Apparatus and method for transmitting voice data on ADSL subscriber card

PURPOSE: A voice data transmitting apparatus of a next-generation ADSL subscriber board and its method are provided to accomplish a stable CVoDSL signaling to enable a CVoDSL(Channelized Voice of xDSL) function, namely, a voice service function of an ADSL subscriber. CONSTITUTION: An exchange matching synchronizer(170) generates a PSTN reference clock and a DMT(Discrete Multi-Tone) data clock and provides them to a modulation/demodulation unit(140). A microprocessor(160) analyzes a signal transmitted to and received from a digital interface controller(130) and the modulation/demodulation unit(140), and controls a bus timing between itself and the digital interface controller(130) by using a user programmable memory. The digital interface controller(130) matches voice data modulated by the modulation/demodulation unit(140) to an ADSL frame and provides it to a digital signal processor(100). The digital signal processor(100) extracts voice data from the ADSL data and provides it to a time switching unit(120). A three-phase buffer(180) is connected to a PCM bus of each channel to prevent mutual interference and collision among voice data.