hi-1579pst Holt Integrated Circuits, Inc., hi-1579pst Datasheet - Page 2

• Manufacturer Part Number: hi-1579pst
• Description: 3.3v Monolithic Dual Transceivers
• Manufacturer: Holt Integrated Circuits, Inc.

PIN DESCRIPTIONS
FUNCTIONAL DESCRIPTION
The HI-1579 dual data bus transceiver contains differential
voltage source drivers and differential receivers. It is in-
tended for applications using a MIL-STD-1553 A/B data
bus. The device produces a trapezoidal output waveform
during transmission.
TRANSMITTER
Data input to the device’s transmitter section is from the
complementary CMOS inputs TXA/B and
transmitter accepts Manchester II bi-phase data and con-
verts it to differential voltages on
The transceiver outputs are either direct or transformer
coupled to the MIL-STD-1553 data bus. Both coupling
methods produce a nominal voltage on the 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
ther at a logic “1” or logic “0” simultaneously. A logic “1” ap-
plied to the TXINHA/B input will force the transmitter to the
high impedance state, regardless of the state of TXA/B and
TXA B.
(DIP & SOIC)
/
PIN
10
11
12
13
14
15
16
17
18
19
20
1
2
3
4
5
6
7
8
9
SYMBOL
TXINHB
TXINHA
RXENA
RXENB
GNDA
GNDB
VDDA
BUSA
BUSA
VDDB
BUSB
BUSB
RXB
RXB
RXA
RXA
TXB
TXB
TXA
TXA
analog output
analog output
analog output
analog output
power supply
power supply
power supply
power supply
FUNCTION
digital output
digital output
digital output
digital output
digital input
digital input
digital input
digital input
digital input
digital input
digital input
digital input
BUSA/B and
HOLT INTEGRATED CIRCUITS
TXA B
TXA B
+3.3 volt power for transceiver A
MIL-STD-1533 bus driver A, positive signal
MIL-STD-1553 bus driver A, negative signal
Receiver A enable. If low, forces RXA and
Ground for transceiver A
+3.3 volt power for transceiver B
MIL-STD-1533 bus driver B, positive signal
MIL-STD-1553 bus driver B, negative signal
Receiver B enable. If low, forces RXB and
Ground for transceiver B
Receiver B output, inverted
Receiver B output, non-inverted
Transmit inhibit, bus B. If high BUSB,
Transmitter B digital data input, non-inverted
Transmitter B digital data input, inverted
Receiver A output, inverted
Receiver A output, non-inverted
Transmit inhibit, bus A. If high BUSA,
Transmitter A digital data input, non-inverted
Transmitter A digital data input, inverted
/ . The
BUSA B
/ are ei-
/
HI-1579
.
2
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 differ-
ential input stage drives a filter and threshold comparator
that produces CMOS data at the RXA/B and
pins.
Each set of receiver outputs can be independently forced
to a logic "0”.
MIL-STD-1553 BUS INTERFACE
A direct coupled interface (see Figure 2) uses a 1:2.5 ratio
isolation transformer and two 55 ohm isolation resistors
between the transformer and the bus.
In a transformer coupled interface (see Figure 3), the
transceiver is also connected to a 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 impedence (Zo) between the coupling
transformer and the bus.
DESCRIPTION
BUSA
BUSB
RXA
RXB
disabled
disabled
low
low
RXA B
/ output