Omron C200HE-CPU42-E Instruction Manual page 92

Wiring
Output Circuits
Output Short-circuit
Protection
Transistor Output Residual
Voltage
Output Leakage Current
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3. Relation between current when the PC is OFF and sensor leakage current:
y I
I
OFF leak
Refer to Input Leakage Current later in this section for details.
The I values differ for each Unit, but is always 1.3 mA for Input Units
OFF
whose OFF current specifications are not given.
Two-wire sensor
V
V : Power voltage
CC
V : PC ON voltage
ON
I : PC ON current
ON
I : PC OFF current
OFF
R : PC input impedance
IN
If a load connected to the output terminals is short-circuited, output elements
and printed boards may be damaged. To guard against this, incorporate a
fuse in the external circuit.
When connecting TTL circuits to transistor Output Units, it is necessary to con-
nect a pull-up resistor and a CMOS IC between the two. This is because of the
residual voltage left on the transistor output after the output turns OFF.
If there is a possibility of leakage current causing a transistor or triac to malfunc-
tion, connect a bleeder resistor across the output as shown below.
PC
Determine the value and rating for the bleeder resistor using the following for-
mula.
Where
V = ON voltage of the load in V
ON
I = leakage current in mA
R = bleeder resistance in kΩ
DC Input Unit
R
R IN
R
V
CC
V : Sensor output residual current
R
I : Sensor control current (load current)
OUT
I : Sensor leakage current
leak
R: Bleeder resistance
OUT
L
R
Bleeder resistor
COM
V
ON
R –––
I
Section 3-2
Load power supply
75