Switching power supply constant-voltage control compensation circuit

Abstract

The invention discloses a constant-voltage control compensation circuit of a switching power supply, and belongs to the technical field of integrated circuits. The circuit comprises a feedback controlsub-circuit and an offset control sub-circuit, the feedback control sub-circuit comprises an operational amplifier OP1 and an operational amplifier OP2, the voltage difference between the output voltage of the operational amplifier OP2 and the reverse input end of the operational amplifier OP1 is converted into current, the current is converted into VEA voltage after being shunted, and the VEA voltage is sampled to control the output power; the offset control sub-circuit converts the output power into offset control voltage and inputs the offset control voltage to the operational amplifier OP2, and the output voltage is formed by the operational amplifier OP2; and the offset control sub-circuit is connected to the reverse input end of the operational amplifier OP1 and shunts the current,so that the purpose of improving the output constant voltage control precision, the linear adjustment rate and the load adjustment rate of the power supply chip is achieved, and meanwhile, the problems that tiny load change cannot be sensed and the load adjustment rate is compensated possibly caused by a fixed comparison point are avoided.

Description

technical field [0001] The invention belongs to the technical field of integrated circuits and is applied to the constant voltage control part of power supply design. Specifically, it relates to a switching power supply constant voltage control compensation circuit. Background technique [0002] In daily life, portable and low power supply voltage devices can be seen everywhere, and the devices are required to be small in size, low in cost and good in safety. [0003] At present, the common non-isolated AC / DC switching power supply on the market generally has low precision when directly outputting low voltage (especially 3.3V and below), and the linear regulation rate (definition: also known as source effect or grid regulation rate, refers The fluctuation of the voltage with the linear change of the input voltage, the condition is full load.) and the load regulation (definition: also known as the load effect, refers to the fluctuation of the output voltage with the change of...

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Problems solved by technology

[0006] In view of this, in order to solve the above-mentioned problems existing in the prior art, the object of the present invention is to provide a switching power supply constant voltage control compensation circuit to achieve the purpose of improving the power chip constant voltage output control accuracy, linear adjustment rate and load adjustment rate, and at the same time It avoids the problem that the small load change that may be caused by the fixed comparison point cannot be sensed, and the load adjustment rate compensation problem

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