HC3-55564-5

Low Bit Rate Voiceband Encoders/Decoder Semiconductor February 1999 T UCT ROD ACEMEN 47 P E 7 T L OLE REP 00-442-7 OBS ENDED 8 M ns 1 .com COM pplicatio @harris E R NO ntral A entapp Ce : c Call or email HC-55564 Continuously Variable Slope Delta-Modulator (CVSD) Features All Digital Requires Few External Parts Low Power Drain: 1.5mW Typical From Single 4.5V To 6V Supply Time Constants Determined by Clock Frequency; No Calibration or Drift Problems: Automatic Offset Adjustment Half Duplex Operation Under Digital Control Filter Reset Under Digital Control Automatic Overload Recovery Automatic “Quiet” Pattern Generation AGC Control Signal Available Description The HC-55564 is a half duplex modulator/demodulator CMOS intergrated circuit used to convert voice signals into serial NRZ digital data and to reconvert that data into voice. The conversion is by delta-modulation, using the Continuously Variable Slope (CVSD) method of modulation/demodulation. While the signals are compatible with other CVSD circuits, the internal design is unique. The analog loop filters have been replaced by very low power digital filters which require no external timing components. This approach allows inclusion of many desirable features which would be difficult to implement using other approaches. The fundamental advantages of delta-modulation, along with its simplicity and serial data format, provide an efficient (low data rate/low memory requirements) method for voice digitizat...