# I (possibly) do not understand topicality of questions on ee.se

More specifically, I don't understand why this question has been well received:

I do not understand behavior of current in 74HC4066

The question simply asks "what does it mean", referring to the following sentence:

To avoid drawing VCC current out of terminal Z, when switch current flows in terminals Yn, the voltage drop across the bidirectional switch must not exceed 0.4 V

As far as I can tell, the OP does not attempt to ask any of the following, which seem to me like they might be considered questions about electronics:

• What is "VCC current"?

• What is a "terminal"?

• What is "switch current"?

• What is a "voltage drop"?

• What is a "bidirectional switch"?

• In this circuit, why would voltage across the bidirectional switch in excess of 0.4V in combination with current flow in terminals Yn, cause VCC current to be drawn from terminal Z?

• Why should I care about whether current is drawn from terminal Z in this circuit?

• What would cause switch current to flow through terminals Yn in this circuit?

• How can I measure voltage across a bidirectional switch?

• How can I limit voltage across a bidirectional switch?

Instead, it seems to be purely asking how to parse the sentence. That is: the information sheet has a sentence of the general form "To avoid W, when X occurs, Y must not exceed Z", and OP is asking what a sentence like that means. To which the answer is: "it means that you must make sure that Y is no more than Z whenever X is happening. If you don't do that, W could happen, and that might be a bad thing. If X isn't happening, then the value of Y doesn't matter, but if it is happening then you need to be careful." Based on how the answers were written, it seems to me that everyone is on the same page that this really is the issue in contention. The answers are padded out with some discussion of the circuit, but that discussion is not answering the actual question.

I think this question is off topic, because it is a question about comprehending the English language rather than a question about electronics design.

What might I have overlooked here?

• I see your point. It's arguably similar to the LED question that you have a good answer to. || I think here it's not largely English language per se that is the problem but technical description - which happens to be in English. || I'm very aware of the sort of issue mentioned here BUT it's understandably confusing to someone without experience of body diodes and related. Yes - asking some of your questions would have been useful BUT the answer are very worthwhile for many people.
– Russell McMahon Mod
Mar 16 at 12:05

#### Interpreting the datasheet is more than English

Interpreting the language in a datasheet is one of the most important tasks when designing a new product, and it is also a skill that has to be learnt and practiced like any other skill. After a while you learn to react when you see something you don't recognize.

Being wary about a section in the datasheet that you think you don't fully understand is completely expected and I would definitely encourage such questions if they are otherwise on topic. One of my better received questions is just like that. On the surface the datasheet is perfectly clear: Do not use below 20 mA, but what does it really mean? My implied question being "what am I missing from this clear statement?"

#### "I do not understand behavior of current in 74HC4066"

This is and was always the title of the question and very much part of it. The question body clarified which part OP did not understand, and many users easily found OP's implied questions, many of which you have kindly written better than I ever could, so I can quote them directly:

• In this circuit, why would voltage across the bidirectional switch in excess of 0.4V in combination with current flow in terminals Yn, cause VCC current to be drawn from terminal Z?
• Why should I care about whether current is drawn from terminal Z in this circuit?
• What would cause switch current to flow through terminals Yn in this circuit?
• How can I limit voltage across a bidirectional switch?

Simply put, "help me understand why this is important and what kind of common designs or mistakes could cause me to break this rule".

The rest is up to the person answering the question to decide, and then to the voting members of the website to rate the answers. Everything working as intended, as far as I can see.

• Nicely explained. We get quite a few questions which have got an implied question that isn't quite the same as the literal one. This question being discussed was an example of that. People were able to see that there were implied questions & answered those. As you say, things seem to have worked as intended. || The one caveat I would add is that going back to the OP to ask constructive "do you mean..."-type question, in comments, can also be a good thing - we should encourage that. Guessing about the implied questions can waste time & effort, if people guess & answer the wrong ones.
– SamGibson Mod
Mar 16 at 12:21