AN1500A

The SA2532K device was developed to provide "plug & play" solution for the Indian DOT, emphasizing high performance voice transmission and reception. In spite of the fact that voice transmission and reception are the most vital features in telephony, they are very often ignored or given lower priority ompared with some more or less useless non-voice features. No compromises were accepted during the design phase of the SA2532K, which is based on the SA2531/2 speech circuit and which supersedes even the hardest PTT requirements worldwide.

The dialler part is based on a long history of producing a wide range of dialer circuits with user-friendly features in compliance with various national PTT regulations. This knowledge enabled us to develop a specific product to meet with DOT type approval.

The last piece in the puzzle to complete the full picture of the first CMOS single chip POT was the tone ringer. A ring frequency discrimination circuit was implemented to avoid false "bell-tinkle" during pulse dialing from a parallel telephone. The 3-tone melody generator provides the ringing signal.

Note: all the subsequent component numbering is referenced to the AN1500 schematic, shown in pt.22