PWM (Pulse-Width Modulation) controller

Abstract

The invention discloses a PWM (Pulse-Width Modulation) controller which comprises an error amplifier, a PWN comparator, a slope compensation current generating circuit, a clamping circuit and a slope compensation superposed circuit. In the PWM controller, the clamping circuit is introduced so that a high-end clamping point output by the error amplifier synchronously changes along with a slope compensation signal and an inductance current peak value is maintained to be unchanged, and thus the problem that the duty ratio affects a peak value current limit is solved, a constant current limit is ensured and the whole system works normally; and a relative earth potential concept is introduced by adding a relative earth potential generating circuit into the PWM comparator, so as to reduce voltage difference between power supply voltages, thus a high-performance high-speed PWM controller can be realized by use of low voltage components.

Description

technical field [0001] The invention belongs to the technical field of power supplies, and in particular relates to the design of a PWM controller. Background technique [0002] Switching power supply has been widely used due to its high efficiency, driving large load and small static power consumption. The pulse width modulation (Pulse Width Modulation, PWM) control method is widely used in switching power supply. There is a close relationship between the performance of the controller, so the study of high-performance PWM controller has great theoretical and practical value. [0003] In switching power supplies, voltage mode and current mode are two commonly used control modes. The current mode is widely used for its fast response, high stability, and cycle-by-cycle current limit. The structure diagram of traditional PWM controller is as follows: figure 1 As shown, the error output signal is directly superimposed with the slope compensation signal to obtain a level that ...

AI Technical Summary

Problems solved by technology

The structure diagram of traditional PWM controller is as follows: figure 1 As shown, the error output signal is directly superimposed with the slope compensation signal to obtain a level that changes with the duty cycle. However, due to the slope compensation, the peak current limit of the traditional current mode will change with the duty cycle. a larger drift

In order to overcome this problem, the traditional solution is implemented by adding an extra comparator, which increases the complexity of the system and greatly limits the application environment

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