PBL 3766
Notes
1.
2.
The overload level is specified at the two-wire port with the signal source at the four-wire receive port.
The two-wire impedance is programmable by selection of external component values according to:
Z
TRX
= Z
T
/|G
2-4
·
α
RSN
|
where
Z
TRX
Z
T
G
2-4
α
RSN
3.
= impedance between the TIPX and RINGX terminals
= programming network between the V
TX
and RSN terminals
= TIPX-RINGX to VTX gain, nominally = 1
= receive current gain, nominally = -1000 (current defined as positive when flowing into the receive summing node,
RSN and when flowing from TIPX to RINGX).
Higher return loss values can be achieved by adding a reactive component to R
T
, the two-wire terminating impedance
programming resistor, e.g. by dividing R
T
into two equal halves and connecting a capacitor from the common point to ground.
For R
T
= 600 kohms the capacitance value is approximately 33 pF.
The overload level is specified at the four-wire transmit port, VTX, with the signal source at the two-wire port. Note that the
gain from the two-wire port to the four-wire transmit port is G
2-4
= 1.
Fuse resistors R
F
impact the insertion loss as explained in the text, section Transmission. The specified insertion loss is for
R
F
= 0.
The specified insertion loss tolerance does not include errors caused by external components.
The level is specified at the two-wire port.
The level is specified at the four-wire receive port and referenced to a 600 ohm impedance level.
The two-wire idle noise is specified with the port terminated in 600 ohms (R
L
) and with the four-wire receive port grounded
(E
RX
= 0, see figure 6).
The four-wire idle noise at VTX is specified with the two-wire port terminated in 600 ohms (R
L
). The noise specification is with
respect to a 600 ohm impedance level at VTX. The four-wire receive port is grounded (E
RX
= 0, see figure 6).
4.
5.
6.
7.
8.
9.
10. With the RD terminal left open, the loop current detector on-hook to off-hook threshold is internally set to 8.0 mA and the off-
hook to on-hook threshold to 7.3 mA. The loop current detection threshold can be set to higher values by connecting a
resistor, R
D
, between terminal RD and V
EE
(-5 V), as described in section Loop Monitoring Functions.
11. Refer to section Loop Monitoring Functions, Loop Current Detector.
12. Power supply rejection ratio test signal is 100 mVrms (sinusoidal).
13. Line resistor R
F
= 0 ohm.
14. Junction to ambient thermal resistance will be dependent on external thermal resistance from VBAT terminals to ambient.
4-7
ERICSSON [ ERICSSON ]
