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SN74AUP2G06: Hi-Z Leakage

Scott Dalton
Prodigy 20 points
Part Number: SN74AUP2G06
Other Parts Discussed in Thread: TMUX1121
  • I'm considering using this part as a 0V/Hi-Z switch to connect a non-inverting op-amp resistor to 0V for > unity gain or to Hi-Z for unity gain.   
  • The supply will be a 1.5V battery and the open-drain output would be connected to ~1V through a 1-2Meg resistor.
  • Will this device work in such an application?  If so, what is the drain leakage when in Hi-Z?
  • 0
    Guru 298360 points

    The Hi-Z leakage is the same as Ioff, i.e., 0.6 µA in the worst case.

    With you resistor values, low leakage current is more important than low on-resistance; consider an analog switch designed for that, e.g., TMUX1121/2/3.

  • 0
    TI__Guru* 97017 points

    Hi Scott,

    I expect that it would work for you -- the equivalent resistance in the Hi-Z state (worst case) would be 1.67 Mohm, so just make sure your resistors are a few orders of magnitude smaller than this to ensure you get close to unity gain. For example, using 10k as a feedback resistor would give a worst-case 'unity gain' of 0.994. With a 1k feedback, that increases to 0.9994.

    Of course, in 'typical' operation (25C, nominal process), the resistance will be much higher and you won't have to worry about it (usually leakage is more like 10nA).

    Also note that the device has a non-zero resistance when turned on -- usually in the ~100 ohm range, so you'd want to consider that in your selection of resistors. You can calculate it with V_OL / I_OL from the datasheet provided electrical characteristics.

  • 0 in reply to Clemens Ladisch
    Prodigy 20 points

    Thanks for the info and good suggestion (analog switch).  I'll check if any analog switches will fit in the small amount of PCB real estate available.

  • 0 in reply to Emrys Maier
    Prodigy 20 points

    Hi Emrys, thanks for the helpful info, analyses and typical leakage current at 25C.  This part and approach still may be good enough for my requirements.