AKMAK7757集成音频DSP的数字音频解决方案

AKM公司的AK7757是一款内置4通道DAC、一个可选输入立体声ADC通道、一个单声道ADC和一个数字音频接口的数字音频信号处理器。该音频数字信号处理器具有在48kHz的采样速率下达到1536阶的并行算法操作性能。本文详细介绍了AK7757的主要特性、内部框图、内部DSP框图以及采用AK7757芯片设计的评估开发板，通过评估板详细介绍了AK7757芯片各种模式下的应用设置及测试，评估板主要有评估板框图、电路原理图。

The AK7757 is a digital signal processor with an integrated 4ch DAC, a stereo ADC with input selector, a mono ADC and an integrated digital audio interface. The audio DSP has 1536 step/fs (at 48kHz sampling) parallel arithmetic operation performance. As the AK7757 is a RAM based DSP, it is programmable for user requirements to realize the audio effects process or the proprietary high-performance HF. It is housed in a 48pin LQFP which is a small package to save the PCB space.

AK7757主要特性

DSP

- Word length: 24bits (Data RAM: F24 floating point)

- Processing Speed: 13.6 ns (9216step/fs; fs = 8kHz)

- Multiplication: 20 x 20 → 36-bit Double precision arithmetic available

- Divider 20 / 20 → 20-bit

- ALU: 40-bit arithmetic operation (overflow margin 4bits) 24-bit floating point arithmetic and logic operation

- Program RAM: 4096 x 36bits

- Coefficient RAM: 4096 x 20bits

- Data RAM: 2048 x 24bits (F24 floating point)

- Delay RAM: 4096 x 20bits, 4096 x 20bits

- Master Clock: 73.7MHz

- JX pins (interrupt)

2ch ADC1

- Sampling Frequency: 8kHz~48kHz

- 3in / 1out Input Selector (Diffrentialx1 single endx1 single end with MicAmpx1)

- ADC S/N: 96dBA, S/ (N+D): 88dB

1ch ADC2

- Sampling Frequency: 8kHz~48kHz

- ADC S/N: 89dBA, S/(N+D): 82dB

4ch DAC

- Sampling Frequency: 8kHz~48kHz

- DAC S/N: 107dBA, S/ (N+D): 92dB

Microphone Interface

- Differential or single-end input

- Programmable Gain (+33dB ~ +15dB and 0dB, 3dB step)

- Low Noise Microphone Bias

Automatic Power Down (CODEC, DSP)

μP I/F: SPI, I2C

Power supply

Analog (AVDD): 3.0V ~ 3.6V (typ.3.3V)

Digital1 (DVDD): 3.0V ~ 3.6V (typ.3.3V)

Digital2 (DVDD18): 1.7V ~ 1.9V (typ.1.8V)

Operating temperature range: -40℃ ~ 85℃

Package: 48pin LQFP

图1.内部框图

图2.内部DSP框图

采用AK7757评估板参考设计

The AKD7757-A is an evaluation board for AK7757, which is a highly integrated digital signal processor with an integrated 4ch DAC, a stereo ADC with input selector, a mono ADC and an integrated digital audio interface. This board is composed of a main board and a sub board. The AKD7757-A can be set-up by a PC via USB port. RCA connector is used for both input and output of the analog signal. Digital audio interfaces are also integrated, enabling to Interface with a digital audio system via optical connectors or SMUX-PORTs.

AK7757评估板参考设计的主要特性

Read/Write access to PRAM, CRAM, OFREG and registers of the AK7757

Compatible with 2 types of digital audio interface

- Optical input (x1) / Optical output (x1)

- 10pin header for interface with external data source (x2)

ADC1 6ch input (differential input 3ch, single-end input 3ch), ADC2 1ch input, DAC 4ch output

USB port for board control

图3.参考设计框图

图4.参考设计原理图(1)

图5.参考设计原理图(2)

图6.参考设计原理图(3)

图7.参考设计原理图(4)

图8.参考设计原理图(5)

图9.参考设计原理图(5)

图10.参考设计原理图(6)

图11.参考设计原理图(7)

图12.参考设计原理图(8)

图13.参考设计原理图(9)