基于CS8422的24位多格式立体声数字音频接收技术

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本文介绍了CS8422主要特性,方框图, 软件和硬件模式连接框图,以及评估板CDB8422主要特性,方框图和详细电路图与元件布局图.
Cirrus 公司的CS8422是24位高性能多格式数字音频接收器,接口标准包括EIAJ CP1201, IEC-60958, AES3和S/PDIF,串行音频输出可设定为24/20/18/16位字长,数据输入可高达24位长.输入和输出数据可以和外接时钟是异步或同步,动态范围140dB,THD+N为-120dB,模拟电源3.3V,数字接口1.8V到5.0V.主要用在家庭影院系统,电视,媒体中心,混响和效果处理器,多轨录音机和PC声卡.
24-bit, 192-kHz, Asynchronous Sample Rate Converter with Integrated Digital Audio Interface Receive
r The CS8422 is a 24-bit, high-performance, monolithic CMOS stereo asynchronous sample rate converter with an integrated digital audio interface receiver that decodes audio data according to the EIAJ CP1201, IEC-60958, AES3, and S/PDIF interface standards.

Audio data is input through the digital interface receiver or a 3-wire serial audio input port. Audio is output through one of two 3-wire serial audio output ports. Serial audio data outputs can be set to 24, 20, 18, or 16-bit word-lengths. Data into the digital interface receiver and serial audio input port can be up to 24-bits long. Input and output data can be completely asynchronous, synchronous to an external clock through XTI, or synchronous to the recovered master clock.

The CS8422 can be controlled through the control port in Software Mode or in a Stand-Alone Hardware Mode. In Software Mode, the user can control the device through an SPI or I2C control port.

Target applications include digital recording systems (DVD-R/RW, CD-R/RW, PVR, DAT, MD, and VTR), digital mixing consoles, high-quality D/A, effects processors, computer audio systems, and automotive audio systems.

The CS8422 is available in a space-saving QFN package in both Commercial (-40℃ to +85℃) and Automotive (-40℃ to +105℃) grades. The CDB4822 is also available for device evaluation and implementation suggestions.

CS8422主要特性:

Sample Rate Converter Features
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140 dB Dynamic Range
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-120 dB THD+N
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No External Master Clock Required
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Supports Sample Rates up to 211 kHz
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Input/Output Sample Rate Ratios from 6:1 to 1:6
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Master Mode Master Clock/Sample Rate Ratio Support: 64, 96, 128, 192, 256, 384, 512, 768, 1024
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16, 18, 20, or 24-bit Data I/O
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Dither Automatically Applied and Scaled to Output Resolution

Multiple Device Outputs are Phase Matched

Digital Audio Interface Receiver Features
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Complete EIAJ CP1201, IEC-60958, AES3, S/PDIF Compatible Receiver
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28 kHz to 216 kHz Sample Rate Range
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2:1 Differential AES3 or 4:1 S/PDIF Input Mux
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De-emphasis Filtering for 32 kHz, 44.1 kHz, and 48 kHz
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Recovered Master Clock Output: 64 x Fs, 96 x Fs, 128 x Fs, 192 x Fs, 256 x Fs,384 x Fs, 512 x Fs, 768 x Fs, 1024 x Fs

49.152 MHz Maximum Recovered Master Clock Frequency

Ultralow-jitter Clock Recovery

High Input Jitter Tolerance

No External PLL Filter Components Required

Selectable and Automatic Clock Switching

AES3 Direct Output and AES3 TX Passthrough

On-chip Channel Status Data Buffering

Automatic Detection of Compressed Audio Streams

Decodes CD Q Sub-Code

System Features

SPI? or I2C? Software Mode and Stand-Alone Hardware Mode

Flexible 3-wire Digital Serial Audio Input Port

Dual Serial Audio Output Ports with Independently Selectable Data Paths

Master or Slave Mode Operation for all Serial Audio Ports

Time Division Multiplexing (TDM) Mode

Integrated Oscillator for use with External Crystal

Four General-purpose Output Pins (GPO)

+3.3 V Analog Supply (VA)

+1.8 V to 5.0 V Digital Interface (VL)

Space-saving 32-pin QFN Package



图1. CS8422方框图



图2.CS8422软件模式连接框图



图3.CS8422硬件模式连接框图



图4.CS8422硬件模式时钟路径图

CS8422评估板CDB8422

Using the CDB8422 evaluation board is an ideal way to evaluate the CS8422. Use of the board requires a digital signal source, an analyzer, and a power supply. A Windows PC-compatible computer is also required if using software mode to configure the CDB8422.

S/PDIF and AES3/EBU input connections are made via RCA phono, optical, or XLR connectors to the CS8422. S/PDIF output connections are made via RCA phono or optical connectors from the CS8406 (S/PDIF Tx). System timing can be provided by a S/PDIF or AES3/EBU input signal, by the CS8422 with supplied master clock, or by an I/O stake header with a DSP connected.

The provided Windows-based software GUI makes configuring the CDB8422 easy. The software communicates through the PC’s USB port to configure the board so that all features of the CS8422 can be evaluated.

The board may also be configured without a PC connection by using hardware switches; however, not all configurations of the CDB8422 are possible in hardware mode.

CS8422评估板CDB8422主要特性:

IEC-60958, AES3/EBU, S/PDIF Inputs

– Single-Ended Inputs via Optical and RCA Input Jacks

– Differential Inputs via XLR Input Jack

S/PDIF Outputs

– Optical and RCA Output Jacks

– CS8406 Digital Audio Transmitter

I/O Stake Headers

– External Control Port Accessibility

– External Serial Audio I/O Accessibility
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3.3 V Logic Interface

Powered by Single External Power Supply or PC USB Port Connection

H/W Control via DIP Switches

FlexGUI S/W Control - Windows? Compatible

– Pre-Defined & User-Configurable Scripts



图5.评估板CDB8422方框图



图6.评估板CDB8422电路图(1): CS8422 & XTI



图7.评估板CDB8422电路图(2): RF输入



图8.评估板CDB8422电路图(3)CM输入插头



图9.评估板CDB8422电路图(4): HW模式控制



图9.评估板CDB8422电路图(5):FPGA



图10.评估板CDB8422电路图(6): MCLK指向



图11.评估板CDB8422电路图(7): 串行音频1输出插头



图12.评估板CDB8422电路图(8): 串行音频2输出插头



图13.评估板CDB8422电路图(9): TDM插头



图14.评估板CDB8422电路图(10): CS8406和辅助TX



图15.评估板CDB8422电路图(11): USB和MCU



图16.评估板CDB8422电路图(12): 电源



图17.评估板CDB8422元件布局图