Switching power supply, control method of switching power supply and control chip

A technology of switching power supply and control method, which is applied in the direction of control/regulation system, electrical components, and adjustment of electrical variables, etc., which can solve the problems of large standby power consumption, reduced energy density and low efficiency of switching duty cycle, and achieve high conversion efficiency , low power consumption, simple circuit effect
CN103166471AActive Publication Date: 2013-06-19BYD SEMICON CO LTD
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Patent Information

Authority / Receiving Office
CN Β· China
Patent Type
Applications(China)
Current Assignee / Owner
BYD SEMICON CO LTD
Publication Date
2013-06-19

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Abstract

The invention provides a switching power supply, a control method of the switching power supply and a control chip. The control method of the switching power supply comprises the following steps: sampling preset output voltages to acquire sampling signals; generating an error voltage according to the sampling signals and a first reference voltage; judging a current state of the switching power supply according to the error voltage, a preset second reference voltage and a third reference voltage; if the error voltage is smaller than the second reference voltage and larger than the third reference voltage, and then the switching power supply is in a first state, and controlling the switching power supply according to the error voltage in a simulated pulse frequency modulation (PFM) mode; if the error voltage is smaller than the third reference voltage, and then the switching power supply is in a second state, and controlling the switching power supply according to the error voltage in a mixed mode of digital pulse width modulation (PWM) and digital PFM. The control method of the switching power supply can meet high accuracy of the output voltage of the switching power supply, and has high conversion efficiency in a full load range, and therefore dynamic response speed of the switching power supply is improved, and voice frequency noise in a light load state can be avoided.
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Description

technical field

[0001] The invention relates to the technical field of switching power supplies, in particular to a switching power supply, a control method thereof, and a control chip. Background technique

[0002] With the increasing awareness of environmental protection and energy saving, countries have stricter requirements on the working efficiency of power adapters and built-in power supplies in AC equipment. Such as figure 1 Shown is the circuit diagram of a switching power supply with traditional secondary feedback control. In order to meet the requirements of precision and isolation safety, the traditional secondary feedback control circuit is equipped with an optocoupler and an operational amplifier ( figure 1 TL431 shown), the output voltage is divided by resistors R6 and R7 and then transmitted to the operational amplifier TL431 for amplification processing, and then the amplified output voltage signal is transmitted to the voltage sampling terminal 2 of the chi...

Claims

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