Error amplifier, controller and primary side feedback control AC ( alternating current)/ DC (direct current) converter

Abstract

The invention relates to an error amplifier, a controller using the error amplifier, and a primary side feedback control AC ( alternating current) / DC (direct current) converter using the controller. The error amplifier comprises an operational transconductance amplifier and a summing module, wherein a noninverting input end of the operational transconductance amplifier receives a sampling voltage, while an inverting input end of the operational transconductance amplifier receives a reference voltage; a first input end of the summing module is connected with an output end of the operational transconductance amplifier through a DC path so as to receive DC output of the operational transconductance amplifier; and a second input end of the summing module is connected with the output end of the operational transconductance amplifier through an AC path so as to receive AC output of the operational transconductance amplifier. By using the error amplifier, the controller using the error amplifier, and the primary side feedback control AC / DC converter using the controller according to the invention, not only the stability of the primary side feedback control AC / DC converter is kept but also the voltage output precision is increased.

Description

technical field [0001] The invention relates to the field of switching power supply control, and more specifically relates to an error amplifier, a controller using the error amplifier and a primary side feedback control AC / DC converter using the controller. Background technique [0002] The primary-side feedback-controlled AC / DC converter is gradually replacing the traditional secondary-side feedback-controlled AC / DC converter in the field of low-power switching power supply adaptation due to its low cost and small size. [0003] figure 1 A typical circuit of a prior art primary side feedback controlled AC / DC converter is shown. The circuit mainly includes a transformer 10 , a power switch tube 20 , a secondary rectifier diode 40 , an output capacitor 45 and a controller 70 . The controller 70 will be powered by the auxiliary winding of the transformer 10 through the rectifier diode 60 . The output voltage is fed back to one side of the controller 70 through the auxiliar...

AI Technical Summary

Problems solved by technology

[0025] The technical problem to be solved by the present invention is to provide a new error amplifier for the defects of poor stability of the primary side feedback control AC / DC converter and low voltage output precision caused by the error amplifier of the prior art. Maintain the stability of the primary side feedback control AC / DC converter while improving the voltage output accuracy

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