Is the LM311DT rail-to-rail?

[AndrewIC]

As per subject, is the ST LM311DT rail-to-rail? Farnell claims that it is, but that's the only place that says it is, I can't find a definitive statement in the datasheet.

(I have used the TI LM311, and that is not rail-to-rail. I need to handle inputs close to Vcc.)

Thanks!

[Peter BENSCH]

Welcome @AndrewIC, to the community!

What catalogue distributors write on their websites is their responsibility, not that of the manufacturer. The respective data sheet is always decisive for technical parameters. But even rail-to-rail is not a clear specification, because it does not say whether it refers to the input or the output.

In this case, it is a voltage comparator that was developed in the last millennium and still uses bipolar technology. If you look at the electrical characteristics in table 4 of the data sheet, you will find the input common mode voltage range, which is specified as VCC=±15V with a typical value of -14.7...+13.8V, and +13V in the worst case. It is precisely this difference, which can be up to 2V, that indicates that there is no RR-I.

Regards
/Peter

 

[AndrewIC]

Thank you Peter, that's exactly what I needed. The was the common mode range is expressed in the ST data sheet wasn't clear to me - I have seen other manufacturers' data sheets specify the upper limit of the common mode voltage as e.g. "Vcc+ minus 2.0V", but what you have said makes perfect sense.

Regards
Andrew