AM79C02AJC datasheet(46/48 Pages) AMD

46 / 48 page

Am79C02/03/031(A) Data Sheet

APPLICATIONS

The DSLAC device performs a programmable codec/

filter function for two telephone lines. It interfaces to

the telephone lines through either a transformer or an

electronic SLIC, such as the AMD SLIC devices. The

DSLAC device provides latched digital I/O to control

and monitor two SLICs and has a selectable clock out-

put to operate the switched mode regulator in an

Am795XX family SLIC. When several line conditions

must be matched, a single SLIC design can be used.

The line characteristics (such as apparent impedance,

attenuation, and hybrid balance) can be modified by

programming each DSLAC channel’s coefficients to

meet desired performance. The DSLAC device can

drive a transformer SLIC device without a buffer.

Connection to a PCM highway backplane is implement-

ed by means of a simple buffer chip. Several DSLAC

devices can be bused together into one bus interface

buffer. An intelligent bus interface chip is not required

because each DSLAC device provides its own buffer

control. The DSLAC device can be controlled through

the Microprocessor Interface, either by a microproces-

sor on the linecard or by a central processor.

Controlling the SLIC

SLIC Chopper Clock

The CHCLK output pin on the DSLAC device drives the

CHCLK inputs for AMD switcher type SLICs. The

CHCLK output is a 256 kHz or 293 kHz, TTL compatible

signal that can drive two SLICs. It is active only when

one or both channels are activated; otherwise, it is held

high internally.

SLIC Input/Output

The Am79C02(A) and Am79C031(A) DSLAC device

have five TTL compatible I/O pins (C1 to C5) for each

channel. The Am79C03(A) DSLAC device has only C1

through C4 available. The outputs are programmed us-

ing Command 15 and the status is read back using

Command 16. The direction of the pins (input or output)

is specified by programming the SLIC I/O direction reg-

ister (Command 17). The C5 pins of the Am79C031(A)

are output only and must be programmed as outputs to

be used.

Calculating Coefficients with

WinSLAC Software

The WinSLAC software is a program that models the

DSLAC device, the line conditions, the SLIC, and the

linecard components to obtain the coefficients of the

programmable filters of the DSLAC device and some of

the transmission performance plots.

The following parameters relating to the desired line con-

ditions and the components/circuits used in the linecard

are to be provided as input to the program:

1. Line impedance or the balance impedance of the

line is specified by the local PTT.

2. Desired two-wire impedance that is to appear at the

linecard terminals of the exchange.

3. Tabular data for templates describing the frequency

response and attenuation distortion of the design.

4. Relative analog signal levels for both the transmit

and receive two-wire signals.

5. Component values and SLIC device selection for

the analog portion of the line circuits.

6. Two-wire return loss template is usually specified

by the local PTT.

7. Four-wire return loss template is usually specified

by the local PTT.

The output from the WinSLAC program includes the

coefficients of the GR, GX, Z, R, X, B, and EPG filters

as well as transmission performance plots of two-wire

return loss, receive and transmit path frequency re-

sponse, and four-wire return loss.

The software supports the use of the AMD SLICs or

allows entry of a SPICE netlist describing the behavior

of any type of SLIC circuit.

AM79C02AJC 数据表(PDF) 46 Page - Advanced Micro Devices

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