Datasheet

C
L1
X2X1
Crystal
C
L2
XCLKIN
External Clock Signal
(Toggling 0-V )
DD
XCLKIN
X2
NC
X1
External Clock Signal
(Toggling 0-V )
DDIO
XCLKIN
X2
NC
X1
TMS320F28335, TMS320F28334, TMS320F28332
TMS320F28235, TMS320F28234, TMS320F28232
www.ti.com SPRS439M –JUNE 2007–REVISED AUGUST 2012
The three possible input-clock configurations are shown in Figure 3-10 through Figure 3-12.
Figure 3-10. Using a 3.3-V External Oscillator
Figure 3-11. Using a 1.9-V External Oscillator
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
• C
L
(load capacitance) = 12 pF
• C
L1
= C
L2
= 24 pF
• C
shunt
= 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.
Copyright © 2007–2012, Texas Instruments Incorporated Functional Overview 59
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