The PCM1721 is a complete low cost stereo audio digital-to-analog converter (DAC) with a phase-locked loop (PLL) circuit included. The PLL derives either 256fS or 384fS system clock from an external 27MHz reference frequency. The DAC contains a 3rd-order modulator, a digital interpolation filter, and an analog output amplifier. The PCM1721 can accept 16-, 20-, or 24-bit input data in either normal or I2S formats.