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.
Complete DTMF Receiver
Low power consumption
Internal gain setting amplifier
Adjustable guard time
Central office quality
Backward compatible with MT8870C/MT8870C-1
Receiver system for British Telecom (BT) or CEPT Spec (MT8870D-1)