PBL 3766
Notes
1. The overload level is specified at the two-wire port with the signal source at the four-wire receive port.
2. The two-wire impedance is programmable by selection of external component values according to:
ZTRX = ZT/|G2-4 · αRSN
|
where
ZTRX = impedance between the TIPX and RINGX terminals
ZT = programming network between the VTX and RSN terminals
G2-4 = TIPX-RINGX to VTX gain, nominally = 1
αRSN = receive current gain, nominally = -1000 (current defined as positive when flowing into the receive summing node,
RSN and when flowing from TIPX to RINGX).
3. Higher return loss values can be achieved by adding a reactive component to RT, the two-wire terminating impedance
programming resistor, e.g. by dividing RT into two equal halves and connecting a capacitor from the common point to ground.
For RT = 600 kohms the capacitance value is approximately 33 pF.
4. 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 G2-4 = 1.
5. Fuse resistors RF impact the insertion loss as explained in the text, section Transmission. The specified insertion loss is for
RF = 0.
6. The specified insertion loss tolerance does not include errors caused by external components.
7. The level is specified at the two-wire port.
8. The level is specified at the four-wire receive port and referenced to a 600 ohm impedance level.
9. The two-wire idle noise is specified with the port terminated in 600 ohms (RL) and with the four-wire receive port grounded
(ERX = 0, see figure 6).
The four-wire idle noise at VTX is specified with the two-wire port terminated in 600 ohms (RL). The noise specification is with
respect to a 600 ohm impedance level at VTX. The four-wire receive port is grounded (ERX = 0, see figure 6).
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, RD, between terminal RD and VEE (-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 RF = 0 ohm.
14. Junction to ambient thermal resistance will be dependent on external thermal resistance from VBAT terminals to ambient.
4-7
ERICSSON [ ERICSSON ]
