SNLS614C September 2018 – April 2024 DP83869HM
PRODUCTION DATA
A 25MHz, parallel, 15pF to 40pF load crystal resonator must be used if a crystal source is desired. Figure 8-2 shows a typical connection for a crystal resonator circuit. The load capacitor values vary with the crystal vendors. Check with the vendor for the recommended loads.
As a starting point for evaluating the oscillator performance, the value of CL1 and CL2 must each be equal to 2x the specified load capacitance from the crystal vendor’s data sheet. For example, if the specified load capacitance of the crystal is 10pF, set CL1 = CL2 = 20pF. CL1, CL2 value may need to be adjusted based on the parasitic capacitance. Depending on the crystal drive level, R1 may or may not be needed.
Specification for 25MHz crystal are listed inTable 8-1 .
PARAMETER | TEST CONDITION | MIN | TYP | MAX | UNIT |
---|---|---|---|---|---|
Frequency | 25 | MHz | |||
Frequency Tolerance | Including Operational Temperature, Aging, and Other Factors | ±100 | ppm | ||
Load Capacitance | 15 | 40 | pF | ||
ESR | 50 | ohm |