PBL 386 50/2
R
S
TIPX
VBExt
PBL 386 50/2
RLRTo
RINGX
Figure 7. Tipx voltage.
Notes
1. The overhead voltage can be adjusted with the ROV resistor
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.
5. Pin PTG = Open sets transmit gain to nom. -6.02dB
Pin PTG = AGND sets transmit gain to nom. -12.04 dB
Secondary protection resistors RF 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.
2. The two-wire impedance is programmable by selection of
external component values according to:
ZTRX = ZT/|G2-4S α RSN| where:
7. The level is specified at the two-wire port.
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).
ZTRX = impedance between the TIPX and RINGX
terminals
ZT = programming network between the VTX and RSN
terminals
The four-wire idle noise at VTX is specified with the two-
wire port terminated in 600 Ω (RL). 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).
G2-4S = transmit gain, nominally = 0.5 (or 0.25 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).
9. Previous state must be active - loop or ground key
detector.
10. If |VBExt| ≥ |VBat + 2 V|, where VBat is the voltage at VBAT pin,
the current ILeak is limited to ≈ 5mA.
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 overhead voltage can be adjusted with the ROV
resistor for higher levels e.g. min 1.6 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 = 0.5 (or 0.25 see
pin PTG). The overhead voltage is dependent on G2-4S and
POV setting.
7
ERICSSON [ ERICSSON ]
