MT8870DS

The MT8870DS is a type of complete DTMF receiver combining both the bandsplit filter and digital decoder functions. The filter section uses switched capacitor techniques for high and low group filters; the decoder of MT8870DS 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 offering of a differential input amplifier, clock oscillator and latched three-state bus interface.

Features of the MT8870DS are:(1)complete DTMF receiver;(2)low power consumption;(3)internal gain setting amplif ier;(4) adjustable guard time;(5)central office quality;(6)power-down mode;(7)Backward compatible with MT8870C/ MT8870C-1.

The absolute maximum ratings and electrical characteristics(VDD=5.0V± 5%, VSS=0V, -40°C TO +85°C,) of the MT8870DS can be summarized as:(1):DC power supply voltage (VDD) is 4.75V min,5.0V typ and 5.25 V max;(2):operating temperature is -40°C min and +85 °C max;(3):crystal/clock frequency is 3.579545 MHz typ;(4): crys tal/clock freq.tolerance is ±0.1 % typ.electrical characteristics:(1):standby supply current is 10 uA typ and 25 A max when  PWDN is VDD;(2):operating supply current is 3.0 mA typ and 9.0 mA max;(3):power consumption is 15 mW typ when fc is 3.579545 MHz;(4):High level input is 3.5 V  min when VDD is 5.0V;(5):low level input voltage is 1.5 V max when VDD is 5.0V;(6)input leakage current is 0.1 A when VIN is VSS or VDD;(7):low level output voltage is VSS+ 0.03 V max of no load;(8):high level output voltage is VDD-0.03 V min of no load;(9):output low (sink) current is 1.0 mA min and 2.5 mA when VOUT is 0.4 V.