Peak current signal generating circuit, switching power supply circuit and method for generating peak current signals

Abstract

The invention provides a peak current signal generating circuit, a switching power supply circuit and a method for generating peak current signals. The switching power supply circuit at least comprises a first power tube. The peak current signal generating circuit comprises a first current source, a peak capacitance, an LPF (Low-Pass Filtering) circuit, a first switch and a first voltage source, wherein the peak capacitance is connected and coupled with the first current source in parallel, and voltage signals at two ends of the peak capacitance are peak current signals; a first end and a second end of the LPF circuit are respectively coupled to the two ends of the peak capacitance, and a control end of the LPF circuit is used for receiving a pulse signal representing a switching period of the first power tube; a first end of the first switch is coupled to a third end of the LPF circuit, and a control end of the first switch is used for receiving a reset signal; and a first end of the first voltage source is coupled to a second end of the first switch, and a second of the first voltage source is coupled to the second end of the LPF circuit. According to the invention, the purposes of regulating the peak current signals according to a load condition, enabling the frequency of the switching power supply circuit to be lowered along with the lowering of the load and avoiding the generation of sub-harmonic oscillation can be realized.

Description

technical field [0001] The present invention relates to a voltage conversion circuit, more specifically, the present invention relates to a switching power supply circuit in the voltage conversion circuit and its peak current signal generation circuit and method. Background technique [0002] Switching power supply circuits usually reduce the switching frequency at light loads to obtain higher efficiency. However, if the switching frequency is too low, the output ripple of the switching power supply circuit will increase, and other performances of the circuit will be affected. Especially in the high side buck (High Side Buck) circuit, the reduction of the switching frequency will make the control circuit unable to detect the output voltage in time, which will affect the transient response of the circuit. Therefore, in a system with current loop control, the method of reducing the peak current signal is usually adopted when the load decreases, so that the switching frequency...

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Problems solved by technology

However, using this method to adjust the peak current signal may produce sub-harmonic oscillation

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