PCM9211
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SBAS495 –JUNE 2010
Figure 21 illustrates the connections for the XTI and XTO pins for both a resonator connection and an external
clock input connection.
Crystal
OSC
Circuit
Crystal
OSC
Circuit
24.576 MHz
Internal Clock
24.576 MHz
Internal Clock
CL1
CL2
Resonator
XTI
XTI
External
Clock
RD
(Optional)
XTO
XTO
Must be open
PCM9211
PCM9211
Resonator Connection
External Clock Input Connection
Figure 21. XTI and XTO Connection Diagram
In XTI mode, the output clocks (SCKO, BCKO, and LRCKO) are generated from the XTI source clock.
Register 24h/OSCAUTO controls whether or not the internal oscillator functions while it is not required. When
using the DIR as a clock source, the XTI source is not required; thus, the internal oscillator can be switched off.
There is a constraint, however, that when the DIR wide mode is being set (for example, in 192-kHz support), the
XTI is always used. The sampling frequency calculator also requires the XTI source.
XMCKO (the XTI clock buffered output) provides a buffered (and divided) XTI clock that can be output to
MPIO_A. Register 24h/XMCKEN controls whether the XMCKO should be muted or not, and Register
24h/XMCKDIV controls the division factor.
DIR Data Description
Decoded Serial Audio Data Output and Interface Format
The PCM9211 supports the following four data formats for the decoded data:
•
•
•
•
16-bit MSB First, Right-Justified
24-bit MSB First, Right-Justified
24-bit MSB First, Left-Justified
24-bit MSB First, I2S
Decoded data are MSB first and twos complement in all formats.
The format of the decoded data is selected by the RXFMT[2:0] register. The possible data formats are shown in
Table 7.
Table 7. DIR Serial Audio Data Output Format Set by RXFMT[2:0]
RXFMT[2:0] SETTING
DIR SERIAL AUDIO DATA OUTPUT FORMAT
24-bit MSB First, Right-Justified
16-bit MSB First, Right-Justified
24-bit MSB First, I2S (Default)
RXFMT2
RXFMT1
RXFMT0
0
0
1
1
0
1
0
0
0
1
0
1
24-bit MSB First, Left-Justified
Copyright © 2010, Texas Instruments Incorporated
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