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.
73M223
1200 Baud FSK Modem
FEATURES
February 1998
• 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 13 14 OSC2
TXD
12
7(67
OSC
PROGRAMMABLE
DIGITAL
DIVIDER
DIGITAL
TIMING
SIGNALS
RXA 2
FIL 5
7(67
TEST
SLICER
DIGITAL
DEMODULATOR
RXF 4
SWITCHED CAP
BANDPASS
FILTER
7;
7
TEST
PHASE
COHERENT
WAVE
SYNTHESIZER
SYNC
PHASE LOCKED
LOOP
DIGITAL
LP
FILTER
DELAY
RANDOM
SEQUENCE
GENERATOR
7(67
TEST
3 CAP
1
VDD
8
VSS
16 TXA
15 CLK
9 SYNC
15 6<1
11 RXD
6 TEST