Has anyone tried this buck converter board?  42 cents each - Page 1
Forum section: electronics / general

author: wnorcott
author_rank: Regular Contributor
timestamp: October 10, 2019, 06:18:33 pm
content: 1PCS Mini DC-DC 12-24V To 5V 3A Step Down Power Supply Module Voltage Buck Converter Adjustable 97.5% 1.8V 2.5V 3.3V 5V 9V 12Vhttps://www.aliexpress.com/item/32884011122.htmlIt's 42 cents for a buck converter that has adjustable step down voltage or if you cut a trace on the back and solder bridge one of the fixed voltage selections (1.8V 2.5V 3.3V 5V 9V 12V) it becomes that. It also has an logic enable/disable line with a pullup resistor so default = enabled.It has a measurement Dynamic Response Speed:5% 200uS does that mean that within 200 microseconds of power on it settles to a regulated voltage within 5% of the setting? Or is it like the slew rate of an op amp, that it can adjust output voltage by 5% every 200uS?I have bought from this particular seller so I am fine with the service and delivery the merchandise but I wanted to know if anyone tried this item in the past? Seems mighty cheap. My only concern is will it spike out the full 24V input voltage before it settles down or anything like that. Thanks.

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 10, 2019, 08:24:41 pm
content: Crazy they can make it that cheap. You can't even get the parts for that price.

author: coppice
author_rank: Super Contributor
timestamp: October 10, 2019, 08:41:13 pm
content: Quote from: Red Squirrel on October 10, 2019, 08:24:41 pmMaking them that cheap is trivial. Selling them one off at that price, and covering the costs involved, is the hard part.

author: floobydust
author_rank: Super Contributor
timestamp: October 10, 2019, 08:50:49 pm
content: The IC is Monolithic Power SystemsMP2315.You won't get near 3A due to heat. I derate by 50% so ~1.5A and add input and output capacitance as they are the smallest value caps to keep costs low.

author: thm_w
author_rank: Super Contributor
timestamp: October 10, 2019, 10:01:35 pm
content: I've used these, they are incredibly convenient with the solder links on the back.Ignore all the specs on the page and look at the datasheet floobydust has linked, and recommendations he's given. It will work fine at lower currents without any modifications.You shouldn't see any sort of spike on the output afaik.

author: amyk
author_rank: Super Contributor
timestamp: October 11, 2019, 12:01:55 pm
content: Quote from: floobydust on October 10, 2019, 08:50:49 pmMP2315 sells for $0.16USD in 1ku+ in China:https://item.szlcsc.com/46892.htmlLCSC sells them at an only slightly higher price:https://lcsc.com/product-detail/DC-DC-Converters_MPS_MP2315GJ-Z_MP2315GJ-Z_C45889.html

author: wnorcott
author_rank: Regular Contributor
timestamp: October 11, 2019, 12:42:40 pm
content: Thanks for the information guys and identifying the chip, this looks like a good chip, I read the datasheet . They keep getting better every few years. I ordered 10 of the boards to try out. Thanks for the tip I will keep the current way under the 3A spec. This board with the multiple solder links for selecting the different fixed voltages will be very useful to me.

author: NobleX13
author_rank: Newbie
timestamp: October 11, 2019, 01:47:18 pm
content: Thanks for sharing this. I might try out a few of these as well. As others have said, I would keep an eye on temps if your power consumption gets over a few hundred mA.

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 11, 2019, 02:15:59 pm
content: Have some of those boards around, they are handy.MPS ICs are quite good actually.Now the boards themselves are obviously minimal, so as said above, don't expect them to be able to dissipate a lot of power. I wouldn't draw much more than 1A, but don't hesitate to experiment with a temperature probe to see how far you can reasonably go.

author: rrinker
author_rank: Super Contributor
timestamp: October 11, 2019, 05:13:24 pm
content: I use some larger ones, I can find them on Amazon for maybe $1.50 each. These are much smaller, now I have to order some, and redraw my PCB to mount them on... The bigger ones use the same chip, no heat sink, so good luck getting 3A out of those, although they do have some copper area under the chip since the boards are much bigger. They also claim up to 40VDC input - yeah, not so much, the cap connected directly across the input has a 25V rating. But that's fine., I'm using them as local stepdowns from a 12-15V power bus (most likely going to be 15 - so I can run 12V devices as well).

author: dragonsan
author_rank: Newbie
timestamp: October 11, 2019, 05:50:33 pm
content: Don't trust the 'fixed' voltage solder points. Check it with a meter, I have found them to be quite inaccurate. Its okay though - use the "ADJ" solder point and adjust to 5.0V, 3.3V, etc.

author: james_s
author_rank: Super Contributor
timestamp: October 11, 2019, 06:14:02 pm
content: Watch out for the pots they use, not surprisingly they are very cheap, and IIRC they are continuous rotation. It's very easy to have the output voltage shoot up unexpectedly so don't set the voltage while it's connected to a sensitive load. Other than that they work fine, as others have said they don't meet claimed specs but that's Chinese Amps for you.

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 11, 2019, 06:18:46 pm
content: Yup. Personally, I would never use the ADJ setting with this pot. Like, really never. Even if you have set it carefully, it may jump unexpectedly at any time due to vibration or a small shock. And then destroy whatever is powered by it. No thanks, way too flimsy.The only position I've used was fixed 3.3V, and it was accurate enough AFAIR. Otherwise, you can always replace one resistor.

author: wnorcott
author_rank: Regular Contributor
timestamp: October 11, 2019, 09:00:03 pm
content: The reason I asked about voltage spikes in my original post is I have some older Chinese bucks, made with LM2596, they have a fake blue Bournes 25-turns pot labeled Buris or something hilarious, that have spike or just glitched for reasons unknown, and fried the board it was trying to power.

author: jonovid
author_rank: Super Contributor
timestamp: October 11, 2019, 09:07:16 pm
content: some have been known to unexpectedly take up smoking

author: thm_w
author_rank: Super Contributor
timestamp: October 12, 2019, 03:53:21 am
content: Quote from: dragonsan on October 11, 2019, 05:50:33 pmLooks like you were dead on. Now we know one reason why they are so cheap, they screwed up the FB resistors.Heres what I measured on two units:Code:12V: 6.56, 11.78V9V: 5.64, 5.43V5V: 3.90, 3.82V3.3V: 2.86, 2.83V1.8V: 1.72, 1.71V

author: sleemanj
author_rank: Super Contributor
timestamp: October 12, 2019, 04:10:15 am
content: These very miniature buck converters are pretty useful when you need maybe up to 2-2.5A peak and more like 1-1.5 continuous, but as another poster above said, they really do need extra capacitance on the output at least.Even just a tiny 1uF electrolytic makes for a significant improvement.

author: 001
author_rank: Super Contributor
timestamp: October 12, 2019, 09:54:19 am
content: Quote from: blueskull on October 10, 2019, 08:46:55 pmWHY? What is the buisnes idea?

author: sleemanj
author_rank: Super Contributor
timestamp: October 12, 2019, 10:19:58 am
content: Quote from: 001 on October 12, 2019, 09:54:19 amPennies make pounds my granddad would say.

author: soldar
author_rank: Super Contributor
timestamp: October 12, 2019, 07:05:19 pm
content: Quote from: 001 on October 12, 2019, 09:54:19 amEven if they lose money on every sale they make up for it in volume.

author: mikerj
author_rank: Super Contributor
timestamp: October 14, 2019, 11:39:05 am
content: Quote from: soldar on October 12, 2019, 07:05:19 pmIf they lose money on every sale, then high volume of sales means going out of business more quickly.

author: soldar
author_rank: Super Contributor
timestamp: October 14, 2019, 12:47:14 pm
content: Quote from: mikerj on October 14, 2019, 11:39:05 amYou don't say! Really?

author: coppice
author_rank: Super Contributor
timestamp: October 14, 2019, 12:52:14 pm
content: Quote from: soldar on October 14, 2019, 12:47:14 pmHe must be young. Nobody could have lived through the dot com bubble and not know that gag.

author: soldar
author_rank: Super Contributor
timestamp: October 14, 2019, 01:11:44 pm
content: Quote from: coppice on October 14, 2019, 12:52:14 pmWhilethe joke is as old as the hills, it seems it isa business strategy the dot.coms have been following.

author: james_s
author_rank: Super Contributor
timestamp: October 14, 2019, 07:28:30 pm
content: Maybe it's a language thing, jokes are notoriously tricky to translate. Also engineers tend to be somewhere on the autistic spectrum and many have a tendency to take things literally.

author: Rick Law
author_rank: Super Contributor
timestamp: October 15, 2019, 02:24:50 am
content: Quote from: james_s on October 14, 2019, 07:28:30 pmProbably more inter-discipline cultural difference than language difference. I first heard that joke in US Sales organizations in the USA in 1980's (before dot-com days). Even then, other non-English speaking Sales folks elsewhere picks it up real quick. Tech-staff typically just display the confused look face.EDIT: adding this point belowPerhaps the reason why Sales is more receptive to that joke is: For many of the companies I've work at, Sales Rep work on commission based on Sales figures and not based on Profit figures. They are given a price schedule and a sales quota to meet, and they go sell. At times, the customer may propose a deal like "we will by a thousand units if you lower the price to X per unit". The Sales guy would bring it back to get their boss to agree. Naturally, the profit is cut to some degree in the process. Typically (at least at the places I've worked) profit margin is the worry of someone higher up than the Sales Rep.If their boss let them out to sell dollar bills at say 75 cents, they will do just that to make their quarterly/monthly sales quota.

author: soldar
author_rank: Super Contributor
timestamp: October 15, 2019, 07:19:42 am
content: I starteda thread about improving unregulated wall warts. I am thinking of buying a bunch of these regulators and regulating them at whatever voltage they can handle.