Author Topic: Has anyone tried this buck converter board? 42 cents each  (Read 1296 times)

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Offline wnorcott

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Has anyone tried this buck converter board? 42 cents each
« on: October 10, 2019, 06:18:33 pm »
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 12V
https://www.aliexpress.com/item/32884011122.html

It'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.
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Offline Red Squirrel

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #1 on: October 10, 2019, 08:24:41 pm »
Crazy they can make it that cheap.  You can't even get the parts for that price.
 

Offline coppice

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #2 on: October 10, 2019, 08:41:13 pm »
Crazy they can make it that cheap.  You can't even get the parts for that price.
Making them that cheap is trivial. Selling them one off at that price, and covering the costs involved, is the hard part.
 

Offline blueskull

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #3 on: October 10, 2019, 08:46:55 pm »
Crazy they can make it that cheap.  You can't even get the parts for that price.

If you followed my FPGA thread and CH552 thread, you would know I was working on a Gowin FPGA board.
The original BOM was $21, excluding ESD parts. If ESD parts were added, expect $23.
After making all but fixed (FPGA and PMIC, $7.6 combined) parts Chinese, the BOM cost became $9 with ESD.

So, we are looking at $1.4 of BOM for Chinese parts from LCSC and Taobao, doing same task as $15.4 imported parts.
That's a 1:11 ratio.

This buck board features a 24V+ buck controller, an inductor and a few caps, which can be made for $1.5 using Western parts if you buy in quantity.
If you apply the same 1:11 ratio, the projected Chinese BOM would be 14 cents.
Add in 5 cents of PCB, 5 cents of SMT, 5 cents of packaging (labor+ESD bag) and 5 cents of logistics, you have a total cost of 34 cents.
Chinese companies are known to sell products at barely the cost, so if the margin is 10%, the wholesale price would be 37 cents, and the rest are seller's profit.
 
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Offline floobydust

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #4 on: October 10, 2019, 08:50:49 pm »
The IC is Monolithic Power Systems MP2315. 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.
 
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Offline thm_w

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #5 on: October 10, 2019, 10:01:35 pm »
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.
 

Offline amyk

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #6 on: October 11, 2019, 12:01:55 pm »
The IC is Monolithic Power Systems MP2315.
MP2315 sells for $0.16USD in 1ku+ in China: https://item.szlcsc.com/46892.html

LCSC sells them at an only slightly higher price: https://lcsc.com/product-detail/DC-DC-Converters_MPS_MP2315GJ-Z_MP2315GJ-Z_C45889.html
 

Offline wnorcott

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #7 on: October 11, 2019, 12:42:40 pm »
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.   
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Offline NobleX13

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #8 on: October 11, 2019, 01:47:18 pm »
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.
 

Offline SiliconWizard

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #9 on: October 11, 2019, 02:15:59 pm »
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.

 

Offline rrinker

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #10 on: October 11, 2019, 05:13:24 pm »
 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).
 

Offline dragonsan

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #11 on: October 11, 2019, 05:50:33 pm »
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.
 
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Offline james_s

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #12 on: October 11, 2019, 06:14:02 pm »
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.
 

Offline SiliconWizard

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #13 on: October 11, 2019, 06:18:46 pm »
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.
 

Offline wnorcott

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #14 on: October 11, 2019, 09:00:03 pm »
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.
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Offline jonovid

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #15 on: October 11, 2019, 09:07:16 pm »
some have been known to unexpectedly take up smoking  :-\
Hobby of evil genius      basic knowledge of electronics
 
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Offline thm_w

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #16 on: October 12, 2019, 03:53:21 am »
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.

Looks like you were dead on :palm:. Now we know one reason why they are so cheap, they screwed up the FB resistors.

Heres what I measured on two units:
Code: [Select]
12V:   6.56, 11.78V
9V:    5.64, 5.43V
5V:    3.90, 3.82V
3.3V:  2.86, 2.83V
1.8V:  1.72, 1.71V

 

Offline sleemanj

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #17 on: October 12, 2019, 04:10:15 am »
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.
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Offline 001

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #18 on: October 12, 2019, 09:54:19 am »

Chinese companies are known to sell products at barely the cost

WHY?  What is the buisnes idea? :-//
 

Offline sleemanj

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #19 on: October 12, 2019, 10:19:58 am »
WHY?  What is the buisnes idea? :-//

Pennies make pounds my granddad would say.
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Offline soldar

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #20 on: October 12, 2019, 07:05:19 pm »
WHY?  What is the buisnes idea? :-//

Even if they lose money on every sale they make up for it in volume.
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Offline mikerj

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #21 on: October 14, 2019, 11:39:05 am »
WHY?  What is the buisnes idea? :-//

Even if they lose money on every sale they make up for it in volume.

If they lose money on every sale, then high volume of sales means going out of business more quickly.
 
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Offline soldar

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #22 on: October 14, 2019, 12:47:14 pm »
WHY?  What is the buisnes idea? :-//

Even if they lose money on every sale they make up for it in volume.

If they lose money on every sale, then high volume of sales means going out of business more quickly.

You don't say! Really?
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Offline coppice

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #23 on: October 14, 2019, 12:52:14 pm »
WHY?  What is the buisnes idea? :-//

Even if they lose money on every sale they make up for it in volume.

If they lose money on every sale, then high volume of sales means going out of business more quickly.

You don't say! Really?
He must be young. Nobody could have lived through the dot com bubble and not know that gag.
 

Offline soldar

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Re: Has anyone tried this buck converter board? 42 cents each
« Reply #24 on: October 14, 2019, 01:11:44 pm »
He must be young. Nobody could have lived through the dot com bubble and not know that gag.

While the joke is as old as the hills, it seems it is a business strategy the dot.coms have been following.
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