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Negative power level conversion

Luke Sun
Intellectual 1830 points
Other Parts Discussed in Thread: SN74LVC1G17

Hi team,

My customer is looking for a chip which could do a 1.8V/3.3V logic ->-5V logic level conversion.

Do we have some part like this?

Thanks

  • 0
    TI__Guru* 96591 points

    Hi Luke,

    We don't have any devices that directly produce this conversion, however I do know of a discrete circuit that can work.  Take a look at the solution I presented in this thread.

    Note that a logic device can be offset from the ground of a system by connecting the supply pins correctly -- for example, you could connect the ground pin of an SN74LVC1G17 to -5V and then connect the Vcc pin to 0V, which still produces a positive 5V supply for the device to operate, but will produce outputs between -5V and 0V. You would just have to be careful about what voltages are applied to the device, since it would be easy to violate the absolute maximum specs at this point (for example, a 3.3V signal would look like an 8.3V signal to the inputs of the device).

  • 0
    TI__Guru* 96591 points
    Can you tell me where this requirement is coming from? I've seen a few similar requests recently, and no one is saying what it's used for.
  • 0 in reply to Emrys Maier
    TI__Intellectual 1830 points

    Emrys,

    Sorry for my late reply.

    Customer is using it for some Microwave Switches (e.g. HMC986A). Such device needs a negative but not a positive digital control interface. Finally customer decides to use amplifier to do this positive->negative voltage conversion.

    Thanks for your support.

  • 0 in reply to Luke Sun
    TI__Guru* 96591 points
    Thanks Luke,
    That's very helpful.