Switching power supply control circuit with jitter frequency

Abstract

The invention provides a switching power supply control circuit. The switching power supply control circuit further comprises a controlled delay circuit and a driving circuit. The controlled delay circuit comprises a programmable counting controller, a programmable current source, an energy storage capacitor C1, a discharging circuit and a comparator, and the frequency of a clock signal output by the comparator changes according to the configuration of the programmable counting controller. And the driving circuit generates a frequency-variable driving control signal based on the frequency-variable clock signal output by the comparator so as to drive the power transistor to be switched on or switched off. Therefore, the frequency jitter of the whole switching power supply system is realized.

Description

technical field [0001] The invention relates to the technical field of power conversion, in particular to a switching power supply control circuit with frequency jitter. Background technique [0002] Switching power supply occupies most of the market of power supply applications with its high efficiency and increasingly mature technology. ) caused more and more attention by system designers, and gradually formed some mandatory standards in the main electronic application fields, such as. In offline power supply systems, system designers often use means such as optimizing the input filter, optimizing the transformer design, optimizing the absorbing circuit, or selecting the main control chip optimized for EMI to improve the ability of the electronic system to resist electromagnetic interference. Among them, the use of EMI-optimized main control chips provides system designers with greater freedom, allowing them to pay more attention to other key performances of the system, w...

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