10

Figure 12. Recommended Non-Isolated Active Receiver with HCPL-4100 Isolated Transmitter for Simplex Point to Point

20 mA Current Loop.

25% distortion data rate at

distortion data rate is defined as

that rate at which 25% distortion

occurs to output bit interval with

respect to the input bit interval.

Maximum data rate (dotted line)

is restricted by device character-

istics. An input Non-Return-to-

Zero (NRZ) test waveform of 16

bits (0000001011111101) was

used for data rate distortion

measurements. Enhanced speed

performance of the loop system

supply levels, as illustrated in

Figure 14. In addition, when loop

current is supplied through a

resistor instead of by a current

source, an additional series

termination resistance equal to

the characteristic line impedance

can be used at the HCPL-4100

transmitter end to enhance speed

of response by approximately

20%.

The cable used contained five

pairs of unshielded, twisted, 22

AWG wire (Dearborn #862205).

Loop current is 20 mA nominal.

Input and output logic supply

voltages are 5 V dc.

Full Duplex

The full duplex point-to-point

communication of Figure 15 uses

a four wire system to provide

simultaneous, bidirectional data

communication between local

and remote equipment. The basic

application uses two simplex

point-to-point loops which have

two separate, active, non-isolated

units at one common end of the

loops. The other end of each loop

is isolated.

Figure 13. Minimum Required Supply

Current Loop Circuit of Figure 13.

Figure 14. Typical Data Rate vs.

Distance and Supply Voltage.

0

12

0

L – LOOP LENGTH (ONE DIRECTION) METERS

100

1000

16

4

28

32

36

40

10000

m

V

24

20

8