HI-1575 HOLTIC [Holt Integrated Circuits], HI-1575 Datasheet - Page 6

• Manufacturer Part Number: HI-1575
• Description: 3.3V Dual Transceivers with Integrated Encoder / Decoders
• Manufacturer: HOLTIC [Holt Integrated Circuits]

The host reads the received word from the HI-1575 RXA or
RXB register. The data word is read by pulsing
while R/
example receive operation. The SYNC output indicates
whether the word had a Command Sync (SYNC=1) or
Data Sync (SYNC=0). SAM register bits 8 and 12
(RSYNCA and RSYNCB) retain the Sync values for the
last word received on each bus.
SAM bits 2 or 3 (RENA, RENB) can be used to
independently enable or disable each receiver. Writing a
'1' to RENA enables receiver A. A '0' disables the receiver.
RENB performs the same function for the MIL-STD-1553
bus B.
Note that because each receiver is internally connected to
its transmitter, when a MIL-STD-1553 word is transmitted
by the HI-1575 it will also be received on the same
channel. This feature allows the terminal to self-monitor
data transmitted to the MIL-STD-1553 data bus.
W
is high and REG is low. Figure 4 shows an
Command Word
Host CPU
Status Word
Data Word
Bit Period
12.0 MHz
3.3 V
SYNC
SYNC
SYNC
SYNC
RCVA
RCVB
ERROR
MR
CLK
STRB
R/W
CHA/CHB
REG
D15:D0
1
FIGURE 6. MIL-STD-1553 BUS CONNECTION
2
FIGURE 7. MIL-STD-1553 WORD FORMATS
SYNC
SYNC
SYNC
VDD
HI-1575
HOLT INTEGRATED CIRCUITS
GND
3
STRB
4
TERMINAL ADDRESS
TERMINAL ADDRESS
BUSB
BUSB
BUSA
BUSA
5
6
low,
HI-1575
7
1:2.5
1:2.5
8
6
R/T
ME
9
MIL-STD-1553 BUS CONNECTION
The HI-1575 includes on-chip MIL-STD-1553 analog
transceivers which are designed to drive the primary
winding of a 1:2.5 turns-ratio MIL-STD-1553 isolation
transformer. Figure 6 shows how the HI-1575 may be
connected to the MIL-STD-1553 data bus as either a
direct coupled stub (Bus A example), or a transformer
coupled stub (Bus B example). Holt Integrated Circuits
offers a wide range of single-core and dual-core coupling
transformers suitable for use with the HI-1575.
10 11
55 Ohms
55 Ohms
DATA WORD
SUBADDRESS
1:1.4
CODE FOR FAILURE MODES
/ MODE
12
52.5 Ohms
52.5 Ohms
13
14 15 16 17 18 19 20
MIL-STD-1553
(Direct Coupled)
DATA WORD
BUS A
COUNT
(Transformer Coupled)
MIL-STD-1553
TF
BUS B
P
P
P