PBL 386 15/1
Control Inputs
The PBL 386 15/1 SLIC has three digital
control inputs, C1, C2 and C3.
AdecoderintheSLICinterpretsthecontrol
input condition and sets up the command-
ed operating state.
C1 to C3 are internal pull-up inputs.
Open Circuit State
In the Open Circuit State the TIPX and
RINGXlinedriveamplifiersaswellasother
circuitblocksarepowereddown.Thiscaus-
es the SLIC to present a high impedance to
the line. Power dissipation is at a minimum
and no detectors are active.
Ringing State
In the ringing state the SLIC will behave as
in the active state with the exception that
the ring relay driver and the ring trip detec-
tor are activated. The ring trip detector will
indicateoffhookwithalogiclowlevelatthe
detector output.
Figure 16. Line voltage measurment
Active State
Active Polarity Reversal State
Line Voltage measurement
TIPX is the terminal closest to ground and
sources loop current while RINGX is the
more negative terminal and sinks loop cur-
rent. The loop current or the ground key
detector is activated. The loop current de-
tector indicates off hook with a logic low
level and the ground key detector indicates
active ground key with a logic high level
present at the detector output.
TIPX and RINGX polarity is reversed com- The line voltage is presented on the detec-
pared to the Active State: RINGX is the tor output as a pulse train (see figure 16)
terminal closest to ground and sources with a frequency inversely proportional to
loop current while TIPX is the more nega- the voltage according to the equation:
tive terminal and sinks current. The loop
current or the ground key detector is acti-
vated. The loop current detector will indi-
cate off hook with a logic low level and the
ground key detector will indicate active
106
freq =
[Hz]
|VTR| + 1
The line voltage measurement will be
groundkeywithalogichighlevelpresentat started when entering this state from any
the detector output.
other state and the SLIC will be as in active
state except for the detector. The data can
be used in variety of ways, for example to
set transmission parameters in a program-
mable CODEC, in line testing where short
circuits on the line can be detected and to
control the metering signal amplitude.
Active Temperature guard state
The temperature guard indicates if an error
has occurred and the temperature guard is
activated. The output pin DET is forced to
a logic low level when activated .
16
ERICSSON [ ERICSSON ]
