AKM AK4390高性能32位音频DAC方案

AKM公司的AK4390是高性能超低等待的32位Delta-Sigma 立体声音频DAC,取样频率高达216kHz,并集成了32位数字滤波器(衰减-100dB,通带起伏0.005dB),具有很宽的动态范围和极好的THD+N(-103dB),信噪比达120dB,电源电压5V ± 5%. AK4390输入信号为192kHz的PCM数据,非常适合DVD音频,高端声卡,数字音频Firewire和USB接口箱以及数字混合器.本文介绍了AK4390的主要特性, 方框图, 系统连接图以及用于PCM数据的两种低通滤波器(LPF)的电路图和频率特性.

AK4390 UltraLow Latency 32-Bit ΔΣDAC

The AK4390 is a high performance stereo DAC capable of sampling up to 216kHz including a 32-bit digital filter. The modulator uses AKMs multi-bit architecture, delivering wide dynamic range while preserving linearity for improved THD+N performance. The AK4390 has fully differential switched-cap filter outputs, removing the need for AC coupling capacitors and increasing performance for systems with excessive clock jitter. The AK4390 accepts 192kHz PCM data, ideal for a wide range of applications including DVD-Audio, high end sound cards, digital audio Firewire and USB interface boxes, and digital mixers.
AK4390主要特性:
128-times Oversampling
Sampling Rate: 30kHz ∼ 216kHz
32Bit 8x Digital Filter
Ripple:  0.005dB, Attenuation: 100dB
Low latency option: 7/fs
High Tolerance to Clock Jitter
Low Distortion Differential Output
Digital De-emphasis for 32, 44.1, 48kHz sampling
Soft Mute
Digital Attenuator (255 levels and 0.5dB step)
THD+N: 103dB
DR, S/N: 120dB
Audio Format: 24/32bit MSB justified, 16/20/24/32bit LSB justified, I2S
Master Clock:
30kHz ~ 32kHz: 1152fs
30kHz ~ 54kHz: 512fs or 768fs
30kHz ~ 108kHz: 256fs or 384fs
108kHz ~ 216kHz: 128fs or 192fs
Power Supply: 5V ± 5%
TTL Level Digital I/F
Package: 30pin VSOP



图1.AK4390方框图



图2.AK4390系统连接图



图3.外接PCM用LPF电路图(1)(fc = 125kHz, Q=0.692)



外接PCM用LPF电路(1)滤波器频率响应特性



图4. 外接PCM用LPF电路图(2)



外接PCM用LPF电路(2)滤波器频率响应特性