March 1999
PBL 3764A/4, PBL 3764A/6
Subscriber Line
Interface Circuit
Description
Note: All data is also valid for PBL 3764A/6, except maximum ratings for battery
voltage. (See next page)
The PBL 3764A/4 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 3764A/4
has been optimized for low cost and to require only a minimum of external
components.
The PBL 3764A/4 is an improved version of the PBL 3764 with an internal
saturation guard programming resistor.
The PBL 3764A/4 programmable, constant-current 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 3764A/4 packages are 22-pin dual-in-line or 28-pin PLCC.
The PBL 3764A/6 package is 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
• -40
°C
to +85
°C
ambient temperature
range
• -85 V battery supply voltage for ring
applications (PBL 3764A/6)
Ring Relay
Driver
DT
DR
TIIPX
HPR
HPT
RINGX
VCC
VEE
VBAT
AGND
BGND
3
4
5
1
22
6
8
20
10
18
7
9
RINGRLY
16
C1
C2
E0
E1
DET
Ring Trip
Detector
Input
Decoder and
Control
15
13
12
14
Ground Key
Detector
Line Feed
Controller
and
Longitudinal
Signal
Suppression
Two-wire
Interface
17
11
RDC
RSG
L
PB
/4
4A
376
L
B /4
P A
37
Off-hook
Detector
64
2
21
RD
VTX
RSN
VF Signal
Transmission
19
22-pin plastic DIP
28-pin PLCC
Figure 1. Block diagram.
1
ERICSSON [ ERICSSON ]
