PBL 386 11/2
VTRMax isdefinedasthebatteryvoltageon
the VBat terminal minus the Battery Over
Head voltage, VBOH, according to the equa-
tion
VTRMax(at IL = 0 mA) = |VBat| - VBOH
Refer to table 2 for typical VBOH values.
VBOH(typ) [V]
AOV-PIN NC
AOV-PIN to AGND
3.7
3.2
Table 2. The battery overhead voltages
at open loop conditions.
Resistive Loop Feed Region
The resistive loop feed (reference D in
figure 14) is programmed by connecting a
resistor RSG , between terminals PSG and
VBAT according to the equation
R
RFeed
=
SG + 40 + 2RF
400
Figure 12. Silent Polarity Reversal
Constant Current Region
If the VB2 voltage is not available, an where
optional external power management re- VMeter is the voltage of the signal at the
The current limit (reference C in figure 14)
is adjusted by connecting a resistor, RLC,
between terminal PLC and ground accord-
ing to the equation:
sistor, RPM, may be connected between the
VBAT2-pinandtheVBAT-pintomovepow- ZLM
er dissipation outside the chip.
metering generator,
is the line impedance seen by the
12 or 16 kHz metering signal,
Calculation of the external power man- G2-4S isthetransmitgainthroughtheSLIC,
14
agement resistor to locate the maximum
power dissipation outside the SLIC is ac-
cording to:
i e -0.5.
500
ILProg
RLC
=
In metering applications with resistive
line feeding characteristic and very strict
requirements(asmentionedearlierinchap-
ter “AOV in resistive loop feed region“), the
meteringsignallevelshouldnotexceed1.6
VRMS 16, since a reduction of the line current
willgenerateatransversal, andsometimes
audible, signal (which is not the case in the
constant current region).
Battery Switch (VBAT2)
|VBat| - 3
RPM
=
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 - 5.3 15
Connect the terminal VBAT2 to the sec-
ondpowersupplyviathediodeDB2 infigure
13.
AnoptionaldiodeDBB connectedbetween
terminal VBAT and the VB2 power supply,
see figure 13, will make sure that the SLIC
continues to work on the second battery
even if the first battery voltage disappears.
ILProg
Metering Applications
It is very easy to use PBL 386 11/2 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
Silent Polarity Reversal
onthemeteringsignal.Choose1/(2πRMCM) The polarity reversal time can be adjusted
≥ 5kHz to suppress low frequency distur- by connecting a capacitor between pin
bances from the metering puls generator. SPR and AGND.
The metering signal gain can be calculated
from the equation:
For an example in silent polarity reversal,
see figure 12.
Please contact Ericsson Microelectron-
ics for further information.
VTR
VMeter
G4-2Metering
=
=
ZT
ZM
ZLM
- G2-4S • (ZLM + 2RF)
•
ZT
αRSN
13
ERICSSON [ ERICSSON ]
