Buck regulators are used to efficiently step down a higher level,unregulated input voltage to a regulated output voltage. In applications requiring DC-DC conversion from a high input voltage, the buck regulator dramatically improves conversion efficiency relative to linear
regulator alternatives. However, applying the buck regulator to applications with high input-to-output step-down ratios creates significant challenges for the pulse-width modulation (PWM) controller. Because the duty cycle of the buck regulator switch is approximately equal to VOUT/VIN, a buck DC-DC converter with high input/output voltage ratio must control very narrow PWM pulses. The switching frequency of a buck regulator is generally set to a
high level to reduce the size of the inductor and capacitors