When I look for ICs online, I often come across a list like this one.

For example, I just searched for the 4N35 optocoupler, and came up with a list:

  • 4N35M
  • 4N35SM
  • 4N35SR2M
  • 4N35SR2VM
  • 4N35SVM
  • 4N35TVM
  • 4N35VM

And this is a relatively short list. Sometimes, differences are obvious (i.e. package type). But the aforementioned are all in DIP package. So is there some sort of a general convention that all manufacturers follow when naming these chips? I mean, how am I supposed to choose which one is right for me? Reading the datasheet searching for a minute difference each and every time can be tedious (sometimes it certainly helps), but I'm wondering if there is a fast way, based on the suffixes of the variants of a component, to tell how it differs from other members in its family.


No standard convention between manufacturers, or sometimes within a single manufacturer.

The different part numbers can refer to:

  • IC Package
  • IC Temperature Rating (Standard, Automobile, Military, Space, etc)
  • Shipping Package (Single, Reel, etc)
  • Voltage Options (i.e. 3v, 3.3v, 5v)
  • Accuracy/Tolerance Options (i.e. 10% vs 5%)
  • Lead Length
  • Lead free or not
  • Speciality options

And so many more, in any combination.


Luke, use the datasheet.

ordering information

No general way around it, I'm afraid. Every manufacturer has its own convention(s).

  • 1
    \$\begingroup\$ I would rather say: "Luke, use the parametric search!" Then after a short list of components has been made, get the datasheets and examine them. \$\endgroup\$ – AndrejaKo Jan 22 '13 at 13:54
  • 3
    \$\begingroup\$ Can we start a new acronym: RTFDS? \$\endgroup\$ – Analog Arsonist Jan 22 '13 at 14:33
  • \$\begingroup\$ Well, I know I can use the datasheet. I was wondering if there is some sort of convention. I guess not. \$\endgroup\$ – capcom Jan 22 '13 at 14:39
  • \$\begingroup\$ @capcom indeed not in the general case. If you read enough datasheets you may find conventions specific to a manufacturer or product family. As practical advice, I'd say don't worry about it as long as you can do a parametric search on package type and other essential parameters. The other variants often vary in less important ways (temperature rating, packaging) such that you either won't care for a hobby project, or won't mind reading the datasheet for a manufactured product. I usually sort by price and pick the cheapest one. \$\endgroup\$ – Phil Frost Jan 22 '13 at 14:45
  • \$\begingroup\$ Thanks Phil, good advice. I was guessing that it's not extremely important as well at the hobby level. But I was just intrigued by so many variations of a single chip. \$\endgroup\$ – capcom Jan 22 '13 at 14:53

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