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SN74LVC1G32: Output of SN74LVC1G32DRYR in 95~100℃ temperature range

Wendy Wang1
Genius 13650 points
Part Number: SN74LVC1G32

Hi team,

My customer uses SN74LVC1G32DRYR, in 95~100℃ temperature range, when VCC goes from 3.3V to below 1.65V, the output will go from 0 to the voltage equal to VCC and follows VCC(which is below 1.65V now). Is it a normal behave of our device during 95~100℃? Or do we have test data of VCC and Vout in this temperature range?

Best regards,

Wendy

  • 0
    Guru 276180 points

    Correct behavior is guaranteed up to 125 °C, but not below 1.65 V if the inputs are changing.

    Do you have measurements, or better oscilloscope traces, of the inputs? I suspect that some input voltage stays high enough to go over the switching threshold, or  that there is noise on the ground.

  • 0 in reply to Clemens Ladisch
    TI__Genius 13650 points

    Hi Clemens,

    Thank you for your help!

    But for temperature below 95℃, the output is correct. Will the threshold change with temperature?

    Best regards,

    Wendy

  • 0 in reply to Wendy Wang1
    Guru 276180 points

    The actual threshold will change, but it is guaranteed to still be somewhere inside the datasheet limits.

  • 0 in reply to Clemens Ladisch
    TI__Genius 13650 points

    Hi Clemens,

    Thank you!

    Customer thinks that it is not related to the temperature and they wonder that whether it is just the behavior of our device if the input voltage goes below 1.65V. Will the output of our device follow the input voltage if the input voltage goes below 1.65V? Do we have any relative information?

  • 0 in reply to Clemens Ladisch
    TI__Genius 13650 points

    Hi Clemens,

    Here is the waveform of OR gate IC and Inverter IC.

    As shown in the figure, after VCC voltage dropped below 1.65Vdc, their output would be changed from 0Vdc to Vcc level, and deceased with Vcc step by step. Customer wonders why the output is not kept at 0Vdc or high impedance when Vcc < 1.65Vdc.

    Thanks a lot!

    Best regards,

    Wendy

  • 0 in reply to Wendy Wang1
    TI__Mastermind 27688 points

    Hey Wendy,

    The recommended operating condition table states the output won't be held once the Vcc goes below 1.5V. If the input is held at their old values while the Vcc is down to 1.5V the output will remain and drive the same value they were before. This is listed as 'data retention only' in the datasheet. 

    When Vcc is between 1.65V and 5.5V, we guarantee the same operating conditions as listed in the datasheet. While in the 1.65 < Vcc < 1.5 range, data retention is possible, as described above. Below 1.5V the output value may change, which is what you're seeing here.

    Their output switches at 1.187V which looks to follow the supply still so the operation conditions here are below the recommended for normal operation and data retention. So it looks like they're crossing some threshold here and switching states but it isn't something we have quantified.
    Sine they're using this device below the recommended Vcc range (1.65V to 5.5V per the datasheet) and below the 1.5V for data retention we don't have data or information and can't really confirm it's expected behavior. 

    Thanks,
    Rami