Audio data is transferred between the host processor and the TAS2505 via the digital audio data serial interface, or audio bus. The audio bus on this device is flexible, including left- or right-justified data options, support for I²S or PCM protocols, programmable data-length options, a TDM mode for multichannel operation, flexible master/slave configurability for each bus clock line, and the ability to communicate with multiple devices within a system directly.

The audio bus of the TAS2505 can be configured for left- or right-justified, I²S, DSP, or TDM modes of operation, where communication with standard telephony PCM interfaces is supported within the TDM mode. These modes are all MSB-first, with data width programmable as 16, 20, 24, or 32 bits by configuring page 0, register 27, bits D5–D4. In addition, the word clock and bit clock can be independently configured in either master or slave mode for flexible connectivity to a wide variety of processors. The word clock is used to define the beginning of a frame, and may be programmed as either a pulse or a square-wave signal. The frequency of this clock corresponds to the maximum of the selected DAC sampling frequencies.

The bit clock is used to clock in and clock out the digital audio data across the serial bus. When in master mode, this signal can be programmed to generate variable clock pulses by controlling the bit-clock divider in page 0, register 30 (see ). The number of bit-clock pulses in a frame may need adjustment to accommodate various word lengths as well as to support the case when multiple TAS2505 may share the same audio bus.

The TAS2505 also includes a feature to offset the position of start of data transfer with respect to the word clock. This offset can be controlled in terms of number of bit clocks and can be programmed in page 0, register 28.

The TAS2505 also has the feature of inverting the polarity of the bit clock used for transferring the audio data as compared to the default clock polarity used. This feature can be used independently of the mode of audio interface chosen. This can be configured via page 0, register 29, bit D3.

By default, when the word clocks and bit clocks are generated by the TAS2505, these clocks are active only when the DAC is powered up within the device. This is done to save power. However, it also supports a feature when both the word clocks and bit clocks can be active even when the codec in the device is powered down. This is useful when using the TDM mode with multiple codecs on the same bus, or when word clocks or bit clocks are used in the system as general-purpose clocks.