Modern switching DC-DC converters are an essential part of most power supplies.
Here, I am looking at actual implementations of DC-DC-converters, often available as affordable and ready-to-use modules from sources like AliExpress.
Simple CV and CC Converters
Classic DC-DC converters are used to power electronic devices with a given steady voltage. These are typically constant-voltage (CV) regulators, and they can be found ubiquitously in “wall warts”, integrated into devices, as notebook power supplies, and more.
Lab bench power supplies are an example of supplies that optionally use constant-current (CC) regulation, i.e. to protect the output from accidental overload or to support special lab scenarios such as battery charging or testing.
Special Converters
Aside from pure CV and CC regulators, there are integrated specialty solutions that may be more adequate for what you are trying to do:
Battery Charging
Dedicated battery charger converters combine DC-DC conversion with a charging algorithm matched to the battery chemistry. For Li-ion batteries, they typically use constant-current (CC) charging until the battery approaches its maximum voltage, then switch to constant-voltage (CV) operation and terminate charging once the current has fallen below a defined threshold.
A general lab bench power supply with CC capability, in contrast, can imitate the basic CC/CV part of this process by manually setting the appropriate voltage and current limits. However, its CC function is primarily an output current limiter, not a complete charging controller.
Dedicated charger converters add the actual charging logic that a general-purpose CC/CV power supply lacks, i.e. automatic termination of charging once the current has fallen below a defined threshold and a reduced-current pre-charge for deeply discharged cells. A laboratory PSU, in contrast, continues regulating its configured voltage and current limits; it does not inherently know when a battery is considered fully charged or when charging should stop or restart.
This makes dedicated charger converters preferable for unattended or permanently installed charging, especially when the DC-DC-controller you are using has no temperature probe that can cut charging in defective batteries or with other failure situations. A CC-capable DC-DC converter (including a lab bench PSU) is useful for testing and manually supervised charging only. In any other cases, you should use a dedicated charger controller instead.
Harvesting Solar Energy
Uses DC-DC converters with MPPT control to operate solar panels efficiently.
In a nutshell, these regulators adjust the current drawn from the panel to keep its input voltage near the point where the panel delivers the most power. When the input voltage drops below this operating point, the regulator reduces the current it draws.
Or put differently, these constant current regulators automatically adjust the constant current to maintain a certain voltage at the input. If this voltage drops, they decrease the constant current.
So in this scenario, the constant current isn’t really constant, but the same regulation technique is used for a different purpose: to keep input voltage constant for a supply like a solar panel that can drop voltage when overloaded.
More advanced MPPT implementations actively search for the optimum operating point as this point isn’t fixed and can vary with temperature, solar intensity, shading, and other factors. A common technique, Perturb & Observe (P&O), repeatedly probes slightly higher and lower input voltages and observes whether the resulting power increases or decreases. Since P&O is complex, such solutions often require a microcontroller as well as voltage and current measurement which makes them a magnitude more expensive. This makes true P&O implementations much more expensive than simple fixed-voltage MPPT regulators. Their additional power consumption can also become significant with small panels and defeat its purpose: to harvest more solar energy.
Simpler implementations regulate the panel to a fixed input voltage that approximates its typical maximum-power voltage. This is less accurate, but inexpensive, often sufficiently effective and typically the better solution for small panels.
LED Drivers
Dimmable constant-current buck, boost, or buck/boost regulators with a PWM or dimming pin to quickly turn the LED current on and off.
Do not confuse this with Enable pins that typically shut down the entire regulator and are commonly used to add a switch for LED lights that turn them permanently on and off. They are typically not suitable for high-frequency switching although exceptions exist where actual PWM pins are labeled Enable.
Powerbanks
Controllers for Powerbanks are typically bi-directional and can be used for charging and discharging.
For example, in simple 1 S powerbanks, they boost the battery voltage (3.7 V) to 5 V USB, and they buck the 5 V USB back to charging voltage when connected to a charger. IP5306 is a good example.
More advanced units support USB PD output at different output voltages and buck/boost converters to deliver voltages below and above the actual battery voltage. IP2369 is a good example.
Depending on implementation and chip, such solutions may contain two separate DC-DC converter stages that can operate independently (one for charging, one for output), or a shared converter stage that can either charge or supply.
The latter is cheaper with lower component count, but the converter itself cannot supply energy from the battery while charging it. In very simple designs (like IP5306), when a regulated input is mandatory (i.e. 5 V), as a workaround, this input voltage is passed through to the output during charging, so it appears as if such boards can deliver power while charging.
One consequence of such designs is a brief power-path transition when the chip switches between external input and battery/boost operation, i.e. when a charger is connected or disconnected. Depending on load and output capacitance, this may cause a short voltage dip or even a brief power “outage” that can reset connected electronics.
“Extras” to Watch Out For
Here is a summary of the most useful “extras” you may find (and possibly need) in DC-DC converters:
-
MPPT / Input Regulation:
Automatic adjustment of the current drawn from a power source based on its input voltage, allowing sources (such as solar panels) to operate near their optimum power point.
-
Dimmable:
Internal circuitry to rapidly enable and disable the output current without upsetting the regulator control loop, typically for LED projects where you either want to dim the LEDs using PWM, or for flash patterns in emergency lights. Here, they work for any kind of lamp, not just LEDs.
-
Combined/Bidirectional Regulators:
Buck and boost functionality for bidirectional operation, i.e. charging and discharging a battery at different voltage levels. Depending on the implementation, this may use separate buck and boost stages or a single bidirectional buck/boost power stage.
Slow Website?
This website is very fast, and pages should appear instantly. If this site is slow for you, then your routing may be messed up, and this issue does not only affect done.land, but potentially a few other websites and downloads as well. Here are simple steps to speed up your Internet experience and fix issues with slow websites and downloads..
Comments
Please do leave comments below. I am using utteran.ce, an open-source and ad-free light-weight commenting system.
Here is how your comments are stored
Whenever you leave a comment, a new github issue is created on your behalf.
-
All comments become trackable issues in the Github Issues section, and I (and you) can follow up on them.
-
There is no third-party provider, no disrupting ads, and everything remains transparent inside github.
Github Users Yes, Spammers No
To keep spammers out and comments attributable, all you do is log in using your (free) github account and grant utteranc.es the permission to submit issues on your behalf.
If you don’t have a github account yet, go get yourself one - it’s free and simple.
If for any reason you do not feel comfortable with letting the commenting system submit issues for you, then visit Github Issues directly, i.e. by clicking the red button Submit Issue at the bottom of each page, and submit your issue manually. You control everything.
Discussions
For chit-chat and quick questions, feel free to visit and participate in Discussions. They work much like classic forums or bulletin boards. Just keep in mind: your valued input isn’t equally well trackable there.
(content created Sep 23, 2026)