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AKM公司的AK4957是集成了麥克風,揚聲器,視頻放大器和LDO的24位立體聲CODEC,具有錄音功能,播放功能和視頻功能,主時鐘有PLL和外接時鐘兩種模式,MIC放大器具有+21dB/+18dB/+16dB/+14dB/+8dB/0dB增益,數字自動音量控制(ALC),模擬電源(AVDD)2.8V-3.6V,數字電源(DVDD)1.6V-2.0V,適合于具有錄音/播放功能的手提設備.本文介紹了AK4957主要特性,框圖, 立體聲和單聲道數字MIC連接圖,以及評估板AKD4957-B功能,框圖,電路圖和PCB布局圖. The AK4957 is a 24bit stereo CODEC with a microphone, speaker, video amplifiers and LDO. The input circuits include a microphone amplifier and the output circuits include a speaker amplifier. It is suitable for portable application with recording/playback function. A one channel composite In/Out video amplifier is also integrated. The AK4957 is available in a small 32pin QFN (4mm x 4mm, 0.4mm pitch), saving mounting area on the board. AK4957主要特性: 1. Recording Functions • Stereo Single-ended input with two Selectors • MIC Amplifier (+21dB/+18dB/+16dB/+14dB/+8dB/0dB) • Digital ALC (Automatic Level Control) (Setting Range: +36dB ∼ −54dB, 0.375dB Step) • ADC Performance: S/(N+D): 83dB, DR, S/N: 88dB (MIC-Amp=+18dB)S/(N+D): 85dB, DR, S/N: 96dB (MIC-Amp=0dB) • Microphone Sensitivity Compensation • 5 Band Notch Filter • Stereo Separation Emphasis Circuit • Digital MIC Interface 2. Playback Functions • Soft Mute • Digital ALC (Automatic Level Control)(Setting Range: +36dB ~ −54dB, 0.375dB Step) • Digital Volume Control (+12dB ~ −115dB, 0.5dB Step & Mute) • Stereo Separation Emphasis Circuit • Stereo Line Output - Output Voltage: 1Vrms (AVDD= 3.3V) - S/(N+D): 85dB - S/N: 92dB • Mono Mixing Output • Mono Speaker-Amplifier - S/(N+D): 65dB@150mW, 60dB@250mW, - S/N: 90dB - BTL Output - Output Power: 400mW@8Ω (AVDD=3.3V) • Analog Mixing: BEEP Input 3. Master Clock: (1) PLL Mode • Frequencies: 11.2896MHz, 12MHz, 13.5MHz, 24MHz, 27MHz (MCKI pin)32fs or 64fs (BICK pin)(2) External Clock Mode • Frequencies: 256fs, 512fs or 1024fs (MCKI pin)Output Master Clock Frequency: 32fs/64fs/128fs/256fs 4. Sampling Frequencies • PLL Slave Mode (MCKI pin):8kHz, 11.025kHz, 12kHz, 16kHz, 22.05kHz, 24kHz, 32kHz, 44.1kHz, 48kHz • PLL Master Mode:8kHz, 11.025kHz, 12kHz, 16kHz, 22.05kHz, 24kHz, 32kHz, 44.1kHz, 48kHz • EXT Master/Slave Mode: 7.35kHz ~ 48kHz (256fs), 7.35kHz ∼ 48kHz (512fs), 7.35kHz ∼ 13kHz (1024fs) 5. μP I/F: 3-wire Serial, I2C Bus (Ver 1.0, 400kHz Fast-Mode) 6. Master/Slave Mode 7. Audio Interface Format: MSB First, 2’s complement • ADC: 24bit MSB justified, 16/24bit I2S • DAC: 24bit MSB justified, 16bit LSB justified, 24bit LSB justified, 24bit I2S 8. Video Functions • One Composite Signal Input • Video Amplifier for Composite Signal Output Gain: +6 / +9 / +12 / +16.5dB • Low Pass Filter 9. Ta = −30 ∼ 85℃ 10. Power Supply: • Analog Power Supply (AVDD): 2.8 ~ 3.6V • Digital Power Supply (DVDD): 1.6 ~ 2.0V • Digital I/O Power Supply (TVDD): 1.6 or DVDD – 0.2 ~ 3.6V Package: 32pin QFN (4.0 x 4.0 mm, 0.4mm pitch) 
圖1. AK4957框圖
圖2. AK4957立體聲數字MIC連接案例圖
圖3. AK4957單聲道數字MIC連接案例圖
圖4. AK4957系統連接圖 評估板AKD4957-B The AKD4957-B is an evaluation board for AK4957, 24bit stereo CODEC with a microphone/ speaker/ video amplifiers, and LDO. The AKD4957-B can control various settings using the USB port, can be easily evaluated. Also features a USB Audio device, the audio signal can be input through the USB port from PC. The AKD4957-B has the Digital Audio I/F and can achieve the interface with digital audio systems via optical connector. AKD4957-B is equipped with Line output, Mic input and Headphone output terminals. Has also carried Flash ROM, a stand-alone operation is possible. 評估板AKD4957-B功能: • DIR/DIT with optical input/output • With USB-Audio device • Equipped with three digital audio interface - Optical Input / Output - USB Input - 10-pin header for external interfaces • USB port for board control
圖5.評估板AKD4957-B框圖
圖6.評估板AKD4957-B電路圖(1)
圖7.評估板AKD4957-B電路圖(2)
圖8.評估板AKD4957-B電路圖(3)
圖9.評估板AKD4957-B電路圖(4)
圖10.評估板AKD4957-B電路圖(5)
圖11.評估板AKD4957-B電路圖(6)
圖12.評估板AKD4957-B布局圖(1)
圖13.評估板AKD4957-B布局圖(2)
圖14.評估板AKD4957-B布局圖(3)
圖15.評估板AKD4957-B布局圖(4)
圖16.評估板AKD4957-B布局圖(5)
圖17.評估板AKD4957-B布局圖(6)
圖18.評估板AKD4957-B布局圖(7) 詳情請見: 
ak4957_f00e.pdf
(961.89 KB)
akd4957-b0-00e.pdf
(2.41 MB)
來源：網絡 |
