EF6805U3 Datasheet, PDF (13/31 Pages) STMicroelectronics – 8-BIT MICROCOMPUTER UNIT

Figure 15 : Clock Generator Options.
EF6805U3
Note : The recommended CL value with a 4.0 MHz crystal is 27pF, maximum, including system distributed capacitance. There is an inter-
nal capacitance of approximately 25pF on the XTAL pin. For crystal frequencies other than 4MHz, the total capacitance on each pin
should be scaled as the inverse of the frquency ratio. For example, with a 2MHz crystal, use approximately 50pF on EXTAL and approxi-
mately 25pF on XTAL. The exact value depends on the Motional-Arm parameters of the crystal used.
Figure 16 : Crystal Motional ARM parameters and Suggested PC Board layout.
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