Adjustable current-limiting protection circuit

Abstract

The invention relates to an adjustable current-limiting protection circuit. The adjustable current-limiting protection circuit comprises an on-chip current-limiting protection circuit and an off-chip current-limiting resistor, wherein the on-chip current-limiting protection circuit comprises an error amplifier, a power tube, a sampling tube, a switching tube, a current mirror circuit and an operational amplifier structure; the size of a limited current is decided by the off-chip current-limiting resistor; when the current flowing through the power tube is relatively low to make the sampling current smaller than the limited current, the switching tube is in a cut-off state, and the protection circuit is not started; and when the current flowing through the power tube is relatively high to make the sampling current larger than the limited current, the switching tube is in conduction state, the protection circuit is started, so that the power tube is cut off, and the effect of the circuit protection is achieved due to reduction of the output current. The limited current is regulated by adjusting the off-chip current-limiting resistor, the switch-on and the switch-off of the switching tube are controlled by comparing the limited current with the sampling current, and thus, the on / off of the current-limiting protection circuit is controlled. The adjustable current-limiting protection circuit has the characteristics of adjustable limited current, simplicity in structure, flexibility, convenience and high practicability.

Description

technical field [0001] The invention belongs to the field of integrated circuits, and in particular relates to a current limiting protection circuit for power management chips. Background technique [0002] In power management chips, as the load current requirements continue to increase, the current flowing through the power tubes in the power chip continues to increase, and large output currents will generate large power consumption, which will easily lead to permanent damage to the chip. In order to avoid circuit damage caused by excessive output load current or output short circuit, an overcurrent protection circuit is generally introduced inside the circuit. Such as figure 1 As shown, a prior art current limiting protection circuit includes a first MOS transistor, a second MOS transistor, a third MOS transistor, a fourth MOS transistor, a fifth MOS transistor, a first current source, a second current source and an error amplifier. The limiting current of the current l...

AI Technical Summary

Problems solved by technology

The existing current-limiting protection circuit has the following two disadvantages: 1. When the circuit is in a state where the input-output pressure difference is large, that is, the power tube source-drain voltage difference is large, if the limit current is large, the The high current of the power tube is easy to generate large power consumption and burn the circuit; 2. When the circuit is in the state of small input-output pressure difference, that is, the voltage difference between the source and drain of the power tube is small, if the limit current is small, the high current will make the circuit burn. The current limiting protection circuit is turned on, causing the power tube to be turned off, and the circuit cannot work normally

However, the existing current-limiting protection circuit with constant limit current is difficult to balance the above two situations.

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