WM8802SCFT datasheet(32/65 Pages) WOLFSON

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WM8802

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PP Rev 1.1 April 2004

IEC61937, DTS-CD/LD DETECTION FLAG OUTPUT

A function to output IEC61937 and DTS-CD/LD detection flags for non-PCM data is provided.

When the UNPCM non-PCM signal output setting is selected, as well as an indication on the AUDIO

pin, an interrupt signal is output from INT upon detection of an IEC61937 or DTS-CD/LD sync signal.

Non-PCM signal details can be known by reading this information from the output register.

The IEC61937 sync signal is detected and output when channel status bit 1 is non-PCM data ("1").

The IEC61937 sync signal is not output if bit 1 is PCM data (“0”).

DTS-CD/LD sync signal detection is done based on the sync pattern and the base frequency. In the

case of DTS-ES data detection, output is performed when the DTS5.1 channel sync signal is

detected and the DTS-ES sync pattern has been verified.

The IEC61937 and DTS-CD/LD detection flags are cleared when fs has changed or upon occurrence

of a PLL lock error or data error.

Since the DTS sync signal is provided within the audio data, digital data with the same code as the

DTS sync signal may in rare cases exist for regular CD/LD records that are not recorded in the DTS

format. Protection using the sync pattern or base frequency is provided so that such data is not

misinterpreted as DTS-CD/LD detection flags. The detection sequence is shown below.

Frame counter

reset

YES

Input data

DTS-CD/LD

SYNC

detection

DTS-CD/LD

data hold

Frame counter

start

YES

PaPb

detection

Bit 1 detection

Bit 1 = 1

PaPb

detection

during 4096

frames

IEC61937 flag OK

INT lowered

IEC61937

flag

IEC61937 data

hold

* Depending on the frame count,

the subsequent detection count

is expanded up to x2.

Periodic fluctuation is supported.

Frame count

512, 1024, 2048, 4096

SYNC detection

Frame count hold

x2 count detection

expansion

DTS-CD/LD flag OK

INT lowered

DTS-CD/LD flag

not valid

INT lowered

Frame counter

reset

Frame counter

start

PaPb

detection

during 4096

frames

512

=> 512 or 1024

1024

=> 1024 or 2048

2048

2048 or 4096

4096

1st count

2nd count

Frame count

512, 1024, 2048, 4096

SYNC detection

Figure 24 Detection Flag Output Flowchart

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