2–2

The external connections to this function allow for dc blocking capacitors to be included on the board, thus

eliminating dc offsets present on the source. A typical implementation would connect the output of the

analog multiplexer (EXT OUTL, EXT OUTR) to the input of this function.

The analog output multiplexer allows selection of the several analog sources input to the device. One of

these audio sources is the output of the DAC. The others are the output of the TV monaural decoder, either

of the two stereo analog inputs, or auxiliary mono input. Mono sources are sent to both right and left

channels. The output of this multiplexer provides stereo outputs on two terminals, each with 10 k

Ω drive

capability. Both terminals are short-circuit protected.

The master clock for the device is derived from an external clock source. Control register 01h selects MCLK

1, or MCLK 2 to be the master clock source. This clock is then used to clock the DAC, the digital audio serial

ports, and the monural decoder, switched-capacitor filter. The serial ports can be selected independent form

the MCLK 1 and MCLK 2 selection. However, the clock rate of the selected clock source partly determines

the sampling rate of the device. Refer to Table 2–1, and the description of control register 00h.

The TLC320AD80 also provides an uncommitted 2:1 mono analog multiplexer. The inputs and outputs of

this device are connected to external terminals.

The voltage reference is used internally for the analog sections of the device. The external terminals must

be connected to decoupling capacitors. In addition, the reference terminals can be externally buffered for

use with external support circuitry.

2.1

Audio Input Ports

The audio inputs consist of: two digital serial interfaces, two stereo analog inputs, one analog TV baseband

audio input, and one mono analog input. The TV baseband audio input is a differential input. All other analog

inputs are single-ended.

The audio input is selected by programming control register 01h. Only one of these inputs is active at any

one time. The others are disabled. That is, if an analog input is selected, then the digital serial interfaces

are inactive.

The two digital serial interfaces provide the input to the DAC through a digital multiplexer. These interfaces

16-bit or 18-bit precision, with MSB first. There is also a DSP-compatible mode available.

All single-ended analog inputs can be passed through to the main output of the device by means of an analog

multiplexer. The differential TV baseband audio input (TV BASEBAND P, TV BASEBAND M) feeds a

monaural decoder which then feeds the same multiplexer.

2.1.1

Serial PCM Data Ports

The device includes two serial ports used to transfer digital audio data from an external digital source to the

DAC: The AUX serial port (ASDATA, ABCLK, and ALRCLK) can be configured to operate in either master

or slave mode. The main serial PCM port (SDATA, BCLK, and LRCLK) always operates in the slave mode.

Note, that the only exclusion is that the AUX port does not support the DSP mode when configured as

master.

Configuration of these serial ports is accomplished by means of the SPI-compatible control serial interface

format (16-bit or 18-bit) are selected by programming control register 00h. The multiplexer selection is

programmed with control register 01h which will also enable or disable these serial data ports.