Adaptive slope compensation circuit suitable for controlling buck converter in peak current mode

Abstract

The invention discloses an adaptive slope compensation circuit suitable for controlling a buck converter in a peak current mode, and belongs to the technical field of an electronic circuit. A voltage in a switching node SW of the buck converter is sampled directly, and then filtering in two times is performed to obtain a direct current value, which is proportional to the output voltage V<o> of the buck converter, to be used as a positive input voltage of an operational amplifier; the operational amplifier clamps the negative input end to a voltage which is the same as that of the positive input end, namely, voltage drop on a fifth resistor R5; next, by virtue of a current mirror which consists of a first PMOS transistor MP1 and a second PMOS transistor MP2, the charging current of a third capacitor C3 is proportional to the current which flows through the fifth resistor R5; the voltage drop on a sixth resistor R6 is equal to the voltage of the third capacitor C3; in addition, a current mirror is formed by a third PMOS transistor MP3 and a fourth PMOS transistor MP4, so that the current which flows through a seventh resistor R7 is proportional to the current which flows through the sixth resistor R6; and finally the obtained voltage drop of the seventh resistor R7 is the adaptive slope compensation voltage which is proportional to the output voltage V<o> 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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