UCBB Sinking vs Sourcing Outputs

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UCBB Sinking vs Sourcing Outputs

Postby Lightning17 » Fri May 01, 2020 3:58 pm

Hello,

The output example circuits in the UCBB manual show them being used as sinking outputs only and no mention is made to their sinking vs sourcing capabilities. My servo drives require sourced signals from the controller since there is a shared common between the signal inputs. The manual states "All outputs are capable to drive any voltage levels upto 24Volts and we recommend driving loads with upto 1Ampers of current" but it only references them being used as sinks. Are the outputs capable of sourcing the 5V signal needed? If so can you please tell me if any changes will need to be made on the BOB or will it automatically determine sink or source based on the polarity of the wiring. I understand how to wire the outputs as sink/vs source but just want to make sure the outputs will be capable of sourcing my signals needed. Thanks in advance for any help that can be provided.
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Re: UCBB Sinking vs Sourcing Outputs

Postby cncdrive » Fri May 01, 2020 9:43 pm

The outputs are Open drain outputs of N channel Mosfets.
This is basically the same as an NPN transistor output with the collector wired out, the only difference is that the Mosfet has a built in body diode while NPN transistors do not. So the Mosfet is protected against reverse voltage transients.
So, the outputs cannot source, they can just sink.
You could use a pullup resistor making it to source...
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Re: UCBB Sinking vs Sourcing Outputs

Postby Lightning17 » Mon May 04, 2020 12:07 pm

Understood. Thanks for your reply.
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