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

圖1.AK4687方框圖

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

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

圖4.評估板AKD4687方框圖

圖5.評估板AKD4687略圖

圖6.評估板AKD4687電路圖(1)

圖7.評估板AKD4687電路圖(2)

圖8.評估板AKD4687電路圖(3)

圖9.評估板AKD4687電路圖(4)

圖10.評估板AKD4687電路圖(5)

圖11.評估板AKD4687電路圖(6)

圖12.評估板AKD4687元件布局圖
詳情請見:
http://www.asahi-kasei.co.jp/akm/en/product/ak4687/ak4687_f00e.pdf
和
http://www.asahi-kasei.co.jp/akm/en/product/ak4687/akd4687-a2-03e.pdf