The BA6566, BA6566F, and BA6566FP are speech network ICs which possess the basic functions required for handset communications. In addition to amplifying signals from a transmitter and sending them to a telephone line, they amplify only reception signals from a telephone line and drive the receiver. They also compensate for fluctuation in the volume at which signals are transmitted and received, caused by the length of the telephone line (AGC).

Features
1) Can accommodate both dynamic and piezoelectric
   receivers, simply by changing the circuit constant for
   a wide dynamic reception range.
2) Automatic gain control (AGC) is used, based on the
   transmission and reception telephone line current,
   for easier compliance with communications standards.
3) Erroneous operation caused by high-frequency electrical
   wave interference is minimized.
4) An HSOP package is used, eliminating the need for
   an attached transistor to dissipate heat. This means
   that a common circuit can be shared when a DIP
   package is used (BA6566FP).
  
Applications
   Telephones and telephone equipment