SCD4444 Rev B

FEATURES

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Transceiver meets MIL-STD-1553A & B, Macair A3818, A4905, A5232 and A5690 specs

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Bipolar Supply ±15V to ±12V, Logic Supply +5V

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Replacement for function of CT3232 & ACT4404 in new designs

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Voltage source output

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Monolithic construction

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Aeroflex is a Class H & K MIL-PRF-38534 Manufacturer

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Miniature Chipscale Package Bumped Chip Carrier

GENERAL DESCRIPTION

The Aeroflex Laboratories transceiver model ACT4444 is a

monolithic transceiver which provides full compliance with Macair and

MIL-STD-1553 data bus requirements. The model ACT4444 performs the front-end analog function of inputting and outputting data through a

transformer to a MIL-STD-1553 or Macair data bus with a few external components.

The ACT4444 can be considered a "Universal" Transceiver in that it is compatible with MIL-STD-1553A, B, Macair A-3818, A-4905, A-5232

and A-5690.

Design of these transceivers reflects particular attention to active filter performance. This results in low bit and word error rate with superior

waveform purity and minimal zero crossover distortion. The ACT4444 active filter design has additional high frequency roll-off to provide the

required Macair low harmonic distortion waveform without increasing the pulse delay characteristics significantly.

Efficient transmitter electrical and thermal design provides low internal power dissipation and heat rise at high and well as low duty cycles.

An optional receiver input threshold adjustment can be accomplished by the use of the "External Threshold" terminals.

TRANSMITTER

The Transmitter section accepts bi-phase TTL data at the input and when coupled to the data bus with a 1:1 transformer, isolated on the data bus

side with two 55 Ohm fault isolation resistors, and loaded by two 70 thru 85 Ohm terminations plus additional receivers, the data bus signal

produced is 7.0 Volts minimum P-P at A-A’ (See Figure 3 or 4). 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 Waveforms - Figure 1).

The transmitter 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 for an indefinite period at 100% duty cycle into a data bus short circuit.

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 1.05 Volts P-P and reject signals less than 0.6 Volts P-P when used

with a 1:1 turns ratio transformer (See Figure 3 or 4 for transformer data and typical connections). This threshold setting can be held by

grounding the appropriate pins or modified with the use of external resistors.

A low level at the Strobe input inhibits the DATA and DATA outputs. If unused, a 2K Ohm pull-up to +5 Volts is recommended.

NOTE: BCC++ and Bumped Chip Carrier are Trademarks of Fujitsu Ltd.

ACT4444 Transceiver

Standard Products

for MIL-STD-1553 / MACAIR in a Chipscale Package

October 1, 2003

Preliminary