28V to 5V buck, 300mA, automotive aftermarket - Page 1
Forum section: electronics / projects

author: rvalente
author_rank: Frequent Contributor
timestamp: October 18, 2019, 11:04:49 am
content: Dear Mates,what would you suggest for a buck converter from 28V to 5V @ 300mA output, very few requirements: internal feedback and enableLitte update, sorry, my requirements were terrible.This product will be used in chassis level, supplied by KL30 and KL15 lines.Its mandatory to have input tolerance up to 60V during 1min, although the device is not required to work.I was thinking something very common, like LM2xxx something or similar.

author: Zero999
author_rank: Super Contributor
timestamp: October 18, 2019, 01:15:28 pm
content: RECOM ROF-78E5.0-0.5SMD-Rhttps://uk.farnell.com/recom-power/rof-78e5-0-0-5smd-r/dc-dc-single-o-p-0-5a-2-5w/dp/2218605http://www.farnell.com/datasheets/2787771.pdf?_ga=2.136389680.1027168967.1571403950-1702035652.1404807855&_gac=1.204680612.1567586830.EAIaIQobChMI8_26mOO25AIVx7TtCh351Al-EAAYASAAEgIjDfD_BwE

author: Zero999
author_rank: Super Contributor
timestamp: October 19, 2019, 12:39:44 pm
content: Either I missed the part about 60V or you edited it in later. There are plenty of DC:DC converters which can take up to 60V in.https://www.mouser.com/catalog/specsheets/xppower_06192019_DS_STH05_170519.pdfhttps://www.mouser.co.uk/ProductDetail/XP-Power/STH0548S05?qs=PzGy0jfpSMvu3ftBUxiygQ==Please refrain from editing posts, unless it's just to correct a typo or spelling error. Posting a follow-up would have been better, as it would push the thread back to the top and increase the chances of a helpful response.

author: mariush
author_rank: Super Contributor
timestamp: October 19, 2019, 02:59:25 pm
content: Why not make your own?Plenty of cheap ICs with good schematics :https://www.digikey.com/short/pn1591for example mpq2459https://www.monolithicpower.com/en/mpq2459-aec1.htmlHere's datasheet, see page 10-12 :https://www.monolithicpower.com/en/documentview/productdocument/index/version/2/document_type/Datasheet/lang/en/sku/MPQ2459-AEC1/document_id/3888/

author: max_torque
author_rank: Super Contributor
timestamp: October 19, 2019, 07:00:18 pm
content: Any EMC limitations?

author: Zero999
author_rank: Super Contributor
timestamp: October 19, 2019, 07:19:41 pm
content: You could also go discrete, with the Black regulator.https://www.romanblack.com/smps/smps.htm

author: DBecker
author_rank: Frequent Contributor
timestamp: October 19, 2019, 10:19:03 pm
content: What are you reliability requirements?For automotive use the world is divided into throw-away quality aftermarket parts, and OEM quality (AEC qualification).The throw-away parts are robust by the standards of the consumer world, but they are built with the assumption that if they fail, it has no critical impact. You can just unplug it, throw it away and buy another. They might handle the voltage spikes of normal operation, but aren't expected to always survive a load dump, 28V jump start or be fully functional at -40C.If you need AEC qualification, you should take a few minutes to research what that means and add it to your requirements.

author: rvalente
author_rank: Frequent Contributor
timestamp: October 20, 2019, 08:10:30 pm
content: Quote from: Zero999 on October 19, 2019, 12:39:44 pmSorry by the confusion I've edited my post.I'm yet not sure what my requirements are, I'm trying to understand it, there is 10 since my last auto oem development and, it was for 12V cars not 24V trucks development.The product will read the right and left speeds from the rear axle, this device will be OEM level but, offered to more them one customer, so my customer, the axle supplier will offer it. He is a mechanical auto parts maker which have none electronic product in his portfolio.Quote from: max_torque on October 19, 2019, 07:00:18 pmNot sure, i believe I should take an standard and follow it up, which one would you suggest?Quote from: DBecker on October 19, 2019, 10:19:03 pmStill looking for the requirements, AECQ200 is a good start point? Should I look at other standards?

author: DBecker
author_rank: Frequent Contributor
timestamp: October 20, 2019, 11:48:10 pm
content: Check out 'ISO 16750-2'What communication do you require?If you need CAN bus, consider using a chip like the TLE9471. It has a switching regulator, CAN transceiver, and a few other handy features. If you are buying in small quantities it's only a bit more than an automotive-qualified switcher plus a transceiver, and it checks a bunch of feature boxes.

author: rvalente
author_rank: Frequent Contributor
timestamp: October 21, 2019, 12:36:18 am
content: Quote from: DBecker on October 20, 2019, 11:48:10 pmInitially none, but in the near future in going CAN, i do not see a reason to use k-line. Any ST suggestion for the smps or smps + can transceiver?My main micro is a STM32F1 for the alpha prototype, I know it is not AEC qualified part but, AEC micros are pretty expensive and will narrow a lot my choices but. If you would suggest one, for a 32 bit dual channel capture time (can be two 16 timers chainned) and CAN, what to suggest?

author: max_torque
author_rank: Super Contributor
timestamp: October 22, 2019, 01:59:20 pm
content: Do you really need a 32b capture to get wheel speed? Assuming you aren't doing ABS or anything like that (in which case your CAN latency is going to be an issue), then an axle goes round at about 1krpm maximum (less for a truck), so even a 16b counter is going to give you something like 0.1 wheel degrees per second resolution !!The important bits to work out before you start spec'ing anything will be:1) Temperature range2) Sealing (IP rating/ salt spray etc)3) Vibration4) Life time (esp for capacitors in hot environments!!)5) EMC requirements (conducted and radiative)6) Power supply (24v nominal systems are actually ~28v when operating, and load dump is up to 212V !)One thing to do would be to ask your customer to what standards and test procedures there (mechanical) product is currently rated, and see if those apply to your electronics!