / System Clock
C513AO
User’s Manual
5-7
05.99
Figure 5-5
On-Chip Oscillator Circuitry
To drive the C513AO with an external clock source, the external clock signal must be applied to
XTAL1, as shown in Figure 5-6. XTAL2 must be left unconnected. A pull-up resistor is suggested
to increase the noise margin, but is optional if
V
OH
of the driving gate corresponds to the
V
IH3
specification of XTAL1.
Figure 5-6
External Clock Source
MCS04015
C513AO
To internal
timing circuitry
**
)
*
)
XTAL2
XTAL1
Crystal or ceramic resonator
Resistor is only in the C513AO-2E
*
)
**
)
C
1
C
2
MCS04016
V
DD
External
Clock
Signal
C513AO
XTAL2
XTAL1
N.C.