MC912DG128ACPVE Datasheet, PDF (205/478 Pages) Freescale Semiconductor, Inc – Upward compatible with M68HC11 instruction set

Freescale Semiconductor, Inc.
Oscillator
MC68HC912Dx128C Colpitts Oscillator Specification
13.4.3 Important Information For Calculating Component Values
Before attempting to apply the information in section 13.4.2.4 Key
Parameters, the following data from the resonator vendor is required:
• Resonator Frequency (f)
• Maximum ESR (R, ESR, or R1)
• Maximum Shunt Capacitance (C0)
• Load Capacitance (CL) — this is not the external component
values but rather the capacitance applied in parallel with the
resonator during the tuning procedure.
13.4.3.1 How to Use This Information
The following tables provide Maximum ESR vs. component value for
various frequencies. This table should be used in the following manner:
1. Choose the set of component values corresponding to the correct
maximum shunt capacitance (equal to the sum of EXTAL–VSS
parasitics in excess of 1pF, plus the C0 of the resonator) and
VDDPLL setting.
2. Determine the range of components for which the Maximum ESR
is greater than the absolute maximum ESR of the resonator
(including ageing, power dissipation, temperature, process
variation or particle contamination).
3. Within this range, choose the EXTAL–XTAL capacitance closest
to (C_{EXTAL–XTAL} = 2*CL – 1pF).
4. If the ideal component is between two valid component values (the
maximum ESR is sufficient for both component values), then
choose the component with the highest maximum ESR or choose
an available component between the two listed values.
5. Choose the size of the XTAL–VSS capacitance equal to the
closest available size to (C_{XTAL–VSS} = 0.82*C_{EXTAL–XTAL}).
MC68HC912DT128A — Rev 4.0
MOTOROLA
Oscillator
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Technical Data
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