PBL38650-2 Ericsson, PBL38650-2 Datasheet - Page 12

• Manufacturer Part Number: PBL38650-2
• Description: Subscriber Line Interface Circuit
• Manufacturer: Ericsson

PBL 386 50/2
Battery Feed
resistive loop feed, programmable
between 2·50 and 2·900 , with
adjustable current limitation. In the
current limited region the loop current
has a slight slope corresponding to
2·30 k , see figure 13 reference B.
between the TIPX and RINGX terminals
is tracking the battery voltage V
signalling headroom, or overhead voltage
V
connected between terminal POV on the
SLIC and ground. Please refer to section
“Programmable overhead voltage(POV)”.
depends on the programmed signal
overhead voltage V
TIP to RING voltage at open loop
conditions according to V
= |V
V
changed when the line current is ap-
proaching open loop conditions. To
ensure maximum open loop voltage,
even with a leaking telephone line, this
occurs at a line current of approximately
6 mA. When the overhead voltage has
changed, the line voltage is kept nearly
constant with a steep slope correspond-
ing to 2·25 (reference G in figure 13).
defined as the difference between the
battery voltage and the crossing point of
all possible resistive feeding slopes, see
figure 13 reference J. The virtual battery
overhead is a theoretical constant
needed to be able to calculate the
feeding characteristics.
figure 13) is programmed by connecting
a resistor, R
and VBAT according to the equation:
12
TRO
OH
The PBL 386 50/2 SLIC emulate
The open loop voltage measured
The battery voltage overhead, V
Refer to table 2 for typical values on
The virtual battery overhead, V
SLIC
PBL 386 50/2 3.0 +V
Table 2. Battery overhead.
The resistive loop feed (reference D in
R
where R
Feed
Bat
and V
, is programmable with a resistor R
| - V
=
R
OHVirt
Feed
OH
SG
.
SG
200
+ 2·10
is in
. The overhead voltage is
, between terminals PSG
V
[V]
OH(typ)
TRO
4
for R
+ 2R
. V
TRO
OH
TR
SG
F
(at I
defines the
and R
V
[V]
4.9 +V
L
OHVirt(typ)
Bat
= 0 mA)
OHVirt
. The
OH
F
in .
,
TRO
, is
OV
13) is adjusted by connecting a resistor,
R
according to the equation:
connected to the device at terminal
VBAT2 to reduce short loop power
dissipation. The SLIC automatically
switches between the two battery supply
voltages without need for external
control. The silent battery switching
occurs when the line voltage passes the
value |VB2| - 40·I
if I
to connect the terminal VBAT2 to the
second power supply via the diode D
in figure 12.
between terminal VB and the VB2 power
supply, see figure 12, will make sure that
the SLIC continues to work on the
second battery even if the first battery
voltage disappears.
VBAT2 is connected to VBAT on the
SLIC and C
Metering applications
please contact Ericsson Microelectronics
for assistance.
CODEC Receive Interface
completely new receive interface at the
four wire side which makes it possible to
reduce the number of capacitors in the
applications and to fit both single and
dual battery feed CODECs. The RSN
terminal, connecting to the CODEC
Figure 11. Programmable overhead voltage (POV). R
LC
The current limit (reference C in figure
where R
A second, lower battery voltage may be
For correct functionality it is important
An optional diode D
If a second battery voltage is not used,
For designs with metering applications
The PBL 386 50/2 SLIC have got a
R
L
12
11
10
, between terminal PLC and ground
> 6 mA.
LC
9
8
7
6
5
4
3
2
1
0
0
=
I
LProg
1000
LC
VB2
is in k for I
+ 4
, D
10
BB
L
- (V
and D
BB
OHVirt
connected
LProg
VB2
20
-1.3),
are removed.
in mA.
VB2
30
R ov (K )
receive output via the resistor R
biased with +1.25V. This makes it
possible to compensate for currents
floating due to dc voltage differences
between RSN and the CODEC output
without using any capacitors. This is
done by connecting a resistor R
tween the RSN terminal and ground.
With current directions defined as in
figure 14, current summation gives:
where V
the CODEC at the receive output.
From this equation the resistor R
calculated as
For values on I
The resistor R
ac transmission.
with the direction of the current defined
as positive when floating into the terminal
RSN.
Programmable overhead voltage(POV)
voltage can be increased.
If the POV pin is left open the overhead
voltage is internally set to 3.2 V
R
1 25
SLIC
PBL 386 50/2
Table 3. The SLIC internal bias current
With the POV function the overhead
R
,
R
I
RSN
T
40
I
125
RSN
,
CODEC
I
L
RT
= 600
R
V
RX
I
is the reference voltage of
50
RRX
1 25
R
CODEC
R
,
RSN
has no influence on the
T
, see table 3.
125
or .
,
I
RR
125
,
125
R
,
60
R
R
I
-155
RSN
V
RX
CODEC
[ A]
Peak
RX
R
R
be-
, is dc
off-hook
on-hook
can be
in off-