EEVblog #1180 - Component Parametric Search Tutorial - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: February 12, 2019, 10:29:18 pm
content: What is parametric searching, how is it useful, and how to best use it.Dave answers a viewer question and hunts down the best microcontroller for the job, explaining and demonstrating parametric search engines in the process.

author: helius
author_rank: Super Contributor
timestamp: February 12, 2019, 11:10:37 pm
content: Octopart (now owned by Altium) is a useful site when performing parametric searches, since it indexes across multiple distributors. Think the Arrow.com parametric search sucks? No problem, just select your parts with Octopart and transfer them to an Arrow shopping cart. You can also use their BOM tool to build multi-supplier BOMs.

author: EEVblog
author_rank: Unknown
timestamp: February 13, 2019, 12:43:53 am
content: BTW, I found out why the OP needed 256K, it's for a large number of text strings. So could easily use an external memory. But given that I found a $1 256K part anyway, meh.

author: johnlsenchak
author_rank: Frequent Contributor
timestamp: February 13, 2019, 03:01:30 am
content: I use that "parametric searching" when Digi-Key had their whole catalog on a compact disc back in the ninnies . It was great fun !

author: golden_labels
author_rank: Super Contributor
timestamp: February 13, 2019, 03:52:12 am
content: The values in parametric search may be wrong in two ways. Finding a part that matches requirements, but in reality it doesn’t, is one issue. The other one isnotfinding a part: e.g. a 47µF capacitor may be listed with the capacity of “47” and “47000”. Even worse if some of the options for the parametric search are ranges. You need a boost voltage regulator for 24V and select the “24V” option? Pay attention: there may be options for “18–28V” and other ranges. This is highly dependent on quality of implementation of the website, but may be a trap.As a hobbyist one may pay more attention to the “In stock” option (if available). When a given component is unavailable, the supplier may send the order in parts. Until now the companies, which I used, were either covering the shipping expenses for additional parcels or waiting until they can complete the order, but this is not always the case.After finding a part, check local companies that do not have parametric search. Large suppliers are great for big orders, but for prototyping and hobby orders it may make much more sense to see what national-level companies and your local shops can offer. For a $4 order you don’t really want to pay $10 in shipping if you can pay $4.20 and pick the order in person.Quote from: EEVblogI do not know the case, but my senses are telling me that I should suggest that option: maybe that external memory could be the device with which the µC communicates through serial interface? Perhaps that device is a PC with 8GiB of RAM and terabytes of non-volatile storage? Missing the most obvious solutions is not uncommon.

author: nctnico
author_rank: Super Contributor
timestamp: February 13, 2019, 01:03:23 pm
content: I often find myself using the various component selectors on manufacturer websites. These often have more details compared to the generic ones from Farnell, Mouser, Digikey, etc. Try and find an opamp with a specific noise level or offset voltage. After having some parts on a short list the distributor websites are a good indication of availability of the part.

author: rrinker
author_rank: Super Contributor
timestamp: February 13, 2019, 02:09:39 pm
content: I recently did just that. I was looking for some sort of capacitor, searching by value, type, and orientation gave me multiple hits from the same manufacturer with no other details other than the part number, so I still wasn't sure which one I should use. So off to the manufacturer's web site, where thy are all nicely broken down, found the one I wanted, and armed with a manufacturer part number, was able to pick exactly that one and not a list of several choices from the original site.However, that's no way to complete a BOM for a more complex project. it would take forever to have to research most every part in that manner. Luckily, the other parts I needed all had adequate descriptions so I could easily determine the correct one from a value and size search. And this is for a simple little project - sometimes these things make me kind of glad I don't do this for a living even though it was my originally chosen career path. WHen it's just a hobby project and I start to get annoyed, I can just stop working on it for a while.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 16, 2019, 03:47:50 pm
content: Sometimes parts are listed wrong, it sometimes gives odd laughs. A while a goo I looked for a multiplexer. For some reason the list also showed an AD831 multiplier. It can also happen the other way around that parts are not found in a selection where it should have been - though hopefully it would not happen with the really cheap parts.Having several possible websites can help, as some search parameters can really suck - e.g. supply voltage ranges that are not really well sorted. So even if they have the right parameter the interface may still make it useless.

author: onlyrgu
author_rank: Newbie
timestamp: February 26, 2019, 02:27:07 pm
content: I tried Parametric search on Microchip site for an AEQ-100(automotive) mC and it threw result of the some controllers . But AEQ-100/automotive was not metioned in the (Atmel )datasheet. So never trust parametric search and always double check the Revised datasheet.