Texas Instruments AM18x eXperimenter's Kit TMDSEXP1808L TMDSEXP1808L 데이터 시트

제품 코드

TMDSEXP1808L

OSCOUT

OSCIN

OSCV

Clock Input
to PLL

AM1808

www.ti.com

SPRS653E – FEBRUARY 2010 – REVISED MARCH 2014

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 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.

Figure 6-7

illustrates the option that uses an external 1.2V clock input.

Figure 6-6. On-Chip Oscillator

Table 6-2. Oscillator Timing Requirements

MIN

MAX

UNIT

osc

Oscillator frequency range (OSCIN/OSCOUT)