Line loss compensation device of switch power supply, integrated circuit and switch power supply

Abstract

The invention discloses a line loss compensation device of a switch power supply, an integrated circuit and the switch power supply. The line loss compensation device comprises a voltage sampling module, an error amplifier, a logic control module and a line loss compensation module. The voltage sampling module is used for sampling a feedback voltage of a feedback end of the switch power supply andoutputting a sampling voltage to the error amplifier. The error amplifier is used for outputting an error voltage according to the sampling voltage and outputting the error voltage to the logic control module and the line loss compensation module. The logic control module is used for controlling a switch tube of the switch power supply according to the error voltage. The line loss compensation module is used for sampling the error voltage, generating a compensation current and outputting the compensation current to the feedback end of the switch power supply. In the invention, the line loss compensation module samples the error voltage so as to generate the compensation current, the compensation current is output to the feedback end so as to realize closed loop control, and a load voltagecan be guaranteed not to change.

Description

technical field [0001] The invention relates to the technical field of switching power supplies, in particular to a line loss compensation device for a switching power supply, an integrated circuit and a switching power supply. Background technique [0002] Such as figure 1 As shown, the circuit of switching power supply is generally composed of switch controller U1, switch tube Q, transformer T1 (primary coil T1A, secondary coil T1B and auxiliary circuit coil T1C), degaussing diode D1, etc., among which switch controller U1 is used to The feedback voltage of the terminal FB controls the switch tube Q, so that the DC voltage Vin is output to a constant DC voltage V1 at the output terminal after passing through the transformer T1. Of course, the switch control is performed after using a bridge stack (such as a bridge stack composed of 4 switching diodes). Can rectify externally input AC (alternating current) to direct current. Since the working current I of the load general...

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Problems solved by technology

Since the working current I of the load generally changes with the working state of the load, and the cable connected between the output terminal of the switching power supply and the load has an impedance Rcable, the voltage drop of the cable also changes with the load, and the diode D1 If the voltage drop Vd and the output voltage V1 remain unchanged, the voltage Vout at both ends of the load will not remain unchanged.

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