Technical Information
Output Configurations for PLUS+1® Controllers
520L0922
• Rev EA • Sep 2013
10
FMEA Considerations
One consideration during a system FMEA (Failure Mode Effects Analysis) on an application is the
possibility of an open wiring connection. Here are three examples.
Effects of an Open Ground
Losing the ground connection can cause the battery current to find another path to ground if it is
available. When the load is grounded externally, rather than through the controller, such a path is
available. Current will find its way through the load even when the output is in the OFF state. This may
result in unintentional movement of the function that is controlled by the load.
Below is a simple schematic to show how this can happen. The arrows indicate the path of current.
2306
Load
Ground
+Batt
Logic circuits
FET
Configuration
FET
Open
The only way to remove the current completely is to return the load current back to the controller,
through another output. If you are driving an EDC type load (dual coil) and are driving both coils to
get a forward / reverse type function, this could be done by driving one coil bi-directionally with no
additional outputs consumed.
If there are enough valves connected to the controller to provide multiple current paths, you might
be able to reduce the amount of current in each valve enough so that it is no longer above the
threshold of any one valve.
If you have multiple ground connections to the controller, you might be able to reduce the
occurrence of the fault enough so that it no longer a significant risk (rates below 100 on the System
FMEA.) You may also be able to improve the wiring integrity to minimize the occurrence of the fault.
Open Wire to
Controller
Open Wire
Losing the B connection can cause the battery current to find another path to ground if it is
available. When the load is tied to externally, rather than through the controller, such a path
is available. Current will find its way through the load even if the output is in the OFF state. This may
result in unintentional movement of the function that is controlled by the load.
Open Ground Wire to
Controller
