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How is it possible to have a open collector comparator?

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Federico Manfrin
Federico Manfrin on 26 May 2020
Answered: Joel Van Sickel on 5 Aug 2020
Hi, I just need an LM2903 type op comparator, wich is open collector output.
The simscape Electrical - Integrated circuit library has a comparator avaible, but the open collector output are not avaible.
How can I configure it?
I was wondering to add a transistor at the output, but I hope there's another solution.


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Answers (1)

Joel Van Sickel
Joel Van Sickel on 5 Aug 2020
Hello Federico,
if you have a spice model of the part, you can import that into simscape, and at that level of fidelity, it should include the open collector aspect (although there are no standards for vendor provided PSPICE models so you should verify).
To import a spice model, please use this documentaiton:
Otherwise, you will have to follow the recomendations in the comparator help file as you suspected. I have posted them here:
Modeling of the output as a controlled voltage source is representative of a totem-pole or push-pull output stage. To model a device with an open-collector:
  1. Connect the output pin to the base of an NPN Bipolar Transistor or PNP Bipolar Transistor block.
  2. Set the Output resistance parameter to a suitable value.


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