The HC5549 is a low power SLIC for use in short loop ISDN, PABX and Pairgain applications.
The HC5549 is a low‑power subscriber line interface circuit (SLIC) designed for short‑loop ISDN, PABX and Pairgain applications. It supports dual‑battery operation, a single additional +5 V supply, and provides loop current, ground key, ring‑trip detection and alarm output functions. The device can be powered from a high‑battery source for on‑hook operation (e.g., fax detection) or from a low‑battery source for standby, achieving very low power consumption.
Typical applications include ISDN NT1+ terminals, Pairgain termination, and any remote terminal that requires emergency power from the line. The datasheet details operating modes, electrical specifications, pin assignments, and a basic application circuit for designers.
| Low Standby Power Consumption | 35 mW |
|---|---|
| Operating Temperature Range | -40 °C to 85 °C |
| Loop Current Limit | 25 mA |
| On‑Hook Power Dissipation (Forward/Reverse, BSEL=0) | 44 mW to 60 mW |
| Low Power Standby Power Dissipation (BSEL=1) | 37 mW to 60 mW |
The device consumes about 35 mW in low‑power standby mode.
It operates from –40 °C up to 85 °C ambient temperature.
The HC5549 supports dual‑battery operation (high and low battery supplies).
The loop current limit is specified as 25 mA.