The AT73C213 is a fully integrated, low-cost, combined stereo audio DAC and audio power amplifier circuit targeted for Li-Ion or Ni-Mh battery powered devices such as mobile phones, smartphones, PDA, DECT phones, digital still cameras, music players or any other type of handheld device where an audio interface is needed. The stereo DAC section is a complete high performance, stereo audio digital-to-analog converter delivering a 93 dB dynamic range. It comprises a multibit sigma-delta modulator with dither, continuous time analog filters and analog output drive circuitry. This architecture provides a high insensitivity to clock jitter. The digital interpolation filter increases the sample rate by a factor of 8 using 3 linear phase half-band filters cascaded, followed by a first order SINC interpolator with a factor of 8. This filter eliminates the images of baseband audio, retaining only the image at 64x the input sample rate, which is eliminated by the analog post filter. Optionally, a dither signal can be added that reduces possible noise tones at the output. However, the use of a multibit sigma-delta modulator already provides extremely low noise tone energy. Master clock is from 256 or 384 times the input data rate, allowing choice of input data rate up to 50 kHz, including standard audio rates of 48, 44.1, 32, 16 and 8 kHz. The DAC section is followed by a volume and mute control and can be simultaneously played back directly through a stereo 32 Ohm headset pair of drivers. |