The TEA1068 is a bipolar integrated circuit that performs all speech and line interface functions required in fully electronic telephone sets, and performs electronic switching between dialling and speech.
The Philips TEA1068 is a bipolar integrated circuit designed to perform all speech and line interface functions required in fully electronic telephone sets. It handles electronic switching between dialling and speech, featuring large gain setting ranges for both microphone and earpiece amplifiers. The circuit includes a voltage regulator with adjustable static resistance and provides supply for external circuitry.
Key features include symmetrical high-impedance inputs for dynamic, magnetic, or piezoelectric microphones, as well as an asymmetrical input for electret microphones. It supports Dual-Tone Multi-Frequency (DTMF) signal input with a confidence tone and offers a mute input for pulse or DTMF dialling. The receiving amplifier supports magnetic, dynamic, or piezoelectric earpieces with adjustable gain.
| Line voltage | 4.2 - 4.7 V |
|---|---|
| Line current (normal operation) | 10 - 140 mA |
| Microphone amplifier gain | 44 - 60 dB |
| Receiving amplifier gain | 17 - 39 dB |
| Exchange supply voltage | 24 - 60 V |
| Ambient operating temperature | -25 +75 °C |
The circuit supports dynamic, magnetic, piezoelectric, and electret microphones.
A HIGH level at MUTE enables the DTMF input and inhibits the microphone and the receiving amplifier inputs.
It reduces supply current to 55 pA and switches off the voltage regulator during line interruptions to minimize current waveform contribution.