Lego Sherlock Holmes figure focuses a light beam on a Lego criminal with a small magnifying glass.

5V Power from Spike Prime

Buck-Boost Converter for 5V

The Vcc pin on the Spike Prime (and Robot Inventor) connector has a voltage of 3.3V for powering sensors. However, some sensors and devices need the other commonly used voltage of 5V. For example, the OpenMV (see my other post on "LEGO Selfie Machine") needs a 5V input. To convert the 3.3V output of Spike Prime to 5V I used a boost converter, as shown in the photo above, with connection as per the schematic below. This particular boost converter is made by SparkFun (, called the Buck-Boost Converter. This device can also "buck" a voltage, which means to lower the voltage, such as converting the 5V output from EV3 to 3.3V. The desired output voltage is selected by a small switch on the side of the Buck-Boost Converter, with options for 3.3V, 5V, and a custom voltage (that you select by adding a resistor circuit). For the case here of needing a 5V output, the switch goes to the 5V setting. For the schematic below, I'm using a Breadboard Connector Kit that goes onto the removed backshell of a Distance Sensor (also used in the "LEGO Selfie Machine").

Schematic for connecting the Sparkfun Buck-Boost Converter