Switching power supply frequency reduction control circuit and control method

A technology of switching power supply and control circuit, which is applied in the direction of control/regulation system, electrical components, and adjustment of electrical variables, etc., and can solve problems such as output voltage fluctuations and switching frequency mutations

Active Publication Date: 2016-01-20
SILERGY SEMICON TECH (HANGZHOU) CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When entering the energy-saving mode, the power switch tube is no longer turned on. It can be seen that the traditional light-load frequency reduction control method is to directly switch between the energy-saving mode and the fixed frequency mode, and the switching frequency will change suddenly, resulting in large fluctuations in the output voltage.

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  • Switching power supply frequency reduction control circuit and control method
  • Switching power supply frequency reduction control circuit and control method
  • Switching power supply frequency reduction control circuit and control method

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Embodiment Construction

[0039] Several preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to these embodiments. The present invention covers any alternatives, modifications, equivalent methods and schemes made on the spirit and scope of the present invention. In order to provide the public with a thorough understanding of the present invention, specific details are set forth in the following preferred embodiments of the present invention, but those skilled in the art can fully understand the present invention without the description of these details.

[0040] refer to figure 2 Shown is the circuit diagram of the first embodiment of the control circuit of the switching power supply according to the present invention. The switching power supply takes a step-down switching power supply as an example, and the step-down switching power supply includes a power switch tube Q, a rectifier tube...

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Abstract

According to a switching power supply frequency reduction control circuit and a control method of the invention, a frequency control circuit generates a first current signal associated with a compensation control signal, and the first current signal changes the size of a first current source so as to make a first clock signal for controlling switching of a power switch tube change with the compensation control signal, and therefore, the switching frequency of the power switch tube is controlled by the compensation control signal. When the compensation control signal is greater than a threshold voltage signal, the switching frequency of the power switch tube is a preset switching frequency; and when the compensation control signal is smaller than the threshold voltage signal, the switching frequency of the power switch tube changes with the difference between the compensation control signal and the threshold voltage signal. The threshold voltage signal in the embodiment is set to represent the output voltage under a light-load or no-load state. The switching power supply makes the switching frequency of the power switch tube not change suddenly, and the output voltage is highly stable.

Description

technical field [0001] The invention relates to the field of switching power supplies, more specifically, to a control circuit and control method for frequency reduction of switching power supplies. Background technique [0002] In the control of switching power supply, when the load enters the light-load state, in order to save energy consumption, it is usually necessary to control the switching frequency of the power switch tube. The working waveform diagram of the traditional light-load frequency reduction method is as follows: figure 1 As shown, the output voltage of the switching power supply is compared with a reference voltage to obtain an error signal, and the error signal is compensated to obtain a compensation control signal Vc. The higher the output voltage Vo, the lower the compensation control signal Vc. The compensation control signal Vc is compared with another reference signal Vth for mode switching. When the compensation control signal Vc is lower than the r...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M3/156
Inventor 罗迪
Owner SILERGY SEMICON TECH (HANGZHOU) CO LTD
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