Decoupling Capacitors and Power Rails

Clean supply, steady chip.

Digital chips draw sudden pulses of current. A small ceramic capacitor, often 100 nF, placed right at each supply pin supplies those pulses locally so the rail does not dip.

Add a larger capacitor near the regulator for slower changes. Short, wide supply tracks and a solid ground reduce noise.

Many random resets and noisy ADC readings trace back to a weak supply.