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AMIC110 Datasheet, PDF (99/214 Pages) Texas Instruments – Sitara Processors
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AMIC110
SPRS971A – AUGUST 2016 – REVISED SEPTEMBER 2016
6.2.2.2 OSC0 LVCMOS Digital Clock Source
Figure 6-11 shows the recommended oscillator connections when OSC0 is connected to an LVCMOS
square-wave digital clock source. The LVCMOS clock source is connected to the XTALIN terminal. The
ground for the LVCMOS clock source and VSS_OSC should be connected directly to the nearest PCB
digital ground (VSS). In this mode of operation, the XTALOUT terminal should not be used to source any
external components. The PCB design should provide a mechanism to disconnect the XTALOUT terminal
from any external components or signal traces that may couple noise into OSC0 via the XTALOUT
terminal.
The XTALIN terminal has a 15- to 40-kΩ internal pulldown resistor which is enabled when OSC0 is
disabled. This internal resistor prevents the XTALIN terminal from floating to an invalid logic level which
may increase leakage current through the oscillator input buffer.
AMIC110
VDDS_OSC
XTALIN
VSS_OSC
XTALOUT
LVCMOS
Digital
Clock
Source
Copyright © 2016, Texas Instruments Incorporated
Figure 6-11. OSC0 LVCMOS Circuit Schematic
Table 6-4. OSC0 LVCMOS Reference Clock Requirements
NAME
DESCRIPTION
MIN
TYP MAX UNIT
ƒ(XTALIN)
Frequency, LVCMOS reference clock
Frequency, LVCMOS reference clock stability and tolerance(1)
19.2, 24, 25,
or 26
–50
MHz
50 ppm
tdc(XTALIN)
tjpp(XTALIN)
tR(XTALIN)
tF(XTALIN)
Duty cycle, LVCMOS reference clock period
Jitter peak-to-peak, LVCMOS reference clock period
Time, LVCMOS reference clock rise
Time, LVCMOS reference clock fall
45%
–1%
55%
1%
5 ns
5 ns
(1) Initial accuracy, temperature drift, and aging effects should be combined when evaluating a reference clock for this requirement.
6.2.2.3 OSC1 Internal Oscillator Clock Source
Figure 6-12 shows the recommended crystal circuit for OSC1 of the ZCE package and Figure 6-13 shows
the recommended crystal circuit for OSC1 of the ZCZ package. TI recommends that preproduction PCB
designs include the two optional resistors Rbias and Rd in case they are required for proper oscillator
operation when combined with production crystal circuit components. In most cases, Rbias is not required
and Rd is a 0-Ω resistor. These resistors may be removed from production PCB designs after evaluating
oscillator performance with production crystal circuit components installed on preproduction PCBs.
The RTC_XTALIN terminal has a 10- to 40-kΩ internal pullup resistor which is enabled when OSC1 is
disabled. This internal resistor prevents the RTC_XTALIN terminal from floating to an invalid logic level
which may increase leakage current through the oscillator input buffer.
Copyright © 2016, Texas Instruments Incorporated
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