73M223 Ver la hoja de datos (PDF) - TDK Corporation
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73M223 Datasheet PDF : 6 Pages
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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
R2
100K
C4
RXA
0.1 µF
C5 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
H
O
U1
28 VCC
27 '&'
26 '65
1
D0
D1
2
D2 3
S
T
25 &76
D3 4
24 MR
D4 5
23 '75
22 576 16C550
D5 6
D6 7
I
21 A0
20 A1
19 A2
18
17
INTRPT
5,
D7 8
9
SIN
SOUT
10
&6# 11
12
XIN
N
T
E
16 5'
15 VSS
XOUT 13
:5 14
R
F
A
C
E
73M223 TYPICAL APPLICATION
5
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