MS8870

MOSA ELECTRONICS Features Complete DTMF receiver Low power consumption Adjustable guard time Central Office Quality CMOS, Single 5V operation O www.DataSheet4U.com MS8870 DTMF Receiver rdering Information MS8870 : 18 PIN DIP PACKAGE Description 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 MITEL8870. 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. Figure 1. Functional Block Diagram － 1 － MOSA ELECTRONICS Pin Description Pin # 1 2 3 4 5 6 7 www.DataSheet4U.com 8 9 10 11-14 15 Name IN + IN GS VREF IC IC OSC1 OSC2 Vss TOE Q1-Q4 StD Description MS8870 DTMF Receiver 16 ESt 17 St/GT 18 VDD Non-inverting op-amp input. Inverting op-amp input. Gain select. Gives access to output of front end differential amplifier for connection of feedback resistor. Reference voltage output, nominally VDD /2 is used to bias inputs at mid-rail (see Fig. 2). Internal connection. Must be tied to Vss. Internal connection. Must be tied to Vss. Clock input. Clock output. A 3.5795 MHz crystal connected between OSC1 and OSC2 completes the internal oscillator cir...