关键词: 降压DC-DC, 脉宽调制, 仿峰值电流模式, 斜坡电流发生器

Abstract: Voltage mode and peak current mode is the most commonly used feedback control method of PWM BUCK DC-DC, both of which have obvious advantages and disadvantages. In this paper, a new PWM control mode named simulated peak current mode is proposed, which adjusts and controls the BUCK DC-DC by periodically simulating the change of the inductor current cycle by cycle. Make the circuit not only retains the peak current mode dynamic response speed, pulse by pulse over current detection, compensation structure is simple, but also has the voltage mode anti-noise ability, duty cycle adjustment is not limited. Based on the UMC 0.25μm 2P5M BCD process, a BUCK type DC-DC with a wide input voltage with an analog peak current mode is designed. Then, the functional simulation of BUCK DC-DC is carried out by Hspice, which proves the superiority of the simulated peak current mode. Finally, the circuit layout design is completed.

Key words: Buck DC-DC, pulse wide modulation, simulated peak current mode, ramp current generator