AKM公司的AK4687是具有两路输入选择器和线路驱动器的异步立体声CODEC,ADC/DAC接口能接纳高达24位输入数据,并支持异步操作.24位立体声ADC采用64x过取样,取样频率高达48kHz,线性相位数字抗混淆滤波器,S/(N+D)为83dB,动态范围99dB,而24位立体声DAC采用128x过取样,取样频率高达192kHz,24位8倍数字滤波器,S/(N+D)为95dB,动态范围105dB.主要用在蓝光影碟机, 家庭影院,DTV,数字录音系统.本文介绍了AK4687主要特性, 方框图,典型应用电路图,以及评估板AKD4687-A功能,方框图和电路图与元件布局图.

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

图1.AK4687方框图

图2.AK4687典型连接图(I2C控制模式, CAD0引脚= “L”,主模式)

图3.AK4687典型连接图(H/W控制模式, MCLK=768fs,主模式)

评估板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.

评估板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

图4.评估板AKD4687方框图

图5.评估板AKD4687略图

图6.评估板AKD4687电路图(1)

图7.评估板AKD4687电路图(2)

图8.评估板AKD4687电路图(3)

图9.评估板AKD4687电路图(4)

图10.评估板AKD4687电路图(5)

图11.评估板AKD4687电路图(6)

图12.评估板AKD4687元件布局图
详情请见:
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