
SLIC Products
11
11. Total Harmonic distortion with metering is specified with a metering signal of 2.2 Vrms at the two-wire output, and a transmit
signal of +3 dBm or receive signal of
–
4 dBm. The transmit or receive signals are single-frequency inputs, and the distortion
is measured as the highest in band harmonic at the two-wire or the four-wire output relative to the input signal.
12. Noise with metering is measured by applying a 2.2 Vrms metering signal (measured at the two-wire output) and measuring
the psophometric noise at the two-wire outputs over a 200 ms time interval.
Note:
* A logic Low on E0 disables DET output into the Open Collector state.
Table 1.
SLIC Decoding
DET Output
State
C3 C2 C1
Two-Wire Status
E0 = 1*
E1 = 0
E0 = 1*
E1 = 1
0
1
2
3
4
5
6
7
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
Open Circuit
Ringing
Active
On-hook TX (OHT)
Tip Open
Reserved
Active Polarity Reversal
OHT Polarity Reversal
Ring trip
Ring trip
Loop detector
Loop detector
Loop detector
Loop detector
Loop detector
Loop detector
Ring trip
Ring trip
Ground key
Ground key
—
—
Ground key
Ground key
Table 2.
User-Programmable Components
Z
T
is connected between the VTX and RSN pins. The fuse
resistors are R
F
, and Z
2WIN
is the desired two-wire AC input
impedance. When computing Z
T
, the internal current amplifier
pole and any external stray capacitance between VTX and
RSN must be taken into account.
Z
RX
is connected from V
RX
to RSN. Z
T
is defined above. This
equation sets the receive gain to 0 dB when the SLIC
terminates with an impedance equal to Z
2WIN
.
R
DC1
, R
DC2
, and C
DC
form the network connected to the RDC
pin. R
DC1
and R
DC2
are approximately equal.
R
D
and C
D
form the network connected from RD to
–
5 V and I
T
is the threshold current between on-hook and off-hook.
Z
M
is connected from V
MG
(metering source) to the RSN pin,
V
M2W
is the desired magnitude of the metering signal at the
2-wire output (usually 2.2 Vrms) and K
1
(
2
) is defined below.
where: CX = The values of the identical capacitors from
A and B to GND
metering frequency
ω
2
π
=
Z
T
510 Z
2WIN
2R
F
)
–
=
Z
RX
0.98 Z
T
)
=
R
DC1
R
DC2
+
50
R
FEED
2R
F
–
(
)
=
C
DC
1.5 ms
R
R
DC1
DC2
R
DC2
--------------+
=
R
D
I
T
365
=
C
D
R
D
0.5 ms
=
Z
M
V
V
M2W
---------------
K
ω
L
K
1
ω
Z
T
(
Z
T
0.51 V
( )
2R
F
Z
L
+
)
+
----------------------------------------Z
=
ω
K
1
ω
( )
1
j
ω
11.5
10
9
–
CX
+
36
(
Z
L
2R
F
+
+
)
+
---------------------------------------------1000
=