CS43198 datasheet(39/137 Pages) CIRRUS

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DS1156F1

CS43198

4.7 Filtering Options

7. After properly unmasked (clearing PLL_READY_INT_MASK and PLL_ERROR_INT_MASK), PLL_READY_INT,

and PLL_ERROR_INT are used to monitor if PLL has been successfully started.

8. Turn on the PLL by setting PLL_START.

4.6.2.2 Powering Down the PLL

1. Clear PLL_START to stop the PLL operation.

2. For further power saving, set PDN_PLL to disable the PLL block.

4.7 Filtering Options

To accommodate the increasingly complex requirements of digital audio systems, the CS43198 incorporates selectable

filters in different playback modes.

For PCM/TDM mode, the following interpolation filtering options can be selected:

• Fast roll-off and slow roll-off interpolation filter options.

• In each option above, both low-latency and normal phase-compensation filtering options can be used.

• Nonoversampling (NOS) mode is provided, which minimizes the internal digital processing. Once NOS mode is set,

the settings on the above two options are ignored.

The combination of the options results in five different filter combinations. The specifications for each filter can be found

in Table 3-7, and response plots can be found in Section 9. These filters have been designed to accommodate a variety

of musical tastes and styles. The PCM filter option register (see Section 7.5.2) is used to select filter options.

When in octuple-speed mode, the filter options above are not available and the internal digital processing is minimized.

See the specification in Table 3-7 for filter characteristics.

The DSD processor mode uses a decimation-free DSD processing technique that allows for features such as matched

PCM level output, DSD volume control, and 50-kHz on-chip filter.

In Direct DSD Mode, the DSD stream directly controls the DAC elements for minimal processing. Since there is no 50-kHz

on-chip filter in the signal path, external filter designs must be compliant with SACD requirements.

4.8 Audio Serial Port (ASP)

The independent, highly configurable ASPs and auxiliary serial ports (XSPs) communicate audio data from other system

devices, such as applications processors. Both ports can be configured to support common audio interfaces, TDM/I2S and

left-justified (LJ).

ASP supports both PCM and DoP stream playback. XSP can only support DoP stream playback. For DAC playback, only

one port needs to be enabled. Both ports are enabled only in specific application, such as PCM notification mixing with

DSD/DoP content. Details regarding this application setup can be found in Section 4.11.

In this section, the reference to both ports is generalized as “xSP” to explain the common settings between the two ports.

4.8.1

Master and Slave Timing

Each serial port can operate as either the master of timing or as a slave to another device’s timing. If xSP_M/S is set, the

serial port acts as a clock master. If xSP_M/S is cleared, the serial port acts as a clock slave.

• In Master Mode, xSP_SCLK and xSP_LRCK are outputs derived from the internal MCLK.

• In Slave Mode, xSP_SCLK and xSP_LRCK are inputs. Although the CS43198 does not generate the interface

timings in Slave Mode, the expected LRCK and SCLK format must be programmed in the same way as in Master

Mode (see Table 3-18).

• In both modes, the serial port sample rate register (xSP_SPRATE) must be set per audio content before enabling

the serial port.

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