AKM公司的AK4688是立体声音频CODEC,集成了具有24位输入/输出数据的ADC和DAC接口,支持异步操作.64x过取样,取样速率高达48kHz,线性相位数字抗混淆滤波器,S/(N+D)为83dB,动态范围105dB,S/N为99dB, 3.3V单电源输出达2Vrms,适合用于数字录音系统,DTV,蓝光记录仪和家庭影院.本文介绍了AK4688主要特性,方框图,典型应用电路以及评估板AKD4688-A主要功能,方框图,电路图和PCB元件布局图.

The AK4688 is a stereo audio CODEC. The integrated ADC and DAC interfaces accept up to 24-bit input/output data and support an asynchronous operation. The input range of the pre-amplifier, that supports line inputs, is adjustable by an external resistor. A ground referenced 2Vrms output with a 3.3V single power supply is achieved by an integrated charge pump, reducing external parts such as AC-coupling capacitors and mute circuits. The ADC block of the AK4688 achieves a dynamic range of 99dB, and the DAC block achieves a dynamic range of 105dB. The AK4688 is suitable for digital recording systems, digital TVs, Blu-ray recorders and Home theater systems.

AK4688主要特性:

􀂆 Asynchronous ADC/DAC Operation

􀂆 Capless Stereo Pre-amplifier for Line Input/Output

􀂆 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 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

PORT1, 2: 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: 36pin QFN

图1.AK4688方框图

图2.AK4688典型应用框图(I2C控制模式, CAD0 引脚= “L”, 主模式)

图3.AK4688典型应用框图(H/W控制模式, MCLK=768fs, 主模式)

评估板AKD4688-A

AKD4688-A is an evaluation board for AK4688, 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 AK4688, 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AKD4688-A功能:

 Compatible with 2 types of digital audio interface

- Optical (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AKD4688-A框图

图5.评估板AKD4688-A电路图(1)

图6.评估板AKD4688-A电路图(2)

图7.评估板AKD4688-A电路图(3)

图8.评估板AKD4688-A电路图(4)

图9.评估板AKD4688-A电路图(5)

图10.评估板AKD4688-A电路图(6)

图11.评估板AKD4688-A PCB元件布局图(顶层)

图12.评估板AKD4688-A PCB元件布局图(底层)
详情请见:
http://www.asahi-kasei.co.jp/akm/en/product/ak4688/akd4688-a-01e.pdf
和
http://www.asahi-kasei.co.jp/akm/en/product/ak4688/akd4688-a-01e.pdf