Standard Products
ACT4808N Dual Transceivers
for MACAIR (A3818, A4905, A5232, A5690) and MIL-STD-1553A/B
www.aeroflex.com/Avionics
May 25, 2005
FEATURES
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ACT4808N Dual Transceiver meets MIL-STD-1553A & B, Macair A3818, A5690,
A5232 and A4905 specs
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New Low Power Model
Operates with 12V to 15V & +5V Power Supplies
Voltage source output
Plug-in or Flat Package
Monolithic construction
Designed for commercial, industrial and aerospace applications
MIL-PRF-38534 compliant devices available
Aeroflex-Plainview is a Class H & K MIL-PRF-38534 manufacturer
GENERAL DESCRIPTION
The Aeroflex-Plainview ACT4808N is a monolithic transceiver design which provides full compliance with Macair
(A-3818, A-4905, A-5232 and A-5690) and MIL-STD-1553A/B data bus requirements and can be considered a
"Universal" Transceiver.
The dual channel transceiver performs the front-end analog function of inputting and outputting data through a
transformer to the MIL-STD-1553 or Macair data bus.
Design of this transceiver 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 ACT4808N series active
transmit 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 as
well as low duty cycles. The receiver input threshold is set Internally.
TRANSMITTER
The Transmitter section accepts bi-phase TTL data at the input and when coupled to the data bus with a 1:1 transformer
the data bus signal produced is 7.0 Volts typical P-P at Point 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” signal
applied to the “INHIBIT” takes priority over the condition of the data inputs and disables the transmitter (See
Transmitter Logic Waveform, 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 (Point A-A’). The Transmitter may be safely operated for an indefinite period with the 1553
bus (Point A) 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 Waveform, Figure 2).
The internal threshold is nominally set to detect data bus signals exceeding 1.10 Vp-p and reject signals less than 0.6
Vp-p when used with a 1:1 turns ratio transformer (See Figure 4 for transformer data and typical connection).
A low level at the Strobe input inhibits the DATA and DATA outputs.
SCD4808N Rev B