The HC5549 Subscriber line
interface circuit is a 100V
diellectrically isolated bipolar
integrated circuit for use in
short loop ISDN, PABX and
Pairgain applications. The HC5549 has been optimized for low
power as required for battery backed remote terminals or for
applications requiring emergency powering from the line such
as European ISDN NT1+ designs.
A high and low voltage battery supply may be connected to
the HC5549 so that power dissipation can be lowered in the
off hook condition in these short loop applications. The high
battery supply can be used in the on-hook condition to allow
interfacing to fax and answering machines that require 48V
to detect end of call status. The HC5549 also has a low
power standby state with very low power consumption
(35mW) resulting in exceptionally low battery drain while
providing continued loop supervision.
The HC5549 provides loop current, ground key and ring trip
detect functions as well as an alarm output to indicate
thermal overload.
2-wire to 4-wire and 4-wire to 2-wire conversion is provided
and impedance matching is achieved using a single external
network. The HC5549 is compatible with dual and single
supply switched capacitor or DSP codec/filters

Features
• Dual Battery Operation
• Single Additional +5V Supply
• Low Standby Power Consumption (48V, 35mW)
• On Hook Transmission
• Tip and Ring Disconnect
• Soft or Hard Polarity Reversal
• Supports 12kHz or 16kHz Pulse Metering
• Ring Relay Driver
• On Chip 2-wire AC/DC Loopback
• 0°C to 70°C or -40°C to 85°C Ambient Temp Range
• Low External Component Count
• Pb-Free Available (RoHS Compliant)

Applications
• ISDN NT1+ Terminals
• Pairgain Remote Termination
• PABX and Key Systems