AM1806 Datasheet, PDF (69/241 Pages) Texas Instruments – AM1806 ARM Microprocessor

AM1806
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SPRS658 – FEBRUARY 2010
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 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 Oscillator
Table 6-2. Oscillator Timing Requirements
PARAMETER
f_osc
Oscillator frequency range (OSCIN/OSCOUT)
MIN
MAX
UNIT
12
30
MHz
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Peripheral Information and Electrical Specifications
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