Has anyone used a SR086 Inductorless Switching Regulator - Page 1
Forum section: electronics / projects

author: dansku
author_rank: Regular Contributor
timestamp: January 06, 2015, 06:47:53 am
content: Has anyone used a SR086 Inductorless Switching Regulator?I just got myself a DC-DC Buck converter (http://www.ebay.com/itm/231381389930?_trksid=p2060778.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT). I was researching on some AC-DC converters to use with it and ended up looking at theSR086 Inductorless Switching Regulator(Datasheet:http://www.mouser.com/ds/2/391/SR086-30993.pdf).I would like to know if anyone knows anything about this chip, if it works well, as it's so simple to use and has no transformer.With this SR086 and a LM2596 you can make a AC-DC variable power supply.Thank you

author: dansku
author_rank: Regular Contributor
timestamp: January 06, 2015, 06:49:07 am
content: Found this picture online, does it look too simple to be true?

author: ConnorGames
author_rank: Regular Contributor
timestamp: January 06, 2015, 07:06:41 am
content: Unless youreallyknow what you are doing, it is dangerous to use a non-isolated supply like this. At the very least, they make testing whatever they are powering a nightmare, and any externally accessible electrical connections from the power supply or equipment it is powering would need to be isolated. I would strongly recommend using an off the shelf plugpack, they are cheap, safe, and readily available.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 06, 2015, 08:22:49 am
content: They work by running at very low power factor -- probably worse than the old standby of a series dropping capacitor. As a result, they aren't scalable, only reasonable for very small loads like night lights, monitoring/home automation stuff (PIR, X10, etc.).Definitely not like bench supply material, or phone charging (needs isolation), or even lighting LEDs (needs too much power).Tim

author: coppice
author_rank: Super Contributor
timestamp: January 06, 2015, 09:44:12 am
content: Quote from: T3sl4co1l on January 06, 2015, 08:22:49 amThey are fine for the little MCU in a typical white goods application, which I think is the main market.

author: coppice
author_rank: Super Contributor
timestamp: January 06, 2015, 09:45:52 am
content: Quote from: T3sl4co1l on January 06, 2015, 08:22:49 amIt was be foolhardy to develop with a power supply like this connected directly to the mains. if you use an isolation transformer during development, where is the problem? These things generally go into products which are entirely non-isolated, like fridges and washing machines.

author: rob77
author_rank: Super Contributor
timestamp: January 06, 2015, 10:37:23 am
content: interresting chip, but completely pointless for small volume production or one-off products. the savings on transformers and high voltage capacitors might be significant in huge volumes, but designing in additional safety because of no mains isolation would be much more expensive for small production volumes.

author: tszaboo
author_rank: Super Contributor
timestamp: January 06, 2015, 10:55:26 am
content: I was describing a power supply some years ago based on this principle! It is awesome that someone actually made it. I see a lot of reasons why someone would use something like this. Think of radio controlled relays, power meter, bias power for SMPS...

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 06, 2015, 12:04:36 pm
content: For this sort of application, Power Integrations' Linkswitch devices are pretty good

author: Seekonk
author_rank: Super Contributor
timestamp: January 06, 2015, 12:27:07 pm
content: People have used this idea before, it just wasn't made into a chip. We had a customer that had about 100 photo switches that used a power supply like this. Typical use for this type of product. They were running off a single transformer at an industrial site. Imagine all those little switches turning on at the same time. It drove the line power nuts! There must have been a lot of complaints. The German company redesigned the power supply six months later.

author: coppice
author_rank: Super Contributor
timestamp: January 06, 2015, 12:29:07 pm
content: Quote from: mikeselectricstuff on January 06, 2015, 12:04:36 pmPower Integrations produce a lot of variants on the theme of a very small switcher. I'm surprised they haven't included something similar to the Supertex/Microchip parts.

author: coppice
author_rank: Super Contributor
timestamp: January 06, 2015, 12:31:22 pm
content: Quote from: Seekonk on January 06, 2015, 12:27:07 pmSupertex have been making these things for a very long time. I think you'd need a fairly extreme case, like the one you described, for them to cause any problems. They are only for <1W applications.

author: albert22
author_rank: Regular Contributor
timestamp: January 06, 2015, 03:05:04 pm
content: QuoteThe datasheet advices not to do that:Quote

author: dh
author_rank: Newbie
timestamp: November 15, 2015, 07:08:07 am
content: Quote from: mikeselectricstuff on January 06, 2015, 12:04:36 pmThis forum is a goldmine! I was really hoping there was something better than the SR086 or the LR645 out there.. Thanks Mike!

author: Phoenix
author_rank: Frequent Contributor
timestamp: November 15, 2015, 07:19:38 am
content: Looks quite similar to the electrophoresis power supply Dave did a tear down off a while ago ()... except for the presence of a transformer. Probably works in much the same way too.

author: dh
author_rank: Newbie
timestamp: November 15, 2015, 07:51:31 am
content: Yeah, that's really the point to all this extra effort... getting rid of the magnetic saves a lot of space and cost!