Lülitirežiimi toiteallikas (SMP -d), also known as switch mode power supply or switch converter, on kõrgsageduslik elektrienergia muundamise seade ja teatud tüüpi toiteallikas. Selle funktsioon on teisendada täpne pinge pingeks või vooluks, mida kasutaja nõuab erinevate arhitektuurivormide kaudu. The input of a switching power supply is mostly an AC power supply (such as mains power) or a DC power supply, while the output is mostly a device that requires a DC power supply, such as a personal computer, and the switching power supply converts the voltage and current between the two.