Voltage regulator

Sometimes we need to step down the voltage

The battery's voltage will unlikely match the voltage used by some of our parts, specifically the microcontroller (STM32 nucleo32 boards accept 7V-12V on VIN but it would be wise to avoid hitting maximum ratings). To get around this problem, we should use a voltage regulator to drop the voltage to a stable output that is desirable for our parts. There are two common types of step-down regulators that are sold: low drop-off (LDO) regulator and buck converters.

Low drop-off regulators (LDO)

LDOs are a type of linear DC regulator that does as the names suggest. Take a voltage input and output a lower, fixed voltage.

Advantages

• plug and play, easy to assemble on PCB

• Less expensive

• better for small power requirements

Disadvantages

• Less power efficient than buck converters

Buck converters

Buck converters are a type of DC-DC converter (which means they use a switching device as a MOSFET transistor) that lowers a voltage input while also increasing output current. They are generally more power efficiency than linear regulators but come at cost of increased complexity, sometimes needing an additional inductor.

Advantages

• more energy efficient (about 90%)

• better for large power requirements

• allows for variable voltage output

Disadvantages

• costlier, usually requires extra parts to assemble

General tips

When choosing a voltage regulator, make sure of the following:

• the voltage regulator accepts the input voltage from your battery

• can output the correct voltage you are looking for.

• check the datasheet for suggested layout of components (important for schematic)

Microcontroller boards usually have a voltage regulator for 3.3V as well as for 5V.