March 1999
PBL 3762A/2, PBL 3762A/4
Subscriber Line
Interface Circuit
Description
The PBL 3762A/2 Subscriber Line Interface Circuit (SLIC) is a bipolar integrated
circuit in 90 V technology which replaces the conventional transformer based analog
line interface circuit in Digital Loop Carrier, PABX and other telecommunications
equipment with a modern, compact solid state design. Not only is required PCB area
reduced, but lesser component weight and height result as well. The PBL 3762A/2
has been optimized for low cost and to require only a minimum of external
components.
The PBL 3762A/2 is an improved version of the PBL 3762.
The PBL 3762A/2 programmable, resistive battery feed system can operate with
battery supply voltages down to 21 V to reduce line card power dissipation.
The SLIC incorporates loop current, ground key and ring trip detection functions as
well as a ring relay driver.
Two- to four-wire and four- to two-wire voice frequency (vf) signal conversion is
accomplished by the SLIC in conjunction with either a conventional CODEC/filter or
with a programmable CODEC/filter (e.g. SLAC, SiCoFi, Combo II). The programmable
line terminating impedance could be complex or real to fit every market.
Longitudinal line voltages are suppressed by a feedback loop in the SLIC. Longitu-
dinal balance specifications exceed Bellcore and EIA requirements.
The PBL 3762A/2 has an external saturation guard programming resistor while the
PBL 3762A/4 has a preset open loop voltage of 45V.
The PBL 3762A/2 and PBL 3762A/4 packages are 22-pin dual-in-line or 28-pin
PLCC.
Key Features
• Battery feed characteristics
programmable via external resistors;
feed characteristics independent of
SLIC battery supply variations
• Battery supply voltage as low as 21 V
for power efficient line card designs
• Ring relay driver
• Loop current, ground key and ring trip
detection functions
• Programmable loop current detector
threshold
• Hybrid function with all types of
CODEC/filter devices
• Programmable line terminating
impedance, complex or real
• On-hook transmission
• Longitudinal balance specifications in
excess of Bellcore and EIA
requirements
• Low 35 mW @-24 V on-hook power
dissipation
• Tip-ring open circuit state for
subscriber loop power denial
Ring Relay
Driver
9
RINGRLY
• -40°C to +85°C ambient temperature
range
DT
DR
TIIPX
HPR
HPT
RINGX
VCC
VEE
VBAT
AGND
BGND
3
4
5
1
22
6
8
20
10
18
7
16
C1
14
DET
Two-wire
Interface
Line Feed
Controller
and
Longitudinal
Signal
Suppression
P
B
Ground Key
Detector
12
E1
L
376 PBL
2A/2
22-pin plastic DIP
28-pin PLCC
Input
Decoder and
Control
13
E0
17
11
RDC
RSG
Off-hook
Detector
2
21
RD
VTX
RSN
VF Signal
Transmission
19
Figure 1. Block diagram.
1
37
62
A
/2
Ring Trip
Detector
15
C2
ERICSSON [ ERICSSON ]
