關鍵詞： AK4687 , AKM , Codec , 家庭影院 , 立體聲

AKM公司的AK4687是具有兩路輸入選擇器和線路驅動器的異步立體聲CODEC,ADC/DAC接口能接納高達24位輸入數據,并支持異步操作.24位立體聲ADC采用64x過取樣,取樣頻率高達48kHz,線性相位數字抗混淆濾波器,S/(N+D)為83dB,動態范圍99dB,而24位立體聲DAC采用128x過取樣,取樣頻率高達192kHz,24位8倍數字濾波器,S/(N+D)為95dB,動態范圍105dB.主要用在藍光影碟機, 家庭影院,DTV,數字錄音系統.本文介紹了AK4687主要特性, 方框圖,典型應用電路圖,以及評估板AKD4687-A功能,方框圖和電路圖與元件布局圖.

The AK4687 is a stereo audio CODEC with 2-channel input selector and a line driver. The interfaces of ADC/DAC can accept up to 24bit input data and support asynchronous operation. The input range of the pre-amplifier, that supports 3ch stereo inputs, is selectable by external resistors. Both the input stereo selector and output drivers support ground reference 2Vrms In/Output, making it possible to remove AC-coupling capacitors and reducing external parts. The AK4687 has a dynamic range of 99dB for ADC, 105dB for DAC. It is well suitable for digital recording systems, digital TVs, Blu-ray recorders and Home theater systems.

AK4687主要特性:

􀂆 Asynchronous ADC/DAC Operation

􀂆 3:1 Capless Stereo Line Input Selector

􀂆 24bit Stereo ADC

- 64x Oversampling

- Sampling Rate up to 48kHz

- Linear Phase Digital Anti-Alias Filter

- S/(N+D): 83dB

- Dynamic Range, S/N: 99dB

- Digital HPF for Offset Cancellation

􀂆 24bit Two Stereo DAC

- 128x Oversampling

- Sampling Rate up to 192kHz

- 24bit 8 times Digital Filter

- S/(N+D): 95dB

- Dynamic Range, S/N: 105dB

- De-emphasis Filter

􀂆 High Jitter Tolerance

􀂆 External Master Clock Input:

256fs, 384fs, 512fs 768fs (fs=32kHz ∼ 48kHz)

128fs, 192fs, 256fs 384fs (fs=64kHz ∼ 96kHz)

128fs, 192fs (fs=128kHz ~ 192kHz)

􀂆 2 Audio Serial I/F (PORT1, PORT2)

- Master/Slave mode (PORT1)

- I/F format

PORT2: MSB, LSB justified (16/24 bit), I2S

PORT1: MSB, LSB justified (16/24 bit), I2S

􀂆 Hardware / I2C-bus Control

􀂆 Operating Voltage:

- Digital I/O and Charge Pump: 3.0V ∼ 3.6V

- ADC Analog: 3.0V ∼ 3.6V

- DAC Analog: 3.0V ∼ 3.6V

􀂆 Package: 48pinLQFP

2011-9-28 10:35:23 上傳

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圖1.AK4687方框圖

2011-9-28 10:35:23 上傳

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圖2.AK4687典型連接圖(I2C控制模式, CAD0引腳= “L”,主模式)

2011-9-28 10:35:23 上傳

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圖3.AK4687典型連接圖(H/W控制模式, MCLK=768fs,主模式)

評估板AKD4687-A

AKD4687-A is an evaluation board for AK4687, which is a single chip 24bit CODEC with a 2ch ADC and a 2ch DAC. It is possible to evaluate not only A/D and D/A of the AK4687, but also asynchronous operation characteristics. Also, the board could be connected to a digital’s audio equipment easily with S/PDIF connectors.

評估板AKD4687-A功能:

􀂆 Compatible with 2 types of digital audio interface

- BNC (S/PDIF) input/output with DIT/DIR (AK4118A)

- 10pin headers for interfacing with external data source

􀂆 Separate power supply or regulator power supply

􀂆 10pin header for register control

2011-9-28 10:35:23 上傳

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