The MS8870 is a complete DTMF receiver integrating both the bandsplit filter and digital decoder functions, fabricated in double poly technology and is pin and function compatible with MITEL 8870.
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 3-state bus interface.