Description

The PBL 386 50/2 Subscriber Line Interface Circuit (SLIC) is a 90 V bipolar integrated

circuit for use in Central Office Metering applications and other telecommunications

equipment. The PBL 386 50/2 has been optimized for low total line interface cost and

a high degree of flexibility in different applications.

The PBL 386 50/2 emulates resistive loop feed, programmable between 2x50

Ω

and 2x900

Ω, with short loop current limiting adjustable to max 45 mA. In the current

limited region the loop feed is nearly constant current with a slight slope

corresponding to 2x30k

Ω.

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 50/2 is compatible with both loop and ground 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 50/2 package options are 24-pin SSOP, 24-pin SOIC or 28-pin PLCC.

Figure 1. Block diagram.

June 1999

PBL 386 50/2

Subscriber Line

Interface Circuit

Key Features

• 24-pin SSOP package

• Programmable two-wire signal

headroom for 2.2 V

• High and low battery with automatic

switching

• Only +5 V feed in addition to battery

• Selectable transmit gain (0.5x or 0.25x)

• 70 mW on-hook power dissipation in

active state

• On-hook transmission

• Long loop battery feed tracks Vbat for

maximum line voltage

• No power-up sequence

• 43V open loop voltage @

-48V battery feed

• Constant loop voltage for line leakage

<5 mA (RLeak ~ >10 k

Ω @ -48V)

• Full longitudinal current capability

during on-hook state

• Analog over temperature protection

permits transmission while the

protection circuit is active

• Line voltage measurement

• Polarity reversal

• Ground key detector

• Tip open state with ring ground

detector

24-pin SOIC, 24-pin SSOP, 28-pin PLCC

1

RRLY

C1

C2

C3

DET

PSG

REF

LP

PLD

PLC

VTX

RSN

PTG

BGND

AGND

VBAT

VBAT2

VCC

HP

RINGX

TIPX

DR

DT

Ring Relay

Driver

Input

Decoder

and

Control

Ring Trip

Comparator

Ground Key

Detector

Line Feed

Controller

and

Longitudinal

Signal

Suppression

Off-hook

Detector

VF Signal

Transmission

Two-wire

Interface

POV

PBL

386

50/2