PBL 3764 A
Subscriber Line
Interface Circuit (SLIC)
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
Figure 1. Block diagram.
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
Off-hook
Detector
2
21
RD
VTX
RSN
VF Signal
Transmission
19
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 technolo-
gy 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. Longitudi-
nal 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.
ERICSSON [ ERICSSON ]
