Preliminary
PBL 386 65/2
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
4.2
3.2
Table 2. The battery overhead voltages
at open loop conditions.
Resistive Loop Feed Region
The resistive loop feed (reference D in
figure 15) is programmed by connecting a
resistor RSG , between terminals PSG and
VBAT according to the equation
R
RFeed
=
SG + 40 + 2RF
Figure 12. Silent Polarity Reversal
400
Constant Current Region
If the VB2 voltage is not available, an where:
The current limit (reference C in figure 15)
is adjusted by connecting a resistor, RLC,
between terminal PLC and ground accord-
ing to the equation:
optional external power management re- VTTX is the voltage of the signal at the
sistor, RPM, may be connected between the metering generator,
VBAT2-pinandtheVBAT-pintomovepow- ZLTTX is the line impedance seen by the
er dissipation outside the chip. 12 or 16 kHz metering signal,
Calculation of the external power man- G2-4S isthetransmitgainthroughtheSLIC,
14
500
RLC
=
agement resistor to locate the maximum
power dissipation outside the SLIC is ac-
cording to:
i e -0.5. (Phase shift 180°)
ILProg
In metering applications with resistive
line feeding characteristic and very strict
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).
Battery Switch (VBAT2)
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
VTR = |VBat2| - 40•IL - 6 15
Connect the terminal VBAT2 to the sec-
ondpowersupplyviathediodeDB2 infigure
14.
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.
|VBat| - 3
RPM
=
ILProg
Metering Applications, TTX
It is very easy to use PBL 386 65/2 in
metering applications; simply connect a
suitable resistor (RTTX) in series with a
capacitor (CTTX) between pin RSN and the
metering source. Capacitor CTTX decou-
ples all DC-voltages that may be superim-
Silent Polarity Reversal
posed on the metering signal. Choose 1/ Thereversaltimeissetbyacapacitor,Csprv,
(2πRTTXCTTX) ≥ 5kHz to suppress low fre- between the pin SPR and AGND. The
quency disturbances from the metering reversal has a setup time and reversal time
puls generator. The metering signal gain see figure 12.
can be calculated from the equation:
The setup time is different in Active- to
Reversal-stateandReversal-toActivestate
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:
VTR
VTTX
G4-2TTX
=
=
ZT
RTTX
ZLTTX
•
ZT
αRSN
- G2-4S • (ZLTTX + 2RF)
tr =CSPR . 9500
13
ERICSSON [ ERICSSON ]
