
PEB/F 4065
Overview
Semiconductor Group
6
1998-03-01
Controlled by C2, the polarity of
V
ab
can be reversed and the DC-line-voltage then is
V
abDC
= – (
V
BAT
–
V
HINT
+
V
fix
– 40
×
V
2WDC
).
The transversal and longitudinal currents are measured in the buffers and scaled images
are provided at the
I
T
and
I
L
pin, respectively:
I
T
= (
I
a
+
I
b
)/100 =
I
ab
/50
I
L
= – (
I
a
–
I
b
)/100 = –
I
Long
/50.
The PEB 4065 operates in four modes controlled by ternary logic signals at the C1 and
C2 input. Additionally, in the active modes a polarity reversal of the output voltage can
be programmed (see
Table 1
).
Power down (PD): Power consumption is reduced by decreasing bias current levels. All
functions operate at some small performance reductions. In this mode each of the line
outputs can be programmed to show high impedance. HI b switches off the TIP buffer,
while the current through the RING output still can be measured by
I
T
or
I
L
. Programming
HI a reverses the polarity and switches off the RING buffer.
Conversation (CONV): This is the regular transmit and receive mode for voiceband and
teletax. The line driving section is operated between
V
BAT
and BGND.
Boosted battery (BB): In order to drive longer telephone lines an auxiliary positive battery
voltage
V
H
is used, enabling a higher DC-voltage across the line.
Ringing (RING): This mode also uses the auxiliary voltage
V
H
in order to provide a
balanced ring signal of up to 85 Vrms. The ring tone without any DC-component has to
be switched to the
V
2W
input. Internally a DC-voltage is superimposed. This voltage is
proportional to the total supply voltage
V
H
–
V
BAT
and amounts to typically 23 V at
V
H
–
V
BAT
= 120 V. The current sensing functions are available for ring trip detection.
The Power Denial (PDN) state is intended to reduce power consumption of the linecard
to a minimum: the PEB 4065 is switched off completely by connecting the PDN pin to
V
DD
, no operation is available.
With respect to the output impedance of TIP and RING two PDN-modes have to be
distinguished. A resistive one (PDNR) provides a connection of 15 k
each from TIP to
BGND and RING to
V
BAT
, respectively, while the outputs of the buffers show high
impedance (
Figure 3
).
The other mode (PDNH) offers high impedance at TIP and RING. It is entered when, in
addition to connecting PDN to
V
DD
, the programming inputs C1, C2 are tied to
V
IL
.
All other combinations of C1, C2 yield the resistive power denial state PDNR.