U4055B Datasheet | TEMIC Semiconductors

Description The U4055B electronic speech circuit is a linear integrated circuit for use in telephone and other line fed terminal equipment. It replaces the mon speech circuit with carbon microphone, hybrid transformer, sidetone equivalent and ear protection rectifiers. A low-cost electrodynamic transducer is used as the earphone. It contains all ponents necessary for amplification of signals and adaption to the line. Features .. D An electronic circuit replaces the microphone hybrid transformer D Symmetrical input for dynamic or piezo microphone D High performance through the use of dynamic transducers as the earphone (non-linear distortion 2 %) D DTMF interface with muting D Supply voltage for dialer D High range of line feeding current D Input resistance independent of line current and sidetone suppression circuit. D Built-in ear protection by earphone voltage limiter D Operation possible from 8 m A x D Automatic line loss pensation U4055B1: High level mute; U4055B: Low level mute Figure 1. Block diagram and pin connection TELEFUNKEN Semiconductors Rev. A1, 06-May-96 1 (10) Preliminary Information U4055B/U4055B1 Pin Description Pin 1, 2 Symbol Function H1 and H2 The push-pull plementary outputs of the receive amplifier. Dynamic transducers with a minimum impedance of 100 W can be directly driven by these outputs. GND Ground. ST The output of the sidetone cancellation signal, which requires a balanced impedance of 8- 10 times the subscribers line impedance to be connected to Pin 13. CK2 Input to the line output driver amplifier. Transmit a.g.c. applied to this stage. CK1 The transmit pre-amp output respective of the DTMF output which is normally capacitively coupled to Pin 5. MIC 1, Inputs of symmetrical MIC 2 microphone amplifier with high mon mode rejection ratio. DTMF IN The DTMF input has an internal resistor connected to ground. It provides the load resistor for the emitter of a CMOS DTMF generator. This input is only active when MUTE (Pin 10) is...