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TIOL111: Current limit of CQ pin for sinking

Holger Ludwig
Prodigy 10 points
Part Number: TIOL111
Other Parts Discussed in Thread: TIOL112

Tool/software:

Hi Team,

I have got a question regarding the current limit of the C/Q pin No. 8, which can be used bidirectional and beside the IO-Link data stream as a standard IO in a second mode.

A current limit can be set by a resistor at pin No. 6 „ILIM_ADJ“ and in the data sheet a current is described in the section „Driver Output (CQ)“, which can be delivered by the C/Q pin (source mode of the C/Q pin), respecting the ajusted current limit of course which I have set by a 47k resistor.

Now my special question is the ability of the C/Q pin for consuming a current (sink mode of the C/Q pin) especially for the standard IO mode where the C/Q pin is used as a digital input.
Is in this case the same current limit for source mode valid for the sinking mode too and does the adjusted current limit by resistor at pin 6 act as well for a sinking current at C/Q pin?

For this case of use I did not find a hint in the data sheet, so far... Maybe somebody can provide me some further information.

Thanks a lot for hints in advance.

  • 0
    TI__Mastermind 33190 points

    Hi Holger,

    The current limit level is the same for both sourcing and sinking current.

    I do want to make sure there is a clear understanding on your understanding of the "current limit" in the TIOL111 vs our TIOL112 because they are slightly different.

    The term "limit" in the TIOL111 is a threshold that if crossed causes the device to disable the driver because the current has exceeded the "limit."  The device does not actually throttle or regulate the current if the load connected to the CQ pin tries to consume more current than the what has been set as the limit level for more than 200us.  A benefit to this approach is that it allows more current to flow for short periods of time which is helpful for sourcing the inrush current on large capacitive loads.

    However, the TIOL112 does have an active current regulation loop that will restrict or throttle the current to ensure it does not exceed the limit level.  Therefore if your expectation is to use the current limit as a feature to ensure the device does not consume more current than the "limit" for any period of time, then the TIOl112 would be a better choice than the TIOL111.  But with the example of a large capacitive load, it would take longer to charge due to the restriction on the inrush current as compared to the TIOL111.

    Both devices have their benefits, but I just wanted to make that distinction so you can be sure to use the device that best fits your needs and expectations.

    Regards,

    Jonathan