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$1.30 Voltage Stepdown Modules — Parallax Forums

$1.30 Voltage Stepdown Modules

ercoerco Posts: 20,256
edited 2014-12-08 08:08 in General Discussion
Just ordered five, works out to $1.30 each shipped: http://www.ebay.com/itm/5pcs-DC-DC-4-5V-28V-to-0-8V-20V-Step-Down-Module-Power-Supply-for-Arduino-Hot-/301297751206

They look nice & small, 96% efficiency claimed. 3 Amps max! Might be good for dialing down a 7.4V LiPo to power servos on a small bot. The only thing I don't cotton to is that tiny adjustment pot. I prefer multiturn worm gear trimpots for fine adjustment.

Anybody tried these yet? Curiousone, you're always one step ahead of me lately.

Comments

  • ercoerco Posts: 20,256
    edited 2014-11-13 20:55
    Specs from http://www.ebay.com/itm/10pcs-Mini-360-DC-DC-Buck-Converter-Step-Down-Module-4-75V-23V-to-1V-17V/251616291869?_trksid=p5713.c100041.m2061&_trkparms=aid%3D333008%26algo%3DRIC.MBE%26ao%3D1%26asc%3D25756%26meid%3D928aba56344c423a95a31e8a562c9f1b%26pid%3D100041%26prg%3D10760%26rk%3D6%26rkt%3D36%26sd%3D370891446922

    Model Name: Mini-360 (ultra small size DC-DC synchronous rectifier buck module)
    Module Properties: non-isolated buck
    Rectification: synchronous rectification
    Input voltage: 4.75V-23V
    Output voltage: 1.0V-17V
    Output Current: lowering the value of 3A, long 1.8A
    Conversion efficiency: 96% (maximum)
    Switching Frequency: 340KHz
    Output ripple: 30mV (no-load)
    Load regulation: ± 0.5%
    Voltage regulation: ± 2.5%
    Working temperature: -40 ℃ to +85 ℃
    External dimensions: 17 * 11 * 3.8 (L * W * H) (mm)
    Features: Use integrally molded power inductor and synchronous rectifier control chip, smaller and more efficient.
  • Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
    edited 2014-11-14 08:12
    Hey erco,

    Can you find the same great deal in something that steps up from 3.3v to 5.0v?
  • ercoerco Posts: 20,256
    edited 2014-11-14 08:30
    Long ago, 5V boosters for under a buck and they work great. http://www.ebay.com/itm/151333666945

    http://forums.parallax.com/showthread.php/149646-5VDC-Boost-Converter

    A lot of sensors and accessories still need 5V, even if you have a 3.3V processor. Some day I'll test what happens if you power 2 CR servos off this module for a mobile bot.

    Edit: I am using one of these now and I noticed a funny thing. There's a red LED power indicator on this USB booster which doesn't light up on 1.5V input, but it's still outputting 5V.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-11-14 08:58
    You can also get these stepdown modules at ElectroDragon. They cost a bit more but ED ships pretty fast.

    It was interesting to read the reviews on this module. It appears most reviewers liked them.
  • Hal AlbachHal Albach Posts: 747
    edited 2014-11-14 09:47
    Although these are twice the size I got ten of these for $11.98 with free shipping from New Jersey, got them in about 4 days. I believe they are slightly cheaper from China, but the free, fast delivery convinced me.
    http://www.ebay.com/itm/10-pcs-DC-DC-LM2596-Step-Down-Adjustable-Converter-Power-Supply-Module1-3V-35V-/301120877446?pt=LH_DefaultDomain_0&hash=item461c33f386
  • User NameUser Name Posts: 1,451
    edited 2014-11-14 10:52
    Hal Albach wrote: »
    Although these are twice the size I got ten of these for $11.98 with free shipping from New Jersey, got them in about 4 days. I believe they are slightly cheaper from China, but the free, fast delivery convinced me.
    http://www.ebay.com/itm/10-pcs-DC-DC-LM2596-Step-Down-Adjustable-Converter-Power-Supply-Module1-3V-35V-/301120877446?pt=LH_DefaultDomain_0&hash=item461c33f386

    Sort of an apples and quinces situation. The OP features the MP1584 and your board features the LM2596. The link Duane provided has a great comparison of the two.

    BTW: The LM2596 works fine. Any hoarder probably has a bunch of them. I have at least 14 that I know of. Many are embedded in devices I built a while ago, and are still going strong today. The MP1584 is intriguing mostly for the slightly greater efficiency, which means less heat dissipated. In some applications I really do need 2A.
  • DomanikDomanik Posts: 233
    edited 2014-11-14 11:03
    Hal Albach wrote: »
    Although these are twice the size I got ten of these for $11.98 with free shipping from New Jersey, got them in about 4 days. I believe they are slightly cheaper from China, but the free, fast delivery convinced me.
    http://www.ebay.com/itm/10-pcs-DC-DC-LM2596-Step-Down-Adjustable-Converter-Power-Supply-Module1-3V-35V-/301120877446?pt=LH_DefaultDomain_0&hash=item461c33f386
    I just bought 10. I like the specs, the 2 large caps, and the multi-turn? adjustment. The pot looks more stable and perhaps has better resolution than the others. I need something for my ancient breadboard to give me 3.3V-- should be able to parallel these off the same input to get 3.3V, 2.5 and 1.5. With a 12V input can also get 5V at 2A.
    Dommy Like It.

    Update: Hooked it up to 22VDC input and tried to adjust to 3.3V and couldn't get it right on. Thought a multi-turn pot would do it but the output range is so wide it can't get fine resolution. It's a 1.5k pot so putting a 10k in series might bring it in tighter.
  • RDL2004RDL2004 Posts: 2,554
    edited 2014-11-14 12:57
    I bought some of those last year. Well, they look the same but they may not be that exact one. I haven't needed to use one yet and I never bothered to unwrap and test them when they arrived. Apparently some people have good luck with them, others don't.

    http://www.eevblog.com/forum/reviews/lm2596-dc-dc-step-down-modules-load-testing/
  • ercoerco Posts: 20,256
    edited 2014-11-14 14:38
    Glad to hear I'm not the only guy who bought some and haven't used or even tried them yet. My to-do list is oppressive...
  • ercoerco Posts: 20,256
    edited 2014-11-15 02:35
    Those little USB 5V booster boards are robust. I cut the connector off and cut the board down to save space on a project tonight. Somehow I shorted the output and the coil smoked when I hooked it up to a LiPo. 3 times it smoked (briefly) until I found the short. I was prepared to toss the unit, but it's still putting out 5.05V pretty as you please. Hard to kill!
  • ercoerco Posts: 20,256
    edited 2014-11-22 15:10
    Got my five units today. Quick-tested one which appears to work well, but I only drew an amp or less, didn't smoke test at 3A yet. I hooked up a 7.4V Lipo battery to input and a DC gearmotor & voltmeter to the output, good power output to the motor over a wide speed range. The downside: there's no "power on" LED (love that on the 5V USB booster), and that little pot is hyper sensitive, as anticipated. There are no stops, it rotates 360 degrees. Lots of friction, it will stay right where you put it. But for fine adjustment or a mission-critical app, you'd want to replace it with a multiturn trimpot.
  • CuriousOneCuriousOne Posts: 931
    edited 2014-11-24 04:03
    The ones based on LM2596 can't provide more than 1.5amp 5VDC output with 12VDC input.
  • CuriousOneCuriousOne Posts: 931
    edited 2014-11-24 23:44
    Talked to a friend which is employed in semiconductor industry and here's what he said about these LM2596 modules. The chip is used is fake. How you can get sure in this, without slicing it, placing in x-ray machine and so on? Just use scope to check frequency. Genuine LM2596 operate @150khz. Fakes usually around 50khz. So if you want to get better result from fake, remove the lousy 33uh inductor, and replace it with higher peak current one, at least 100uh.
  • CuriousOneCuriousOne Posts: 931
    edited 2014-11-24 23:57
    Just measured the fake one. Frequency is around 58khz.
  • User NameUser Name Posts: 1,451
    edited 2014-12-07 20:19
    erco wrote: »
    Got my five units today. Quick-tested one which appears to work well, but I only drew an amp or less, didn't smoke test at 3A yet. I hooked up a 7.4V Lipo battery to input and a DC gearmotor & voltmeter to the output, good power output to the motor over a wide speed range. The downside: there's no "power on" LED (love that on the 5V USB booster), and that little pot is hyper sensitive, as anticipated. There are no stops, it rotates 360 degrees. Lots of friction, it will stay right where you put it. But for fine adjustment or a mission-critical app, you'd want to replace it with a multiturn trimpot.

    A fine review. Objective and accurate.

    Now for the subjective, hyperbolic, and annoying review:

    The MP1584 is fabulous! Thanks to synchronous rectification using internal MOSFETs, conversion efficiency is way high. That, combined with the high operating frequency, makes for a truly tiny board with outstanding current-handling capability. Almost has to be seen to be believed. It garners my vote for EFOTY.
  • CuriousOneCuriousOne Posts: 931
    edited 2014-12-08 00:41
    Yes but datasheet clearly shows external schottky diode?
  • ercoerco Posts: 20,256
    edited 2014-12-08 08:08
    @UserName: OK, I'll bite.

    EFOTY=Erco Find Of The Year? :)
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