参数资料
型号: PBL38661-2
厂商: ERICSSON
英文描述: LUG,BATTERY CABLE
中文描述: 用户线接口电路
文件页数: 13/18页
文件大小: 115K
代理商: PBL38661-2
PBL 386 61/2
13
Preliminary
leaving the AOV-pin open.
V
is defined as the battery voltage on
the VBat terminal minus the Battery Over
Head voltage, V
BOH
, according to the equa-
tion
V
TRMax
(at I
L
= 0 mA) = |V
Bat
| - V
BOH
Refer to table 2 for typical V
BOH
values.
V
BOH
(typ) [V]
AOV-PIN NC
AOV-PIN to AGND
Table 2. The battery overhead voltages
at open loop conditions.
4.2
3.2
Resistive Loop Feed Region
The resistive loop feed (reference D in
figure 13) is programmed by connecting a
resistor R
, between terminals PSG and
VBAT according to the equation
R
= R
SG
+ 40 + 2R
F
400
Constant Current Region
The current limit (reference C in figure 13)
is adjusted by connecting a resistor, R
,
between terminal PLC and ground accord-
ing to the equation:
LC
= 500
14
R
LProg
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
|V
| - 40
I
- 6
15
Connect the terminal VBAT2 to the sec-
ond power supply via the diode D
B2
in figure
12.
An optional diode D
connected between
terminal VBAT 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.
If the V
voltage is not available, an
optional external power management re-
sistor, R
, may be connected between the
VBAT2-pin and the VBAT-pin to move pow-
er dissipation outside the chip.
Calculation of the external power man-
agement resistor to locate the maximum
power dissipation outside the SLIC is ac-
cording to:
PM
= |V
Bat
| - 3
R
LProg
Metering Applications
It is very easy to use PBL 386 61/2 in
metering applications; simply connect a
suitable resistor (R
) in series with a ca-
pacitor (C
) between pin RSN and the
metering source. Capacitor C
decouples
all DC-voltages that may be superimposed
on the metering signal. Choose 1/(2
π
R
C
)
5kHz to suppress low frequency distur-
bances from the metering puls generator.
The metering signal gain can be calculated
from the equation:
4-2Metering
= V
TR
=
G
Meter
Z
T
Z
LM
Z
M
Z
T
- G
2-4S
(Z
LM
+ 2R
F
)
α
RSN
where
V
Meter
is the voltage of the signal at the
metering generator,
is the line impedance seen by the
12 or 16 kHz metering signal,
is the transmit gain through the SLIC,
i e -0.5.
Z
LM
G
2-4S
In metering applications with resistive
line feeding characteristic and very strict
requirements (as mentioned earlier in chap-
ter “AOV in resistive loop feed region“), the
metering signal level should not exceed 2.2
V
RMS 16
, since a reduction of the line current
will generate a transversal, and sometimes
audible, signal (which is not the case in the
constant current region).
Analog Temperature Guard
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
reaches approximately 145
°
C and increas-
es it again automatically when the temper-
ature drops.
The detector output, DET, is forced to a
logic low level when the temperature guard
is active.
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.
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,
I
, where the loop current detector chang-
es state, is programmable with the R
LD
resistor. R
connects between pin PLD
and ground and is calculated according to:
LD
= 500
R
LTh
The current detector is internally filtered
and is not influenced by the ac signal at the
two wire side.
Ring Trip Detector
Ring trip detection is accomplished by con-
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
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