Notes on power supply circuits for Arduinos, Raspberry Pis, ESP32s, and other 5V/3.3V devices
The following table compares various small DC-DC buck convertor modules commonly found on Amazon, AliExpress etc.
| Image | Description | Chipset | Input | Output | Max Current | Switching Frequency1 | Pot. Adj. | Fixed Adj. | Notes |
|---|---|---|---|---|---|---|---|---|---|
 |
CA1235 module | MP1495 | 5-16V | 1.25-5V | 3A | 500kHz | ✅ | ✅ | Adjustable voltage output selectable by pot or solder joints. Large holes designed for wire-to-board mean this can't easily be PCB mounted. |
 |
"Mini" | Marked as "DKGAA" | 12-24V* | 1.8-12V | 3A | 500kHz | ✅ | ✅ | Adjustable (need knife to break trace as described here). Amazon reviews say not to exceed 15V input |
 |
MP1584EN | MP1584 | 4.5-28V | 0.8-20V | 3A | 1.5MHz | ✅ | ⬜ | Pot adjustment only |
 |
QSKJ "Fine" | MP2315 | 6.5-24V | 5V | 3A | 500Khz | ⬜ | ⬜ | Output is only via a USB socket |
However, all of these modules have flaws of one sort of other:are typically based on somewhat old Monolithic Power Systems ICs which are not recommended for new designs.
- MP1495 (used in "CA1235") and MP1584 are both old ICs from Monolithic Power Systems not recommended for new designs. (The MP2338 is the recommended alternative instead).
- MP2315 (used in "QSKJ Fine") is also not recommended for new designs, with the MP2393 suggested alternative instead.
- The QSKJ is not usable on a PCB due to the output only having a USB interface, while the CA1235 not usable in a custom PCB design due to its non-standard pin diameter.
- The "Mini" uses a "DKGAA" chip of unknown origin or specs, and it requires manual modification (removing trace to the potentiometer) to make it output a fixed voltage
So, one alternative is to design a custom power subsystem. There's a useful reference article here: https://medium.com/supplyframe-hardware/designing-power-supplies-that-are-97-efficient-179e8ab887c5 (based on the same MP2315 as the QSKJ Fine, which, as previously mentioned, is not recommended for new designs)
| Chipset | Input | Output | Max Current | Switching Frequency | Notes | Circuit |
|---|---|---|---|---|---|---|
| XL1509 | 5-16V | 1.25-5V | 2A | 150kHz | Used in Kincony power supply circuitry with relatively few additional components: https://www.kincony.com/kc868-a4-hardware-design-details.html |  |
| XL1507-5.0 | 4.5-40V | 5V (fixed version) | 3A | 150kHz | More current than above. Available in fixed and adjustable versions. 5000 in stock at LCSC. |  |
| XL1530 | 3.6-18V | 0.8-16V | 3A | 380kHz | 4000 in stock at LCSC |  |
| Various TI chips, e.g. TPS543320? | See https://www.ti.com/lit/sg/slyt729b/slyt729b.pdf?ts=1732728465255 |
For subsequent stepdown to 3.3V, take 5V output and send through an AMS1117. TPS7A92 is similar to AMS1117 (slightly more expensive at $0.60) but gives you 2A of output current. Or, if more current is required, could simply feed to AMS1117 in parallel, as in the design of the Kincony A64.
Also see
- https://blog.yavilevich.com/2017/03/efficient-dc-12v-to-5v-conversion-for-low-power-electronics-evaluation-of-six-modules/
- https://discord.com/channels/560138831853125653/687761124728635397/1259447808889589794
Footnotes
-
Higher switching frequency will mean less ripple on the output (more accurate voltage/current) but causes more overhead due to switching, which reduces the efficiency somewhat. ↩