How are ICs found and chosen? - Page 1
Forum section: electronics / beginners

author: Cyao
author_rank: Newbie
timestamp: February 25, 2025, 04:05:38 pm
content: Currently I am looking for a power mux IC (I also see it called priority power), but I am quite lost on how to find one that suits my needs.Normally I would just go on Digikey, and select the appropriate categories and define my limits, then just use the part with the most stock. But this time for the power mux, I couldn't find an appropriate category: Someone on Discord recommended me the TPS25947, which is in the eFuse category, and I also found the TPS2116, which is define as a power switch/driver. So what can I do in this situation? And more generally, what should I do/where should I go to find the most appropriate ICs?Also when there is two ICs that both suit my needs, is there a rule of thumb about which one to pick?Thanks in advance!

author: jumpstart
author_rank: Newbie
timestamp: February 25, 2025, 06:25:49 pm
content: Here are a few more options from TI, similar to the TPS2116 with other voltage/current ratings:https://www.ti.com/power-management/power-switches/power-muxes/products.htmlTPS2117 is essentially the same as TPS2116 but higher current rating at 4AThe TPS25947 is a bit different, it is only a single switch, so you would need two in a mux configuration. It has some additional protection features: overvoltage, overcurrent, short circuitCan you describe the application, or specify voltage and current requirements? That would help narrow down which specific IC would be most appropriate for the application. It is not uncommon that multiple parts meet the specs you need, then I look at other factors like temperature rating, common footprint, availability, and price to narrow down my selection.

author: Cyao
author_rank: Newbie
timestamp: February 25, 2025, 07:19:55 pm
content: Thanks! My main application is to be able to supply current to a lot of neopixels (5V, ~2A per column). And I need a power mux that will draw current from a dedicated power supply when it's connected, but switch to another common power supply when it isn't (The brightness will be lowered in firmware). I will have a couple columns that all have access to a main power supply, and each have a non-mandatory dedicated supply.But the main thing I want to learn is how people choose parts, what platforms does people use, what are the most important indicators people look at and if there is any way other then flipping a coin to decide when everything meets the needs? So I wouldn't need to always ask other people to search for the parts I need :3

author: jumpstart
author_rank: Newbie
timestamp: February 25, 2025, 09:42:20 pm
content: Digikey, Mouser, and Octopart are my go to's. They work great for searching and selecting your standard to mid-complexity parts, but not as helpful with more application specific parts like the priority power mux you are looking at. It gets tricky because part manufacturers like to come up with their own trade names for specific-use parts.Then it's back to Google and Manufacturer websites:TI - Power MuxGLF - IqSMART Power MuxAnalog Devices - PowerPathI am always assessing these questions after finding a part that meets the required electrical specs:1. Is the part readily available from multiple suppliers in the quantities I need?2. Is the part recommended for new design?3. Are there drop-in alternates or similar parts available from other manufacturers if I cannot get this part anymore?4. Is this part used in any reference designs or eval boards? Prior validation and reference material increases confidence.5. Have I checked the datasheet for any exceptions or footnotes that may impact my design?I would probably lean towards one of the TI parts for this application given the availability, pricing, and reference material available:https://www.ti.com/tool/TPS25947EVMhttps://www.ti.com/tool/TPS2117EVM

author: TomWinTejas
author_rank: Regular Contributor
timestamp: February 26, 2025, 02:31:44 am
content: This is one of the use cases where LLMs do pretty well, at least for a starting point. For example here's what Claude says about your specifics:Based on your requirements, here are some suitable options:TPS2115A/TPS2116A (Texas Instruments)- Power mux specifically designed for your use case with automatic switching between power sources based on availability and priorityCan handle 5V, with current limits up to 2AHas a built-in current limiting featureAvailable in small packages (TSSOP-8)LTC4412 (Analog Devices/Linear Technology)- Low-loss PowerPath controllerWorks as an "ideal diode" controllerGood for automatic power source switchingRequires some external components (MOSFETs)TPS2420/TPS2421 (Texas Instruments)- Hot swap controllers with power limitingHigher current capability if neededMore protection featuresMAX40200 (Maxim/Analog Devices)- Ideal diode controllerVery low voltage dropSimple implementationIt also suggest using these search terms:"Power multiplexer""Power OR-ing controller""Ideal diode controller""PowerPath controller""Auto power source selector"

author: CatalinaWOW
author_rank: Super Contributor
timestamp: February 26, 2025, 03:24:26 am
content: Two part answer. Part one, how do you find what kind of part to look for. There are two old school methods which haven't been mentioned yet. Talk to a manufacturers rep. Obviously this isn't too successful for hobbiests and students, but even there if you use it lightly you can get help because they hope sometime later you will really generate some sales. And read trade the trade press. This used to be magazines, now is on line.Part two, how do you select a part once you have some candidates. There is really only one answer here, which is to understand all of your requirements and pick the one that best meets them. These requirements can include many things not in the search columns of the on line distributors. Some things to think about future: availability of the part, any limitations from use in your country, your comfort with the vendor, quality of documentation, availability of support software, your familiarity with the part family/technology (which translates into how much of yor time will be spent learning how to use it), development board availability, sample availability and others. Even within the parameters given by the distributors you need to decide each of the attributes is to your top care about and so on down the line. Is price more important than power margin and so on. Do you really care about lead time?This can grow into a huge task. At some point you have to decide enough is enough, be sure that some small number of parts meets all of the requirements you really care about, and use dice or other method to pick one of them. If you correctly identified what you care about the choice won't really matter.