Current-limiting protection circuit and control method thereof

Abstract

The invention discloses a current-limiting protection circuit and a control method thereof. The current-limiting protection circuit is arranged between a power supply end and an equipment end, and comprises a first loop comprising a first switch member and a second loop comprising a second switch member, the first loop is connected with a power supply end and the equipment end and is controlled bythe first switch member to be on and off, the second loop is connected with the power supply end and the ground and is controlled by the second switch member to be on-off, the first switch member adopts a PMOS transistor, a trigger resistor R5 connected in parallel between the source electrode and the grid electrode of the circuit provides a conduction voltage, the second switch member adopts a switching triode Q2, a resistor module is connected in series in the first loop, and after the current in the first loop rises to a preset value, the switching triode Q2 is conducted, the trigger resistor R5 is short-circuited, the first switch piece is disconnected, and the first loop is disconnected, so that the purpose of current-limiting protection is achieved; and the resistor module is arranged in a form that a plurality of first resistors are connected in parallel, and at least one of the first resistors is arranged to be an adjustable resistor, so the upper limit value of current limiting of the current-limiting protection circuit can be adjusted.

Description

technical field [0001] The present invention relates to a protection circuit, more specifically, it relates to a current limiting protection circuit and its control method. Background technique [0002] When using an external power supply to supply power to multiple devices (such as chips), if the device has a short circuit or a sudden increase in power consumption, the output of the external power supply will increase, which will affect other devices. Since each device needs to operate normally under the rated power, when the current suddenly increases, it is necessary to limit the current between the external power supply and the device. [0003] Current limiting circuits in the prior art, such as figure 1 As shown, when the current is less than the set value, the bias current of Q1 is provided by R1, and Q1 is saturated and turned on, which does not control the current; when the current is greater than or equal to the set value, the voltage drop on R increases, The sum ...

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Problems solved by technology

[0003] Current limiting circuits in the prior art, such as figure 1 As shown, when the current is less than the set value, the bias current of Q1 is provided by R1, and Q1 is saturated and turned on, which does not control the current; when the current is greater than or equal to the set value, the voltage drop on R increases, The sum of the voltage drop on R and the junction voltage of the transistor is close to the voltage drop of R2, so it starts to limit the current passing through Q1, thus limiting the current to a certain level

However, it can also be seen from the above-mentioned current-limiting circuit that the magnitude of the above-mentioned current-limiting current is not convenient for judging and adjusting

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