TLC320AC02C_15 Datasheet, PDF (18/86 Pages) Texas Instruments – Single-Supply Analog Interface Circuit

2.3 Master-Slave Terminal Function
Table 2–1 describes the function of the master/slave (M/S) input. The only difference between master and
slave operations in the TLC320AC02 is that SCLK and FS are outputs when M/S is high and inputs when
M/S is low.
Table 2–1. Master-Slave Selection
MODE
M/S†
FS
SCLK
Master and Stand Alone
H
Output
Output
Slave and Codec Emulation
L
Input
Input
† _{When the stand-alone mode is desired or when the device is}
permanently in the master mode, M/S must be high.
2.4 ADC Signal Channel
To produce excellent common-mode rejection of unwanted signals, the analog signal is processed
differentially until it is converted to digital data. The signal is amplified by the input amplifier at one of three
software-selectable gains (typically 0 dB, 6 dB, or 12 dB). A squelch mode can also be programmed for the
input amplifier.
The amplifier output is filtered and applied to the ADC input. The ADC converts the signal into discrete digital
words in 2s-complement format corresponding to the analog-signal value at the sampling time. These 16-bit
digital words, representing sampled values of the analog input signal, are clocked out of the serial port
(DOUT), one word for each primary communication interval. During secondary communications, the data
previously programmed into the registers can be read out with the appropriate register address and with the
read bit set to 1. When a register read is not requested, all 16 bits are 0.
2.5 DAC Signal Channel
DIN receives the 16-bit serial data word (2s complement) from the host during the primary communications
interval and latches the data on the seventeenth rising edge of SCLK. The data are converted to an analog
voltage by the DAC with a sample and hold and then through a (sin x)/x correction circuit and a smoothing
filter. An output buffer with three software-programmable gains (0 dB, – 6 dB, and – 12 dB), as shown in
register 4, drives the differential outputs OUT + and OUT –. A squelch mode can also be programmed for
the output buffer. During secondary communications, the configuration program data are read into the
device control registers.
2.6 Serial Interface
The digital serial interface consists of the shift clock, the frame-synchronization signal, the ADC-channel
data output, and the DAC-channel data input. During the primary 16-bit frame-synchronization interval, the
SCLK transfers the ADC channel results from DOUT and transfers 16-bit DAC data into DIN.
During the secondary frame-synchronization interval, the SCLK transfers the register read data from DOUT
when the read bit is set to a 1. In addition, the SCLK transfers control and device parameter information into
DIN. The functional sequence is shown in Figure 2–1.
2–4