19.2.2 External Clock Input
Circuit Configuration: An external clock signal can be input as shown in the examples in figure
19-5. If the XTAL pin is left open, the stray capacitance should not exceed 10 pF. If the stray
capacitance at the XTAL pin exceeds 10 pF in configuration a, use configuration b instead and
hold the clock high in standby mode.
Figure 19-5 External Clock Input (Examples)
EXTAL
XTAL
EXTAL
XTAL
74HC04
External clock input
Open
External clock input
a. XTAL pin left open
b. Complementary clock input at XTAL pin
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