Description
These electronic subscriber loop interface circuits (SLICs) are optimized for low power consumption while providing an extensive set of features.
The SLICs include an auxiliary battery input and a built-in switch. In short-loop applications, they can be used in high battery to present a high on-hook voltage, and then switched to low battery to reduce offhook power.

FEATUREs
■ Auxiliary input for second battery, and internal switch to enable its use to save power
■ Low active power (typical 125 mW during on-hook transmission)
■ Supports meter pulse injection
■ Spare op amp for meter pulse filtering
■ –16 V to –60 V power supply operation
■ Distortion-free on-hook transmission
■ Convenient operating states:
    — Forward powerup
    — Disconnect (high impedance)
    — 2-wire wink (zero loop voltage)
■ Adjustable supervision functions:
    — Off-hook detector with longitudinal rejection
    — Ground key detector
    — Ring trip detector
■ Independent, adjustable, dc and ac parameters:
    — dc feed resistance
    — Loop current limit
    — Termination impedance
■ Thermal protection