ADM3202 - Unconnected/Unused pins - 1 channel usage

Hi,

I would like to use ADM3202 as one channel UART (I am using just Rx and Tx).

My application in this scenario might be power consumption critical.

I was not able to find in the datasheet a recommendation for unused pins from a power consumption point of view.

Was this scenario considered and tested?

Is there any recommendation on how to connect pins, or leave them unconnected (concretely TIN, TOUT, RIN, ROUT pins)?

Regards,

Arnost

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  • +1
    •  Analog Employees 
    on Jun 3, 2021 3:32 PM

    Hi Arnost,

    You can leave the Receiver input (RIN) pins disconnected. This can be found on page 9 of the datasheet on the receiver section. "Unconnected inputs are pulled to 0 V by the internal 5 kΩ, pull-down resistor. This results in a Logic 1 output level for unconnected inputs or for inputs connected to GND. " so if you don't connect the receiver input pins, it will result in logic 1 at the receiver output.

    However, you cannot leave the TIN pins floating as TOUT pins can go high or low.  I'd recommend using a pull-up or a pull down-resistor on TIN pins so TOUT is not left hanging.

    Regards,

    Naveen

  • 0
    •  Analog Employees 
    on Jun 8, 2021 10:02 AM in reply to Naveen Afzal

    Hi Naveen,

    this explanation helps a lot. 

    Maybe can you suggest to me, if it is better from a consumption point of view to tight TIN directly to GND or to use 4k7 pull-down? (I am not going to use this input at all, so pull down is not needed in that matter, but I was thinking, maybe it can limit the potential current flowing from the pin? Maybe my hypothesis is wrong.) - see figure 

    Regards,

    Arnost

  • 0
    •  Analog Employees 
    on Jun 8, 2021 10:59 AM in reply to APavlik

    Hi Arnost,

    Since it does not act like a switch and you never use T2IN, I don't think you need  a pull down. You can directly connect it to GND. A pull down resistor is needed to limit the current drawn from whatever is driving the T2IN pin to GND. In this case, pull down is doing nothing since there's nothing driving the T2IN pin (It is not connected to anything and you want it to be at logic LOW forever) So it's basically directly connected to GND. Your model becomes something like this: so I think a pulldown serves no purpose here. 

    Regards,

    Naveen

  • 0
    •  Analog Employees 
    on Jun 8, 2021 12:51 PM in reply to Naveen Afzal

    Hi Naveen,

    thank you for your answers.

    Have a good day. 

    Regards,

    Arnost

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