Switching regulator, DC/DC converter, and LSI system with switching regulator

Abstract

A synchronous rectification switching regulator comprising: first and second switches (SW1, SW2) connected in series between a power supply (Vdd) and a ground (Vss); switching the switches (SW1, SW2) on and off A switching control unit (1) for controlling; a smoothing circuit (4) for smoothing an output node potential (Vnd). During the conduction period of the first switch (SW1), if the signal (Sc1) indicates that the output node potential (Vnd) is lower than the first reference potential (Vr1) which is the benchmark for inrush current detection, the control circuit (10) will switch the first switch to (SW1) is disconnected. In other words, in the present invention, the inrush current is detected by using the voltage drop caused by the on-resistance of the first switch ( SW1 ), so no resistance element for detecting the inrush current is required.

Description

technical field [0001] The present invention belongs to a switching regulator used to detect and suppress the inrush current generated when the power is turned on, that is, the so-called initial operation, or such as a short-circuit fault in the output voltage smoothing capacitor. technology of excess current. Background technique [0002] Generally speaking, in a switching regulator used to convert a DC power supply voltage into another DC voltage, how to suppress the generation of inrush current and excess current is a big issue. Here, the inrush current is a current that inrushes to charge the output voltage smoothing capacitor when a switch connected to the power supply is turned on during an initial operation such as when the power supply is turned on. The excess current is an excess current that flows from the power source to the load when a switch connected to the power source is turned on, for example, when a short-circuit fault occurs in the output voltage smoothin...

AI Technical Summary

Problems solved by technology

[0008] First, if Figure 11 As shown, there is a problem that the power conversion efficiency decreases in the structure using the inrush current suppression circuit

That is, in Figure 11 In the structure, since the resistance element 51 used to detect the inrush current is inserted in the current path from the power supply, the power loss is on the resistance element 51, and that part of the power consumption reduces the power conversion efficiency of the switching regulator.

[0009] Furthermore, if Figure 12 and Figure 14 As shown, in the structure using a sawtooth wave for the initial operation, although the inrush current generated during the initial operation can be suppressed, the excess current generated during the stable operation cannot be detected and suppressed.

In addition, there is another problem that the time required for initialization becomes longer

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