AD1849 데이터 시트보기 (PDF) - Analog Devices

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AD1849

Serial-Port 16-Bit SoundPort® Stereo Codec

Analog Devices 

AD1849K

The loopback modes are shown graphically in Figure 3.

LINE, MIC

INPUT

DISCONNECTED

LINE 0,

OUTPUT

LINE 1

FUNCTIONAL

GAIN

A/D

AD1849K

MUTE

0

D/A

1

␮/A-LAW

ENCODE

MONITOR

DISABLE

␮/A-LAW

DECODE

Analog Loopback D-A-D

SDTX

SDRX

LINE, MIC

INPUT

LINE 0,

LINE 1

OUTPUT

FUNCTIONAL

GAIN

A/D

␮/A-LAW

ENCODE

AD1849K

MONITOR

MUTE

D/A

␮/A-LAW

ENCODE

Digital Loopback D-D

Figure 3. Loopback Modes

SDTX

SDRX

Clocks and Sample Rates

The AD1849K can operate from external crystals, from a 256 ×

FS input clock, from an input clock with a programmable divide

factor, or from the serial port’s bit clock (at 256 × FS), selected

under software control. Two crystal inputs are provided to

generate a wide range of sample rates. The oscillators for these

crystals are on the AD1849K, as is a multiplexer for selecting

between them. They can be overdriven with external clocks by

the user, if so desired. The recommended crystal frequencies are

16.9344 MHz and 24.576 MHz. From them the following sample

rates can be internally generated: 5.5125, 6.615, 8, 9.6, 11.025,

16, 18.9, 22.05, 27.42857, 32, 33.075, 37.8, 44.1, 48 kHz.

Regardless of clock input source, a clock output of 256 × FS is

generated (with some skew). If an external input clock or the

serial port’s bit clocks are selected to drive the AD1849K’s

internal operation, they should be low jitter clocks. If no external

clock will be used, Analog Devices recommends tying the clock

input pin (CLKIN) to ground. If either external crystal is not

used, Analog Devices recommends tying its input (CIN1 and/or

CIN2) to ground.

–10–

REV. A

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