Worlds Smallest DC Power Supply

World’s Smallest (unofficially, maybe?) DC Power Station, 5cm by 3cm!

No matter the project, I always seem to need either 3 volts or 5 volts. In my small apartment, I usually to take out a bulky DC power supply, take out some cables, and make sure I'm near an outlet... Until I built this convenient 3v/5v power supply. I ended up using this power supply so much that it convinced me to make an Instructable.

It’s capable of providing around 1 amp at 1500mAh, or 0.5 amps for to 2-3 hours! I usually use the supply for a few minutes each week (or month) when I quickly need 3 or 5 volts and I don’t feel like dragging out all my equipment, so one battery typically lasts me months.

1. 22uF Capacitors (0805) ×3

smooth out voltage spikes and help maintain stable power.

1. 2-Pin Headers (2.54mm) ×3

male pin connectors used for connecting 5v, 3v, Gnd using jumper wires.

1. R2 – 732kΩ Resistor (0805) ×1

precise output regulation in the boost converter.

1. R1, R3 – 100kΩ Resistors (0805) ×2

voltage divider circuit.

1. LED Indicator (0805) ×1

indicates when the power station is turned on.

1. 1µH Inductor (Würth WE-MAPI 4020) ×1

high-efficiency inductor required by the boost converter to step up 3V to 5V smoothly.

1. CR123 Battery Holder ×1

CR123 battery (3V) holder (I find cheaper ones on Amazon).

1. Slide Switch ×1

small switch to turn the power station on or off.

1. TPS61023 Instruments Boost Converter IC ×1

heart of the circuit: this chip boosts 3V (from the CR123) to a stable 5V

1. CR123A Battery

The 3 volts go to the Texas Instruments TPS61023, which then passes the current to the inductor, where it’s stored in the inductor’s magnetic field (that’s just what inductors do).

The TPS61023 collapses the magnetic field, and the resulting voltage is added, in series, to the existing 3 volts.

Rinse and repeat thousands of times a second, and you get 5 volts.

The TPS61023 monitors the voltage thru voltage dividers, knowing when to stop adding voltage from the magnetic field.

You can order the PCB here: Link to PCB

Built in kicad and modeled from this board

Solder Tools I Used:

1. 110V 850W hot plate (mine’s big, a smaller one is fine)
2. Solder paste,flux, squeegee

Assembly

1. Align the stencil,
2. apply solder paste,
3. place components (watch silkscreen dot for chip orientation),
4. and melt the solder on the hot plate 2
5. I place the assembled board when the plate is off and remove the board when the plate reaches 215 °C

The TPS61023 is small!

I had some solder bridges. Grab a soldering iron and some flux. Apply a little flux to the bridge, then gently scrape it with a clean, hot soldering iron. The bridge should either transfer to the iron or separate and settle onto the TPS61023 pads or pins.

Look at the TPS61023 under good lighting and with moderate contrast to see the orientation.

Test it with a voltmeter, plug it into your favorite projects using some jumper wires, and store it with your tools!

This power station was born out of necessity. It offers portability and convenience. Hopefully, it’s great for your small spaces and quick prototyping and it’s now one of my most used tools, always within reach.