HI-1570
PIN DESCRIPTIONS
PIN
SYMBOL
FUNCTION
DESCRIPTION
1
2
VCONT A/B
BUSA
BUSA
RXENA
GNDA
VDDA/B
BUSB
BUSB
RXENB
GNDB
RXB
analog Input
analog output
analog output
digital input
power supply
power supply
analog output
analog output
digital input
power supply
digital output
digital output
digital input
digital input
digital input
digital output
digital output
digital input
digital input
digital input
Transmit output amplitude control (0 - 5 Vdc, see Figure 4)
MIL-STD-1533 bus driver A, positive signal
MIL-STD-1553 bus driver A, negative signal
Receiver A enable. If low, forces RXA and RXA low
Ground for channel A
3
4
5
6
+5 volt power for both channel A and channel 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 RXB low
Ground for channel B
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Receiver B output, inverted
RXB
Receiver B output, non-inverted
TXINHB
TXB
Transmit inhibit, channel B. If high BUSB, BUSB disabled
Transmitter B digital data input, non-inverted
Transmitter B digital data input, inverted
Receiver A output, inverted
TXB
RXA
RXA
Receiver A output, non-inverted
TXINHA
TXA
Transmit inhibit, channel A. If high BUSA, BUSA disabled
Transmitter A digital data input, non-inverted
Transmitter A digital data input, inverted
TXA
FUNCTIONAL DESCRIPTION
RECEIVER
The HI-1570 data bus transceiver contains differential volt-
age source drivers and differential receivers. They are in-
tended for applications using a MIL-STD-1553 A/B data
bus. The device produces a trapezoidal output waveform
during transmission.
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/TTL data at the RXA/B and RXA/B
output pins.
TRANSMITTER
Data input to the device’s transmitter section is from the
complementary CMOS / TTL inputs TXA/B and TXA/B.
The transmitter accepts Manchester II bi-phase data and
converts it to differential voltages on BUSA/B and BUSA/B.
The transceiver outputs are either direct or transformer cou-
pled to the MIL-STD-1553 data bus. Both coupling meth-
ods produce a nominal voltage on the bus of 7.5 volts peak
to peak at VCONT A&B = 5.0 Vdc. Refer to Figure 4 for
transmitter output amplitudes at other values of VCONT
A&B between 0 - 5 Vdc. (Contact your Holt Sales Repre-
sentative about the 0 - 10 Vdc Control Voltage option).
Each set of receiver outputs can be independently forced
to a logic "0" by setting RXENA or RXENB low.
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 connected to a 1:1.79 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 transmitter is automatically inhibited and placed in the
high impedance state when both TXA/B and TXA/B are ei-
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.
HOLT INTEGRATED CIRCUITS
2
HOLTIC [ HOLT INTEGRATED CIRCUITS ]
