Description of MT8870 DTMF Receiver The MT8870D/MT8870D-1 is a complete DTMF receiver integrating both the bandsplit filter and digital decoder functions. The filter section uses switched capacitor techniques for high and low group filters; the decoder uses digital counting techniques to detect and decode all 16 DTMF tonepairs into a 4-bit code. External component count is minimized by on chip provision of a differential input amplifier, clock oscillator and latched three-state bus interface. Features Complete DTMF Receiver Low power consumption Internal gain setting amplifier Adjustable guard time Central office quality Power-down mode Inhibit mode Backward compatible with MT8870C/MT8870C-1 Applications Receiver system for British Telecom (BT) or CEPT Spec (MT8870D-1) Paging systems Repeater systems/mobile radio Credit card systems Remote control Personal computers Telephone answering machine
