AM79Q02JC AMD (ADVANCED MICRO DEVICES), AM79Q02JC Datasheet - Page 60

• Manufacturer Part Number: AM79Q02JC
• Manufacturer: AMD (ADVANCED MICRO DEVICES)

Specifications of AM79Q02JC

• Lead Free Status / RoHS Status: Supplier Unconfirmed

APPLICATIONS
The QSLAC device performs a programmable codec/
filter function for four telephone lines. It interfaces to the
telephone lines through an AMD SLIC device or a
transformer with external buffering. The QSLAC device
provides latched digital I/O to control and monitor four
SLICs and provides access to time-critical information,
like off/on-hook and ring trip, for all four channels via a
single read operation. When various country or
transmission requirements must be met, the QSLAC
device enables a single SLIC design for multiple
applications. The line characteristics (such as apparent
impedance, attenuation, and hybrid balance) can be
modified by programming each QSLAC device
channel’s coefficients to meet desired performance.
The QSLAC device requires an external buffer to drive
transformer SLICs.
Connection to a PCM back plane is implemented by
means of a simple buffer chip. Several QSLAC devices
can be tied together in one bus interfacing the back
plane through a single buffer. An intelligent bus
interface chip is not required because each QSLAC
device provides its own buffer control (TSXA/B). The
Q S L AC d ev i c e i s c o n t r o l l e d t h r o u g h t h e
microprocessor interface, either by a microprocessor
on the linecard or by a central processor.
Controlling the SLIC
The A m79 Q0 21 Q S LAC dev ic e ha s fi ve TTL -
compatible I/O pins (CD1, CD2, C3 to C5) for each
channel. The Am79Q031 QSLAC device has only CD1
and CD2 available. The outputs are programmed
using Command 19, and the status is read back using
Command 20. CD1 and CD2 for all four channels can
be read back using Command 16. The direction of the
I/O pins (input or output) is specified by programming
the SLIC I/O direction register (Commands 21 and 22).
Default Filter Coefficients
The default filter coefficients were calculated assuming an
Am7920 SLIC with 50
transversal impedance (Z
impedance (Z
(G
relative level was set to +0.28 dBr, and the receive
60
TX
) and a current gain of 500 (K1). The transmit
RX
). This SLIC has a transmit gain of 0.5
protection resistors, a 178 k
T
), and a 90.5 k
Am79Q02/021/031 Data Sheet
receive
relative level was set to –4.39 dBr. The equalization
filters (X and R) were not optimized. The balance filter
was designed to give acceptable balance into a variety
of impedances. The nominal input impedance was set
to 815 . If the SLIC circuit differs significantly from this
design, the default filters cannot be used and must be
replaced by programmed coefficients.
Calculating Coefficients with WinSLAC Software
The WinSLAC software is a program that models the
QSLAC device, the line conditions, the SLIC, and the
linecard components to obtain the coefficients of the
programmable filters of the QSLAC device and some
of the transmission performance plots.
The following parameters relating to the desired line
conditions 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
2. Desired two-wire impedance that is to appear at the
3. Tabular data for templates describing the frequency
4. Relative analog signal levels for both the transmit
5. Component values and SLIC device selection for
6. Two-wire return loss template is usually specified
7. Four-wire return loss template is usually specified
The output from the WinSLAC program includes the
coefficients of the GR, GX, Z, R, X, and B filters as
well as transmission performance plots of two-wire
return loss, receive and transmit path frequency
responses, 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.
line is specified by the local PTT.
by the local PTT.
linecard terminals of the exchange.
response and attenuation distortion of the design.
and receive two-wire signals.
the analog portion of the line circuits.
by the local PTT.