原标题：AKM AK4558 32位数字音频系统CODEC解决方案

　　akm公司的AK4558是低电压32位216kHz数字音频系统编译码器(CODEC),支持各种信号,具有较好的带外噪音和低功耗,主要用在高档音响设备和电子乐器以及音频接口.本文介绍了AK4558主要特性和框图,系统连接框图以及评估板AKD4558-A功能,框图,电路图和PCB元件布局图.

　　The AK4558 is a low voltage 32bit 216kHz CODEC for high performance battery powered digital audiosubsystems. An internal circuit includes newly developed 32-bit Digital Filter achieving short group delayand high quality sound. In addition, “OSR-Doubler” technology is newly adopted, making the AK4558capable of supporting wide range signals and achieving low out-of-band noise while realizing low powerconsumption. The AK4558 is ideal for a wide range of applications that demands high sound qualityincluding Electronic musical instruments and Audio Interfaces. The analog inputs and outputs aresingle-ended to minimize pin count and external filtering requirements. The AK4558 is housed in a verysmall 28-pin QFN. It is ideal for space-sensitive applications.

　　AK4558主要特性:

　　 Single-ended ADC

　　- Dynamic Range, S/N: 108dB@AVDD=3.3V

　　- S/(N+D): 92dB@AVDD=3.3V

　　- Selectable HPF for DC-offset cancel (fc = 1Hz @ fs=48kHz)

　　- 4-types Digital Filter for High Sound Quality

　　 Single-ended DAC

　　- Dynamic Range, S/N: 108dB@AVDD=3.3V

　　- S/(N+D): 100dB@AVDD=3.3V

　　- Digital de-emphasis for 32kHz, 44.1kHz and 48kHz sampling

　　- 5-types Digital Filter for High Sound Quality

　　- Channel Independent Digital Attenuator (256 levels, 0.5dB steps)

　　 Audio I/F format: MSB First, 2’s Complement

　　- ADC: 24/32bit MSB justified , 24/32bit I2S compatible or TDM

　　- DAC: 24/32bit MSB justified, 16/20/24/32bit LSB justified,

　　24/32bit I2S compatible or TDM

　　 Input/Output Voltage: ADC = 2.64Vpp @ AVDD=3.3V

　　DAC = 2.51Vpp @ AVDD=3.3V

　　 Master/Slave mode

　　 P I/F: I2C Bus

　　 Sampling Rate:

　　(1) PLL Mode

　　• PLL Slave Mode (LRCK pin): fs = 8kHz 216kHz

　　• PLL Slave Mode (BICK pin): fs = 8kHz 216kHz

　　• PLL Master Mode: 8kHz, 11.025kHz, 12kHz, 16kHz, 22.05kHz, 24kHz, 32kHz,44.1kHz,

　　48kHz,54kHz,88.2kHz,96kHz,128kHz,176.4kHz,192kHz

　　(2) External Clock Mode

　　• Normal Speed: 8kHz to 54kHz (256fs or 512fs)

　　8kHz to 48kHz (384fs or 768fs)

　　• Double Speed: 54kHz to 108kHz (256fs)

　　48kHz to 96kHz (384fs)

　　• Quad Speed: 108kHz to 216kHz (128fs)

　　96kHz to 192kHz (192fs)

　　 Master Clock:

　　(1) PLL Mode

　　• MCKI pin: 27MHz, 26MHz, 24MHz, 19.2MHz, 13.5MHz, 13MHz, 12.288MHz, 12MHz,

　　11.2896MHz

　　• LRCK pin: 1fs

　　• BICK pin: 32fs, 64fs, 128fs(TDM), 256fs(TDM)

　　(2) External Clock Mode (MCKI pin)

　　• Slave mode: 256fs, 384fs, 512fs or 768fs (Normal Speed)

　　256fs or 384fs (Double Speed)

　　128fs or 192fs (Quad Speed)

　　• Master mode: 256fs or 512fs (Normal Speed)

　　256fs (Double Speed)

　　128fs (Quad Speed)

　　 Power Supply:

　　• AVDD = 2.4 to 3.6V (typ. 3.3V)

　　• TVDD = 1.7 to 3.6V (typ. 1.8V)

　　 Power Supply Current: 18mA(fs=48kHz)

　　 Ta = -40 to 105℃

　　 Package: 28-pin QFN (0.5mm pitch)

　　图1. AK4558框图

　　图2. AK4558系统连接框图(PS pin= “H”, LDOE pin= “H”)

　　图3. AK4558系统连接框图(PS pin= “L”, LDOE pin= “L”)

　　AK4558评估板AKD4558-A

　　The AKD4558-A is an evaluation board for AK4558, which is 24/32bit, CODEC including 2ch ADC and2ch DAC. The control settings of this board may be controlled via USB port, allowing for easy A/D andD/A evaluation. BNC connectors are used for the input and output of the analog signals. This board alsohas a digital interface which can be connected to the digital audio system via optical connector.

　　评估板AKD4558-A功能:

　　Clock generator circuit (AK4118A used)

　　Compatible with 2types of digital audio interface

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

　　- Pin header for external data source

　　BNC connector for an external clock input

　　ADC 2ch input, DAC 2ch output

　　USB port and 10pin header for board control

　　图4.评估板AKD4558-A框图

　　图5.评估板AKD4558-A板框图

　　主要元件描述:

　　(1) U1 ( AK4558 )

　　24/32bit,2ch A/D Converter, 2ch D/A Converter.

　　(2) J200, J201, J202, J203 ( Analog data )

　　J200, J201 BNC connector : Analog Input for LIN, RIN.

　　J202, J203 BNC connector : Analog Output for LOUT, ROUT.

　　(3) PORT1, PORT2 ( Optical Connector )

　　PORT1 : Input optical signal to AK4118A.

　　PORT2 : Output optical signal from AK4118A.

　　(4) J700, J701, J702, J703, J704, J705, J706 ( Power supply )

　　J700 (+12V) : +12V Power Supply

　　J701 (AVDD1), J704 (D3.3V) : 3.3V Power Supply

　　J702 (TVDD) : 1.8V/3.3V Power Supply

　　J703 (VDD18) : 1.8V Power Supply

　　J705 (AVSS), J706 (DGND) : GND

　　(5) U2 ( AK4118A )

　　AK4118A has DIR, DIT and X’tal oscillator.

　　Transports input data to AK4558 when working in master mode, and output data from AK4558 when working inslave mode.

　　(6) U60 ( PIC18F4550 )

　　USB control chip. Sets up AK4558 registers from PC via USB port (PORT600).

　　(7) J400 (BNC Connector)

　　Input external clock source.

　　(8) SW300 ( Dip-switch )

　　DIP type switch. Sets clock and audio format of AK4118A. DIF[2:0] used to set audio interface format and

　　OCKS[1:0] used to master clock frequency.

　　(9) SW500, SW501 ( Dip-switch )

　　DIP type switch. Sets clock and audio format and filter of AK4558.

　　(10)SW400 ( Toggle switch )

　　Toggle type-switch PDN for AK4558.

　　“H” : PDN = High

　　“L” : PDN = Low

　　(11)SW401 ( Toggle switch )

　　Toggle type-switch PDN for AK4118A.

　　“H” : PDN = High

　　“L” : PDN = Low

　　(12)T1, T2, T3 ( regulator )

　　Regulator for AK4558, AK4118A, Logic Circuit.

　　T1 : Regulated AVDD1, TVDD (3.3V) from +12V.

　　T2 : Regulated TVDD, VDD18 (1.8V) from +12V.

　　T3 : Regulated D3.3V (3.3V) from +12V.