• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 34 subscribers
  • Views 506 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TCA6416A Analogue inputs causing increased power supply current

Graham Smith64
Prodigy 20 points
Other Parts Discussed in Thread: TCA6416A

Hi there,

I am trying to use a TCA6416A in my design. I want to be able to insert a fault on an analogue voltage, but otherwise measure with a separate A/D port the analogue value. I am using the TCA6416A as inputs which is working correctly except the VCCP power pin is drawing increased current when the analogue voltage is about mid rail. Otherwise the part is working exactly as I hoped with the outputs selectable when required.

My question is, is this correct behaviour for this device? Appreciate I'm using it outside of the designers intent, but I didn't think an analogue voltage on a digital input would cause this type of issue...

If this part is not suitable for this is there anything else TI can offer for this application?

Graham

  • 0
    TI__Expert 5140 points

    Hi Graham,

    This is an interesting use case! Is there a specific reason that you are incorporating the fault into your application? Thanks for sharing this.

    This behavior is normal for the use case. Since you are holding your voltage at the mid rail, you will see an increase in current (this is due to the internal circuitry). However, once you reach your full supply, you will see this current decrease.

    Thanks,
    Siby

  • 0 in reply to Siby James
    Prodigy 20 points

    Hi Siby,

    Thanks for that. I wondered if it was correct operation. I am feeding 12 analogue signals from temperature sensors into a multiplexer to send to A/D converter. I need to prove the multiplexer is working correctly for safety reasons. I had hoped this device would inject a fault when required and prove the circuit was working correctly. I guess I will now need to add individual transistors to each channel and control these from the TCA6416A outputs?

    Graham

  • 0 in reply to Graham Smith64
    TI__Expert 5140 points
    Hi Graham,

    In order to force an analog "0" or fault, you would need the transistors on your ports. This is correct.

    Thanks,
    Siby