Soft-start circuit applied to DC-DC converter

Abstract

The invention provides a soft start circuit applied to a DC-DC converter, which includes: a conversion unit that converts the input voltage of the input terminal into an output voltage of the output terminal based on the signal of the control terminal; a sampling circuit that collects the voltage of the conversion unit The output voltage at the output terminal obtains a feedback voltage; a soft-start switch; an error amplifier, whose first input terminal is connected to the reference voltage, whose second input terminal receives the feedback voltage, and whose output terminal is controlled by the soft-start switch and the conversion unit end connected. During the initial start-up, the soft-start switch is controlled to continuously turn on and off, and when the start-up is completed, the soft-start switch is controlled to continue to turn on. This not only enables the soft-start function, but also eliminates the need for large external capacitors. Each module can be integrated into the same chip, reducing chip pins and peripheral devices. The application cost is lower, and competition in practical applications is improved. force.

Description

【Technical field】 [0001] The invention relates to the field of circuit design, in particular to a soft start circuit applied to a DC-DC converter. 【Background technique】 [0002] figure 1 An example of a direct current-direct current (DC-DC) converter with soft-start function is shown. Such as figure 1 As shown, the DC-DC converter includes a conversion unit 110, an error amplifier EA, a compensation circuit 120, a sampling circuit 130, and an output capacitor COUT. [0003] The conversion unit 110 converts the input voltage VIN at the input terminal to the output voltage VOUT at the output terminal according to the signal at the control terminal, and the output capacitor COUT is connected between the output terminal of the conversion unit 110 and ground. The sampling circuit 130 includes a first divider resistor R1 and a second divider voltage R2 connected in series between the output terminal of the conversion unit 110 and the ground, and the voltage at the middle node ...

AI Technical Summary

Problems solved by technology

[0007] The advantage of this method is that it is simple and easy to use. The disadvantage is that a soft-start capacitor Css is needed to control the soft-start time. This capacitor is often very large and cannot be integrated with the error amplifier EA, the conversion unit 110, the compensation circuit 120, and the acquisition circuit 130. On the same chip, this will increase the chip pins and peripheral devices, the application cost is relatively high, and it lacks competitiveness in practical applications

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