C540U_1 Datasheet, PDF (45/200 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Reset / System Clock
C540U / C541U
To Internal
Timing Circuitry
XTAL2
12 MHz
XTAL1
C540U
C541U
C₁
C₂
MCD03395
Figure 5-8
On-Chip Oscillator Circuiry
To drive the C540U/C541U with an external clock source, the external clock signal has to be applied
to XTAL1, as shown in figure 5-9. XTAL2 has to be left unconnected. A pullup resistor is suggested
(to increase the noise margin), but is optional if V_OH of the driving gate corresponds to the V_IH2
specification of XTAL1.
External
Clock
Signal
Figure 5-9
External Clock Source
V _CC
N.C.
C540U
C541U
XTAL2
XTAL1
MCD03396
Semiconductor Group
5-8
1997-10-01