SN74HC573A-Q1: applying vil max or vih min at all input at once

That sentence just says that data and nondata inputs behave the same.

All inputs must be below V_IL(max) or above V_IH(min).

Thank you for your Clemens.

Which sentence do you refer to?

If you mean ""The nondata inputs (e.g., direction, clear, enable, and preset) may be considered unused inputs and may not be at threshold conditions."" 

I understand  only control inputs must be below or above threshold, (by deduction according to datasheet, data input can be at threshold vil max and vih min don't you think?)

That sentence is not very clear. Calling out nondata inputs does not make sense, and the term "threshold condition" is not defined. Just ignore it.

All inputs, whether data or control, whether used or unused, must have a valid voltage, i.e., ≤ V_IL(max) or ≥ V_IH(min).

Hello Clemens, thank you again for your help. 

I understand what ou mean but i 'm not totally convinced as you.

A) The threshold values is kown as the level input to a logic gate that determine whether a particular input is interpreted as a logic 0 or a logic 1.

2 theshold are defined, vil max and vh min

B) for you non data input does not make sense but it is defined as  "the nondata inputs (e.g., direction, clear, enable, and preset) "

C) my question is "according to datasheet about vil max and vih min, is it allowable to apply these level on all input at once or not?"

It would be very interesting if a Texas Instruments tech support could answer.

Hi Yohann,

Clemens is correct. There is no real distinction. All inputs ("data" or "nondata", does not matter) register a logic high and a logic low. If you are not below Vil max or above Vih min for any more than the maximum input transition time, you risk damaging the device with the amount of current that goes through both CMOS fets.

So no, to answer your original question, I wouldn't recommend holding all input values at exactly the Vil max or Vih minimum voltages. As long as you stay within datasheet specifications you should be fine (i.e., once again,  ≤ V_IL(max) or ≥ V_IH(min))

Best,

Malcolm

Hi Malcom,

Thank you for your answer.

You wrote " I wouldn't recommend holding all input values at exactly the Vil max or Vih minimum voltages"

 It is an answer to my question and thank you again.

Could you please give me the official document in which this rule is recommended? 

Best regards,

Yohann