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External Clock Signal
(Toggling 0−V
DDIO
)
XCLKIN
X2
NC
X1
External Clock Signal
(Toggling 0−V
DD
)
XCLKIN
X2
NC
X1
C
L1
X2X1
Crystal
C
L2
XCLKIN
TMS320F2809, TMS320F2808, TMS320F2806
TMS320F2802, TMS320F2801, TMS320C2802
TMS320C2801, TMS320F28016, TMS320F28015
SPRS230L–OCTOBER 2003–REVISED DECEMBER 2009
www.ti.com
The three possible input-clock configurations are shown in Figure 3-11 through Figure 3-13.
Figure 3-11. Using a 3.3-V External Oscillator
Figure 3-12. Using a 1.8-V External Oscillator
Figure 3-13. 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 20 MHz are listed below:
• Fundamental mode, parallel resonant
• C
L
(load capacitance) = 12 pF
• C
L1
= C
L2
= 24 pF
• C
shunt
= 6 pF
• ESR range = 30 to 60 Ω
TI recommends that customers have the resonator/crystal vendor characterize the operation of their
device with the DSP 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.
48 Functional Overview Copyright © 2003–2009, Texas Instruments Incorporated
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Product Folder Link(s): TMS320F2809 TMS320F2808 TMS320F2806 TMS320F2802 TMS320F2801 TMS320C2802
TMS320C2801 TMS320F28016 TMS320F28015