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TS3A4751PWR analog switch off leakage spec issue

Naser S.
Genius 11605 points


Customer  needs to know if we have a spec on how much isolation they have between the NO and COM pins when the switch is disabled. 

See numbers  below to show you that they are different from the leakage numbers given in the data sheet.

 I believe that we are losing some current to leakage (I assume that goes to GND), but there should be some that gets passed through the switch.  If they can provide a parameter or minimum value for resistance when the switch is open, that is what I need to know (e.g. “The open/disabled switch will provide at least 10Mohms of isolation between COM and NO in a steady-state condition”).

 The numbers are below, but it appears that there is leakage through the switch as well as possibly to the rails.

~300nA on the “NO” side, and ~20nA on the “COM” side.  There is a leakage parameter, and I thought that might be what I am looking for, but the leakage parameter is 1nA max at room temperature.

Regards,

  • 0
    TI__Mastermind 45595 points

    Naser,

    We do provide a parameter or minimum value for resistance when the switch is open in a steady state condition (off leakage current) and across frequency (off isolation).  The minimum resistance value of the signal path when the switch is off can be calculated from the off leakage current spec. 

    R = V / I

    R = 3 V / 18nA 

    R = 300M ohms 

    You can look at these other post for other examples on this calculation.  

     

    The way the leakage measurement is taken is powering the IC with Vcc = 3.6V, placing 0.3 V on COM and 3 V on the NO pin and measuring the current.  The leakage path is predominately measuring is from the NO/COM pin to ground.  

    Do you notice any other abnormalities with other specs with the device?      

    What else do you have on your board that might be creating a path to ground? 

    Thank you,

    Adam