2−1

2 Functional Description

2.1

Device Requirements and System Overview

The TLV320AD543 device consists of single codec channel, a hybrid circuit with external resistors and

capacitors for setting gain and filter poles, serial port, and miscellaneous other logic functions.

2.2

Codec Functions

The codec portion of the device performs the functions for:

•

One channel of analog-to-digital conversion

•

Digital-to-analog conversion

•

Low-pass filtering

•

Control of analog input and output gains

•

Internal oversampling coupled with internal decimation and interpolation

•

A 16-bit serial port interface to the host processor.

The maximum sample rate is 11.025 kHz.

2.3

Hybrid Functions

The hybrid circuitry has integrated amplifiers whose gains and filter pole frequencies are set by external

resistors and capacitors. This allows maximum flexibility to make adjustments for board variations and

international standards while providing integration of the function. The filter amplifier stages are followed

by a programmable gain amplifier, which feeds an 8

Ω differential speaker driver for the AT41 call progress

monitor speaker. The monitor speaker driver can be programmed for 0 dB gain or muted through control

register 2. The source for the monitor speaker input can be chosen to be either the amplified DAC output

(Data_Out PGA) or the ADC input signal through control register 1 (see Appendix A).

2.4

Miscellaneous Logic and Other Circuitry

The logic functions include the circuitry required to implement serial port and control register programming

through secondary communication on those serial ports. Two control registers can be programmed during

secondary communications from the serial port. These control registers set amplifier gains, select loopback

functions, and read ADC overflow flags. In addition, a flash write enable (FWE) circuit takes an external logic

input and provides current to power the write enable circuit of an external memory device. The flash write

enable circuit is powered from the digital power supply.