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SN74LVC2G17 Vp+

Shu-Cheng LIN
Guru 11785 points

Other Parts Discussed in Thread: SN74LVC2G17, SN74LV1T34, SN74AHCT1G125

Hi Sirs,

Sorry to bother you.

We have use SN74LVC2G17, had issue at the Vp+

Our Vcc is 5v, the positive-going input threshold voltage is 2.97v.
Now 5v Vcc test result at datasheet. (Only 4.5/5.5v)

I think 2.97v can be positive trigger but actually it's doesn't.

I think datasheet range ( Vcc 5.5v, Vp+ 2.2v-3.7v) is mean all SN74LVC2G17 could positive trigger between this spec.
Is possible IC had different tolerance. Like one is 2.97v trigger, another one maybe need 3.1v...

So, we would like survey does TI have similar function and the Vp+ max is lower 2.97v when Vcc is 5V??

Thanks

  • 0
    Guru 326900 points

    MIN = 2.2 V, MAX = 3.7 V means that the actual threshold could be anywhere between these two limits.
    In other words, to guarantee that the output stays low, the input must be below 2.2 V, and to guarantee that the output goes high, the input must be above 3.7 V.

    To get a threshold of no more than 2.11 V, use a level-shifter device such as the SN74LV1T34.
    To get a threshold of no more than 2 V, use a device with TTL-compatible inputs (HCT, ACT, AHCT).

  • 0
    TI__Guru 64200 points
    Thanks Clemens for your inputs.I always value your inputs and opinions.
    The datasheet always give min and max spec combining and taking into account all the possible variations involved with the device from manufacturing , process , testing , environmental and temperature effects.
    Each device will have its values which will typically be centered , however it cannot be guaranteed to be a precise value.
  • 0 in reply to ShreyasRao
    Intellectual 460 points

    Dear TI Supporters,

    I'd like to get help from you all.

    Currently we are using Fairchild's NC7WZ17 (dual buffer with Schmitt trigger inputs) for VGA's sync signals as 3.3V-in-5V-out's solution. However, we have an application that has a higher load on system 3V. When all the 3V peripheral devices working at the same time, the voltage level of system 3V will drop to around 2.9V which makes the input of NC7WZ17 not be identified as a high so the Schmitt trigger output will be kept as low eventually no VGA output.

    So now, I'd like to get TI's help to check if TI has any solution can meet below requirements,

    1. As a replacement of NC7WZ17, the solution should has the same package SC70 and the same pin assignment.

    2. The maximum input voltage identified as a higher should lower than 3.135V(3.3V-5%)

    3. 5V output, a Schmitt trigger output is better for sync signals for VGA.

    Best Regards,

    S.P. Lin @ADLINK

     

     

  • 0 in reply to user446310155
    Guru 326900 points

    Fairchild's NC7WZ17 essentially is a clone of the SN74LVC2G17.

    There is no TI device with a compatible package, pinout, and VCC, and a lower guaranteed threshold. And all manufacturers use the same standard logic families, so I doubt you'd find such a device elsewhere.

    As far as I can see, your best choice would be to bodge two SN74LV1T34 or SN74AHCT1G125 devices onto your board.