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It looks like there is a difference in ESR range for crystals on these two processors. If a 20 MHz crystal with ESR of 60 ohms is used for the F28035, can that same crystal be used for the F28335? It appears not. Can someone confirm that a lower ESR crystal is necessary for proper operation of the F28335?
F28335:
3.6.1.1 External Reference Oscillator Clock Option
The typical specifications for the external quartz crystal for a frequency of 30 MHz are listed below:
• Fundamental mode, parallel resonant
• CL (load capacitance) = 12 pF
• CL1 = CL2 = 24 pF
• Cshunt = 6 pF
• ESR range = 25 to 40Ω
TI recommends that customers have the resonator/crystal vendor characterize the operation of theirdevice with the DSC chip. The resonator/crystal vendor has the equipment and expertise to tune the tank circuit. The vendor can also advise the customer regarding the proper tank component values that will produce proper start up and stability over the entire operating range.
F28035:
3.8.2 Crystal Oscillator Option
The typical specifications for the external quartz crystal (fundamental mode, parallel resonant) are listed in Table 3-17.
Furthermore, ESR range = 30 to 150 Ω.
