AS2535 Analog Telephone IC

Description

The AS253x is a very flexible CMOS integrated circuit family that contains all the functions needed to build a high performance electronic telephone set with basic features.

The AS253x incorporates a line interface, a speech circuit, a dialler and ringer. It is a real single-chip / single-die IC with 28 pins. It allows either package mounting or chip-onboard mounting.

The device is available in 4 versions (pin-compatible) with different features ranging from LNR only (last number redial) to 4 direct (one-touch) memories and 10 indirect (two-touch) memories. The sliding cursor procedure makes the LNR function easy to use under various PABX systems.

The versatility of the circuit is provided by pin options and a few external components. This allows fast time-to-market and easy adaptation to different PTT requirements. A unique EMI performance has been achieved due to the consequent use of CMOS amplifiers.

Key Features

• Line Interface and Speech Circuit
  • Electronic Rx volume control
  • Electronic microphone mute
  • Microphone amplifier with symmetrical input
  • Rx and Tx soft clipping to avoid harsh distortion
  • Real or complex impedance (EU compliant)
  • Stabilized supply for dialler and peripherals
  • Automatic line loss compensation
  • Operating range from 13 mA to 100 mA (down to 5 mA with reduced performance)
  • Unique EMI performance (EU compliant)
• Dialler
  • LD/MF dialing and mixed-mode dialing
  • 31 digit last number redial (LNR)
  • 4 direct/10 indirect (AS2533/6), 12 direct (AS2535)
  • Repeat dialing by busy or engaged (not AS2535)
  • Confidence tone during memory programming and mute
  • Notepad memory function
  • Pause key for access pause or wait function
  • 3 flash timings, 100 ms, 280 ms and 375/600 ms
  • Sliding cursor protocol with comparison
• Ringer
  • Ring frequency discrimination
  • 3-tone melody generator
  • Ring melody selection via keyboard
  • Ring volume selection via keyboard
• Package
  • SOIC 28 or DIE

Block diagram for AS2535 Analog Telephone IC