HI-8382, HI-8383
FUNCTIONAL DESCRIPTION
The driver can beexternally powered down by applying a logic
high tothe STROBE inputpin. Ifthis featureis not being used,
the pinshouldbetiedtoground.
The SYNC and CLOCK inputs establish data synchronization
utilizing two AND gates, one for each data input. Each logic
input, including the power enable (STROBE) input, are
TTL/CMOS compatible. Besides reducing chip current drain,
STROBE also floats each output. However the overvoltage
fuses anddiodes oftheHI-8382arenotswitchedout.
The CA and CB pins are inputs to unity gain amplifiers.
Therefore they must be allowed to swing to -5V. Provision to
switch capacitors must be done with analog switches that
allowvoltages belowtheirground.
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. The
differential output voltage swing will equal 2VREF. If a value of
VREF other than +5V is needed, a separate +5V power supply
is requiredforpinV1 .
+5V
+15V
V
REF
OUT
V
1
SYNC
DATA (A)
CLOCK
With the DATA (A) input at a logic high and DATA (B) input at a
logic low, AOUT will switch to the +VREF rail and BOUT will
switch to the -VREF rail (ARINC HIGH state). With both data
input signals at a logic low state, the outputs will both switch to
0V (ARINC NULLstate).
+V
-V
INPUTS
TO ARINC BUS
B
STROBE
GND
DATA (B)
C
C
The driver output impedance, ROUT, is nominally 75 ohms.
The rise and fall times of theoutputs can be calibrated through
the selection of two external capacitor values that a re
connected to the CA and CB i nput pins. Typical values for
high-speed operation (100KBPS) are CA = CB = 75pF and for
low-speedoperation(12.5to14KBPS) CA = CB = 500pF.
-15V
Figure 1. ARINC 429 BUS APPLICATION
+V
C
REF
A
OUTPUT
DRIVER (A)
DATA (A)
CLOCK
SYNC
LEVEL SHIFTER
AND SLOPE
CONTROL (A)
FA
ROUT/2
R L
C L
LEVEL SHIFTER
AND SLOPE
FB
ROUT/2
DATA (B)
CONTROL (B)
OUTPUT
DRIVER (B)
OVER VOLTAGE
CLAMPS
CURRENT
REGULATOR
V1
Not included on HI-8383
STROBE
B
-V
GND
C
B
OUT
Figure 2. FUNCTIONAL BLOCK DIAGRAM
HOLT INTEGRATED CIRCUITS
2
HOLTIC [ HOLT INTEGRATED CIRCUITS ]
