PFM control method of switching power converter and realizing device thereof

Abstract

The invention belongs to the technical field of switching power supply, and particularly relates to a PFM control method of a switching power converter and a realizing device thereof. The method comprises the following steps: detecting the partial voltage value of the output voltage, comparing the rising edge with VREF in each clock cycle, and if the rising edge is lower than VREF, enabling a power-level switching tube to conduct a signal with fixed duty cycle by using a control logic circuit and a power driving circuit; and if the rising edge is high than VREF, skipping the cycle. Meanwhile, the current detection circuit detects a load current and compares the load current with preset threshold, and a current interval judging device selects the appropriate dimensions of the power tube according to the detection current and controls the segment selector to select the segmented power level, thereby realizing an optimal PFM control. The optimal PFM control can keep high efficiency and reduce the ripples of the output voltage, as well as prevent the switching frequency of the system from entering the audible range.

Description

technical field [0001] The invention belongs to the technical field of switching power supplies, and in particular relates to a PFM control method of a DC-DC switching power supply converter and a realization circuit thereof. Background technique [0002] Today, consumer electronics technology is in a period of rapid development. There is an increasing demand for consumer electronics, especially portable battery-operated consumer electronics. With the rapid progress of semiconductor process technology and the continuous strengthening of consumer demand for product functions, the scale of chips in products is also expanding. This will inevitably lead to an increase in chip power consumption, thereby greatly reducing the battery life of the product. For handheld devices, battery life is one of the most concerned issues for consumers. Since the output voltage of the battery changes with the use time, the power management chip is required to provide a stable power supply volt...

AI Technical Summary

Problems solved by technology

However, the traditional PFM control has two disadvantages in practical applications: one is that the output ripple is larger under light load, and the lighter the load, the larger the output ripple

However, due to the small duty cycle required under light load, the switching frequency is easy to enter the audio frequency range when using constant on-time or skip cycle PFM control, which will introduce audio noise to other modules in the system

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