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SN74LS240: Threshold Voltage

Intellectual 1495 points

Replies: 4

Views: 99

Part Number: SN74LS240

Hi team,

SN74LS240NS shows hysteresis on the datasheet but it doesn't specify its threshold voltage.

Could you please provide each high→low and low→high threshold voltage?

Best regards,

Shota Mago

  • Hi Shota,

    The VIL or VIH are listed in the electrical characteristics section of the datasheet shown below.



  • In reply to Karan Kotadia:

    Hi Karan-san

    Thanks for your quick reply.

    In accordance to datasheet, it shows that hysteresis voltage is 0.4V(typ).

    So I think there is actual threshold voltage for each Low→High/High→Low which should be VT+ − VT-−=0.4V.

    Is it possible to provide the actual threshold voltage if you have?

    Best regards,

    Shota Mago

  • In reply to Shota Mago:

    The datasheet specifies the hysteresis, but not the absolute voltage of the thresholds. They can be anywhere between VIL and VIH.

  • In reply to Clemens Ladisch:


    You should never be operating near the threshold voltages. The VIH and VIL specs I have given is what you should conform to when switching on the device. The hysteresis will help if the input signal has a slow rising or falling edge as the device will not falsely switch or oscillate at the output.