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MC4x parallel HS output usage

Chris Litwin 2 months ago in Master modules / MC4x updated by Gustav Widén (System support) 1 month ago 5

When an MC4x DOUT HS is wired in parallel, are you able to drive a single output as long as the over current limit is not met? What I driving at is activating both outputs initially, and deactivating one later.

The Digital out HS open load detect will be triggered on the DOUT that you deactivate.

You could avoid this if you disable open load detect on the pin properties. 

I'm assuming the parallel outputs are from the same module? If a Digital out HS is wired in parallel with an output on another module, you can have reverse feed to the module if they are switched on and off at different times. 

Yes, parallel outputs from the same MC4x. How does the output that is deactivated detect an open load if the output pins are tied together? Maybe I am misunderstanding the schematic, or don't understand the b side pins?

The Digital out HS has an internal pull up resistor that is used for detecting if a load is connected.  

When the DOUT is OFF and the load is connected, the voltage on the pin is be zero (assuming the load draws enough current). This is OK.  

When the DOUT is OFF but there is an open circuit (no connection to ground via the load), the voltage on the pin will +BAT. This triggers the open load error on the DOUT channel. 

In the application with two different DOUT channels connected in parallel, both must be activated at the same time. Otherwise, the one that is OFF will measure a voltage on its pin when the other is activated. And to the channel that is off, this looks like an open load. 

+1

Oh ok, now I understand.

Thank you.