A High-Efficiency Fast Transient COT Control DC–DC Buck Converter With Current Reused Current Sensor

This article presents a high-efficiency fast transient constant
on
-time (COT) control dc–dc buck converter for the Internet of Things applications. The current reused current sensor is proposed to enhance the loop stability and improve the power conversion efficiency at light load. Input current is sensed and added to the feedback voltage of the dc–dc converter to increase the sensed output ripple voltage. Fast transient dc-offset cancelation technique is introduced to achieve a fast transient recovery time and to cancel the output dc offset. This chip is fabricated with a 0.13-
μ
m CMOS process. A standard supply voltage of 7–15 V is applied to produce the output voltage of 5–5.33 V. The total die area is 2 mm × 1.5 mm. The settling time is 17
μ
s. The transient recovery time from light to heavy load and from heavy load to light load are 3
μ
s and 2.7
μ
s, respectively, with a maximum dc offset of 3.5 mV. The overshoot voltage is 85 mV and the undershoot voltage is 72 mV. The peak efficiency of the proposed design is 95.56% at 0.5 A and efficiency at the light load of 10 mA is 84.60%.