COT control circuit and method

Abstract

The embodiment of the invention relates to a COT control circuit and method. The control circuit comprises a phase-locked loop circuit and a COT control unit. The phase-locked loop circuit is used for comparing the phases of the control signal and the external clock signal and providing a phase error signal representing the phase difference of the control signal and the external clock signal. The COT control unit receives a phase error signal, a clock signal, an input voltage equivalent signal, an output voltage equivalent signal and a voltage feedback signal and generates a control signal. The COT control unit introduces frequency information of a clock signal into a control signal in advance by introducing the clock signal, adjusts the frequency of the control signal to a basic frequency close to the frequency of the clock signal in advance, and then adjusts the basic frequency of the control signal to be the same as the frequency of the clock signal through a phase-locked loop circuit, namely, the basic frequency is synchronous with the frequency of the clock signal. The requirement for the output capacity of the phase-locked loop circuit is not large, design of the phase-locked loop circuit is facilitated, and meanwhile the system stability is improved.

Description

technical field [0001] The present invention relates to an electronic circuit, and more particularly, to a frequency-synchronized constant on / off time (Constant On / Off Time, COT) control circuit and method. Background technique [0002] In power systems, COT control has been widely used in DC-DC converters due to its superior transient response. Compared with peak current control and average current control, the switching frequency of COT-controlled power system is variable and cannot be well controlled. In some applications, the switching frequency of the COT-controlled power system needs to be synchronized with the external clock frequency, that is, the switching frequency and the external clock frequency are exactly the same. In the prior art, a phase-locked loop is often used to phase-lock the switching frequency of the system and the external clock frequency. However, due to the wide variation range of the external clock frequency, the switching frequency of the power...

AI Technical Summary

Problems solved by technology

However, due to the large variation range of the external clock frequency, the switching frequency of the power system will also change with the input voltage VIN and output voltage VOUT of the power system.

In this case, the output capability of the phase-locked loop is very high, which will make the design of the phase-locked loop itself more difficult.

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