U4090B
Monolithic Integrated Feature Phone Circuit
Description
The
µc
controlled telephone circuit U4090B is a linear
integrated circuit for use in feature phones, answering
machines and fax machines. It contains the speech circuit,
tone ringer interface with dc/dc converter, sidetone
equivalent and ear protection rectifiers. The circuit is line
powered and contains all components necessary for
amplification of signals and adaptation to the line.
An integrated voice switch with loudspeaker amplifier
allows loudhearing or handsfree operation. With an
anti-feedback function, acoustical feedback during
loudhearing can be reduced significantly. The generated
supply voltage is suitable for a wide range of peripheral
circuits.
Features
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DC characteristic adjustable
Transmit and receive gain adjustable
Symmetrical input of microphone amplifier
Anti-clipping in transmit direction
Automatic line loss compensation
Symmetrical output of earpiece amplifier
Built-in ear protection
DTMF and MUTE input
Adjustable sidetone suppression independent
of sending and receiving amplification
Speech circuit with two sidetone networks
Built-in line detection circuit
Integrated amplifier for loudhearing operation
Anti-clipping for loudspeaker amplifier
Improved acoustical feedback suppression
Power down
D
Voice switch
D
Tone ringer interface with dc/dc converter
D
Zero crossing detection
D
Common speaker for loudhearing and tone ringer
D
Supply voltages for all functional blocks of a
subscriber set
D
Integrated transistor for short circuiting the line
voltage
D
Answering machine interface
D
Operation possible from 10 mA line currents
Benefits
D
Savings of one piezo electric transducer
D
Complete system integration of analog signal proces-
sing on one chip
D
Very few external components
Applications
Feature phone, answering machine, fax machine, speaker
phone
Speech
circuit
Voice
switch
Audio
amplifier
Loudhearing
and
Tone ringing
MC with
EEPROM/
DTMF
94 8741
Tone
ringer
TELEFUNKEN Semiconductors
Rev. C1, 28-Oct-96
1 (34)
Preliminary Information
TEMIC [ TEMIC SEMICONDUCTORS ]
