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22.2
Troubles and Countermeasures for DC Output
Circuits
Examples of troubles in DC output (transistor (sink) output) circuits and countermeasures are shown below.
A load momentarily turns on from off when the system is powered off
■Cause
When an inductive load is connected, [2] Load may turn on from off due to a diversion of back electromotive force at [1]
Shutoff.
FPGA module
DC output (sink output)
ON
OFF
■Action
Take one of the two actions shown below.
Action 1. To suppress the back electromotive force, connect a diode parallel to the load where back electromotive force is
generated.
[3]
+ Counter-electromotive force –
Load
Action 2. Configure a sneak current path by connecting a diode across positive and negative of the external power supply.
FPGA module
DC output (sink output)
ON
OFF
D1:
Reverse voltage VR (VRM)
Forward current IF (IFM)
*1 Approximately 10 times the rated voltage in the specifications
Example: 24VDC Approx. 200VDC
*2 Twice the maximum load current (common) in the performance specifications or more
Example: 0.4A/1 common (0.1A 4 points) 0.8A or more
22 TROUBLE EXAMPLES of DC INPUT/OUTPUT
448
22.2 Troubles and Countermeasures for DC Output Circuits
+ Counter-electromotive force –
[3]
Load
Y0
[2]
Load
Y1
[1] Shut off
COM
+ Counter-electromotive force –
Load
Y0
[2]
Load
Y1
[1]
Shut off
COM
D1
[3]
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Table of Contents
Troubleshooting
