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FUNCTIONAL DESCRIPTION
The SYNC and CLOCK inputs establish data synchronization
utilizing two AND gates, one for each data input. Each logic
input, including the power enable (
TTL/CMOS compatible. Besidesreducing chip current drain,
also floats each output. However the overvoltage
fusesanddiodesoftheHI-8382arenotswitchedout.
) input, are
Figure 1 illustrates a typical ARINC 429 bus application.
Three power supplies are necessary to operate the HI-8382;
typically +15V, -15V and +5V. The chip also works with ±12V
supplies. The +5V supply can also provide a reference
voltage that determines the output voltage swing.
differentialoutputvoltageswingwillequal2V
V
otherthan +5V isneeded, a separate +5V power supply
isrequiredforpinV .
1
The
. Ifavalueof
Withthe DATA(A)inputatalogichighandDATA(B)inputata
logic low, A
will switch to the +V
switch to the -V
rail (ARINC HIGH state). With both data
inputsignalsatalogiclowstate,theoutputswillbothswitchto
0V(ARINCNULLstate).
rail and B
will
The driver output impedance, R
Theriseandfalltimesoftheoutputscanbecalibratedthrough
the selection of two external capacitor values th
connected to the C
and C
input pins. Typical values for
high-speed operation (100KBPS) are C = C = 75pF and for
low-speedoperation(12.5to14KBPS)C =C =500pF.
, is nominally 75 ohms.
re
STROBE
STROBE
REF
REF
OUT
REF
OUT
REF
OUT
A
B
A
at a
Thedrivercanbeexternallypowereddownbyapplyingalogic
hightothe
inputpin. Ifthisfeatureisnotbeingused,
thepinshouldbetiedtoground.
The C
Therefore they must be allowed to swing to -5V. Provision to
switch capacitors must be done with analog switches that
allowvoltagesbelowtheirground.
and C
pins are inputs to unity gain amplifiers.
STROBE
A
B
Figure 2.
FUNCTIONAL BLOCK DIAGRAM
DATA (A)
OUT
DATA (B)
INPUTS
TO ARINC BUS
B
REF
V
1
V
SYNC
CLOCK
-V
+V
STROBE
GND
C
C
-15V
+15V
+5V
HI-8382, HI-8383
Figure 1.
ARINC 429 BUS APPLICATION
DATA (A)
DATA (B)
SYNC
CLOCK
V
1
STROBE
LEVEL SHIFTER
AND SLOPE
CONTROL (A)
LEVEL SHIFTER
AND SLOPE
CONTROL (B)
CURRENT
REGULATOR
OUTPUT
DRIVER (B)
OUTPUT
DRIVER (A)
R
/2
OUT
R
/2
OUT
F
A
F
B
OVER VOLTAGE
CLAMPS
C
L
R
L
OUT
B
B
C
GND
-V
A
C
+V
REF
Not included on HI-8383
HOLT INTEGRATED CIRCUITS
2