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I have a regulator on an Arduino Mini Pro board (Chinese clone) which should be a 3V3, but it seems it's a 5V one (by measured voltage). The markings on the component are BALG. Does anyone know what it is?

Edit: have added a picture of the board. I need a 3V3 one because I have a communication board that requires that voltage.

Board picture

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    \$\begingroup\$ And the package type? \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Commented Feb 4, 2015 at 4:22
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    \$\begingroup\$ A close-up photo would help a lot. \$\endgroup\$
    – Dwayne Reid
    Commented Feb 4, 2015 at 4:47
  • \$\begingroup\$ Question: does it matter that it's 5V instead of 3V3? Many Arduino boards run at 5V. Check what the micro can handle for supply voltage. If it's a 3V3 part rather than a 5V part, you can probably count on having to replace it as well. \$\endgroup\$
    – Dwayne Reid
    Commented Feb 4, 2015 at 4:49
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    \$\begingroup\$ After a quick look it appears even the official one has 3V3 and 5V versions, the only difference being the clock speed of 8 MHz versus 16. What crystal frequency does it have and if you want 3V3 for another reason maybe you could just check the PCB layout is the same and order what's on the original BOM? \$\endgroup\$
    – PeterJ
    Commented Feb 4, 2015 at 10:13
  • \$\begingroup\$ It's a cheap Chinese thing, I doubt you can find the BOM on the internet, especially since this is sold as 3V3, but I measured it to output 5V \$\endgroup\$
    – rslite
    Commented Feb 6, 2015 at 3:05

3 Answers 3

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It cannot be either the PAM2301/AME5110, this is because those are switching regulators and there are no inductors on that board's top. Secondly the fact that there SMD codes are BA*** or BAR** respectively which does not match your model.

It is possible that it is RT9193 5 volt LDO regulator from richtek. This is as its code is BA, the LG is the lot code. And it is obvious it is the 5v version because of your VCC reading.

The manual is here, this is found on s-manuals where there is a table of smd codes linking to datasheets where you can look for the respective component, this works as you can look for the respective component according to functionality.

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SMD markings are unfortunately not unique.

It may be a PAM2301 or AME5110 step-down dc-dc converter, but you have to compare how it's wired in your circuit with the datasheet.

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Sorry for bringing up an old discussion, but I was just checking up about this myself and thought it might be useful if anyone else is looking in the future. Searching for 'balg voltage regulator' led me to a datasheet for a Seaward SE5509B linear regulator. On their markings, the second letter is Vout, (a/b/c/d/e/f = 3.3/2.8/2.5/1.8/1.5/3.0). So BALG should give a 3.3V output. Looking at the schematic, the RAW input should be connected to the regulator's Vin, and the Vout is connected to the board's Vcc. If that's the case, then it's possible the regulator's not working properly.

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  • \$\begingroup\$ Hmm, as sometimes happens, just after I post I then realise I'm probably being daft. The datasheet I found actually says the case marking should be 509ALz, so the fact that the part numbers ends in BALG for a 3.3V regulator, which is what the part should be, could just be coincidence.In fact I've just checked mine and it's giving Vout of 5V from a 12V supply. \$\endgroup\$
    – Snufkin
    Commented Mar 13, 2015 at 12:29
  • \$\begingroup\$ If you're being daft, feel free to delete this answer. You can always write a better one later. \$\endgroup\$
    – Dave Tweed
    Commented Mar 13, 2015 at 14:30

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