Adaptive Slope Compensation Circuit for Buck Converter with Peak Current Mode Control

Abstract

The invention relates to an adaptive slope compensation circuit suitable for a peak current mode control step-down converter, belonging to the technical field of electronic circuits. Directly sample the voltage at the switch node SW of the step-down converter, and then filter it twice to obtain a DC quantity proportional to the output voltage Vo of the step-down converter as the positive input voltage of the operational amplifier, and the operational amplifier takes its negative input The terminal is clamped to the same voltage as the positive input terminal, that is, the voltage drop on the fifth resistor R5; and then through the current mirror formed by the first PMOS transistor MP1 and the second PMOS transistor MP2, the charging current of the third capacitor C3 Proportional to the current flowing through the fifth resistor R5, the voltage drop across the sixth resistor R6 is equal to the voltage of the third capacitor C3, and the third PMOS transistor MP3 and the fourth PMOS transistor MP4 form a current mirror, so that the current flowing through the seventh The current of the resistor R7 is proportional to the current flowing through the sixth resistor R6, and finally the voltage drop of the seventh resistor R7 is obtained as an adaptive slope compensation voltage, which is proportional to the output voltage Vo of the buck converter.

Description

technical field [0001] The invention belongs to the technical field of electronic circuits, and in particular relates to an adaptive slope compensation generating circuit suitable for compensation of a step-down DC-DC converter based on peak current mode control. Background technique [0002] Today, as electronic devices are widely used, the market demand for power management integrated circuits continues to rise, and step-down (Buck) DC-DC converters are widely used in communications, computers, industrial automation and other fields. Traditional step-down DC-DC converters are divided into three control modes: current mode, voltage mode and hysteresis control. Among them, the fixed-frequency PWM technology using peak current mode control is widely used because of its good dynamic performance, wide gain bandwidth, easy compensation and excellent EMI characteristics. [0003] However, when the duty cycle of the peak current mode is greater than 50%, there will be sub-harmoni...

AI Technical Summary

Problems solved by technology

[0003] However, the peak current mode will have sub-harmonic oscillation when the duty cycle is greater than 50%, so a slope compensation circuit is required to increase system stability

The traditional compensation methods include fixed slope compensation and segmented linear compensation. In the case of a wide range of duty ratio changes under different application conditions, excess compensation will occur, resulting in a decrease in system load capacity and poor transient response characteristics.

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