Features

• Because it is possible to switch the Balancing Network between two systems, one for the near end and one for the far end, in accordance with the line current, this IC provides excellent sidetone characteristics over a wide range of line currents.

• Receiver amplifier supports ceramic receivers and dynamic receivers.

• Power amplifier on chip (VCC = 5 V, RL = 8 Ω, PO = 200 mW).

• Crosspoint switches allow full mixing, permitting the implementation of a variety of functions, such as three- or four-way calls.

• Digital volume control on chip (power system output).

Functions

Speech network block

• 2-wire/4-wire conversion

• Line driver

• Transmitting amplifier

• Receiving amplifier (with ATT)

• Power supply switching circuit

• Impedance matching

• DTMF interface

• Key tone interface

• BN circuit network switching circuit (BN = Balancing Network)

Signal processor block

• Record preamplifier (with ALC)

• Record amplifier

• Power amplifier (VCC = 5 V, RL = 8 Ω, PO = 200 mW)

• Playback equalizer amplifier

• Voice detector (VOX)

• Electronic volume control (4 dB, 7 steps)

Crosspoint switch block

• Crosspoint switches (mixing available)

• CPU interface