Author Topic: MC050-110 Pin C1P31 Powered all the time  (Read 423 times)

Offline dlewis

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MC050-110 Pin C1P31 Powered all the time
« on: April 20, 2022, 02:34:25 PM »
Has anyone had issues with the MC050-110 powering pin C1P31 even though the input to the DigOut is set to false?   I've had two controllers do this so far.  Even after downloading a blank program into the controller, the pin is always live.

Offline niteRider

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Re: MC050-110 Pin C1P31 Powered all the time
« Reply #1 on: April 20, 2022, 02:38:49 PM »
I've had that happen when power is (accidentally) applied to the wire connect to the pin when the controller is powered down... it blows the output pin and essentially shorts it to power.  Any chance of that being your case?

Offline dlewis

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Re: MC050-110 Pin C1P31 Powered all the time
« Reply #2 on: April 20, 2022, 03:41:54 PM »
That's an interesting situation, but it is not our case.  The output pin drives a solenoid.  I don't see how we could get back feed from the solenoid back to the output pin when the controller is off.

Offline ToddT

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Re: MC050-110 Pin C1P31 Powered all the time
« Reply #3 on: April 20, 2022, 04:22:10 PM »
I have had this occur on C1P32, essentially the same type of output pin. The pin was not able to handle the turn-off energy fully. For an application with a high inductive load, the IC high side driver may not be able to absorb the turn-off energy fully, thus resulting in the output shorted to power and the IC damaged. Adding recirculating diodes to the coils with high inductive loads can be used to avoid this condition, but be aware turn off times maybe extended.

Offline dlewis

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Re: MC050-110 Pin C1P31 Powered all the time
« Reply #4 on: April 20, 2022, 05:56:38 PM »
The thing is, the pin failed before it was set to "true" for the first time.