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Im new to electrical engineering. For a project I want to supply an ESP8266 with power by using a 28V Milwaukee Battery. My Question is:

Can i supply the esp at the VIN PIN using the 2411?

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  • \$\begingroup\$ Which ESP8266 module? Everybody and his dog seems to make one. The ESP8266 itself is a 3.3V part, so it will all depend on the voltage regulator of the module. Your 2411 converter put out 5V. Is that in the input range of your ESP8266? Quite likely, but without knowing the particulars of your module it's hard to say if there might be a problem. Maybe your module doesn't have a regulator, and only operates on 3.3V. Maybe it has a regulator, but it is a piece of crap that needs 6V into to provide 3.3V. \$\endgroup\$
    – JRE
    Mar 29, 2019 at 12:06

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The simple answer is maybe, but with several caveats.

  1. Regulator Output Voltage:

As JRE notes, you must verify that the ESP8266 module you selected accepts 5V. I see that, for example, the SparkFun ESP8266 module (WRL-13678) only operates with an input voltage of 3.0-3.6V. A 5V regulator would be no-go for that module.

  1. Regulator input voltage range:

A 28V battery should be fine with a regulator input range up to 36V. OK there.

  1. Check the supply current requirement for the module you have selected.

For example, the SparkFun WRL-13678 datasheet says it can draw up to 215 mA. A 200mA regulator would be marginal at best. Conservative design practice dictates use of a regulator able to provide 1.5X the maximum load current. And don't forget to add in the current draw for any additional components you want to use.

  1. Don't forget to use input and output capacitors.

Most voltage regulator modules REQUIRE external input and output capacitance. Use the voltage regulator data sheet Applications section to determine what external components are necessary.

Finally, do you actually need an isolated output regulator? They are considerably more expensive. The TRN1-2411 is about $10. A simpler and cheaper choice would be something like the CUI P78E05-1000 which provides 5V @1A for about $3. For a 3.3V module try the CUI VXO7803-500 to get 3.3V @500mA for $2.50. I use the helpful search filters on digikey.com to shop for appropriate and inexpensive components.

In summary:

  1. Verify regulator output voltage matches module input voltage range.

  2. Verify the raw power source (battery) voltage is well within the input voltage range of the regulator.

  3. Verify the regulator can supply plenty of current for the selected module.

  4. Follow the regulator's datasheet for external component requirements.

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  • \$\begingroup\$ 1. Yes my board accepts 5V. But i guess i should also be fine with a 3.3V esp which has an onboard regulator? 2. thanks. 3. i should be fine here since i only got a bluetooth module and 2 logic-level mosfets attached to the esp. 4. i guess i dont need an isolated regulator. And thanks for the hint regarding the capacitors. \$\endgroup\$
    – bautista
    Apr 2, 2019 at 13:04
  • \$\begingroup\$ i just looked into the datasheet of the 7803-500 cui.com/product/resource/vxo78-500.pdf (just as an example). In the datasheet it is stated that you just need the capacitors at an input voltage >30VDC. Would i need one in this case? \$\endgroup\$
    – bautista
    Apr 2, 2019 at 13:30
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    \$\begingroup\$ If the data sheet for the module does not explicitly say it will accept 3.3V then assume it won't. Always read and follow the manufacturer's recommendations i.e. don't guess or assume. Take a look at the regulator data sheet Figure 1 and Table 1 which calls out use of a 10uF cap at Vin and a 22uF cap at Vout. A switching regulator always requires input and output capacitors regardless of the operating voltage. Some regulator modules might include them on-board. This one does not. \$\endgroup\$
    – Randy Nuss
    Apr 3, 2019 at 14:59

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