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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.

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

the HCPL-4100 transmitter

optocoupler data sheet for

specified device performance.

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.