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# TIOS101: Definition of output current

Part Number: TIOS101

Hi,

I'm using TIOS101.

According to datasheet, Current can be limited by adjusting Rset.

And this seems to be possible regardless of PNP and NPN.

But in my opinion PNP is true, but not NPN.

Because PNP is current source, so current flow is Driver to PLC.

But NPN is current sink, so current flow is PLC to Driver.

So I think the following expression is correct.

When the driver is NPN, the limit for current input is 200mA.

(If my definition is correct, TIOS101 means that current can be limited for input / output current. Is it true?)

It's still very confusing, but I'd like to ask for clarification.

Thank you.

• Hello Geonwoo,

I understand the confusion, but it sounds like your understanding is correct - that is, the "output current" setting applies for both PNP (high-side) and NPN (low-side) modes.  Another way you could think of it is that in PNP mode the polarity of the output current is positive, in NPN mode the polarity of the output current is negative, and the current limit setting applies to the absolute value (magnitude) of the current regardless of polarity.

Regards,
Max

• In reply to Max Robertson:

I have a one more question.

The datasheet shows that the current is limited only for the output current, which is confusing.

In terms of current flow, not absolute value, I wonder if TIOS can limit the input and output of the current.

Specifically, I am wondering if TIOS can be limited for current input when it is NPN, and limited for current output when it is PNP.

Thank you.

• In reply to Geonwoo Ban:

Yes, the same limit applies to both directions of current flow (input and output).

By the way, I just wanted to clarify on the current limit function since it can be confusing.  The device is capable of outputting (or inputting) current for short durations beyond the current limit.  If the current exceeds the limit for some time, though, then the output will shut off temporarily.  Later, it will automatically re-enable itself.  If the current is still too high (above the limit setting), the output will cycle back off.  This continues until the load current remains below the current limit threshold.

Regards,
Max