PBL 386 61/2
Preliminary
leaving the AOV-pin open.
VTRMax isdefinedasthebatteryvoltageon
even if the first battery voltage disappears.
If the VB2 voltage is not available, an
Analog Temperature Guard
the VBat terminal minus the Battery Over optional external power management re-
Head voltage, VBOH, according to the equa- sistor, RPM, may be connected between the
The widely varying environmental condi-
tions in which SLICs operate may lead to
the chip temperature limitations being ex-
ceeded. The PBL 386 61/2 SLIC reduces
the dc line current and the longitudinal
current limit when the chip temperature
reachesapproximately145°Candincreas-
es it again automatically when the temper-
ature drops.
tion
VBAT2-pinandtheVBAT-pintomovepow-
er dissipation outside the chip.
VTRMax(at IL = 0 mA) = |VBat| - VBOH
Calculation of the external power man-
agement resistor to locate the maximum
power dissipation outside the SLIC is ac-
cording to:
Refer to table 2 for typical VBOH values.
VBOH(typ) [V]
AOV-PIN NC
AOV-PIN to AGND
|VBat| - 3
The detector output, DET, is forced to a
logic low level when the temperature guard
is active.
4.2
3.2
RPM
=
ILProg
Table 2. The battery overhead voltages
at open loop conditions.
Metering Applications
It is very easy to use PBL 386 61/2 in
metering applications; simply connect a
suitable resistor (RM) in series with a ca-
pacitor (CM) between pin RSN and the
metering source. Capacitor CM decouples
all DC-voltages that may be superimposed
onthemeteringsignal.Choose1/(2πRMCM)
≥ 5kHz to suppress low frequency distur-
bances from the metering puls generator.
The metering signal gain can be calculated
from the equation:
Loop Monitoring Functions
The loop current and ring trip detectors
report their status through a common out-
put, DET. The status of the detector pin,
DET, is selected via the two bit control
interface C1 and C2. Please refer to sec-
tion Control Inputs for a description of the
control interface.
Resistive Loop Feed Region
The resistive loop feed (reference D in
figure 13) is programmed by connecting a
resistor RSG , between terminals PSG and
VBAT according to the equation
R
RFeed
=
SG + 40 + 2RF
400
Loop Current Detector
The loop current detector indicates that 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 threshold value,
ILTh, wheretheloopcurrentdetectorchang-
es state, is programmable with the RLD
resistor. RLD connects between pin PLD
and ground and is calculated according to:
Constant Current Region
VTR
VMeter
The current limit (reference C in figure 13)
is adjusted by connecting a resistor, RLC,
between terminal PLC and ground accord-
ing to the equation:
G4-2Metering
=
=
ZT
ZM
ZLM
- G2-4S • (ZLM + 2RF)
•
ZT
αRSN
14
500
RLC
=
ILProg
where
Battery Switch (VBAT2)
500
ILTh
VMeter is the voltage of the signal at the
metering generator,
ZLM
RLD
=
To reduce short loop power dissipation, a
second lower battery voltage may be con-
nected to the device through an external
diode at terminal VBAT2. The SLIC auto-
matically switches between the two battery
supply voltages without need for external
control. The silent battery switching occurs
when the line voltage passes the value
|VBat2| - 40•IL - 6 15
Connect the terminal VBAT2 to the sec-
ondpowersupplyviathediodeDB2 infigure
12.
AnoptionaldiodeDBB connectedbetween
terminal VBAT and the VB2 power supply,
see figure 12, will make sure that the SLIC
continues to work on the second battery
is the line impedance seen by the
12 or 16 kHz metering signal,
The current detector is internally filtered
and is not influenced by the ac signal at the
two wire side.
G2-4S isthetransmitgainthroughtheSLIC,
i e -0.5.
In metering applications with resistive Ring Trip Detector
line feeding characteristic and very strict
Ring trip detection is accomplished by con-
requirements(asmentionedearlierinchap-
ter “AOV in resistive loop feed region“), the
meteringsignallevelshouldnotexceed2.2
VRMS 16, since a reduction of the line current
willgenerateatransversal, andsometimes
audible, signal (which is not the case in the
constant current region).
necting an external network to a compara-
tor in the SLIC with inputs DT and DR. The
ringing source can be balanced or unbal-
anced e g superimposed on the battery
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
13
ERICSSON [ ERICSSON ]
