PBL 386 20/2
Notes
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 G2-4S = 1 (or 0.5 see pin PTG)
5. Pin PTG = Open sets transmit gain to nom. 0.0dB
Pin PTG = AGND sets transmit gain to nom. -6.02 dB
Secondary protection resistors R F and tertiary protection
resistors RP impact the insertion loss as explained in the
text, section Transmission. The specified insertion loss is
for RF = RP = 0.
1. The overload level can be adjusted with the resistor ROV
for higher levels e.g. min 3.1 VPeak and 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/|G2-4S α RSN| where:
ZTRX = impedance between the TIPX and RINGX
terminals
ZT = programming network between the VTX and RSN
terminals
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 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).
G2-4S = transmit gain, nominally = 1 (or 0.5 see pin PTG)
α
RSN = receive current gain, nominally = 200 (current
defined as positive flowing into the receivesumm-
ing node, RSN, and when flowing from ring to tip).
The four-wire idle noise at VTX is specified with the two-
wire port terminated in 600 ohms (R L). The noise
specification is referenced to a 600 ohm programmed two-
wire impedance level at VTX. The four-wire receive port is
grounded (E RX = 0).
3. Higher return loss values can be achieved by adding a
reactive component to RT, the two-wire terminating
impedance programming resistance, e.g. by dividing RT
into two equal halves and connecting a capacitor from the
common point to ground.
4. The overload level can be adjusted with the resistor R OV
for higher levels e.g. min 3.1 VPeak and is specified at the
7
ERICSSON [ ERICSSON ]
