CS4364 datasheet(25/50 Pages) CIRRUS

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DS619F1

CS4364

4.7

ATAPI Specification

The CS4364 implements the channel mixing functions of the ATAPI CD-ROM specification. The

ATAPI functions are applied per A-B pair. Refer to Table 9 on page 41 and Figure 17 for additional informa-

tion.

4.8

Direct Stream Digital (DSD) Mode

In Software Mode the DSD/PCM bits (Reg. 02h) are used to configure the device for DSD mode. The

DSD_DIF bits (Reg 04h) then control the expected DSD rate and MCLK ratio.

The DIR_DSD bit (Reg 04h) selects between two proprietary methods for DSD to analog conversion. The

first method uses a decimation free DSD processing technique which allows for features such as matched

PCM level output, DSD volume control, and 50kHz on chip filter. The second method sends the DSD data

directly to the on-chip switched-capacitor filter for conversion (without the above mentioned features).

The DSD_PM_EN bit (Reg. 04h) selects Phase Modulation (data plus data inverted) as the style of data

input. In this mode the DSD_PM_Mode bit selects whether a 128Fs or 64x clock is used for phase modu-

lated 64x data (see Figure 18). Use of Phase Modulation Mode may not directly effect the performance of

the CS4364, but may lower the sensitivity to board level routing of the DSD data signals.

The CS4364 can detect errors in the DSD data which does not comply with the SACD specification. The

STATIC_DSD and INVALID_DSD bits (Reg. 04h) allow the CS4364 to alter the incoming invalid DSD data.

Depending on the error, the data may either be attenuated or replaced with a muted DSD signal (the

MUTEC pins would be set according to the DAMUTE bit (Reg. 08h)).

More information for any of these register bits can be found in the “Parameter Definitions” on page 47.

The DSD input structure and analog outputs are designed to handle a nominal 0 dB-SACD (50% modulation

index) at full rated performance. Signals of +3 dB-SACD may be applied for brief periods of time however,

performance at these levels is not guaranteed. If sustained +3 dB-SACD levels are required, the digital vol-

ume control should be set to -3.0 dB. This same volume control register affects PCM output levels. There

is no need to change the volume control setting between PCM and DSD in order to have the 0 dB output

levels match (both 0 dBFS and 0 dB-SACD will output at -3 dB in this case).

ΣΣ

A Channel

Volume

Control

Aout Ax

AoutBx

Left Channel

Audio Data

Right Channel

Audio Data

BChannel

Volume

Control

MUTE

SDINx

Figure 17. ATAPI Block Diagram (x = channel pair 1, 2, or 3)

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