stlc3040 STMicroelectronics, stlc3040 Datasheet - Page 5

• Manufacturer Part Number: stlc3040
• Description: Subscriber Line Interface Codec Filter, Cofislic
• Manufacturer: STMicroelectronics

Figure 4.
functions. This voltage is then combined with the
AC and DC analog impedance signals, plus a
TTX pulse, in a summing buffer that feeds the Vin
pin of the HV (L3000N, L3000S, STLC3170).
The architecture of the digital section is based on
Digital Signal Processor which synthetises 7 digi-
tal filters (B, Z, X, R, KD, GX, GR). KA uses the
some register value as KD. In Table 1 you can
find the number of coefficients and their bit width
for each filter.
Table 1:
(*) KA is a subset of KD = most significant bits, (5-12) but sign bit,
Filter coefficients can be programmed by 14 bits
of KD register.
FILTER
KA, KD
GR
GX
R
B
X
Z
100mA
(typ)
I
I
LIM
LIM
I
I
I
L
L
L
COEFFICIENTS
NUMBER OF
R
FEED
R
8
4
4
1
1
1
3
FEED
= 2 * R
= 2 * R
R
P
COEFFICIENT
FEED
8, 14 BITS (*)
P
+ n * 100
+ n * 100
14 BITS
14 BITS
14 BITS
14 BITS
WIDTH
8 BITS
8 BITS
= 2R
P
V
V
V
BAT -5.85V
V
DROP
BAT -22V
OL
RING MODE
STAND-BY MODE
I
deep registers. These internal filters can be en-
abled setting the most significant 5 bits of CR4
register and CR11 (1). PCM encoding and ITU-T
high/lowpass-filtering are done by dedicated state
machines. Setting the bit 0 of CR4 register A-law
or
In order to match the complex line impedance,
both amplitude and phase can be programmed
using Filter Z.
The two to four wires echo cancellation is imple-
mented thanks to programmable echo canceler
(B Filter) with Gain and Group-delay equalizer.
Two programmable FIR filters X and R, can be
set in order to guarantee the best overall line fre-
quency response in the frequency domain, ac-
cording to the local specifications. In this way the
signal distorsion can be reduced with 14-bits
resolution.
Gain Setting, both in transmission and in receive,
is done by two FIR filters (GX for transmission,
GR for Receive).
A coefficient optimization software let the users
calculate GX and GR filters coefficients.
In transmission the maximum achievable gain
without distortion is 3dB.
LIM
: 0-70mA 1.1mA step
V
I
LIM
law can be selected.
DROP
: 0-70mA 1.1mA step
= 9.6V + V
D95TL208D
V
BAT
dTTX
V
V
V
.40
L
L
L
(see par 4.3.2.1)
STLC3040
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