PBL 386 21/2
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
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 resistors RP impact
the insertion loss as explained in the text, section
Transmission. The specified insertion loss is for RF = RP = 0.
6. The specified insertion loss tolerance does not include
errors caused by external components.
Notes
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
7. The level is specified at the two-wire port.
G2-4S = transmit gain, nominally = 1 (or 0.5 see pin PTG)
8. The two-wire idle noise is specified with the port
terminated in 600 Ω (RL) and with the four-wire receive
port grounded (ERX = 0; see figure 6).
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 Ω (R L). The noise
specification is referenced to a 600 Ω programmed two-
wire impedance level at VTX. The four-wire receive port is
grounded (ERX = 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 R T
into two equal halves and connecting a capacitor from the
common point to ground.
7
ERICSSON [ ERICSSON ]
