PWM/PFM seamless switching controller suitable for switching power supply and control method thereof
A seamless switching, switching power supply technology, applied in control/regulation systems, output power conversion devices, instruments, etc., can solve the problems of system control signal disorder and output voltage fluctuation, and achieve the effect of delaying switching and ensuring accuracy
Active Publication Date: 2021-07-16
NORTHEASTERN UNIV
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Problems solved by technology
In order to realize the combination of PWM and PFM, a PWM / PFM switching controller is indispensable, but the existing PWM / PFM switching controller is realized by a single multi-choice data selector, and its structure is simple. When PFM is switched to PWM due to The target modulation mode requires stabilization time, which leads to the disorder of the control signal in the system, so there is a large fluctuation in the output voltage during the switching period
Method used
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[0033] The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.
[0034] On the one hand, a PWM / PFM seamless switching controller suitable for switching power supplies, such as figure 1 As shown, including PWM controller, PFM controller, PWM preset circuit, PWM&PFM mode controller, data selector;
[0035] The output port of the PFM controller is connected with the 0 input channel of the data selector, the PWM signal output port of the PWM controller is connected with the 1 input channel of the data selector, and the error signal of the PWM controller The output port is connected to the first input port of the PWM preset circuit, the output port of the PWM&PFM mode controller is connected to the second input port of the PWM preset circui...
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The invention provides a PWM / PFM seamless switching controller suitable for a switching power supply and a control method thereof, and relates to the technical field of integrated circuits. The switching controller comprises a PFM controller for generating a PFM control signal; a PWM controller used for generating a PWM control signal; a PWM preset circuit used for detecting an intermediate signal in a PWM operation process and generating a mode selection signal; a PWM& PFM mode controller used for judging a working mode required by the system according to the size of the load; and a data selector used for outputting a corresponding control signal according to the mode selection signal. According to the PWM / PFM seamless switching controller, the mode selection signal is generated by combining an intermediate signal in the PWM starting process with the magnitude of the current of a load point, so that when the current reaches a switching point, the system does not immediately switch, but waits for the PWM to start to a certain threshold value, and then switches between the PFM and the PWM, thereby realizing seamless switching between the two modes.
Description
technical field [0001] The invention relates to the technical field of integrated circuits, in particular to a PWM / PFM seamless switching controller suitable for switching power supplies and a control method thereof. Background technique [0002] In DC-DC switching power supply, Pulse Width Modulation (PWM) and Pulse Frequency Modulation (PFM) are two commonly used modulation modes. PWM fixes the switching frequency, and controls the opening of the power tube in the DC-DC system by adjusting the duty cycle. Time, and then adjust the output voltage, PFM fixed switching time, by adjusting the off time to control the switching frequency of the power tube, to achieve the adjustment of the output voltage. [0003] PWM and PFM modulation modes have their own advantages and disadvantages. At light load, PFM has higher conversion efficiency due to variable switching frequency, but its output ripple and response speed and other system performance are weaker than PWM in the full load ...
Claims
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IPC IPC(8): H02M3/00H02M1/00H02M1/08
CPCH02M3/00H02M1/00H02M1/08
Inventor 程铭金硕巍闫爱云刘治良杨东升王爱侠
Owner NORTHEASTERN UNIV