73M223

1200 Baud FSK Modem

February 1998

DESCRIPTION

The 73M223 modem device receives and transmits

serial and binary data over existing telephone

networks using Frequency Shift Keying (FSK). It

provides the filtering, modulation, and demodulation

to

implement

a

serial,

asynchronous

data

communication channel. The 73M223 employs the

CCITT V.23 signaling frequencies of 1302 and 2097

Hz, operating at 1200 baud, and is intended for half

duplex operation over a two-line system.

The 73M223 provides a cost-effective alternative to

existing modem solutions. It is ideally suited for R.F.

data links, credit verification systems, point-of-sale

terminals, and remote process control.

CMOS technology ensures small size, low-power

consumption and enhanced reliability.

FEATURES

•

Low cost FSK Modem

•

1200 baud operation

•

CMOS switched capacitor technology

•

Built-in self-test feature

•

On-chip filtering, and

Modulation/Demodulation

•

Uses CCITT V.23 frequencies

•

On chip crystal oscillator

•

Low power/High reliability

•

Does not require a microprocessor

•

10 mW @ 5 V supply

•

16-pin plastic packages

BLOCK DIAGRAM

OSC1

OSC2

OSC

13

14

TXD

12

7(67

TEST

7;

7

16

15

PHASE

COHERENT

WAVE

SYNTHESIZER

PROGRAMMABLE

DIGITAL

DIVIDER

DIGITAL

TIMING

SIGNALS

SYNC

PHASE LOCKED

LOOP

TXA

CLK

9

15

SYNC

6<1

7(67

TEST

SLICER

RXA

FIL

5

2

DIGITAL

DEMODULATOR

DIGITAL

LP

FILTER

DELAY

TEST

7(67

11

RXD

TEST

6

RANDOM

SEQUENCE

GENERATOR

SWITCHED CAP

BANDPASS

FILTER

4

RXF

3

CAP

1

VDD

8

VSS