HD64F3437TF16 Datasheet, PDF (126/752 Pages) Hitachi Semiconductor – 12 V must not be applied to the S-mask model (single-power-supply specification), as this may permanently damage the device.

Not allowed
Signal A
Signal B
C_L2
XTAL
EXTAL
C_L1
Figure 6.10 Notes on Board Design around External Crystal
Input of External Clock Signal
Circuit Configuration: An external clock signal can be input as shown in the examples in figure
6.11. In example (b) in figure 6.11, the external clock signal should be kept high during standby.
If the XTAL pin is left open, make sure the stray capacitance does not exceed 10 pF.
EXTAL
XTAL
Open
External clock input
(a) Connections with XTAL pin left open
EXTAL
XTAL
74HC04
External clock input
(b) Connections with inverted clock input at XTAL pin
Figure 6.11 External Clock Input (Example)
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