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TS3DV621: ON Resistance for Vi/o between 0V and 1.5V?

Kareem Moulana
Intellectual 2480 points
Part Number: TS3DV621
Other Parts Discussed in Thread: TS3DV642

Hi team,

The TS3DV6421 12-channel Mux has ON-resistance listed on page 6 of the datasheet as follows: At Vcc=3V, the spec is 6.5Ω typical, 9.5Ω max over a Vi/o range of 1.5V to Vcc.

What is the ON resistance for the Vi/o range between 0V and 1.5V?  We're planning on using the device over the full range of 0V to Vcc in this application.

Regards,

Kareem

  • 0
    TI__Mastermind 45350 points

    Kareem,

    The Ron vs Vi/o of a switch can be predicted based on the type of switch architecture NMOS, NMOS parallel with PMOS, or NMOS with its gate connected to a charge pump.

    The Ron vs Vi/o of an NMOS switch is exponentially increasing as the Vi/o voltage approaches Vcc greatly reducing the gate to source (Vgs) voltage turning off the FET. 

    The TS3DV642 however includes a charge pump boosting the gate voltage so the reduction of the Vgs as Vi/o increases doesn't turn off the switch leaving a much flatter Ron vs Vi/o curve.

    You can see that the TS3DV642 Ron vs Vi/o is mostly flat varying <1.5 ohm.  Based on the theory above, we can predict that the Ron at lower Vi/o voltages will not be significantly different than what it is at 1.4 V but a little less. 

    You can read more about the different switch architectures and their performance trade offs in this app note.

    We recommend using the newer TS3DV642 for designs as you can see in this thread

    What are you doing with this switch that you are concerned about the Ron across Vi/o?

    Thank you,

    Adam

  • 0 in reply to Adam Torma
    TI__Intellectual 2480 points
    Thank you Adam, I appreciate the quick and in depth response. Could you shed any light on why the datasheet only shows half the supply range? Perhaps there is some difficulty in measurement?

    Regards,
    Kareem
  • 0 in reply to Kareem Moulana
    TI__Mastermind 45350 points
    Kareem,

    The datasheet was specified based on the HDMI and Display Port signals standards which operate differentially with common mode voltage. Since they have a common mode voltage in the application there wasn't a need to specify the Ron across the entire voltage range. Even though this part can be used in may more applications other than HDMI and Display Port, TI's culture wasn't as catalog friendly as it is today when they designed and specified this device.

    Thank you,
    Adam