A Light Load Current Compensation Circuit for Cuk Type Switching Converter

Abstract

The invention relates to an underloading current compensation circuit of a cuk type switching convertor, which comprises a hysteresis comparator and a regulating tube, wherein the in-phase end of the hysteresis comparator is connected with a reference voltage Vref; the invert-phase end of the hysteresis comparator is connected with a feedback resistance string; an output end of the hysteresis comparator is connected to a grid of the regulating tube MP1; an input voltage is connected to a source electrode of the regulating tube MP1; a drain electrode of the regulating tube MP1 is connected to the output voltage of the cuk convertor. Under the underloading condition, when current on an output inductor is discharged to zero so that the output voltage is reduced to a certain threshold value, the output of the hysteresis comparator switches on the regulating tube MP1 to charge an output capacitor of the cuk convertor; when the output voltage of the convertor rises to a overturning threshold value again, the output of the hysteresis comparator is overturned again and the regulating tube is switched off. According to the invention, the underloading current compensation circuit of the cuk type switch convertor is capable of acquiring accurate voltage output under the heavy load condition and can also effectively compensate deviation of the output voltage under the underloading condition so as to obtain negative voltage output with low ripple wave and high precision.

Description

technical field [0001] The invention belongs to the field of microelectronics and switching power supply, and belongs to a light-load current compensation circuit of a cuk switching converter with single-cycle control plus type III compensation negative pressure, and specifically relates to a light-load current compensation circuit of a cuk-type switching converter. Background technique [0002] Organic Light Emitting Diode OLED (Organic Light Emitting Diode OLED) has the characteristics of softness, transparency, clear picture quality, energy saving and environmental protection, and is regarded as the most promising next-generation flat-panel display technology. In order to maximize the brightness of light emission, the cathode of the OLED display needs a negative voltage for power supply, so the design of negative voltage chips has become the mainstream trend in this field. The cuk circuit adopts DC chopper technology, which has the characteristics of low output current ri...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to aim at the existing single-cycle control plus type III compensation converter loop under light load conditions, when the second inductance L2 discharges to zero, the output capacitor C2 will discharge to the input capacitor C1 through the inductance, and the output The voltage will drop significantly, so that it deviates from the preset threshold range. Under the action of the control loop of single-cycle control and type III compensation, a cuk-type switch conversion is designed to perform current compensation on the output voltage under light load conditions. tor’s light load current compensation circuit

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