HCPL-4200 Datasheet, PDF (10/13 Pages) Agilent(Hewlett-Packard) – Optically Coupled 20 mA Current Loop Receiver

200
C_L = 15 pF
V_CC
20 V
150
t_PHZ
4.5 V
100
20 V
50
t_PZH
4.5 V
0
-60 -40 -20 0 20 40 60 80 100
T_A – TEMPERATURE –°C
Figure 14. Typical Logic High Enable Propagation Delay vs. Temperature.
100
C_L = 15 pF
V_CC
20 V
80
t_PLZ
4.5 V
60
20 V
40
t_PZL
4.5 V
20
0
-60 -40 -20 0 20 40 60 80 100
T_A – TEMPERATURE –°C
Figure 15. Typical Logic Low Enable Propagation Delay vs. Temperature.
Figure 16. Test Circuit for Common Mode Transient Immunity.
Applications
Data transfer between equipment which employs cur-
rent loop circuits can be accomplished via one of three
configurations: simplex, half duplex or full duplex com-
munication. With these configurations, point-to-point
and multidrop arrangements are possible. The appropri-
ate configuration to use depends upon data rate, num-
ber of stations, number and length of lines, direction of
data flow, protocol, current source location and voltage
compliance value, etc.
Simplex
The simplex configuration, whether point to point or
multidrop, gives unidirectional data flow from transmit-
ter to receiver(s). This is the simplest configuration for use
in long line length (two wire), for high data rate, and low
current source compliance level applications. Block dia-
grams of simplex point-to-point and multidrop arrange-
ments are given in Figures 17a and 17b respectively for
the HCPL-4200 receiver optocoupler.
For the highest data rate performance in a current loop,
the configuration of a non-isolated active transmitter
(containing current source) transmitting data to a re-
mote isolated receiver(s) should be used. When the cur-
rent source is located at the transmitter end, the loop is
charged approximately to V (2.5 V). Alternatively, when
MI
the current source is located at the receiver end, the loop
is charged to the full compliance voltage level. The lower
the charged voltage level the faster the data rate will be.
In the configurations of Figures 17a and 17b, data rate is
independent of the current source voltage compliance
level. An adequate compliance level of current source
must be available for voltage drops across station(s) dur-
ing the MARK state in multidrop applications or for long
line length. The maximum compliance level is deter-
mined by the transmitter breakdown characteristic.
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