Industry's popular SMPS for microcontroller? - Page 1
Forum section: electronics / projects

author: Mecanix
author_rank: Frequent Contributor
timestamp: May 05, 2020, 08:52:03 pm
content: Hey guys,Just want to ask what is the favorite smps for powering MCUs. I'm looking for a generic DC-DC converter to power future designs which will mostly be 3V3 rail based in my case. The source is automotive therefore between 12v(min)~14.5v(max) DC > Step-down to 5V > to 3V3 LDO > to MCU.Reason I ask is I am feeling much like my wife in a cosmetic store facing a marketing panel of eternal colors, packaging, scents and other gimmicks. Whether that is pros & cons of low/mid/high switching freq, requires more or less passives, better/worst efficiencies, price, noise, ripple specs, rms competition, the list goes on and on forever I could test/breadboard smps for the next 170 months to find one that finally outputs DC lol. At the end of the day, I just need 3V3 reallySo...What is "The Chip" guys?

author: Etesla
author_rank: Regular Contributor
timestamp: May 05, 2020, 08:59:29 pm
content: I don't think there is a 'the chip' for this category. I think that DC DC regulator IC's like this onehttps://www.onsemi.com/pub/Collateral/NCP1522B-D.PDFare too new for there to be a old standard one. I have used maybe 5 or 6 of them before so I am no expert, but out of those 5 or 6 I haven't had a single one not do what it was supposed to do designing around the datasheets recommended values and layout. I usually just pick the cheapest one available that meets my needs, they seem to be pretty foolproof in general.

author: Mecanix
author_rank: Frequent Contributor
timestamp: May 05, 2020, 09:06:47 pm
content: Quote from: Etesla on May 05, 2020, 08:59:29 pmYou see that's the problem, why can't we just call one up. The selection is overwhelming and borderline embarrassing if I may add. They are everywhere and each and everyone of them claims they will "output DC". Can't we just find one that, like, "works" and make it the industry's popular?I'd love for this thread to pick-up wind and have all of you guys listing the one that works for you so we can pick the best out i.e. the one that is mentioned most often. /venting semi-completed ;-)

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: May 05, 2020, 09:12:22 pm
content: Quote from: Mecanix on May 05, 2020, 08:52:03 pmHi,There are some pretty nasty transients in the automotive environment. There are ISO specifications and the major automotive manufacturers have there own specifications.A modern vehicle has central load dump protect and essentially has a voltage clamp of 36V. Older vehicles do not have this and the load dump transient is specified at 72V.So I would choose a part that can take about 40V maximum.Is this devices going to be on all the time? In which case you need low quiescent current so the devices doesn't kill the battery. (Especially these days, when I use my car about once per week). If it only when the car is running you don't have to be as concerned about the quiescent current.There are lots of choices, some are mechanical are you comfortable soldering very small surface mount packages?How much power does your micro need?I am afraid there are more questions than answers.Regards,Jay_Diddy_B

author: Mecanix
author_rank: Frequent Contributor
timestamp: May 05, 2020, 09:21:34 pm
content: Quote from: Jay_Diddy_B on May 05, 2020, 09:12:22 pmThanks Jay. The rant is more about generic use of SMPS for harmless MCUs in all honesty. In my case, and since you are asking, its fair enough for me to let you know that I am powering a MCU meant to interface & comm with a K-Line (performance mapping & data logging). We are talking a insignificant <100mA with ESD and other basic protection (i sense, filtering, etc). Nothing fancy, hardware-wise anyway...Appreciate the concerns you've mentioned, all valid points taken and to be considered indeedQ/A: smaller than 0603 (or 0.3mm pitch) I start to talk to myself when assembling :/Q/A: the device is powered by the driver and when needed, disconnected otherwise.

author: Mecanix
author_rank: Frequent Contributor
timestamp: May 05, 2020, 10:04:40 pm
content: Fwiw this is what is in operation at the moment. Standalone and sufficient to power a small MCU and a slow 10400 baud uart just fine, for now.LIN Transceiver with Voltage Regulatorhttp://ww1.microchip.com/downloads/en/DeviceDoc/20002298C.pdfGreat features and up to the task, although less the SMPS part which I'll need to add to the design (and many others I'm sure) soon or later. I'll also need the additional 5V for something else plus the 3V3 so can't escape re-designing this from the bottom up. I'm just getting frustrated with the forever choices given by manufacturers and was hoping to find that "The Chip". If that exist lolAnyway. If you know of any quick implementation "that works along the typical mfg recommendation" for 3V3 MCU please do chime in, that'd be useful not only for myself but for quite a few others who are also in that cosmetic store like I'm feeling now.Thanks guys, all the best