The MT8870/CS9370 is a complete DTMF receiver integrating both the band-split 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 tone-pairs 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. CS9370 is pin to pin compatible with MT8870. PCB layout or circuit for MT8870 can be replaced with CS9370. Read datasheet for details of both the IC.