GENERAL DESCRIPTION
The UBA1707 is a BiCMOS integrated circuit intended for use in mains-powered telecom terminals. It performs all speech and line interface functions, DC mask for voltage or current regulation and electronic hook switch control. The device includes an auxiliary amplifier, a loudspeaker channel and general purpose switches.

FEATURES
Line interface
• Low DC line voltage; operates down to 1.2 V (excluding polarity guard)
• Voltage regulator with adjustable DC voltage
• DC mask for voltage or current regulation (CTR 21)
• Line current limitation for protection
• Electronic hook switch control input
• Transmit amplifier with:
    – Symmetrical inputs
    – Fixed gain
    – Large signals handling capability.
• Receive amplifier with fixed gain
• Transmit and receive amplifiers AGC for line loss compensation.

Auxiliary amplifier
• Fixed gain.

Loudspeaker channel
• Dual inputs
• Rail-to-rail output stage for single-ended load drive
• High output current capability
• Dynamic limiter to prevent distortion
• Digital volume control
• Fixed maximum gain

General purpose switches
• Three switches with open-collector.

3-wires serial bus interface
Allows to control:
• DC mask (voltage or current regulation)
• Receive amplifier mute function
• AGC:
    – On/off
    – Slope
    – Istart line current.
• Auxiliary amplifier mute function
• Loudspeaker channel:
    – Input selection
    – Volume setting
    – Dynamic limiter inhibition
    – Power-down mode.
• General purpose switches state
• Global power-down mode.

Supply
Operates with external supply voltage from 3.0 to 5.5 V.

APPLICATIONS
• Cordless base stations
• Answering machines
• Mains or battery-powered telephone sets.