74HC942 Datasheet | National Semiconductor

Description The MM74HC942 is a full duplex low speed modem It provides a 300 baud bidirectional serial interface for data munication over telephone lines and other narrow bandwidth channels It is Bell 103 patible The MM74HC942 utilizes advanced silicon-gate CMOS technology Switched capacitor techniques are used to perform analog signal processing Features Y Y Y Y Y Y Y .. MODULATOR SECTION The modulator contains a frequency synthesizer and a sine wave synthesizer It produces a phase coherent frequency shift keyed (FSK) output LINE DRIVER AND HYBRID SECTION The line driver and hybrid are designed to facilitate connection to a 600X phone line They can perform two-to-fourwire conversion and drive the line at a maximum of 0 d Bm DEMODULATOR SECTION The demodulator incorporates anti-aliasing filters a receive filter limiter discriminator and carrier detect circuit The nine pole receive filter provides 60 d B of transmitted tone rejection The discriminator is fully balanced for stable operation Drives 600X at 0 d Bm All filters on chip Transmit level adjustment patible with universal service order code TTL and CMOS patible logic All inputs protected against static damage g 5V supplies Low power consumption Full duplex answer or originate operation Analog loopback for self test Power down mode Applications Y Y Y Y Y Y Y Y Built-in low speed modems Remote data collection Radio telemetry Credit verification Stand-alone modems Point-of-sale terminals Tone signalling systems Remote process control TRI-STATE is a registered trademark of National Semiconductor Corp Connection and Block Diagrams Dual-In-Line Package TL F 5348- 1 Top View Order Number MM54HC942 or MM74HC942 TL F 5348 - 2 C1995 National Semiconductor Corporation TL F 5348 RRD-B30M105 Printed in U S A Absolute Maximum Ratings (Notes 1 2) Operating Conditions Supply Voltage (VCC) Supply Voltage (VBB) DC Input or Output Voltage (VIN VOUT) Operating Temp Range (TA) MM74HC Input Rise or Fall Times (tr...