June 1999
PBL 386 20/2
Subscriber Line
Interface Circuit
Description
The PBL 386 20/2 Subscriber Line Interface Circuit (SLIC) is a 90 V bipolar integrated
circuit for use in PBX,Terminal adapters and other telecommunications equipment.
The PBL 386 20/2 has been optimized for low total line interface cost and a high
degree of flexibility in different applications.
The PBL 386 20/2 has constant current feed, programmable to max. 30 mA.
A second lower battery voltage may be connected to the device to reduce short
loop power dissipation. The SLIC automatically switches between the two battery
supply voltages without need for external components or external control.
The SLIC incorporates loop current, ground key and ring trip detection functions.
The PBL 386 20/2 is compatible with loop start signaling.
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
two-wire impedance, complex or real, is set by a simple external network.
Longitudinal voltages are suppressed by a feedback loop in the SLIC and the
longitudinal balance specifications meet Bellcore TR909 requirements.
The PBL 386 20/2 package options are 24-pin SSOP, 24-pin SOIC and 28 pin PLCC.
Key Features
• 24-pin SSOP package
• High and low battery with automatic
switching
• 60 mW on-hook power dissipation in
active state
• On-hook transmission
• Long loop battery feed tracks Vbat for
maximum line voltage
• Only +5 V feed in addition to battery
• Selectable transmit gain (1x or 0.5x)
• No power-up sequence
• 44V open loop voltage @ -48V battery
feed
• Full longitudinal current capability
during on-hook state
• Analog over temperature protection
permits transmission while the
protection circuit is active
• Integrated Ring Relay driver
• Ground key detector
• Programmable signal headroom
Ring Relay
Driver
RRLY
DT
DR
TIPX
RINGX
HP
Ring Trip
Comparator
Input
Decoder
and
Control
C1
C2
C3
DET
Ground Key
Detector
LP
VBAT2
VBAT
Off-hook
Detector
PLD
REF
AGND
BGND
VF Signal
Transmission
VTX
RSN
P
B
PLC
3
PBL
86 2
0/2
PTG
24-pinSOIC, 24-pin SSOP, 28-pin PLCC
Figure 1. Block diagram.
1
38 PB
6 L
20
/2
Two-wire
Interface
L
38
VCC
Line Feed
Controller
and
Longitudinal
Signal
Suppression
POV
PSG
6
20
/2
ERICSSON [ ERICSSON ]
