Choosing appropriate power supply for a heat-constrained ESP32 devkit - Page 1
Forum section: electronics / general

author: extan
author_rank: Newbie
timestamp: March 07, 2022, 03:17:40 pm
content: I'd like to run an ESP32 devkit in an automotive application using a small, plastic enclosure. I won't be using radios on the ESP, so its nominal current requirement is less than 100mA at 5V (typically closer to 50mA). Nonetheless, given that there is minimal air circulation inside the enclosure, I'm keeping an eye on heat dissipation.With a nominal 14.4V supply, and 5V required to power the devkit, a linear regulator could easily dissipate 0.5W, and though I can't quantify the thermal characteristics of the enclosure, it feels like 0.5-0.7W may be a bit sketchy in a closed box on a hot day.However, when I look at small-ish buck converter specs, (for example the LMR14010Ahttps://www.ti.com/lit/ds/symlink/lmr14010a.pdf) I'm not seeing output current numbers under 100mA. When I plug my numbers into TIs nifty Webench interactive designer (https://webench.ti.com/wb5/PartDesigner/quickview.jsp) it tells me it can't find any solutions.So I'm wondering if a buck converter is just an inappropriate choice for this application and I should really go with a linear regulator (getting over my concerns about 0.5-0.7W getting everything too hot).Any thoughts on a good solution, or my assumptions, are greatly appreciated!

author: PlainName
author_rank: Super Contributor
timestamp: March 07, 2022, 03:31:41 pm
content: QuoteYou could arrange for a minimum load, but perhaps using the buck to get down to, say, 5V and then a LDO regulator to derive 3.3V from that might solve the issue. I am not sure but Ithinkwith too low a load the supply voltage may rise above the set limit, hence the LDO will deal with that and not have to dump 11V to do so.

author: extan
author_rank: Newbie
timestamp: March 07, 2022, 06:54:17 pm
content: (To clarify: when I say "devkit" I'm referring to a module with the ESP32 with a usb and a 5V to 3.3V LDO mounted together on the same board. I'm looking to power this with a 5V input)But the question remains: is a buck converter suitable for taking 14V to 5V supplying only 50-100mA?After a ton of searching I found the MP2359 and MP2315, which look good, but are, sadly, not available. (I also found the PAM2312, but it's only good up to 5V input.)So it is at least possible for such a converter to exist, but I can't seem to find one that is available (I've really searched!). I'm surprised, as I'd think powering a microcontroller with a buck converter is a pretty common application...Perhaps I should ask a more specific question: Does anyone know of an available converter that can supply 50-100mA at 5V from a 14V supply?

author: kripton2035
author_rank: Super Contributor
timestamp: March 07, 2022, 06:57:42 pm
content: does this answer you ?https://www.romanblack.com/smps/smps.htm

author: Davor
author_rank: Contributor
timestamp: March 07, 2022, 10:44:18 pm
content: MCP16331 is working fine for me, but not available now.RT8258GJ6 is available in Digi-Key, should be OK, never tried it.

author: extan
author_rank: Newbie
timestamp: March 08, 2022, 02:41:55 pm
content: Thanks for the link, kripton. However, I'd prefer to use a commercial controller.And thank you Davor! That RT8258GJ6 looks great!