differences and reduction of
power supply requirements. With
this combination of HCPL-4100/
-4200 optocouplers, specific
current loop noise immunity is
provided, i.e., minimum SPACE
state current noise immunity is 1
mA, MARK state noise immunity
is 8 mA.
the HCPL-4100 transmitter
optocoupler data sheet for
specified device performance.
Voltage compliance of the current
source must be of an adequate
level for operating all units in the
loop while not exceeding 27 V dc,
the maximum breakdown voltage
for the HCPL-4100. Note that the
HCPL-4100 transmitter will allow
loop current to conduct when
input VCC power is off. Consult
For more information about the
HCPL-4100/-4200 optocouplers,
consult Application Note 1018.
Figure 22. Half Duplex Current Loop System Configurations for
(a) Point-to-Point, (b) Multidrop.
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HP [ HEWLETT-PACKARD ]
