pbl386302 ETC-unknow, pbl386302 Datasheet - Page 11

• Manufacturer Part Number: pbl386302
• Description: Subscriber Line Interface Circuit
• Manufacturer: ETC-unknow

When choosing R
load of the VTX terminal is >20 k .
yields a balance network containing an
inductor, an alternate method is recom-
mended. Contact Ericsson Microelectron-
ics for assistance.
used together with programmable CODEC/
filters. The programmable CODEC/filter
allows for system controller adjustment of
hybrid balance to accommodate different
line impedances without change of hard-
ware. In addition, the transmit and receive
gain may be adjusted. Please, refer to the
programmable CODEC/filter data sheets
for design information.
Longitudinal Impedance
A feed back loop counteracts longitudinal
voltages at the two-wire port by injecting
longitudinal currents in opposing phase.
pear as longitudinal currents and the TIPX
and RINGX terminals will experience very
small longitudinal voltage excursions, leav-
ing metallic voltages well within the SLIC
common mode range.
wire, Z
20 to longitudinal disturbances. It should
be noted that longitudinal currents may
exceed the dc loop current without disturb-
ing the vf transmission.
Capacitors C
The capacitors designated C
in figure 11, connected between TIPX
and ground as well as between RINGX
and ground, can be used for RFI filtering.
The recommended value for C
is 2200 pF. Higher capacitance values
may be used, but care must be taken to
prevent degradation of either longitudinal
balance or return loss. C
contribute to a metallic impedance of
1/( f C
impedance of 1/(2 f C
to ground impedance of 1/(2
If calculation of the Z
The PBL 386 30/2 SLIC may also be
Thus longitudinal disturbances will ap-
The SLIC longitudinal impedance per
LoT
TC
) = 1/( f C
and Z
TC
and C
LoR
TX
, appears as typically
, make sure the output
RC
), a TIPX to ground
RC
TC
TC
B
) and a RINGX
formula above
and C
TC
TC
f C
and C
and C
RC
RC
).
RC
RC
Figure 9. Hybrid function.
AC - DC Separation Capacitor, C
The high pass filter capacitor connected
between terminals HP and TIPX provides
the separation of the ac signal from the dc
part. C
response break point of the ac loop in the
SLIC. Refer to table 1 for recommended
values of C
Example: A C
tion the low end frequency response 3dB
break point of the ac loop at 1,8 Hz (f
according to f
R
High-Pass Transmit Filter
The capacitor C
between the VTX output and the CODEC/
filter forms, together with R
input impedance of a programmable
CODEC/filter, a high-pass RC filter. It is
recommended to position the 3 dB break
point of this filter between 30 and 80 Hz to
get a faster response for the dc steps that
may occur at DTMF signalling.
Capacitor C
The capacitor C
the terminals CLP and VBAT, positions
together with the resistive loop feed resis-
tor R
end frequency break point of the low pass
filter in the dc loop in the SLIC. C
with R
HP
386 30/2
= 600 k .
SG
SG
HP
(see section Battery Feed), the high
, C
PBL
positions the low end frequency
HP
HP
LP
and Z
.
HP
3dB
LP
TX
value of 150 nF will posi-
, which connects between
VTX
RSN
= 1/(2 R
T
in figure 11 connected
(see section Two-Wire
Z
T
HP
TX
C
and/or the
R
LP
Z
HP
TX
RX
together
) where
HP
Z
3dB
B
)
Impedance) forms the total two wire output
impedance of the SLIC. The choise of
these programmable components have an
influence on the power supply rejection
ratio (PSRR) from VBAT to the two wire
side at sub-audio frequencies. At these
frequencies capacitor C
the transversal to longitudinal balance in
the SLIC. Table 1 suggests suitable values
on C
Typical values of the transversal to longitu-
dinal balance (T-L bal.) at 200Hz is given in
table 1 for the chosen values on C
Table 1. R
ent feeding characteristics.
R
[ ]
2 50
2 200
2 400
2 800
Feed
LP
for different feeding characteristics.
SG
R
[k ]
0
60,4
147
301
SG
, C
Combination
CODEC/Filter
R
FB
LP
and C
C
[nF]
150
100
47
22
PBL 386 30/2
LP
HP
LP
values for differ-
T-L bal. C
@200Hz
[dB]
-46
-46
-43
-36
also influences
V
V
T
RX
LP
[nF]
47
150
150
150
.
HP
11