70 Ohm terminations plus additional
receivers, the data bus signal
produced is 7.5 volts nominal P-P at
A-A’. (See Figure 5) When both
DATA and DATA inputs are held low
or high, the transmitter output
becomes a high impedance and is
“removed” from the line. In addition,
an
overriding
“INHIBIT
input
provides for the removal of the
transmitter output from the line. A
logic “1” applied to the “INHIBIT”
takes priority over the condition of
the data inputs and disables the
transmitter. (See Transmitter Logic
Waveform, Figure 1.)
The transceiver utilizes an active
filter to suppress harmonics above
1 MHz to meet Macair specifications
A-3818, A-4905, A-5232 and
A-5690. The Transmitter may be
safely operated at 100% duty
cyclefor an indefinite period into a
short circuited, the 1553 or Macair
bus.
The pre-set internal thresholds will
detect data bus signals exceeding
1.150 Volts P-P and reject signals
less than 0.6 volts P-P when used
with a 1:1 turns ratio transformer.
(See Figure 5 for transformer data
and typical connection.)
Receiver
The Receiver section accepts
bi-phase differential data at the input
and produces two TTL signals at the
output. The outputs are DATA and
DATA, and represent positive and
negative excursions of the input
beyond
a
pre-determined
threshold.(See
Receiver
Logic
Waveform Figure 2).
Figure 1 – Transmitter Logic Waveforms
DATA IN
DATA IN
INHIBIT
LINE TO LINE
OUTPUT
NOTES:
1. DATA and DATA inputs must be complementary waveforms or 50% duty cycle average, with no delays between them.
2. DATA and DATA must be in the same state during off time (both high or low).
Figure 2 – Receiver Logic Waveforms
LINE TO LINE
INPUT
DATA OUT
DATA OUT
Note overlap
NOTE
:
Waveforms shown are for normally low devices. For normally high receiver output
level devices,the receiver outputs are swapped as shown by the dashed lines.
,
Aeroflex Circuit Technology
2
SCD4810 REV B 8/12/98
Plainview NY (516) 694-6700
AEROFLEX [ AEROFLEX CIRCUIT TECHNOLOGY ]
