fx469 Consumer Microcircuits Limited, fx469 Datasheet - Page 4

• Manufacturer Part Number: fx469
• Description: 1200/2400/4800 Baud Ffsk Modem
• Manufacturer: Consumer Microcircuits Limited

Application Information
Fig.2 External Components
Fig.3 Suggested FX469 Test Set-Up
Component
PSEUDO-RANDOM
PREAMBLE &
GENERATOR
R
C
C
C
C
C
C
C
X
1
1
1
2
3
4
5
6
7
DATA
C
1
C
C
6
2
V
Tx SYNC
DD
C
X
7
DATA
1
I/P
Tx
1.008MHz
4.032MHz
1.0MW
33.0pF
33.0pF
R
Value
1.0µF
0.1µF
0.1µF
1.0µF
1.0µF
1
or
OSCILLOSCOPE
TRANSMITTER
Tx SIGNAL O/P
BANDPASS O/P
(components
AMMETER
as Fig. 2)
Tx SYNC O/P
XTAL/CLOCK
MILLI-
FX469
Tx DATA I/P
Rx ENABLE
Tx ENABLE
V
DD
XTAL
V
V
V
SS
BIAS
SS
‘Clock-Rate’
SIGNAL
Tolerance
O/P
Tx
±10%
±20%
±10%
±20%
See
Pin
VOLTMETER
1
2
3
4
5
6
7
8
9
10
11
TRUE RMS
(INTERFACE)
BUFFER
CIRCUIT
FX469J
V
V
DD
SS
4
Notes
1. V
2. Use C
3. The value of C
4. C
5kHz BW noise gen)
when input signals are referenced to the V
input signals referenced to V
using C
decouple V
constant. A long time constant results in improved noise
immunity but increased response time. C
to trade-off response time for noise immunity.
Application Note D/XT/2 December 1991.
(with attenuator
TELEPHONE
SIMULATOR
19
18
16
13
22
20
17
15
14
12
21
CHANNEL
BIAS
7
reduces Xtal voltage overshoot. Refer to CML Xtal
&
may be decoupled to V
5
2
when input signals are referenced to V
CARRIER DETECT
TIME CONSTANT
CLOCK RATE
4800 BAUD SELECT
Rx SYNC O/P
1200/2400 BAUD SELECT
CARRIER DETECT O/P
CLOCKED DATA O/P
UNCLOCKED DATA O/P
V
only.
C
DD
DD
VOLTMETER
3
TRUE RMS
.
SIGNAL
Rx SIGNAL I/P
Rx
I/P
4
determines the Carrier Detect time
(components
AMMETER
RECEIVER
as Fig. 2)
MILLI-
FX469
V
V
SS
DD
V
SS
SS
SS
and V
, decouple V
CARRIER
DETECT
C
C
O/P
CLOCKED
DATA O/P
5
4
SYNC
DD
Rx
using C
4
may be varied
DETECTOR
DETECTOR
O/P HIGH
CARRIER
BIAS
DETECT
ERROR
BIAS
2
pin. For
and C
to V
SS
, to
SS
6