Overcurrent protection circuit for negative output LDO stabilizer

Abstract

The invention belongs to the field of electronic technology, and particularly relates to an overcurrent protection circuit for a negative output LDO stabilizer. The circuit includes an overcurrent signal VS generating circuit, an overcurrent signal reference voltage VT generating circuit and a comparison output circuit. The output end of the VS generating circuit is connected with the negative input end of the comparator. The input end of the VS generating circuit is connected with the base of the adjusting tube. The VT generating circuit is connected with a temperature independent current source. The output end of the VT generating circuit is connected with the positive input end of the comparison output circuit. The negative input end of the comparison output circuit is connected with the output end of the VS generating circuit. The positive input end of the comparison output circuit is connected with the output of the VT generating circuit. The output end of the comparison output circuit is connected with the output point of the error amplifier (EA) which is also called the base point of the adjusting tube.

Description

technical field [0001] The invention belongs to the field of integrated circuits, and in particular relates to an overcurrent protection circuit of a negative voltage output LDO (LOW DROP-OUT linear regulator) circuit. Background technique [0002] The traditional LDO circuit is composed of a bandgap reference circuit, an error amplifier, a power transistor and a resistor feedback network. The bandgap reference circuit generates a reference voltage V that is independent of temperature and power supply. REF , operational amplifier and power tube M P The formed feedback loop is used to keep the output voltage stable. [0003] In the actual application process, over-temperature protection, over-current protection and reverse output protection will be added to the circuit. The effective activation of the protection circuit can make the chip work safely and avoid damage to the chip caused by factors such as overcurrent. [0004] In the traditional overcurrent protection circui...

AI Technical Summary

Problems solved by technology

However, since resistors with small resistance values ​​generally have low precision, in order to improve the precision of the current-limiting threshold, it is inevitable to add links to improve the precision, such as trimming, which wastes the chip area

The small resistance added to the emitter will also increase the input-output voltage difference and reduce the efficiency of the chip under the condition of large output current.

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