AKM AK4955带录音播放功能24位立体声CODEC解决方案
AKM公司的 AK4955是集成了麦克风放大器，扬声器放大器，视频放大器，LCD和DSP的 24位立体声CODEC，具有录音功能，播放功能，电源管理以及主从模式，主要用在带录音/播放功能的手提设备。本文介绍了AK4955主要特性，方框图以及AKD4955-A评估板方框图，电路图和PCB布局图。
The AK4955 is a 24bit stereo CODEC with a microphone amplifier, speaker amplifier, video amplifier, LDO, and DSP. 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 internal charge pump generates a negative power eliminating the need for AC-coupling capacitors. The AK4955 is available in a small 36pin CSP (3.0mm 3.1mm, 0.5mm pitch), saving mounting area on the board.
Applications: DSCs, DVCs
AK4955主要特性：
Recording Functions
· Stereo Single-ended input with two Selectors
· MIC Amplifier (+24dB/+21dB/+18dB/+16dB/+14dB/+11dB/+8dB/+5dB/0dB)
· Digital ALC (Automatic Level Control) (Setting Range: +36dB ~ -54dB, 0.375dB Step)
· ADC Performance: S/(N+D): 81dB, DR, S/N: 88dB (MIC-Amp=+18dB)S/(N+D): 82dB, DR, S/N: 96dB (MIC-Amp=0dB)
· 5 Band Notch Filter
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