A New Pulse Frequency Modulated Switching Power Supply

Abstract

The invention relates to a novel pulse frequency modulation switching power supply, and particularly relates to a switching power supply circuit. The novel pulse frequency modulation switching power supply comprises a first switching device group, an operating circuit provided with an energy storage element and a control circuit, and is characterized in that the first switching device group is turned on or off alternatively under the action of a pulse modulation signal; the operating circuit is switched between a charging mode and a discharging mode under the action of the first switching device group; and the control circuit is used for generating the pulse modulation signal according to first reference voltage, a voltage feedback signal, a current detection signal and a clock signal. The control circuit comprises an error amplifier and a clock signal generator, wherein the error amplifier is used for comparing the first reference voltage and the voltage feedback signal so as to acquire an error amplifying signal; and the clock signal generator receives compensation of the error amplifying signal so as to adjust the clock signal. According to the circuit structure of the novel pulse frequency modulation switching power supply, a clock signal adjusting circuit is newly added, the frequency of the clock signal is controlled directly through output of the error amplifying signal, thereby enabling the frequency to be distributed uniformly, and reducing ripple of the output voltage.

Description

technical field [0001] The invention relates to the field of electronic technology, in particular to a switching power supply circuit. Background technique [0002] In switching power converters, in order to stabilize the output voltage at a set value and not change with changes in the external environment, PWM (Pulse Width Modulation, pulse width modulation mode) and PFM (Pulse Frequency Modulation, pulse frequency modulation mode) are two PWM mode is widely used to achieve good efficiency under medium and heavy load regulation, but the efficiency drops significantly under light load conditions. In the prior art, in order to improve the efficiency under light load or standby conditions Circuit efficiency, set a low power consumption mode, also known as: skip cycle control mode (Skip Cycle Mode), when the circuit is in light load or standby condition, control the PWM controller to intermittently send pulse signals to achieve a constant frequency The efficiency of light load...

AI Technical Summary

Problems solved by technology

[0002] In switching power converters, in order to stabilize the output voltage at a set value and not change with changes in the external environment, PWM (Pulse Width Modulation, pulse width modulation mode) and PFM (Pulse Frequency Modulation, pulse frequency modulation mode) are two PWM mode is widely used to achieve good efficiency under medium and heavy load regulation, but the efficiency drops significantly under light load conditions. In the prior art, in order to improve the efficiency under light load or standby conditions Circuit efficiency, set a low power consumption mode, also known as: skip cycle control mode (Skip Cycle Mode), when the circuit is in light load or standby condition, control the PWM controller to intermittently send pulse signals to achieve a constant frequency The efficiency of light load and standby is improved by reducing the number of switching times and increasing the duty cycle. The waveform diagram of the pulse modulation signal PFM1 in the skip cycle control mode is as follows figure 1 As shown, however, this method will cause higher output ripple, and the control method is not ideal

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