Counter based ringer interface

A counter based ringer interface circuit for generating a ringer signal for controlling a ringer in a telephone, comprising:

• a first frequency divider, said first frequency divider adapted to receive a ringer clock signal and generate a first frequency divider output therefrom;
• a second frequency divider coupled to receive said first frequency divider output, said second frequency divider adapted to generate a second frequency divider output using said first divider frequency output, said second frequency divider further adapted to generate a oversampled audio frequency signal;
• a third frequency divider coupled to receive said second frequency divider output, said third frequency divider adapted to generate a period signal using said second frequency divider output;
• and
• a modulator coupled to receive said oversampled audio frequency signal and said period signal, said modulator adapted to generate a ringer signal having a pulse width according to said oversampled audio frequency signal and a period according to said period signal, said modulator further adapted to output said ringer signal to control a telephone ringer, said modulator including a positive and negative ringer frequency output such that said ringer signal is output differentially;
• a ringer enable input coupled to said modulator, said first frequency divider, said second frequency divider, and said third frequency divider to enable or disable said ringer interface circuit.

In a counter based ringer interface circuit coupled to a ringer in a telephone, a method of generating a ringer signal for controlling the ringer, the method comprising the steps of:

• a) receiving a ringer clock signal;
• b) generating a first divided frequency output using the ringer clock signal;
• c) generating a second divided frequency output using the first divided frequency output;
• d) generating a register output by counting the first divided frequency output;
• e) generating a period output by counting the second divided frequency output;
• f) generating a ringer signal having a pulse width according to said register output and a level setting and a period according to said period output;
• and
• g) outputting said ringer signal to control the ringer of a telephone.