Texas Instruments PCM4222EVM, User Manual

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2.9 Modulator Output Operations
3 Hardware Reference
Hardware Reference
The PCM4222 supports a multi-bit modulator (MBM) output mode, where the 6-bit data for the left and
right channels are output directly from the delta-sigma modulators. The MBM output data are buffered and
routed to the modulator data port, or header J4.
Table 21 lists the pin configuration for header J4.
Table 21. Modulator Data Port Header Pin Configuration
Header J4 Pin Name Modulator Data Port Signal Name, Description
1 MOD1, Modulator Data Output 1 (LSB)
3 MOD2, Modulator Data Output 2
5 MOD3, Modulator Data Output 3
7 MOD4, Modulator Data Output 4
9 MOD5, Modulator Data Output 5
11 MOD6, Modulator Data Output 6 (MSB)
13 MCKO, Modulator Data Clock Output (Rate = MCKI)
15 WCKO, Modulator Word Clock Output (Rate = MCKI
÷
2)
2,4,6,8,10,12,14,16,17,18,19,20 Ground
The MBM output mode is enabled or disabled using the MODEN input (pin 23). This input is controlled via
the MODEN element on switch SW1.
Table 22 summarizes the operation of this switch. When MBM mode
is enabled, the PCM and DSD output modes are disabled, because some of the pins used for these
modes are remapped as modulator data and clock outputs. The PCMEN input (pin 16) must be set to the
LO position when the MBM output is enabled. When MBM mode is disabled, all data and clock outputs
associated with the interface are driven low (assumes PCM and DSD modes are also disabled).
Table 22. Multi-Bit Modulator (MBM) Output Mode Configuration
Switch SW1, MODEN Switch SW1, PCMEN Switch SW1, DSDEN MBM Output Mode
LO X X Disabled
HI LO X Enabled
Referring to the electrical schematic in Figure 4 , when MODEN is set to a LO state, the outputs of tri-state
buffer U6 are enabled, allowing the elements of switch SW1 and SW2 that are related to the PCM and
DSD output modes to control the configuration of the PCM4222. When MODEN is HI, the outputs of buffer
U6 are disabled and set to a high-impedance state. In addition, when MODEN is HI, tri-state buffer U7 is
enabled, allowing the modulator output data and clocks to be routed to the modulator data port (header
J4).
For more information regarding Multi-Bit Modulator output mode operation, timing, and specifications, see
the
PCM4222 datasheet .
This section provides the electrical schematics and the Bill of Materials for the PCM4222EVM evaluation
board. The components shown in the schematic are listed in
Table 23 , the Bill of Materials, for reference.
16 PCM4222EVM User's Guide SBAU124 – December 2006
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