Comment on Using the LM311 comparator, as a faster replacement for LM741 in project
lordofflies@lemmy.ml 1 week agoThere is an IC tester in our lab and it says GOOD everytime I’ve plugged in. By die shots you mean like opening up the IC and viewing it under the microscope and testing it?
j4k3@lemmy.world 1 week ago
You would need to know how the IC tester works. I’ve built my own op amp tester before. All I did was check that some basic inputs yield the correct polarity of output capable of lighting an LED. Characterization involves verifying the actual specifications such as quiescence.
Look through old datasheets and databooks. Back in the 1980s and older, it was common for nearly all ICs to have full documentation. Many are all the way down to the transistor level of stuff like op amps. These often have example circuits you should save and keep for reference. You are likely to encounter test circuits for characterization in some of them. BitSavers.org is a repo of such things. This place is hard to navigate for anything specific. Their stuff is on archive.org too. While it will not help you in this instance, here is a list of logic databooks on archive. It is not complete. github.com/…/ListOfLogicDatabooksOnArchive.md (Aside: Pay special attention to the 1996 Motorola databook on that list. Motorola tried to defy the 4k and 74 series logic nomenclature/syntax that originated with Texas Instruments. Motorola had a history of trying to out quality and document the competition in exchange for exploitive brand locking and manipulation so you had to always buy Motorola exclusively. Around the mid to late 1990s they shifted documentation to focus more on compatibility as the company was floundering. This results in an outstanding source of useful information.)
Search the eevblog forum for information and circuits for characterizing.
Keep in mind that the English world is often stupid prejudice. Many times people do not look past the part number. Many of the old part numbers are based on expired patents. So anyone with an ancient fab sitting around is able to make these parts. The datasheet specifications from one manufacturer is not relevant to any other. The part number is just a general thing with no regulatory body or requirement for maintaining some fictional standard. Even with the original part from ages ago when it was patented, had a distribution curve of quality and behavior with a published failure rate. Many of the specifications show typical values on the datasheet without a minimum or maximum because of the potential failure rate and distribution curve of parts that pass initial automated inspection.
Lastly, yes, search YT for channels like ElectronUpdate that use sulfuric acid to dissolve the epoxy packaging and photograph the die under a microscope. Ignore anyone that simply claims parts are fake but does nothing to prove their claims through rigorous testing and shows evidence.