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Original question:

CD4053B: unselected channel has 1.8V voltage

CD4053B: Switches & multiplexers - INTERNAL forum

Kelly Tian
Prodigy 721 points
Part Number: CD4053B

Tool/software:

Hi Team,

I am still working on the problem of 1.8V detected at the unselected pin. According to your previous answer, the voltage at the unselected pin is due to the leakage current. Could you please provide me some possible causes of the leakage current so that I can have a check on my customer's circuits?

Best Regards,

Kelly Tian

  • 0
    TI__Genius 12465 points

    Hello Kelly,

    Our switches and muxes are essentially a FET that opens to let the signal through or is closed to stop the signal from passing. However, this case is only true in an ideal world. In reality, these switches have parasitic components and will add loss. 

    In your case it is either drain or source and there are two paths for it to "leak" through to the other side. 

    Thanks,

    Nir 

  • 0 in reply to Nir Gilgur
    TI__Prodigy 721 points

    Hi Nir,

    Thank you for your reply. I still have two questions here:

    1. For a 10M Ohm load, I think 10 nA leakage current is needed to induce a 1V voltage at the pin. Under what test condition can leakage current reach this level?

    2. Does the leakage current come from the input current or the system supply?

    Thank you for your time!

    Best Regards,

    Kelly

  • 0 in reply to Kelly Tian
    TI__Genius 12465 points

    Hello Kelly 

    1. Leakage current can increase with temperature, or when the devices behavior is faulty. I am not sure exactly what is the case here. You mentioned: "According to your previous answer, the voltage at the unselected pin is due to the leakage current". Can you please link the thread of where the answer was posted for more context about your issue?

    2. There is current leakage from any signal going into the mux. The leakage itself comes from the FETs inside the mux. 

    Thanks,

    Nir 

  • 0 in reply to Kelly Tian
    TI__Genius 12465 points

    Hello Kelly,

    Thank you for providing the link and the context. 

    It seems this issue can be replicated to other CD4053B devices. It won't damage the device as Kameron mentioned in the previous thread. But if the customer is concerned I would suggest replacing the CD4053B with the SN74LV4053A. 

    Thanks,

    Nir