Current-limiting circuit

Abstract

A current-limiting circuit comprises a sampling resistor, a filter capacitor connected with an output terminal, a current-limiting triode, a control triode and a control switch triode, wherein the base electrode of the current-limiting triode is connected with the collecting electrode of the control triode, the emitting electrode of the current-limiting triode is connected with a power supply circuit output terminal, and the collecting electrode of the current-limiting triode is connected with the output terminal; the base electrode of the control triode is connected with the power supply circuit output terminal, and the emitting electrode of the control triode is connected with a +12V power supply; the sampling resistor is connected between the power supply circuit output terminal and the +12V power supply; the emitting electrode of the control switch triode is grounded, the base electrode of the control switch triode is connected with an enable signal end, and a current-limiting resistor is connected in series between the base electrode of the control switch triode and the enable signal end; the collecting electrode of the control switch triode is connected with the base electrode of the current-limiting triode, and a divider resistor is connected in series between the collecting electrode of the control switch triode and the base electrode of the current-limiting triode; the collecting electrode of the control triode is connected with the +12V power supply, and another divider resistor is connected in series between the collecting electrode of the control triode and the +12V power supply. According to the current-limiting circuit, the current-limiting value does not fluctuate along with variation of voltage, is relatively high in precision, has the negative temperature coefficient characteristic, and is reduced along with temperature rise of the circuit, so that the electric energy is saved.

Description

technical field [0001] The present application relates to a current limiting circuit, in particular to a current limiting circuit used in a low-voltage power line carrier communication module. Background technique [0002] The currently known current limiting circuit has complex circuit structure, numerous circuit components, high production cost, positive temperature coefficient, and low accuracy of current limiting value. [0003] Such as figure 1 The current limiting circuit in the carrier module shown in the figure is to limit the maximum current consumption of the carrier module to +12V. If the current amplification factor of the triode HFE=300, the limited output current should not exceed 156mA. When the circuit enters the current limit After mode, the triode V3 will heat up, and the temperature will rise, which will cause the current amplification factor HFE of the triode to increase, so that the output current will increase. The temperature of the triode V3 will co...

AI Technical Summary

Problems solved by technology

[0004] This application aims at the problems of complex structure, numerous circuit components, high production cost, positive temperature coefficient and low accuracy of current limiting value in the existing current limiting circuit, and designs a current limiting circuit

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