AM79C03JC AMD (ADVANCED MICRO DEVICES), AM79C03JC Datasheet - Page 23

• Manufacturer Part Number: AM79C03JC
• Manufacturer: AMD (ADVANCED MICRO DEVICES)

Specifications of AM79C03JC

• Lead Free Status / RoHS Status: Supplier Unconfirmed

Distortion Correction and Equalization
The DSLAC device contains programmable filters in the
receive (R) and transmit (X) directions that may be pro-
grammed for line equalization and to correct any atten-
uation distortion caused by the Z filter.
Transhybrid Balancing
The DSLAC device’s programmable B filter is used to
adjust transhybrid balance. The filter has a single pole
IIR section (BIIR) and an eight tap FIR section (BFIR),
both operating at 16 kHz. The DSLAC device has an
optional Adaptive mode for the B filter, which may be
used to achieve optimum performance. The Echo
Path Gain (EPG) and Error Level Threshold (ELT) reg-
isters contain values that determine the Adaptive
mode performance.
Gain Adjustment
The DSLAC device’s transmit path has two programma-
ble gain blocks. Gain block AX is an analog gain of 0 dB
or 6.02 dB, located immediately before the A/D convert-
er. Gain block GX is a digital gain that is programmable
to any gain from 0 dB to 12 dB with a worst-case step
size of 0.3 dB for gain settings above 10 dB. The filters
provide a net gain in the range of 0 dB to 18 dB.
The DSLAC device receive path has two programmable
loss blocks. Loss block GR is a digital loss that is pro-
grammable from 0 dB to 12 dB with a worst-case step
size of 0.1 dB. Loss block AR is an analog loss of 0 dB
or 6.02 dB, located immediately after the D/A converter.
This provides a net loss in the range of 0 dB to 18 dB.
Transmit Signal Processing
In the transmit path, the analog input signal is A/D con-
verted, filtered, companded (A-law or µ-law), and made
available for output to the PCM highway. The signal pro-
cessor contains an ALU, RAM, ROM, and control logic
to implement the filter sections. The B, X, and GX blocks
Digital
Loop-
back
(#13)
VIN
VOUT
*
programmable blocks
AISN
+
*
AX
*
AR
*
Analog Loopback
ADC
DAC
(also uses
RX Cutoff)
(#21)
Decimator
polator
Inter-
& HPF
Cutoff
Figure 8. DSLAC Block Diagram
RX
Z
+
*
mator
Deci-
polator
Inter-
SLAC Products
B
+
are user-programmable digital filter sections with coef-
ficients stored in the coefficient RAM while AX is an
analog amplifier that can be programmed for 0 dB or
6.02 dB gain. The filters may be made transparent when
not required in a system.
The decimator reduces the high input sampling rate to
16 kHz for input to the B, GX, and X filters. The X filter
is a six tap FIR section, which is part of the frequency
response correction network. The B filter operates on
samples from the receive signal path in order to provide
transhybrid balancing in the loop. The high-pass filter
rejects low frequencies such as 50 or 60 Hz and may
be disabled.
Transmit PCM Interface
The transmit PCM interface receives an 8-bit com-
pressed code from the digital A-law/µ-law compressor.
Transmit logic controls the transmission of data onto the
PCM highway through output port selection and time/
clock slot control circuitry.
The frame sync (FS) pulse identifies the beginning of a
transmit frame and all channels (time slots) are refer-
enced to it. The logic contains user programmable
Transmit Time Slot and Transmit Clock Slot registers.
The Time Slot register is 7 bits wide and allows up to
128 8-bit channels (using a PCLK of 8.192 MHz) in each
frame. This feature allows any clock frequency between
128 kHz and 8.192 MHz (2 to 128 channels) in a system.
The Clock Slot register is 3 bits wide and may be pro-
grammed to offset the time slot assignment by 0 to 7
PCLK periods to eliminate any clock skew in the system.
The data is transmitted in bytes with the most significant
bit first.
An exception occurs when division of the PCLK fre-
quency by 64 kHz produces a nonzero remainder, R
(R = f
mit clock slot is greater than R. In that case, the R-bit
*
GR
GX
*
*
PCLK
X
R
*
*
modulo 64 kHz, R > 0), and when the trans-
& HPF
LPF
LPF
Compressor
Expander
TSA Loopback
(also uses
TX Cutoff)
(#21)
TX Cutoff
TSA
TSA
Highway
PCM
09875H-018
Digital
Digital
RX
TX
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