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I currently use a step up converter from China. (https://www.amazon.co.uk/gp/product/B01534P0OI/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1)

All of the step-up converter schematics i've seen seem only to be able to cope with 3.3V to 12V rather than the 3.3V to 24V that I require. (Without adding components to run the IC out of spec)

The IC on this circuit is unmarked, and even with plenty of research, I can't seem to ID it. (Could it be MT3608?) (Is there any evidence of LM2577 in this package?)

I could either do with someone who can identify the mystery IC, or more preferably provide a schematic for the PCB below!

Current DCDC Converter

Thanks in advance!

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closed as off-topic by Enric Blanco, laptop2d, Nick Alexeev♦ May 16 '17 at 20:06

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – Enric Blanco, laptop2d, Nick Alexeev
If this question can be reworded to fit the rules in the help center, please edit the question.

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    \$\begingroup\$ You can't just post the picture of a PCB and expect people to give you a schematic. We are not a free reverse-engineering service, nor are we able to magicly know what the bottom layer or components are suppoed to be hooked up to. \$\endgroup\$ – Joren Vaes May 15 '17 at 14:03
  • \$\begingroup\$ Fair point; there's nothing on the bottom layer. That aside, I made it quite clear from my question what the pcb is hooked up to: a 3.3V source and a 24V drain (current not relevant). Can anyone beat my current best guess of MT3608? \$\endgroup\$ – Alfred Ernesto May 15 '17 at 14:08
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    \$\begingroup\$ The link you give says it's LM2577.... \$\endgroup\$ – user3528438 May 15 '17 at 14:10
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    \$\begingroup\$ Post this question to the Amazon seller. EE.SE isn't his volunteer technical support. \$\endgroup\$ – Nick Alexeev♦ May 15 '17 at 14:33
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    \$\begingroup\$ It seems curious to need to boost 3.3V to 24V. The garden of 24V hardware is rich and diverse... and almost all of it eats current for lunch. Your 3.3V supply is going to need a lot of capacity to do anything useful at 24V. Usually if you're working at 24V you drive it with 24V equipment - because it's tough and designed for heavy duty use. Plugging a 3.3V toy into a 24V system feels fragile and wrong to me. If you absolutely need the 3.3V hardware in the system I would generally want it to be switching 24V rather than boosting to match, I think. \$\endgroup\$ – J... May 15 '17 at 18:22
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Despite the seller's misleading description on that Amazon page you linked which claims it is a "Yeeco LM2577 DC DC Boost Converter Step-up Voltage Regulator", that description is clearly wrong, since the LM2577 is not available in the small SOT23-6 package, shown in this photo from that Amazon web page as U1:

front of PCB - from Amazon seller's web page

The answer to your question is on the reverse of the PCB, where the manufacturer's part number "XY-016" is shown (this photo is again from that Amazon web page):

back of PCB - from Amazon seller's web page

Searching on that number shows that other vendors describe the module as "DC-DC Step Up Power MT3608 XY-016", with a photo that matches the module on the Amazon web page you linked. And the Aerosemi MT3608 ("High Efficiency 1.2MHz 2A Step Up Converter") is available in that IC package. (Here is the MT3608 datasheet on the Olimex website.)

Therefore I agree with your hunch - that board uses the MT3608 (or a clone of it - perhaps like the SX1308 (PDF datasheet), but it could be any other clone). Also see "Update 2" below.

Whether those modules are safe or not, is a completely different question... For example, on YouTube - Caught on FIRE?? MT3608 DC DC step up boost coverter. The module in that video is a slightly different but very similar module, which claims to use the MT3608.

It is worth reading the comments under that YouTube video, which point out that some load may be required on the module's output, for correct operation. The typical lack of documentation for these modules, means that some "trial and error" and/or reverse-engineering is often needed, to find out how best to use them.

Update:

As Spehro Pefhany has kindly highlighted in his answer, we can't be sure which IC is used (and that would still be true, even if the IC did have the correct "top code" for a genuine MT3608, as those can be faked). Therefore there is always an element of risk with such modules, especially those coming from vendors and manufacturers who don't have a reputation which they need to maintain.

Update 2:

It's also interesting that at time 14:44 in that YouTube video linked above (direct link to that point in the video), the video's producer says "Upon closer inspection, the ICs have 4 different part numbers" (out of 20 modules). Obviously that raises concern about quality control and the sourcing of the ICs!

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    \$\begingroup\$ Aha! Well that serves me right for always dismissing the Chinese nonsense written on PCBs!! I'm hoping i'm safe with it, as i'm only working with low current - Bench PSU states 190mA. More research on the fire situation required! \$\endgroup\$ – Alfred Ernesto May 15 '17 at 14:27
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If the IC is actually unmarked it's not a genuine anything.

It may have the same pinout as a MT3608 and it may meet some or all of the specs, but there is no way of telling. It may be able to go to 28V as the real chip would or it may be extremely marginal (or fail immediately) at a much lower voltage.

https://www.gislounge.com/here-be-dragons/

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    \$\begingroup\$ Very true (+1) - I was just editing my answer with a link to one example of an MT3608 clone when you wrote your answer :-) \$\endgroup\$ – SamGibson May 15 '17 at 15:25
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    \$\begingroup\$ @SamGibson +1 for you then. \$\endgroup\$ – Spehro Pefhany May 15 '17 at 15:41
  • \$\begingroup\$ @SpehroPefhany: What is with the dragon thing? \$\endgroup\$ – Keno May 15 '17 at 16:34
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    \$\begingroup\$ @keno Allegedly (it's actually mostly a myth) cartographers in medieval times would place "here be dragons" on maps when the area was unexplored and they had no idea whatsoever what was in the area (and it might be something scary). In same way, we have no idea what die is inside that SOT-23-6 package (and it might be something scary). \$\endgroup\$ – Spehro Pefhany May 15 '17 at 16:47
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And there it is! One of the few step up converters to use 2 caps rather than 3. Credit to @SamGibson

MT3608:

enter image description here

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  • \$\begingroup\$ What does this add to the previous answer that you credited? \$\endgroup\$ – The Photon May 15 '17 at 16:16
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    \$\begingroup\$ "One of the few step up converters to only use two caps." And one inductor. Very significant difference. If there was a boost circuit that could boost 3.3 V to 24 V using only two capacitors and no inductors, I'd be very impressed. \$\endgroup\$ – nitro2k01 May 15 '17 at 16:35

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