High accuracy constant-off average output current control scheme

摘要

A high accuracy constant-off average output current control is provided. It is composed of the reference block generates preset reference and converts the reference signal into a suitable format; the state detecting block, the state variables of switching power converter are detected and the detected signals are converted into the same signal format as one of output from reference block; The error-zero detector is used to detect the error between the outputs from reference block and state detected block and trigger constant off timer as the error is cross over zero; the constant off timer, the constant off time is dependent on the input and output voltages of the switching converter. Four function blocks can be simple as comprising of a basic operation and be implemented with several operation functions. The present invention can make the accuracy of the switching converter's output average current independent of the input and output voltages of the switching converter and accuracy of circuit devices and constant off time and in the simplest and lowest cost to implement the average current control of step-down switching converter.