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TMS320C6748
SPRS590G – JUNE 2009 – REVISED JANUARY 2017
6.5
Crystal Oscillator or External Clock Input
The device includes two choices to provide an external clock input, which is fed to the on-chip PLLs to
generate
high-frequency system clocks. These options are illustrated in
frequencies between 12 and 20 MHz, a crystal with 80 ohm max ESR is recommended. For input clock
frequencies between 20 and 30 MHz, a crystal with 60 ohm max ESR is recommended. Typical load
capacitance values are 10-20 pF, where the load capacitance is the series combination of C1 and C2.
The CLKMODE bit in the PLLCTL register must be 0 to use the on-chip oscillator. If CLKMODE is set to 1,
the internal oscillator is disabled.
Figure 6-6
illustrates the option that uses on-chip 1.2V oscillator with external crystal circuit.
illustrates the option that uses an external 1.2V clock input.
f
Oscillator frequency range (OSCIN/OSCOUT)
osc
86
Peripheral Information and Electrical Specifications
C
2
OSCIN
X
1
OSCOUT
C
1
OSCV
SS
Figure 6-6. On-Chip Oscillator
Table 6-2. Oscillator Timing Requirements
PARAMETER
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Figure 6-6
and
Clock Input
to PLL
Copyright © 2009–2017, Texas Instruments Incorporated
TMS320C6748
www.ti.com
Figure
6-7. For input clock
Figure 6-7
MIN
MAX
UNIT
12
30
MHz
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