Picking the best DC-DC converter for Arduino and ESP32 projects starts with a question that trips up a lot of beginners: do you need to step voltage down, step it up, or handle both because your power source swings across the target voltage? Buy a buck-only converter for a project that needs boost, and it simply won’t work no matter how you wire it.
This guide covers five ways to get the voltage your project actually needs: a classic adjustable buck converter, a smaller and more efficient buck alternative, a boost converter for stepping voltage up, an automatic buck-boost module built specifically for single-cell battery projects, and a USB-C PD trigger module that skips conversion circuitry entirely by asking a modern charger for the voltage directly.
Building out a bench setup to go with this? Check out our Best Bench Power Supply for Arduino and ESP32 Projects guide, and if these converters are headed for a robot build, our Best Arduino Robot Car Kits roundup covers the rest of the parts list.
Quick Comparison Table
| Converter | Type | Input Range | Output Range | Best For |
|---|---|---|---|---|
| HiLetgo LM2596 | Buck (step-down) | 4–40V | 1.25–37V adjustable | Budget/beginner step-down |
| HiLetgo MP1584EN | Buck (step-down) | 4.5–28V | 0.8–20V adjustable | Compact, efficient step-down |
| HiLetgo MT3608 | Boost (step-up) | 2–24V | 5–28V adjustable | Step-up voltage |
| EC Buying XL63020-3.3 (TPS63020) | Buck-boost (automatic) | 1.8–5.5V | 3.3V/4.2V/5V selectable | Single-cell LiPo/battery projects |
| Lonely Binary USB-C PD Trigger | PD negotiation, not conversion | USB-C PD source | 5V/9V/12V/15V/20V fixed | Tapping charger voltage directly |
1. Best Budget Buck (Step-Down) Converter: HiLetgo LM2596
HiLetgo LM2596 Adjustable Buck Converter Module
Best for: Beginners who need a reliable, well-documented way to step a higher voltage down to what their project needs.
The LM2596 is the buck converter most hobbyists reach for first, and it’s earned that spot through sheer reliability and documentation. It steps a higher input voltage down to whatever you set on the onboard potentiometer, handling everything from dropping a 12V car battery down to 5V for a microcontroller to converting a 24V power supply down to 12V for accessories. The built-in LED voltmeter display lets you dial in the exact output voltage without reaching for a separate multimeter.
Wiring is about as simple as DC-DC conversion gets: terminal blocks accept bare wire on both input and output sides, so no soldering is required to get a working setup on the bench. The tradeoff for that simplicity is efficiency: at 150kHz switching frequency, it runs a bit warmer and less efficiently than newer, higher-frequency buck designs, which matters more for battery-powered projects than ones running off a wall adapter.
Specifications:
- Type: buck (step-down) only
- Input voltage: 4V to 40V
- Output voltage: 1.25V to 37V, adjustable
- Max output current: 3A (2A recommended for sustained use)
- Efficiency: up to 92%
- Switching frequency: 150kHz
- Connections: terminal block, no soldering required
Why it stands out:
- Built-in LED voltmeter display shows output voltage without a separate multimeter
- Terminal block connections mean a working setup with zero soldering
- Massive tutorial and project base, this is the buck converter most guides assume you’re using
- Overheat and short-circuit protection built in
- Wide input range covers everything from battery packs to wall adapters
Things to keep in mind:
- Buck-only: output voltage must be lower than input, it cannot boost
- Input voltage must be at least 1.5V above the desired output for stable regulation
- Owners occasionally report needing to strengthen heat dissipation for continuous loads above 15W
👉 Buy HiLetgo LM2596 Buck Converter on Amazon
Verdict: The right default buck converter for almost any Arduino or ESP32 project that needs to step voltage down. Simple, well documented, and forgiving for beginners.
2. Best Compact Buck Converter: HiLetgo MP1584EN
HiLetgo MP1584EN Mini Buck Converter Module
Best for: Projects where board space is tight and a smaller, more efficient buck converter is worth the tradeoff in convenience.
The MP1584EN does the same basic job as the LM2596, stepping voltage down, but in a footprint roughly a quarter the size. That size difference comes from running at a much higher switching frequency, which allows smaller inductors and capacitors, and it’s marketed as a drop-in replacement for the LM2596 in projects where board space matters more than having a voltmeter display built in.
It skips the terminal blocks and LED display of the LM2596 in favor of bare solder pads, which means you’ll need to solder wires or headers to use it, a reasonable tradeoff given how much smaller it ends up. For projects going into a compact enclosure, a wearable, or anywhere the LM2596’s larger board simply won’t fit, this is the natural alternative.
Specifications:
- Type: buck (step-down) only
- Input voltage: 4.5V to 28V
- Output voltage: 0.8V to 20V, adjustable
- Max output current: 3A
- Efficiency: up to 92%
- Switching frequency: 1.5MHz (typical 1MHz)
- Connections: solder pads
Why it stands out:
- Roughly a quarter the size of the LM2596 for the same core buck-conversion job
- Higher switching frequency means smaller components and less board space
- Same 3A max output current as the larger LM2596
- Solder pads keep the board compact for space-constrained enclosures
- Explicitly marketed and used as a drop-in LM2596 replacement
Things to keep in mind:
- Requires soldering, no terminal blocks or plug-and-play wiring like the LM2596
- No LED voltmeter display, you’ll need a multimeter to set the output voltage
- Some listings note no built-in short-circuit protection and recommend avoiding light-load or no-load operation
👉 Buy HiLetgo MP1584EN Mini Buck Converter on Amazon
Verdict: The pick when the LM2596’s size is the problem, not its performance. Same core capability in a much smaller footprint, at the cost of needing to solder it in.
3. Best Boost (Step-Up) Converter: Dorhea MT3608
Dorhea MT3608 DC-DC Boost Converter Module
Best for: Projects that need to step a lower voltage up, the opposite job from everything above.
Where the LM2596 and MP1584EN only step voltage down, the MT3608 does the reverse: it takes a lower input voltage and boosts it up to whatever you set, useful for powering a 12V accessory off a 5V USB source, or getting a stable 5V out of a partially discharged battery pack that’s already dropped below that level. Like the buck converters above, output is set with an onboard potentiometer.
The MT3608 needs a specific first-use step that catches some people off guard: fresh out of the package, the potentiometer is often set near maximum boost, so the first thing to do is turn it down before connecting a sensitive load. Built-in under-voltage lockout, current limiting, and thermal protection add a real safety margin once it’s dialed in.
Specifications:
- Type: boost (step-up) only
- Input voltage: 2V to 24V
- Output voltage: 5V to 28V, adjustable (must exceed input by at least 2V)
- Max output current: 2A
- Efficiency: up to 93%
- Protection: under-voltage lockout, current limiting, thermal overload
Why it stands out:
- Handles the opposite job from buck converters: stepping a lower voltage up
- Built-in protection suite (under-voltage lockout, current limit, thermal) beyond what basic buck modules include
- Useful for powering higher-voltage accessories off USB or low-voltage battery packs
- Reasonably high 93% efficiency for a budget boost module
- Small, breadboard-friendly footprint
Things to keep in mind:
- Boost-only: output must be higher than input, it cannot step down
- Factory-default potentiometer setting is often near maximum, adjust before connecting a load
- Maximum 2A output is lower than the buck converters above, check your current needs before relying on it
👉 Buy Dorhea MT3608 Boost Converter on Amazon
Verdict: The converter to reach for whenever a project needs more voltage than its source provides. Just remember to wind the potentiometer down before your first test.
4. Best Automatic Buck-Boost for Battery Projects: EC Buying XL63020-3.3 (TPS63020)
EC Buying XL63020-3.3 Buck-Boost Converter Module
Best for: Single-cell LiPo or Li-ion battery projects where the battery voltage swings both above and below the target output.
A single-cell LiPo battery is the reason true buck-boost converters exist. Fully charged, it sits around 4.2V; discharged, it drops to roughly 3.0V. If your project needs a stable 3.3V or 5V rail, that swing crosses right through the target, meaning a plain buck converter fails once the battery discharges below your target voltage, and a plain boost converter fails while the battery is still above it. The XL63020-3.3, built around the TPS63020 chip, automatically switches between bucking and boosting as needed, so the output stays stable through the entire battery discharge curve. If you haven’t picked a battery yet, our Best LiPo Battery and Charger for Arduino and ESP32 guide covers capacity, protection circuits, and charger modules in detail.
Output voltage is set via solder jumpers between 3.3V, 4.2V, and 5V rather than a continuously adjustable potentiometer, which trades flexibility for simplicity and reliability in a battery-management context where you generally want one fixed target voltage anyway. The 2.4MHz switching frequency keeps the board small and the efficiency high across the entire input range.
Specifications:
- Type: buck-boost, automatic switching
- Input voltage: 1.8V to 5.5V
- Output voltage: 3.3V, 4.2V, or 5V (jumper-selectable)
- Max output current: 1.3A at 3.3V, 1A at 4.2V, 0.9A at 5V
- Efficiency: up to 96%
- Switching frequency: 2.4MHz
Why it stands out:
- Automatically handles both stepping up and down as a single-cell battery discharges
- Purpose-built for the exact voltage range of common LiPo and Li-ion cells
- High 96% efficiency, important for maximizing battery runtime
- Small footprint suited to portable and wearable projects
- LED output indicator confirms the module is delivering power
Things to keep in mind:
- Fixed voltage jumper selection (3.3V/4.2V/5V) rather than continuously adjustable output
- Lower max output current than the dedicated buck or boost modules above, check against your project’s draw
- Input voltage range is narrow by design (1.8V–5.5V), it’s not a general-purpose converter for higher voltages
👉 Buy EC Buying XL63020-3.3 Buck-Boost Converter on Amazon
Verdict: The right choice specifically for single-cell battery projects, where the battery voltage crossing your target rail makes a plain buck or boost converter the wrong tool for the job.
5. Best USB-C PD Trigger Module: Lonely Binary 12-Pack
Lonely Binary 12-Pack USB-C PD Trigger Module
Best for: Tapping a stable, higher voltage directly from a USB-C PD charger without any conversion circuitry at all.
This one works on a completely different principle from everything else in this guide. A USB-C PD trigger module doesn’t convert voltage at all, it negotiates for it. Modern USB-C chargers that support Power Delivery can supply several different voltages (5V, 9V, 12V, 15V, 20V) depending on what the connected device requests. This module sits between the charger and your project, requests a specific voltage via a DIP switch, and passes that voltage straight through once the charger agrees to provide it.
That makes it a genuinely different tool than a buck or boost converter: there’s no stepping up or down happening on the board itself, which means near-zero conversion loss, but it also means the module is entirely dependent on the connected charger actually supporting the requested voltage. With screw terminals and breadboard-friendly pins, and explicitly built with Arduino and ESP32 projects in mind, it’s a clean way to get 9V or 12V for accessories directly from a phone charger or power bank you already own.
Specifications:
- Type: PD/QC voltage negotiation, not a converter
- Input: USB-C PD or QC-capable charger
- Output: 5V, 9V, 12V, 15V, or 20V, fixed via DIP switch
- Max rating: 100W (actual output depends on charger and cable)
- Connections: screw terminals and breadboard pins
Why it stands out:
- No conversion circuitry means no conversion loss, output is whatever the charger provides directly
- Screw terminals and breadboard pins make it easy to wire into a project without extra adapters
- Explicitly designed with Arduino and ESP32 projects in mind
- Lets you reuse any USB-C PD charger or power bank as a project power supply
- 12-pack makes it cheap to keep several on hand for different projects
Things to keep in mind:
- Only works if the connected charger actually supports the requested voltage, not all chargers support all five options
- If the requested voltage isn’t supported, the module falls back to the next lowest voltage the charger does support
- This is not a substitute for a buck or boost converter when your power source isn’t USB-C PD to begin with
👉 Buy Lonely Binary USB-C PD Trigger Module on Amazon
Verdict: A genuinely different approach worth knowing about: when a USB-C PD charger is already in the picture, this skips conversion circuitry entirely and just asks for the voltage you need.
Which DC-DC Converter Should You Buy?
The right DC-DC converter for Arduino or ESP32 comes down to one question first: does your project need to step voltage down, up, or both, and only after that does budget or board size matter.
For most projects stepping a higher voltage down to power a microcontroller or accessory, the HiLetgo LM2596 is the default choice, cheap, well documented, and easy to wire with its terminal blocks and built-in voltmeter. When board space is tight, the HiLetgo MP1584EN does the same buck job in a quarter of the size, at the cost of needing to solder it in. If a project needs to step a lower voltage up instead, the HiLetgo MT3608 is the direct equivalent for boost conversion.
Single-cell battery projects are a special case worth calling out separately. Since a LiPo or Li-ion cell’s voltage swings both above and below common target rails like 3.3V or 5V as it discharges, neither a plain buck nor a plain boost converter covers the whole range. That’s exactly what the EC Buying XL63020-3.3 is built for, automatically switching between bucking and boosting as the battery discharges.
And if a USB-C PD charger is already part of your setup, whether it’s the wall adapter you already own or a power bank you’re reusing, the Lonely Binary USB-C PD Trigger Module is worth considering before reaching for a converter at all. It skips conversion circuitry entirely by asking the charger to supply the voltage directly.
Buck vs. Boost vs. Buck-Boost: How Each Converter Actually Works
All the converters in this guide (aside from the USB-C PD trigger, which works completely differently) are switched-mode power supplies, meaning they rapidly switch a transistor on and off to control how much energy passes from input to output, rather than simply dissipating excess voltage as heat the way a linear regulator does. That switching approach is why these modules run efficiently even with a large gap between input and output voltage.
Buck converters, like the LM2596 and MP1584EN, step voltage down. During the transistor’s “on” phase, current flows through an inductor and charges it with energy; during the “off” phase, that stored energy releases into the output at a lower voltage than the input. The output can never exceed the input voltage, which is the fundamental limit of this topology.
Boost converters, like the MT3608, work in reverse. The inductor charges during the “on” phase just like in a buck converter, but the switching arrangement directs that stored energy to add on top of the input voltage during the “off” phase, producing an output higher than the input. The output can never be lower than the input, the opposite limitation from a buck converter.
Buck-boost converters, like the XL63020-3.3, combine both topologies with control circuitry that continuously monitors the input voltage relative to the target output and switches between bucking and boosting as needed, often many times per second if the input is fluctuating near the target. This is what makes them the right choice for battery-powered projects where the source voltage isn’t reliably above or below the target the whole time.
USB-C PD Trigger Modules: Not a Converter, a Negotiation
It’s worth being clear about why the USB-C PD trigger module in this guide doesn’t fit the buck, boost, or buck-boost categories above: it isn’t doing voltage conversion at all.
USB-C Power Delivery is a communication protocol layered on top of the physical USB-C connection. A PD-capable charger and a connected device exchange data over the USB-C data lines to agree on a voltage and current the charger will supply, rather than the charger always outputting a fixed 5V the way older USB chargers do. A PD trigger module acts as a stand-in “device” that requests a specific voltage from that negotiation, typically selected through a DIP switch or solder jumpers, and then simply passes that negotiated voltage through to its output terminals.
Because there’s no switching regulator doing conversion work, a PD trigger module has essentially no conversion loss of its own, whatever voltage the charger agrees to supply is what comes out the other side. The tradeoff is total dependence on the charger: if you request 12V from a charger that only supports 5V, 9V, and 20V, the module will fall back to 9V rather than delivering 12V, since it has no way to generate a voltage the charger itself can’t provide.
Final Recommendation
For most Arduino and ESP32 projects, the HiLetgo LM2596 remains the best all-around starting point for a DC-DC converter for Arduino and ESP32 builds: cheap, terminal-block simple, and the buck converter most tutorials assume you’re using. Battery-powered projects should look at the EC Buying XL63020-3.3 for its automatic buck-boost handling, and anyone already working with a USB-C PD charger should consider the Lonely Binary PD Trigger Module before reaching for a converter at all.
ArduinoYard doesn’t have a dedicated buck/boost converter tutorial yet, but two guides cover closely related power topics: the IoT-Based Water Tank Monitoring Using ESP8266 and Solar Power project walks through a real solar-powered build where voltage regulation matters, and the ESP32 Sleep Modes and Wake-up Sources guide covers the other half of getting good battery life out of a low-power project.
Rounding out your power setup? Check out our guides on the Best Bench Power Supply for Arduino and ESP32 Projects, Best LiPo Battery and Charger for Arduino and ESP32, Best Breadboard and Jumper Wire Kit, and Best Relay Module for Arduino and ESP32.