ICS PCI-16ISO, Руководство пользователя

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1-2 PCI-16ISO User’s Guide
The input impedance of each isolated input is approximately 560 ohms
(factory default). The opto-isolator requires approximately 3mA to turn on.
The maximum input current is 60mA. There are two things to consider when
selecting the input resistor. The first is
turn on voltage for the circuit to sense,
and second is the maximum input voltage . Maximum input voltage must not
provide too much power to the input resistor and must not overdrive the
opto-isolator input current specification. The following formulas apply:
Turn on current: 3 mA
Isolator diode drop: 1.1 V
Resistor power Max: .25 W
Turn on voltage = diode drop + (turn on current) x (resistance)
or : 1.1 + (.003) x R
Maximum voltage = square root of (.25 (resistor value))
The following table shows four common input resistors, the range of voltages,
and maximum current associated with each.
Increasing the input resistor accordingly can increase the maximum input
voltage. Because socketed DIP resistor networks are utilized, they can be
replaced with a different value. This can be done at the factory if necessary.
Input
Resistor
(Ohms)
Min Turn-On
(Volts)
Max Input
Range
(Volts)
Max
Current
(mA)
220 1.76 7 27
560 2.8 12 20
1K 4.1 16 15
2.2K 7.7 24 10
CAUTION
The maximum ratings for inputs are:
- AC = 42.4V peak
- DC = 60V