AM1707_1008 Datasheet, PDF (46/199 Pages) Texas Instruments – ARM Microprocessor

AM1707
SPRS637A – FEBRUARY 2010 – REVISED APRIL 2010
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6.6 Crystal Oscillator or External Clock Input
The device includes two choices to provide an external clock input, which is fed to the on-chip PLL to
generate high-frequency system clocks. These options are illustrated in Figure 6-6 and Figure 6-7. For
input clock 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 C1, C2 values are 10-20 pF.
• Figure 6-6 illustrates the option that uses on-chip 1.2V oscillator with external crystal circuit.
• Figure 6-7 illustrates the option that uses an external 1.2V clock input.
C₂
OSCIN
X₁
OSCOUT
C₁
Clock Input
to PLL
OSCV_SS
Figure 6-6. On-Chip 1.2V Oscillator
Table 6-3. Oscillator Timing Requirements
PARAMETER
f_osc Oscillator frequency range (OSCIN/OSCOUT)
MIN
MAX
UNIT
12
30
MHz
46
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