TMS320F28335, TMS320F28334, TMS320F28332
TMS320F28235, TMS320F28234, TMS320F28232
SPRS439I–JUNE 2007–REVISED MARCH 2011
www.ti.com
The three possible input-clock configurations are shown in Figure 3-10 through Figure 3-12.
XCLKIN
X1
X2
NC
External Clock Signal
(Toggling 0-VDDIO
)
Figure 3-10. Using a 3.3-V External Oscillator
XCLKIN
X1
X2
External Clock Signal
)
NC
(Toggling 0-VDD
Figure 3-11. Using a 1.9 -V External Oscillator
XCLKIN
X1
X2
C
L2
C
L1
Crystal
Figure 3-12. Using the Internal Oscillator
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 40 Ω
TI recommends that customers have the resonator/crystal vendor characterize the operation of their
device 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.
60
Functional Overview
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