Start-up circuit and operation method thereof

Abstract

The invention provides a start-up circuit and an operation method thereof. The start-up circuit is suitable for a switched capacitor type voltage stabilizing circuit. A startup circuit initializes a voltage of a capacitor of a switch-capacitor regulator. The startup circuit includes a voltage forming circuit and a control unit. The voltage forming circuit selectively electrically connected to thetop and the bottom of the capacitor. In a first operation phase, the voltage forming circuit is electrically connected to the top and bottom of the capacitor, and the top and bottom of the capacitor are connected to each other, and the voltages of the top and bottom are set as a preset high voltage. In a second operation phase, the voltage forming circuit disconnects the top and the bottom, and generates current flowing out from the bottom of the capacitor until the voltage cross the capacitor is equal to the preset initial voltage. In the third operation phase, the start-up circuit is disconnected from the capacitor.

Description

technical field [0001] The present invention relates to a start-up circuit, in particular to a start-up circuit capable of initializing the voltage difference between a top end and a bottom end of a capacitor of a switched capacitor type voltage stabilizing circuit to a preset initial voltage. Background technique [0002] In recent years, switched capacitor voltage regulator circuits have the advantage of high conversion efficiency, so more and more chips use switched capacitor voltage regulator circuits. When the switched-capacitor regulator starts to operate, it requires an initial voltage across the capacitor. For example, a 3-level buck converter requires an initial voltage across the charge pump capacitor (fly capacitor). The initial voltage is half of the input voltage VIN (0.5VIN). [0003] In order to reduce the on-resistance, most switched-capacitor voltage regulator circuits, such as three-order buck converters, use low-voltage components, but this design require...

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Problems solved by technology

[0003] In order to reduce the on-resistance, most switched-capacitor voltage regulator circuits, such as three-order buck converters, use low-voltage components, but this design requires that the initial voltage across the capacitor must be accurate, otherwise it may Will burn low-voltage components and cause chip damage

In order to make the switched capacitor type voltage stabilizing circuit power on, its capacitor has an initial cross-voltage, and the capacitor switching type voltage stabilizing circuit may have to provide a large current to charge the capacitor at the initial stage, but this operation is prone to generate inrush current (inrush current ) and damage the chip

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