Source control logic vs. Sink control logic?

Hi

I have been reading some manuals for different AC and DC drives. Al

of them seem to always have digital inputs which you use t start/stop the drive. From what I gather, it seems that these drive either use "Source Control Logic" or "Sink Control Logic" for thes inputs. I have been reading a few electronics books, but I don' really understand these concepts. If anyone could give me a brie explanation, or point me towards something else I can read, I woul really appreciate it

thank

Paul :?

Reply to
PaulKraemer
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'Tis very simple, actually, and (if I'm understanding things correctly) they both have to do with how the output switching is done.

With "source control," what's likely happening is that the ouput line of a given IC is being used to bias on a PNP transistor to switch the power-supply side of the output device.

With "sink control," it's just the opposite. An IC is used to bias on an NPN transistor on the ground side of the device.

An example of either would be where you want to drive a relay coil with an IC output. You need to supply power to one side of the coil, and ground to the other. Source vs. sink simply determines where you put the switching element.

I'm going entirely off of memory here, so corrections or additional info from others would be appreciated.

Keep the peace(es).

--
Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute.
(Known to some as Bruce Lane, ARS KC7GR, 
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Reply to
Dr. Anton T. Squeegee

The esteemed Dr. Squeegee has the basic point.

Source control logic generally means we switch the more positive rail on and off for control (we *source* current).

Sink control logic means we switch the negative rail (sinking current).

The terms 'source' and 'sink' are used in the conventional flow - Positive to negative - sense.

Cheers

PeteS

Reply to
PeteS

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