GENERAL DESCRIPTION
The TEA1093 is a bipolar circuit intended for use in line-powered telephone sets. In conjunction with a member of the TEA1060 family or PCA1070 transmission circuits, the device offers a hands-free function for line powered telephone sets. It incorporates a supply, a microphone channel, a loudspeaker channel and a duplex controller with signal and noise monitors on both channels.

FEATURES
• Line powered supply with:
   – adjustable stabilized supply voltage
   – power down function
• Microphone channel with:
   – externally adjustable gain
   – microphone mute function
• Loudspeaker channel with:
   – externally adjustable gain
   – dynamic limiter to prevent distortion
   – rail-to-rail output stages for single-ended or bridge-tied load drive
   – logarithmic volume control via linear potentiometer
   – loudspeaker mute function
• Duplex controller consisting of:
   – signal envelope and noise envelope monitors for both channels with:
      externally adjustable sensitivity
      externally adjustable signal envelope time constant
      externally adjustable noise envelope time constant
   – decision logic with:
      externally adjustable switch-over timing
      externally adjustable idle mode timing
      externally adjustable dial tone detector in receive
      channel
   – voice switch control with:
      adjustable switching range
      constant sum of gain during switching
      constant sum of gain at different volume settings.
  
APPLICATIONS
• Line-powered telephone sets with hands-free/listening-in functions.