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HI-2579

3.3V MIL-STD-1553/1760 Dual Transceiver with Integrated Transformers

Holt Integrated Circuits 

HI-2579, HI-2581

FUNCTIONAL DESCRIPTION

The HI-2579 family of data bus transceivers contains

differential voltage source drivers, differential receivers

and integrated transformers. They are intended for

applications using a MIL-STD-1553 A/B data bus.

Transmitter

Data is input to the device’s transmitter section from

the complementary CMOS inputs TXA/B and TXA/B.

The transmitter accepts Manchester II bi-phase data

and converts it to differential voltages which drive the

internal transformers on BUSA/B and BUSA/B. The

transformer outputs are either direct or transformer

coupled to the MIL-STD-1553 data bus. Both coupling

methods produce a nominal voltage on the main bus of

7.5 volts peak to peak.

The transmitter is automatically inhibited and placed in

the high impedance state when both TXA/B and TXA/B

are either at a logic “1” or logic “0” simultaneously. A logic

“1” applied to the TXINHA/B input forces the transmitter

to the high impedance state, regardless of the state of

TXA/B and TXA/B.

Receiver

The receiver accepts bi-phase differential data from

the MIL-STD-1553 bus through the same direct or

transformer coupled interface as the transmitter. The

receiver’s differential input stage includes a filter and

threshold comparator that produces CMOS data at the

RXA/B and RXA/B output pins. When the MIL-STD-1553

bus is idle and RXENA or RXENB are high, RXA/B will

be logic “0” on HI-2579 and logic “1” on HI-2581.

Each set of receiver outputs can also be independently

forced to the bus idle state (logic “0” on HI-2579 or logic

“1” on HI-2581) by setting RXENA or RXENB low.

MIL-STD-1553 Bus Interface

There are two ways of connecting to the MIL-STD-1553

bus, using a direct coupled interface or a transformer

coupled interface (see Figure 3).

A direct coupled interface uses the internal 1:2.5 ratio

isolation transformer and two 55Ω isolation resistors

between the transformer and the bus.

In a transformer coupled interface, the transceiver is

connected to the internal 1:2.5 isolation transformer

which in turn is connected to a 1:1.4 coupling transformer.

The transformer coupled method also requires two

coupling resistors equal to 75% of the bus characteristic

impedance (Zo) between the coupling transformer and

the bus. The coupling transformer and coupling resistors

are commonly integrated in a single device known as a

stub coupler.

Figure 4 and Figure 5 show test circuits for measuring

electrical characteristics of both direct and transformer

coupled interfaces respectively (see “electrical

characteristics” on the following pages) .

ABSOLUTE MAXIMUM RATINGS

Supply voltage (VDD)

Logic input voltage range

Receiver differential voltage

Driver peak output current

Power dissipation at 25°C

Solder Temperature

Junction Temperature

Storage Temperature

-0.3 V to +5 V

-0.3 V DC to +3.6 V

50 Vp-p

+1.0 A

1.0 W

245oC max.

175oC

-65oC to +150oC

RECOMMENDED OPERATING

CONDITIONS

Supply Voltage

Temperature Range

Industrial Screening

Hi-Temp Screening

VDD 3.3V ± 5%

-40oC to +85oC

-55oC to +125oC

NOTE: Stresses above absolute maximum ratings or outside

recommended operating conditions may cause permanent

damage to the device. These are stress ratings only. Operation

at the limits is not recommended.

HOLT INTEGRATED CIRCUITS

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