Aeroflex Circuit Technology

SCD4435 REV B 2/3/99 Plainview NY (516) 694-6700

2

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 1 mHz to meet H 009 Macair speci-

fications. 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 repre-

sent 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 1.05 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.)

A low level at the Strobe input inhibits the DATA

and DATA outputs. If unused, a 2K pull-up to +5 Volts

is recommended

DATA IN

DATA IN

INHIBIT

LINE TO LINE

OUTPUT

Figure 1 - Transmitter Logic Waveforms

Figure 2 - Receiver Logic Waveforms

Note overlap

devices, the receiver outputs are swapped as shown by the dashed lines

level

LINE TO LINE

INPUT

Rx DATA OUT

Rx DATA OUT

Notes: 1. Data and DATA inputs must be complementry 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, (Terminate Mode), Region 3, Transmitter signal

on, low Z.

Region 1

2

3