SALE (CN): $1.99-DC-DC Buck Converter Step Down LM2596 Low Ripple Power Supply - Page 1
Forum section: electronics / general

author: Peggy CH
author_rank: Newbie
timestamp: June 24, 2013, 02:34:47 am
content: Spam Removed by moderator

author: don.r
author_rank: Frequent Contributor
timestamp: June 24, 2013, 02:39:12 am
content: Or get it for $1.20 on eBay:http://www.ebay.ca/itm/DC-DC-Buck-Converter-Step-Down-Module-LM2596-Power-Supply-Output-1-23V-30V-L8-/380663936838?pt=LH_DefaultDomain_0&hash=item58a156b746&_uhb=1

author: Skimask
author_rank: Super Contributor
timestamp: June 24, 2013, 12:24:36 pm
content: Quote from: AcHmed99 on June 24, 2013, 10:40:15 amI dunno, but I bought 8 of them about a month ago, and I'll be damned, they all work as I'd expect them to work. I can't find any obvious failure points.

author: madires
author_rank: Super Contributor
timestamp: June 24, 2013, 12:56:25 pm
content: Quote from: don.r on June 24, 2013, 02:39:12 amUnder "shipping" I found this:"2.We Ship Worldwide BUT NOT TO ITALY, HK, CHINA, AFRICA."A seller in China doesn't ship to customers in China?

author: ddavidebor
author_rank: Super Contributor
timestamp: June 24, 2013, 01:23:09 pm
content: Why not to italy?

author: mariush
author_rank: Super Contributor
timestamp: June 24, 2013, 01:29:50 pm
content: Horrible customs from what i heard, they keep packages up to 50-60 days, and a small percent gets lost or buyer is never notified to get his package.Anyway.. back to achmed99's question about what's the catch ... my guess would be some company went bankrupt or cancelled a big order and a pcb assembler got stuck with thousands of this chip and offloaded them....or maybe some device didn't pass some certifications and maybe the manufacturer just dumped the pcbs for a cheap price to some chinese guys who then desoldered the parts...

author: Bored@Work
author_rank: Super Contributor
timestamp: June 24, 2013, 05:26:15 pm
content: Quote from: AcHmed99 on June 24, 2013, 10:40:15 amI have a few of them. The ones I have all measure having a 50 kHz switching frequency under load. However, the LM2596 is specified as a 150 kHz fixed-frequency switcher. Draw your own conclusion.

author: madires
author_rank: Super Contributor
timestamp: June 24, 2013, 08:17:16 pm
content: Quote from: Bored@Work on June 24, 2013, 05:26:15 pmThe LM2576 has 52kHz (fixed) :-)

author: c4757p
author_rank: Super Contributor
timestamp: June 24, 2013, 08:20:07 pm
content: Quote from: Peggy CH on June 24, 2013, 02:34:47 amQuote from: Bored@Work on June 24, 2013, 05:26:15 pmQuote from: madires on June 24, 2013, 08:17:16 pmOne of these things is not like the others...Oops, were you insinuating that's what's on the board? Sorry, went over my head.

author: Bored@Work
author_rank: Super Contributor
timestamp: June 24, 2013, 08:32:51 pm
content: Then someone must have gone through the trouble to relabel them as LM2596, because that is what is printed on the IC.

author: madires
author_rank: Super Contributor
timestamp: June 24, 2013, 08:39:59 pm
content: Quote from: c4757p on June 24, 2013, 08:20:07 pmYep, also 3A but only 52kHz, i.e. larger inductor and output cap are required.

author: Monkeh
author_rank: Super Contributor
timestamp: June 25, 2013, 02:26:43 am
content: Quote from: Peggy CH on June 25, 2013, 12:54:28 amYou got the info from? They provided you the detailed info?Please stop lying: You work for icstation.com, and everyone can see that.

author: edavid
author_rank: Super Contributor
timestamp: June 25, 2013, 03:43:41 am
content: Quote from: Peggy CH on June 25, 2013, 03:40:50 amDo you have one of their buck converter boards? Please measure the switching frequency and let us know.

author: sleemanj
author_rank: Super Contributor
timestamp: June 25, 2013, 10:11:30 am
content: I have used and sold many of these 2596 buck, and 2577 sepic modules (although not the specific "brand" here) which are ridiculous cheap out of China. As another poster says, they do what they say on the box.Out of interest, I just grabbed a random 2596 and hooked it up to my crappy old analog scope and found a workable waveform, by my reckoning, 150Khz give or take, but I a'int no good wif maths so somebody will correct me if I'm wrong. Image shows timebase 2 uS per div.The one under test here is unbranded. I scoped another one in my box-o-bits branded LEIVIN, slightly different design board, slightly different markings on the IC (both marked LM2596S, but the quality of the markings says at least one of them is probably "brand fake") similar frequency found.I had the scope probe connected to one end of the switching diode.

author: eKretz
author_rank: Frequent Contributor
timestamp: June 26, 2013, 06:21:32 pm
content: Quote from: sleemanj on June 25, 2013, 10:11:30 amLooks pretty darn close to me.

author: c4757p
author_rank: Super Contributor
timestamp: June 26, 2013, 06:23:07 pm
content: I hope you've learned your lesson about camera flash and CRTs.

author: miceuz
author_rank: Frequent Contributor
timestamp: January 14, 2014, 11:16:41 pm
content: I've had a good experience with one of those modules, unfortunately I don't remember it's measurements, now it's gone with a project I've done. Encouraged by this experience I bought 5 more. Those run at 52kHz and have a 200mV ripple when outputing 300mA of current. Input voltage 9V, output voltage 3.3V. Crap.

author: strangelovemd12
author_rank: Regular Contributor
timestamp: January 14, 2014, 11:55:53 pm
content: Quote from: madires on June 24, 2013, 12:56:25 pmI doubt China subsidizes shipping to China.

author: mubes
author_rank: Regular Contributor
timestamp: January 15, 2014, 09:19:25 am
content: I always keep a few of these in my bitsbox. Apart from one (IIRC) with a duff inductor they've always performed exactly how I've expected them to and they're great for hackups (or even semi-permanent stuff, with a suitable blob of nail varnish).DAVE

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: January 15, 2014, 10:48:40 am
content: Quote from: strangelovemd12 on January 14, 2014, 11:55:53 pmThe reason a lot of Chinese/Hong Kong sellers exclude China/Hong Kong in their shipping destination lists is not about shipping costs. It is mainly to avoid competitors in the same region to easily see their listings (there are ways around it though). Also, it's not uncommon for a competing seller to order from a competitor and intentionally leave negative feedback! It is truly dirty and sad but it is unfortunately a real issue with some sellers from this part of the world. It happened to another seller I know and that's when we both realised the problem and blocked China/HK buyers too.

author: strangelovemd12
author_rank: Regular Contributor
timestamp: January 15, 2014, 02:54:29 pm
content: @iloveelectronicsGood to know, thanks! To what extent is foreign shipping subsidized there, if at all? I'm only going on hearsay and assumptions. It's also amusing that pretty much everything I have ordered from China turned out to be a "gift".

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: January 15, 2014, 04:02:11 pm
content: Quote from: strangelovemd12 on January 15, 2014, 02:54:29 pmI don't actually know if the government actually "subsidizes" it, but postage fees are generally much lower here than most parts of the world, especially for lighter and smaller packages. To give you an example, a 200g package would cost less than $3.5 to air mail to pretty much anywhere in the world. The fee is calculated based on increments of 10g (I believe it is even 1g in mainland China), hence the intensive use of bubble wraps instead of cardboard boxes, because every gram counts and cardboard is much heavier.Having said all that, it still puzzles me how some sellers manage to sell at impossible prices which won't even cover shipping from here...

author: Mr Smiley
author_rank: Frequent Contributor
timestamp: January 15, 2014, 04:55:38 pm
content: I was just looking at the ti data sheet for the lm2596.http://www.ti.com/lit/ds/symlink/lm2596.pdfThe graph at the top of page 26.Am i looking at the graph wrong, or is the graph wrongAccording to that, the lower the input voltage, the higher the junction temperature rise above ambientAs an example,Vout 3.3v, Vin 5v Temp above amb 53'CVout 3.3v, Vin 40v Temp above amb 24'CDo i need more fish in my diet

author: edavid
author_rank: Super Contributor
timestamp: January 15, 2014, 07:13:35 pm
content: Quote from: Mr Smiley on January 15, 2014, 04:55:38 pmIt's a switching regulator... the higher the duty cycle, the higher the power dissipated in the internal switch.

author: MatCat
author_rank: Frequent Contributor
timestamp: January 15, 2014, 07:22:04 pm
content: I recently did a product using the LM2596 and one thing I found was that the cheap Chinese chips had ripple 10x higher then authentic ones.

author: edavid
author_rank: Super Contributor
timestamp: January 15, 2014, 10:40:23 pm
content: Quote from: MatCat on January 15, 2014, 07:22:04 pmIs that because they were running at a lower frequency, or for some other reason?

author: miceuz
author_rank: Frequent Contributor
timestamp: January 16, 2014, 11:06:19 am
content: I guess it all depends on your luck. I've had one which was acceptable, don't remember it's frequency, but the last batch I got is almost unusable. I've ordered another one that is advertised as 150kHz, will measure it and post results.

author: MatCat
author_rank: Frequent Contributor
timestamp: January 16, 2014, 06:31:56 pm
content: Quote from: edavid on January 15, 2014, 10:40:23 pmTo be honest I never even checked the frequency, I saw 330mv of ripple and said yep, not using these.

author: PeteAU
author_rank: Contributor
timestamp: July 18, 2014, 02:16:48 pm
content: I measured one of these ebay "x4.cn" green boards. It's switching at 57 KHz but ripple isn't terrible (5V @ 250mA draw).