Buck converter
also: step-down converter · switching regulator · DC-DC converter
A switching power supply that efficiently steps a higher DC voltage down to a lower one, such as 12 V to 3.3 V, by switching rapidly and filtering the result.
A buck converter switches a transistor on and off at high frequency, storing energy in an inductor and smoothing the output with capacitors. Because it doesn't burn off the voltage difference as heat, as a linear regulator does, it stays efficient even when input and output voltages are far apart, which matters for battery life and heat.
The trade-offs are switching noise, more components (inductor, capacitors, sometimes a diode), more demanding PCB layout, and sometimes poor efficiency at very light loads unless the converter has a low-power mode.
Where it bites: a poorly laid-out buck converter is a classic source of EMI failures and noisy analog measurements. Following the chip's reference layout closely is usually the fastest path.
Founder takeaway
Use a buck converter whenever the voltage drop or current is significant, follow the reference layout closely, and check light-load efficiency for battery products.
engineer review pending