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Número de pieza | 73M223 | |
Descripción | 1200 Baud FSK Modem | |
Fabricantes | ETC | |
Logotipo | ||
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No Preview Available ! 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
TEST
PHASE
COHERENT
WAVE
SYNTHESIZER
SYNC
PHASE LOCKED
LOOP
7;
7
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
1 page APPLICATION INFORMATION
The 73M223 modem chip allows low cost
communications in a private network, utilizing
twisted pair telephone wires. This chip is the prime
choice of those designers who require an efficient,
high performance modem solution for dedicated
private networks, HDX dial-up and other specialized
applications. Such applications include credit
verification systems, point-of-sale terminals, remote
process control, satellite and RF telemetery, private
data links and acoustic modem designs. No
microprocessors or external adjustments are
necessary with this device.
Utilizing a crystal input of 3.1872 MHz*, the 73M223
is a V.23 main channel 1200 Baud, FSK modem.
The signaling frequencies generated are 1302 Hz for
a logic “1” and 2097 Hz for a logic “0.” Crystals with
frequencies varying between 330 kHz to 7.0 MHz or
higher can be used. The baud rate and signaling
frequencies vary linearly with variation in crystal
73M223
1200 Baud FSK Modem
frequency. If compatibility with V.23 is not required, a
color burst 3.579 MHz crystal can be used as long
as the other modem uses the same frequency offset.
A typical implementation on the 73M223 is shown in
the figure below. A 73M1550 UART receives data to
be transmitted from a microprocessor bus. The
UART sends the data in a serial format to the
73M223 modem after inserting the necessary start
and stop bits. The modem transmits this data to the
far end via the TXA pin. Full-duplex operation can be
implemented by utilizing separate transmit and
receive circuits. A USART can be used instead of a
UART if synchronous operation is desired. With
synchronous operation, a USART uses the modem’s
SYNC signal for timing to sample the received data,
and the modem’s CLK signal for timing to send data
to be transmitted.
* Available from Ecliptek Corp. (714) 433-1200 and
SMI Inc. (916) 477-5085.
TXA
VDD
VDD
RXA
R2
100K
C4
C5 1 µF
0.1 µF
C3
R3
100K
0.1 µF
3.1872
MHz
C2
30 pF
Typ.
Y1
R1
1 MΩ
C1
30 pF
Typ.
U1
1
VDD
2 RXA
3
4 CAP
5 RXF
6
FIL
TEST
7 7;
8 VSS
73M223
TXA 16
CLK 15
OSC2 14
OSC1 13
TXD
RXD
12
11
6<1 10
SYNC 9
U1
28 VCC
27 '&'
1
D0
D1
2
26 '65
D2 3
25 &76
D3 4
24 MR
D4 5
23 '75
D5 6
22 576 16C550
D6 7
21 A0
D7 8
20 A1
19 A2
18
17
INTRPT
5,
SIN
SOUT
&6#
XIN
9
10
11
12
16 5'
XOUT 13
15 VSS
:5 14
73M223 TYPICAL APPLICATION
H
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5 Page |
Páginas | Total 6 Páginas | |
PDF Descargar | [ Datasheet 73M223.PDF ] |
Número de pieza | Descripción | Fabricantes |
73M223 | 1200 Baud FSK Modem | ETC |
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