Overview

This page gives an overview of available options to power your projects: alternatives that go beyond the development board's built-in USB connector. Broad categories, and simple product matrices will be presented.

The intention is to make it easier to find the right product/solution without having to continuously re-read all product description pages. My interpretation of these pages might not be fully accurate. Unfortunately, there appears to be no way for others to inform me of such mistakes. I am hoping a similar document in "Explore & Learn" section will eventually replace this one.

Regulation: Linear/Buck/Boost

Regulators tend to come in 3 flavours:

• Linear regulators: Fed from a higher voltage. Typically less efficient than their "switching regulator" counterparts. Typically powered by another (higher voltage) regulator such as a DC power adapter.
• Step-down ("buck"): A switching (voltage) regulator fed from a higher voltage. Typically powered by another (higher voltage) regulator such as a DC power adapter, but can also be driven by a battery.
• Step-up ("boost"): A switching (voltage) regulator fed from a lower voltage. A useful tool to generate higher voltages on devices that aren't normally expected to need them. Commonly used in battery-driven applications where you cannot (don't want?) rely on batteries to generate the high voltages needed.

🧠️Smart load sharing

Some solutions include "smart load sharing". As with everything, not all "load sharing" is created equal, but will tend to implement the following current/power management features:

• Simultaneously power your project while charging.
• Redirect excess current to charge battery when plugged in.
• Avoid unnecessary battery charge/discharge cycles +extending battery life.
• Can be used without a battery being connected.
• Live disconnection of battery or main power source *without losing power.
  • *Check product specs to make sure this is actually supported.
  • Otherwise: glitches could result in unreliable power or unsafe conditions (damage circuits).

Watch this Adafruit product video (1000C) for further explanation.

Portable solutions: batteries & solar

At the time of writing, there are 4 popular solutions to power portable projects:

• Non-charging: converting battery voltages up ("boost") or down ("buck") to something better suited for your project.
• "Just charger": Separate battery chargers. Won't directly power the project, but used to complement "non-charging" solution.
• USB-fed battery chargers: Not only can your project be powered by a battery, but some options allow that battery to get charged up automatically when connected through a USB port. This is what happens inside most cell modern phones.
• Solar-capable battery chargers: For even more autonomy, some options allow the connection of solar cells. Many solar capable solutions also allow for safe USB battery charging even when connected to a solar cell. Note that not all solar-capable chargers allow safe charging on USB, and so choosing the right might require some additional investigation.

Non-charging solutions

Non-charging solutions mostly provide basic voltage regulation and filtering. Because of this, non-charging solutions have fewer limitations on the power source when compared to charging solutions. Such sources include DC power adapters, USB ports, and batteries of various chemistry (ex: alkaline, NiMH, Li-ion, and LiFePO4).

Adafruit has quite a few buck & boost breakout boards with a somewhat "standard" (to Adafruit) 4-pin breakout:

• Search: Step-down/buck converters (CAT#573)
• Search: Step-up/boost converters (CAT#570)

See individual product pages for more details on the input/output voltages/current capabilities of each breakout.

If looking for solutions with a more convenient form-factor or connector type, here are a few more options:

NOTE:

• See product pages/base spec sheets for correct specs/limits. Information here has been oversimplified to allow for a condensed presentation.
• Check out MiniBoost (#4654) product page for an example on how output voltages/currents depend on available input voltages/currents.
• LiPo SHIM (3196) includes alternate output headers (not exclusively for Raspberry Pi - just conveniently shaped).

"Just charger" solutions

Just chargers. Not really designed to simultaneously power a project:

Charging: USB-fed

Most charging solutions available through Adafruit are designed to work with Li-Ion/Li-Poly batteries. Note that other battery types exist that require different chargers. Also: not all Li-Ion/Li-Poly batteries are created equal - and so not all chargers are cross-compatible within the Li-Ion/Li-Poly world either.

Make sure to use only chargers compatible with your batteries (or vice-versa).

NOTE:

• Many chargers include "EN" pins that can be used to power down charger output and reduce power consumption.
  • Others, like the ItsyBitsy backpack might require to cut power lines directly, and connect slide switches on provided jumper pins.
• Some "charger" solutions are designed to get their charging lines cut - thus allowing support for different battery types. See product pages for more details
  • Ex: PiCowbell
• All feathers are supposed to support LiPo/LiIon chargers (see "VBAT" section of feather specification here).
• 🧠️: Smart load-sharing.

Charging: ☀️Solar-capable

NOTE:

• Product documentation indicates charger #4755 is the "newer, easier, and cheaper design" replacing #390 (with a few tradeoffs).
• 🧠️: Smart load-sharing.

Wired solutions: DC adapters & USB PD

High-power: DC adapters

Regulators built into most microcontroller development boards typically cannot supply much current. A common solution is to use an DC power adapter (barrel/terminal blocks):

• Wall supplies (CAT#137)
• DC adapters (CAT#557)

Some interesting options to take note of:

NOTE:

• See product pages/base spec sheets for correct specs/limits. Information here has been oversimplified to allow for a condensed presentation.

High-power: USB-PD

Another solution for powering your project is to use adapters supporting USB-PD:

• USB-PD adapters - integrated cable (#5968): Multiple voltages, up to 5A output
• USB-PD adapters - no cable (#6030): Multiple voltages, up to 3A

USB-PD cables/adapters require an intelligent power delivery block often called "USB PD chargers" on sites like Amazon - since they are commonly used to "charge up" portable devices.

If you want to skip the barrel jack completely, Adafruit has USB-PD breakout boards that might better suit your project:

Additional resources

🎞️ Videos

• PowerBoost 1000C product video: Talks about 🧠️ smart charging/load-sharing.
• PowerBoost by Adafruit: Explains product line (ex: basic vs charger).
• Collin's Lab: Powerful Battery Usage with Ladyada @adafruit
• Collin's Lab: Battery Basics
• Collin's Lab: History of the Battery
• Collin's Lab: Solar
• Battery Self-Discharge - Collin’s Lab Notes
• Beware of Bad Lipos - Collin’s Lab Notes
• LiPo Longevity - Collin’s Lab Notes

Learn guides