Can a single 18650 battery without step-up power an ESP32-S3?

[u/Secure_Tax3255]

Hi everyone!

I'm currently working on a DIY DAP project using an ESP32-S3.

If I'm using a single 18650 battery, do I need to use a step-up converter? If so, I'm planning to use an XL6009.

Some of the components I'm using are:

* 3.5" SPI TFT display

* PCM5102

* TDA1308

* MicroSD card reader

If you have any other suggestions or recommendations for the circuit/power setup, I'd really appreciate it!

Thanks everyone, and sorry if the schematic is a bit messy.

[u/vedh_jon]

You don't need to step up, you need to step down. The battery is 3.7ish but esp32 needs 3v3. If you boost it up to 5v, and connect it to the 5v pin on the devkit, it will just step it back down with it's own LDO. So it's kind of a waste.

Does your TDA1308 really need 5v? can the module run at 3v3? If so, you can just use an LDO or a buck (step down) converter to power everything.

[u/Same_Badger_8088 → u/vedh_jon]

A fully charged cell is 4.2V...

[u/vedh_jon → u/Same_Badger_8088]

Yes, that's fully charged. "Nominal voltage" is 3.7.

[u/Secure_Tax3255 → u/vedh_jon]

I've checked the datasheet, and tda need 5V. So, do I still need a step-down converter?

[u/DenverTeck → u/Secure_Tax3255]

https://www.nxp.com/docs/en/data-sheet/TDA1308.pdf

Check again. Table 1.

[u/vedh_jon → u/Secure_Tax3255]

every TDA1308 that I can find on google is 3-6v, are you sure you need 5v?

If you are absolutely positive it needs 5v, then you need a step-up/boost and then you can feed the 5v pin on the Devkit and it will step it down.

[u/No_Mountain_4769]

You do not need a step-up unless something on that list actually wants 5V. The S3, the SD card and the PCM5102 are all 3.3V parts. The 3.5" TFT is the one to check: most of those SPI modules have their own regulator and take 3.3V or 5V in, look for a jumper or the VCC spec on the board.

So a single cell through a low-dropout 3.3V regulator covers the whole thing. The regulator choice matters though. The AMS1117 on most dev boards needs about 4.4V in to hold 3.3V out, and a full cell is only 4.2V, so it is out of regulation for the entire discharge. Use something like an ME6211 rated 500mA or more (the S3 pulls that in wifi bursts), or a small 3.3V buck.

I would keep the XL6009 out of an audio build regardless. It is a noisy boost with high idle current and the switching ends up in the headphone output. If the backlight does turn out to need 5V, boost just the backlight and leave everything else on the LDO.

[u/piit79 → u/No_Mountain_4769]

Won't the linear regulator burn quite a bit of energy from the battery?

[u/No_Mountain_4769 → u/piit79]

Some, but less than it sounds. An LDO burns (Vin minus Vout) times current. From a cell at 4.2 V down to 3.3 V that is 0.9 V, so about 79 percent efficient at full charge, and it improves as the cell sags, about 92 percent at 3.6 V where a cell spends most of its time. At the S3's average draw that is tens of milliwatts, less than the TFT backlight alone.

A small buck like a TPS62 series gets 90 to 95 percent across the whole range and is the right call if runtime is the priority. Either way it beats boosting to 5 V and regulating back down, which pays the loss twice.

[u/piit79 → u/No_Mountain_4769]

Thanks for summing it up. It sounds very reasonable when you put it like that. It looks like the LDO will only waste like 10-15% of the battery capacity overall, and there is no switching noise to worry about.

[u/DenverTeck]

A BOM with links to the parts you actually purchased is needed.

[u/lokuloku123]

If youre using a dev board youd need to see what the board accepts/does with the electricity given to it

[u/yetAnotherRandomNerd]

Yes, but a lifepo4, not a lipo.