AKM 公司的AK4621是高性能 24位立體聲音頻CODEC,支持192kHz錄音和播放,器件具有兩路24位ADC和24位DAC,全差分輸入和可選擇的數字濾波器, ADC的S/(N+D)為102dB,S/N為 115dB,DAC的S/(N+D)為100dB,S/N為115dB,非常適合用在Pro Audio聲卡,數字音頻工作站,DVD-R,硬盤,CD-R錄音/播放系統和音樂設備錄音.本文介紹了AK4621主要特性,方框圖, 輸入緩沖電路圖, 輸出外接LPF電路圖以及AK4621評估板AKD4621-B方框圖和電路圖.
The AK4621 is a high performance 24-bit CODEC that supports up to 192kHz recording and playback. The on-board analog-to-digital converter has a high dynamic range due to AKM’s Enhanced Dual-Bit architecture. The DAC utilizes AKM’s Advanced Multi-Bit architecture that achieves low out-of-band noise and high jitter tolerance through the use of Switched Capacitor Filter (SCF) technology. The AK4621 is ideal for Pro Audio sound cards, Digital Audio Workstations, DVD-R, hard disk, CD-R recording/playback systems, and musical instrument recording.

AK4621主要特性:
□ 24-bit 2-channel ADC
- Full Differential Inputs
- Selectable Digital Filter
1. ADC Digital Filter 1 (GD=39/fs)
Passband: 0 ~ 21.8kHz (@fs=48kHz)
Stopband Attenuation: 100dB
2. ADC Digital Filter 2 (GD=14/fs)
Passband: 0 ~ 21.7kHz (@fs=48kHz)
Stopband Attenuation: 80dB
- S/(N+D): 102dB
- S/N: 115dB
- Digital High-pass Filter for Offset Cancellation
- Overflow Flag
- Audio Interface Format: MSB justified or I2S
□ 24-bit 2-channel DAC
- Selectable Digital Filter
1. DAC Digital Filter 1 (GD=27/fs)
Passband: 0 ~ 21.8kHz (@fs=48kHz)
Stopband Attenuation: 70dB
2. DAC Digital Filter 2 (GD=27/fs)
Passband: 0 ~ 8.9kHz (@fs=48kHz)
Stopband Attenuation: 73dB
3. DAC Digital Filter 3 (GD=7/fs)
Passband: 0 ~ 21.8kHz (@fs=48kHz)
Stopband Attenuation: 70dB
- Switched-cap Low Pass Filter
- Differential Outputs
- S/(N+D): 100dB
- S/N: 115dB
- De-emphasis for 32kHz, 44.1kHz, 48kHz Sampling
- Output Digital Attenuator: 0dB ~–72dB, Linear 256 + 16steps
- Zero Detection Function
- Audio Interface Format: MSB justified, LSB justified, I2S
□ High Jitter Tolerance
□ Sampling Rate: 32kHz ~ 216kHz
□ μP Interface: 3-wire Serial Interface
□ Master Clock: 128fs/192fs/256fs/384fs/512fs/768fs/1024fs
□ Power Supply
Analog: 4.75 ~ 5.25V (typ. 5.0V)
Digital: 3.0 ~ 3.6V (typ. 3.3V)
Digital I/O: DVDD ~ 5.25V (typ. 5.0V)
□ Package: 30pin VSOP
□ Ta: -10~70℃

圖1. AK4621方框圖

Notes:
- VSS1 and VSS2 must be connected to the same analog ground plane.
- When AOUT+/- drives some capacitive load, some resistance must be added in series between AOUT+/- and
capacitive load.
All digital input pins must not be left floating.
Typical Connection Diagram

圖2. AK4621輸入緩沖電路圖(1)

圖3. AK4621外接LPF電路圖(1): (fc = 136kHz, Q=0.694)

圖4. AK4621外接LPF電路圖(2)

AK4621評估板AKD4621-B

The AKD4621-B is an evaluation board for the AK4621, the 24Bit A/D & D/A converter. The AKD4621-B can evaluate A/D converter and D/A converter separately in addition to loopback mode (A/D→D/A). The AKD4621-B also has the digital audio interface and can achieve the interface with digital audio systems via opt-connector.

圖5.評估板AKD4621-B方框圖

圖6.評估板AKD4621-B電路圖(1)

圖7.評估板AKD4621-B電路圖(2)