PBL386151 Ericsson, PBL386151 Datasheet - Page 14

• Manufacturer Part Number: PBL386151
• Description: Subscriber Line Interface Circuit
• Manufacturer: Ericsson

PBL 386 15/1
Silent Polarity Reversal
C
reversal has a setup time and reversal time
see figure 14.
Reversal-state and Reversal- to Active state
but the silent polarity reversal time is the
same Active- to Reversal-state and Rever-
sal- to Active state. To calculate the silent
polarity reversal time use following for-
mula:
to Active state and the setup time use
following formulas.
and 90% of the line voltage. The reversal
time is independent of line load and line
current.
Analog Temperature Guard
conditions in which SLICs operate may
lead to the chip temperature limitations
being exceeded. The PBL 386 15/1 SLIC
reduces the dc line current and the
longitudinal current limit when the chip
temperature reaches approximately 145 C
and increases it again automatically when
the temperature drops.
logic low level when the temperature guard
is active.
exclusively viewed at detector output see
section Active Temperature guard.
detectors report their status through a com-
mon output, DET. The status of the detec-
tor pin, DET, is selected via the three bit
control interface C1, C2 and C3. Please
refer to section Control Inputs for a descrip-
tion of the control interface.
14
sprv,
The reversal time is set by a capacitor,
The setup time is different in Active- to
t
Active- to Reversal-state and Reversal-
Active
t
Reversal
t
The time is measured between 10%
The widely varying environmental
The detector output, DET, is forced to a
The Active state temperature guard is
Loop Monitoring Functions
The loop current, ground key and ring trip
r
Act
Rev
=C
between the pin SPR and AGND. The
SPR
Rev =
Act =
.
C
9500
C
Reversal:
SPR
SPR
Active:
.
17500
.
15500
Loop Current Detector
the telephone is off hook and that DC
current is flowing in the loop by putting the
output pin DET, to a logic low level when
selected. The loop current detector thresh-
old value, I
tector changes state, is programmable with
the R
PLD and ground and is calculated accord-
ing to:
the ground key is pressed (active) by put-
ting the output pin DET to a logic high level
when selected. The ground key detector
circuit senses the difference between TIPX
and RINGX currents. The detector is trig-
gered when the difference exceeds the
current threshold.
Figure 14. Silent Polarity Reversal
The loop current detector indicates that
R
Ground Key Detector
The ground key detector indicates when
LD
LD
=
resistor. R
500
I
LTh
LTh
, where the loop current de-
LD
connects between pin
C2 = 5 V, C1 = 0 V
C
R
L
SPR
= 600
= 4.7 F / 6V
connecting an external network to a com-
parator in the SLIC with inputs DT and DR.
The ringing source can be balanced or
unbalanced e g superimposed on the bat-
tery voltage or ground. The unbalanced
ringing source may be applied to either the
ring lead or the tip lead with return via the
other wire. A ring relay driven by the SLIC
ring relay driver connects the ringing source
to tip and ring.
ity change at the comparator input when
the line goes off-hook. In the on-hook state
no dc current flows through the loop and
the voltage at comparator input DT is more
positive than the voltage at input DR. When
the line goes off-hook, while the ring relay
is energized, dc current flows and the com-
parator input voltage reverses polarity.
detection network. This network is applica-
ble, when the ring voltage superimposed
on the battery voltage is injected on the ring
lead of the two-wire port. The dc voltage
across sense resistor R
the ring trip comparator input DT and DR
via the filter network R
C
line on-hook (no dc current). The DET
output will report logic level high, i.e. the
detector is not tripped. When the line goes
off-hook, while ringing, a dc current will flow
2
Ring Trip Detector
Ring trip detection is accomplished by
The ring trip function is based on a polar-
Figure 15 gives an example of a ring trip
R
. DT is more positive than DR, with the
FEED
= 2 *25
1
, R
RT
2
is monitored by
, R
3
, R
4
, C
1
and