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AKM公司的AK4678是24位立體聲CODEC,具有內置麥克風放大器,接收放大器,單聲道D類揚聲器放大器,無電容的G類耳機放大器和線路放大器.除了音頻I/F外還有兩個PCM I/F.播放功能包括5波段參數EQ和動態范圍控制,因此能自動調整合適音量而不失真.本文介紹了AK4678主要特性,模擬和數字方框圖,以及評估板 AKD4678-B功能,方框圖,電路圖和PCB元件布局圖. The AK4678 is a 24bit stereo CODEC with a built-in Microphone-Amplifier, Receiver-Amplifier, Mono Class-D Speaker-Amplifier, Cap-less Class-G Headphone-Amplifier and Line-Amplifier. The AK4678 features dual PCM I/F in addition to audio I/F that allows easy interfacing in mobile phone designs with Bluetooth I/F. The playback features also include 5-band Parametric EQ and Dynamic Range Control, therefore the AK4678 can automatically adjust a comfortable volume without distortion and provides great flexibility. The AK4678 is available in a 49pin CSP, utilizing less board space than competitive offerings. AK4678主要特性: 1. Recording Function (Stereo CODEC) • 4 Stereo Input Selectors • 4 Stereo Inputs (Single-ended) or 3 Mono Input (Full-differential) • MIC Amplifier: +24dB ~ −6dB, 3dB step • 2 Output MIC Power Supplies • Digital ALC (Automatic Level Control): +36dB ~ −54dB, 0.375dB Step, Mute • ADC CHARACTERISTICS: S/(N+D): 80dB, DR, S/N: 87dB (MIC-Amp=+18dB)S/(N+D): 80dB, DR, S/N: 92dB (MIC-Amp=0dB) • Stereo Digital MIC Interface • Wind-noise Reduction Filter • Stereo Separation Emphasis • 3-band Programmable Notch Filter • Audio Interface Format: 24/16bit MSB justified, 24/16bit I2S, 16bit DSP Mode 2. Playback Function (Stereo CODEC) • Digital Volume (+6dB ~ −57.0dB, 0.5dB Step, Mute) • Digital ALC (Automatic Level Control): +36dB ~ −54dB, 0.375dB Step, Mute • Stereo Separation Emphasis • Dynamic Range Control • 5-band Parametric Equalizer • Stereo Line Output (Selectable Full-differential / Single-ended) • Mono Receiver-Amp - BTL Output - Output Power: 60mW @ 32Ω - Analog Volume: +12 ~ −30dB & Mute, 3dB Step • Cap-less Stereo Class-G Headphone-Amp - Output Power: 25mW @ 32Ω, 45mW @ 16Ω - Analog Volume: +6 ~ −62dB & Mute, 2dB Step - Zero crossing Detection - pop Noise Free at Power-ON/OFF • Mono Class-D Speaker-Amp - BTL Output - Short Protection Circuit - Output Power: 1.1W @ 8Ω, SVDD=4.2V, THD+N = 10% 0.89W @ 8Ω, SVDD=4.2V, THD+N = 1% - Analog Volume: +12 ~ −30dB & Mute, 3dB Step - Pop Noise Free at Power-ON/OFF • Audio Interface Format: - 24/16bit MSB justified, 16bit LSB justified, 16/24bit I2S, 16bit DSP Mode 3. Dual PCM I/F for Baseband & Bluetooth Interface • Four sample Rate Converters (Up sample: up to x6: Down sample: down to x1/6) • Sample Rate: - PORTA (Mono): 8 ~ 16kHz - PORTB (Stereo): 8 ~ 48kHz • Digital Volume • Slave Mode • Audio Interface Format: - 16bit Linear, 8bit A-law, 8bit μ-law - Short/Long Frame, I2S, MSB justified 4. Power Management 5. Master Clock(Audio I/F): (1) pLL Mode •Frequencies: 11.2896MHz, 12MHz, 12.288MHz, 13MHz, 13.5MHz, 19.2MHz, 24MHz, 25MHz, 26MHz, 27MHz (MCKI pin) 32fs or 64fs (BICK pin) (2) External Clock Mode •Frequencies: 256fs, 512fs or 1024fs (MCKI pin) 6. Output Master Clock Frequencies(Audio I/F): 32fs/64fs/128fs/256fs 7. Sampling Frequency (Audio I/F) •pLL Slave Mode (BICK pin): 8kHz ~ 48kHz •pLL Master Mode: 8kHz, 11.025kHz, 12kHz, 16kHz, 22.05kHz, 24kHz, 32kHz, 44.1kHz, 48kHz •EXT Master/Slave Mode: 8kHz ∼48kHz (256fs), 8kHz ~ 24kHz (512fs), 8kHz ~ 12kHz (1024fs) 8. Audio I/F: Master/Slave mode 9. μP I/F: I2C Bus (Ver 1.0, 400kHz Fast Mode) 10. Ta = −30 ~ 85?C 11. power Supply: •SVDD (SPK/RCV/LINE-Amp): 3.0 ~ 5.5V •AVDD (Analog): 1.7 ~ 2.0V •DVDD (Digital Core): 1.7 ~ 2.0V •pVDD (HP-Amp & Charge Pump): 1.7 ~ 2.0V •TVDD (Digital I/F): 1.6 ~ 3.6V 12. Package : 49pin CSP(2.96 x 2.96 mm, 0.4mm pitch) 
圖1.AK4678模擬方框圖
圖2.AK4678數字方框圖
圖3.AK4678典型連接圖(電源部分) AK4678評估板 AKD4678-B(Rev.1) The AKD4678-B is an evaluation board for AK4678, 24bit stereo CODEC with Microphone/Receiver/Headphone/ Speaker/ Line amplifier. The AKD4678-B has the Digital Audio I/F and can achieve the interface with digital audio systems via optical connector. 評估板 AKD4678-B功能: • DIR/DIT with optical input/output • 10pin Header for Digital Audio I/F and PCM I/F (Baseband, Bluetooth) • 10pin Header for I2C control mode
圖4.評估板AKD4678-B方框圖
圖5.評估板AKD4678-B電路圖(1)
圖6.評估板AKD4678-B電路圖(2)
圖7.評估板AKD4678-B電路圖(3)
圖8.評估板AKD4678-B元件布局圖 詳情請見: 
ak4678_f01e.pdf
(2.3 MB)
akd4678-b1-00e.pdf
(1.23 MB)
來源：網絡 |
