MX802J 查看數據表（PDF） - MX-COM Inc

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MX802J

DVSR CODEC

MX-COM Inc  

DVSR CODEC

14

MX802

4.3 Encoder and Decoder Control : Analog Input and Output Control

The Control Register, Byte 0: bits 0 to 5, are used together with the codec Powersave Bit (Byte 1: bit 3) to

control codec input/output conditions and sample rates. Figure 3 shows the codec functional situation.

AUDIO IN

MOD

DEMOD

AUDIO OUT

INPUT

BIAS

CVSD CODEC

200 k

(nom)

VBIAS

AUDIO

BYPASS

500 k

(nom)

VBIAS

Figure 3: Analog Control (with reference to Figure 1)

OUTPUT

BIAS

Control Register

Codec

Powersave

Bit

Decoder

Control

0

000

0

001

0

010

0

011

–

–––

0

111

1

000

1

001

1

010

1

011

–

–––

1

111

Encoder

Control

0

000

0

001

0

010

0

011

-

–––

0

111

1

000

-

---

1

111

Circuit Switches

Audio Audio Output

Bypass Out

Bias

OFF

ON

OFF

OFF

–

OFF

OFF

ON

OFF

OFF

-

OFF

ON

OFF

OFF

ON

–

ON

OFF

OFF

OFF

OFF

–

OFF

Input

Bias

ON

OFF

OFF

OFF

–

OFF

ON

-

ON

OFF

OFF

OFF

OFF

–

OFF

ON

OFF

ON

ON

-

ON

OFF = Switch Open

ON = Switch ON

Decoder idling fed with

“1010101…” pattern at

32kbps.

Decoder running at the

selected sampling rate.

Decoder circuits

powersaved.

Encoder running at 32kbps

but Encoder Data O/P forced

to idle pattern “01010…”

Encoder running at selected

sampling rate

Encoder circuits powersaved.

Note

1

1

2

Table 7: Analog Control (with reference to Figure 3)

Notes

1. If the Delta Codec is in the Direct Access mode, these sampling rates will be as provided by the externally

applied clock.

2. The input bias switch is operated by the Control Register Codec Powersave and Encoder Control bits to

provide a relatively low impedance path for VBIAS to charge the input coupling capacitor whenever the

codec is powersaved, or the encoder control bits are set to 0, so that input bias can be established

quickly prior to operation.

1998 MX-COM, Inc.

www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054

Doc. # 20480033.008

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA

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