A-A’ (See Figure 5). When both
DATA and DATA inputs are held low
or high, the transmitter output
impedance is low, and signal is
“removed” from the line. In
addition, an overriding “INHIBIT”
input returns the output impedance
to a high state. A logic “1” applied
to the “INHIBIT” takes priority over
the condition of the data inputs and
disables the transmitter. (See
Transmitter
Logic
Waveforms,
Figure 1).
The transmitter utilizes an
active filter to suppress harmonics
above 1MHz to meet H009
specification. The transmitter may
be safely operated for an indefinite
period with the output short
circuited at 100% duty cycle.
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
Waveforms, Figure 2).
The internal threshold is
nominally set to detect data bus
signals exceeding 1.0 Volts P-P
when used with a 1:1 turns ratio
transformer (See Figure 5 for
transformer data and typical
connection).
A low level at the Strobe input
inhibits the DATA and DATA
outputs. The strobe is internally
pulled up, therefore a pull resistor
is not needed.
Figure 1A – Tx Output Truth Table
DATA
X
H
L
H
L
DATA
X
H
L
L
H
INHIBIT
H
L
L
L
L
OUTPUT
High Z
Low Z
(No signal)
Low Z
(Signal)
Figure 1B - Transmitter Logic Waveforms
Region
DATA IN
1
2
3
4
1
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, and in the same state during
the off time (both high and low).
2.
Region 1;
no output signal, High Z state, (Receive Mode),
Region 2;
No Output signal, Low Z state,
Region 3;
Transmitter signal
on, low Z (Transmitter mode),
Region 4;
No Output signal, Low Z state, (Terminate Mode).
Figure 2 - Receiver Logic Waveforms
LINE TO LINE
INPUT
Rx DATA OUT
Note overlap
Rx DATA OUT
Aeroflex Circuit Technology
2
SCD4469D REV A 5/21/01 Plainview NY (516) 694-6700
AEROFLEX [ AEROFLEX CIRCUIT TECHNOLOGY ]
