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SN74CB3Q3257: voltage level on data I/O port

Mark Chen52
Expert 8135 points
Part Number: SN74CB3Q3257


Hi Expert,

To check datasheet for SN74CB3Q3257DBQR, and it states the Vih Min is 1.7V and Vil Max is 0.7-0.8V. I wanted to confirm that this is only for “control input” (OE and select pins), and not for data I/O ports?

On the first page it also says that 0.8V and 1.2V are supported for data I/O, but still I would like to make sure that 1V application in the data I/Os is ok.

Regards,

Mark

  • +1
    Guru 317750 points

    Yes, the specifications labelled with "control input" apply only to the control inputs.

    The data I/Os are not buffered and do not have switching thresholds. The voltages mentioned on page one are just examples; this device supports all voltages in the VI/O range specified in the recommended operating conditions table.

  • +1
    TI__Genius 10974 points

    Hi Mark,

    You are correct. The data I/Os can go up to 5V given a 3.3V supply and 3.3V given a 2.5V supply. The control/digital inputs can go up to 5V as well (VIH/VIL refers to the voltage needed for the control inputs to register as an active high/low in order to switch the active channels of the device).

    To be clear for your application, 1V is perfectly fine to pass through the switch. You just need to make sure you have an acceptable logic voltage to make sure you can register highs and lows properly and a power supply of at least 2.3V (can be up to 3.6V).

    Thanks!

    Bryan