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