CN-122018618-A - Constant current protection circuit and system

CN122018618ACN 122018618 ACN122018618 ACN 122018618ACN-122018618-A

Abstract

The invention discloses a constant current protection circuit and a constant current protection system, which belong to the technical field of electronics and comprise a constant current sub-circuit, an input sampling sub-circuit, a power supply sub-circuit, a control sub-circuit and a power transmission sub-circuit, wherein the constant current sub-circuit is used for detecting sampling voltage output by the input sampling sub-circuit and setting a constant current voltage threshold value through the power supply circuit, and comparing the sampling voltage with the constant current voltage threshold value, and when the sampling voltage exceeds the constant current voltage threshold value, the constant current sub-circuit sends a constant current protection control signal to the control sub-circuit so as to enable the control sub-circuit to control the power transmission sub-circuit to conduct constant current protection until the sampling voltage is within the constant current voltage threshold value. The method disclosed by the invention combines the constant current sub-circuit with the control sub-circuit positioned at the front-stage input end, avoids the defect that the circuit structure is too complex when the constant current protection circuit is positioned at the rear end, and reduces the circuit structure complexity of the constant current protection circuit.

Inventors

LV PENGTAO
LI GANNIAN
ZHANG HONGKE
DONG GUOLIANG
DUAN RAN

Assignees

上海军陶科技股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260128

Claims (10)

1. The constant current protection circuit is characterized by comprising a constant current sub-circuit, an input sampling sub-circuit, a power supply sub-circuit, a control sub-circuit and a power transmission sub-circuit, wherein: the first input end of the constant current sub-circuit is electrically connected with the output end of the input sampling sub-circuit; the second input end of the constant current sub-circuit is electrically connected with the output end of the power supply sub-circuit; The output end of the constant current sub-circuit is electrically connected with the first input end of the control sub-circuit; a first output end of the control sub-circuit is electrically connected with a first input end of the power transmission sub-circuit; The control sub-circuit is electrically connected with the power supply sub-circuit, and the power transmission sub-circuit is electrically connected with the power supply sub-circuit; The constant current sub-circuit is used for detecting the sampling voltage output by the input sampling sub-circuit, setting a constant current voltage threshold value through the power supply circuit, and comparing the sampling voltage with the constant current voltage threshold value: when the sampling voltage exceeds the constant-current voltage threshold, the constant-current sub-circuit sends a constant-current protection control signal to the control sub-circuit so as to control the power transmission sub-circuit to perform constant-current protection until the sampling voltage is within the constant-current voltage threshold.
2. The constant current protection circuit of claim 1, wherein the constant current sub-circuit comprises an NMOS tube, an operational amplifier, a diode, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor, wherein a third input terminal of the constant current sub-circuit is electrically connected to a second output terminal of the control sub-circuit, wherein: The source electrode of the NMOS tube is used as a first input end of the constant current sub-circuit, and the drain electrode of the NMOS tube is electrically connected with one end of the first resistor; The grid electrode of the NMOS tube is used as a third input end of the constant current sub-circuit, is electrically connected with one end of the second resistor, and is electrically connected with one end of the third resistor; The non-inverting input end of the operational amplifier is electrically connected with the other end of the third resistor, is electrically connected with one end of the fourth resistor, is electrically connected with one end of the sixth resistor, and is electrically connected with one end of the third capacitor; The inverting input end of the operational amplifier is electrically connected with the other end of the first resistor, the other end of the second resistor, one end of the fifth resistor, one end of the second capacitor and one end of the seventh resistor; the output end of the operational amplifier is electrically connected with the cathode of the diode and one end of the fourth capacitor; the positive power input end of the operational amplifier is used as a second input end of the constant current sub-circuit, is electrically connected with one end of the first capacitor, and is electrically connected with the other end of the fourth resistor; the negative power input end of the operational amplifier is grounded; the anode of the diode is used as a second input end of the constant current sub-circuit; The other end of the fifth resistor is grounded; the other end of the sixth resistor is grounded; The other end of the seventh resistor is electrically connected with the other end of the fourth capacitor; the other end of the first capacitor is grounded; the other end of the second capacitor is grounded; the other end of the third capacitor is grounded.
3. The constant current protection circuit according to claim 2, further comprising an input sub-circuit and an output sub-circuit, wherein: The first output end of the input sub-circuit is electrically connected with the second input end of the power transmission sub-circuit; the second output end of the input sub-circuit is electrically connected with the input end of the input sampling sub-circuit; The input end of the output sub-circuit is electrically connected with the output end of the power transmission sub-circuit; The input sub-circuit is used for transmitting electric energy to the output sub-circuit through the power transmission sub-circuit and providing sampling current for the input sampling sub-circuit.
4. A constant current protection circuit according to claim 3, wherein the constant current sub-circuit is configured to detect a sampled voltage output from the input sampling sub-circuit, and to set a constant current voltage threshold by the power supply circuit, and to compare the sampled voltage with the constant current voltage threshold, and comprises: The input sampling sub-circuit samples the current output by the input sub-circuit to obtain the sampling current, and converts the sampling current into the sampling voltage so as to output the sampling voltage to the constant current sub-circuit; The power supply circuit outputs standard voltage to the constant current sub-circuit so that the constant current sub-circuit sets a constant current voltage threshold value through voltage division; Comparing the sampling voltage with the constant current voltage threshold.
5. The constant current protection circuit according to claim 4, wherein the power supply circuit outputs a standard voltage to the constant current sub-circuit to cause the constant current sub-circuit to set a constant current voltage threshold by voltage division, comprising: The power supply circuit outputs a standard voltage to the constant current sub-circuit; And the second input end of the constant current sub-circuit receives the standard voltage, the standard voltage is used as the positive input of the power supply of the operational amplifier, and the constant current voltage threshold value is set through the voltage division of the fourth resistor and the sixth resistor.
6. The constant current protection circuit according to claim 3, wherein the second resistor and the third resistor are adjustable resistors for adjusting an output constant current value required for constant current protection, wherein: When the resistance value of the second resistor increases, the output constant current value relatively decreases; when the resistance value of the third resistor increases, the output constant current value relatively increases.
7. A constant current protection circuit according to claim 3, wherein after the constant current sub-circuit is configured to detect the sampled voltage output from the input sampling sub-circuit and set a constant current voltage threshold by the power supply circuit, the constant current protection circuit further comprises: When the sampling voltage is within the constant-current voltage threshold, the constant-current sub-circuit sends a normal working signal to the control sub-circuit so as to control the power transmission sub-circuit to keep the output voltage unchanged.
8. The constant current protection circuit of claim 7, further comprising an output sampling feedback sub-circuit, wherein: the input end of the output sampling feedback sub-circuit is electrically connected with the output end of the output sub-circuit; The output end of the output sampling feedback sub-circuit is electrically connected with the second input end of the control sub-circuit; the output sampling feedback sub-circuit is used for sampling the voltage output by the output sub-circuit to obtain feedback compensation voltage, and outputting the feedback compensation voltage to the control sub-circuit so as to control the power transmission sub-circuit to perform constant current protection.
9. The constant current protection circuit according to claim 8, wherein the output terminal of the control sub-circuit generates a periodic square wave signal for controlling the on-time of the power transmission sub-circuit, wherein: When the constant current sub-circuit sends out a constant current protection control signal, the control sub-circuit controls the power transmission sub-circuit to reduce the conduction time of the periodic square wave signal based on the feedback compensation voltage so as to perform constant current protection; When the constant current sub-circuit sends out a normal working signal, the control sub-circuit controls the power transmission sub-circuit based on the feedback compensation voltage to not change the conduction time of the periodic square wave signal so as to keep the output voltage unchanged.
10. A constant current protection system, comprising a direct current input power supply, a load, and the constant current protection circuit according to any one of claims 1 to 9, wherein: the direct current input power supply is electrically connected with an input sub-circuit of the constant current protection circuit; The load is electrically connected with an output sub-circuit of the constant current protection circuit.

Description

Constant current protection circuit and system Technical Field The invention belongs to the technical field of electronics, and particularly relates to a constant current protection circuit and a system. Background At present, a module power supply mainly comprises an input circuit, a power transmission circuit, an output circuit, an input end control circuit, an output end feedback and constant current circuit. When the output load current is continuously increased and reaches a constant current working point, the constant current circuit is triggered, the working state of an output end is processed and fed back to an input end control circuit, the control circuit adjusts the working mode and the power transmission working state, the module power supply enters the constant current mode, namely, the output current is kept constant, the output voltage is reduced along with the change of the load, so that the constant current protection function is realized, the reliability of the power supply is vital, and the module power supply and load equipment are effectively protected from overcurrent damage. However, the existing constant current protection circuit generally adopts a scheme of connecting a high-precision low-temperature drift power resistor in series on a rear-stage output ground wire, when the output load current changes, the voltage at two ends of the power resistor can change along with the change of the load current, and then the constant current function is realized by collecting, processing and feeding back the voltage of the power resistor to the control circuit. For a system with a control circuit at a front stage and a rear-stage constant current function, the traditional architecture has a complicated circuit structure and requires an additional independent power supply system, so that the design difficulty and the production cost are increased, and the development of a module power supply in the directions of miniaturization and high integration level is restricted. Therefore, the realization mode of the constant current protection function of the module power supply in the prior art has the defect of complex circuit structure. Disclosure of Invention The invention aims to provide a constant current protection circuit and a system, which are used for solving the technical problems and reducing the complexity of the circuit structure of the constant current protection circuit. In order to solve the technical problem, a first aspect of the present invention provides a constant current protection circuit, which comprises a constant current sub-circuit, an input sampling sub-circuit, a power supply sub-circuit, a control sub-circuit and a power transmission sub-circuit, wherein: the first input end of the constant current sub-circuit is electrically connected with the output end of the input sampling sub-circuit; the second input end of the constant current sub-circuit is electrically connected with the output end of the power supply sub-circuit; The output end of the constant current sub-circuit is electrically connected with the first input end of the control sub-circuit; a first output end of the control sub-circuit is electrically connected with a first input end of the power transmission sub-circuit; The control sub-circuit is electrically connected with the power supply sub-circuit, and the power transmission sub-circuit is electrically connected with the power supply sub-circuit; The constant current sub-circuit is used for detecting the sampling voltage output by the input sampling sub-circuit, setting a constant current voltage threshold value through the power supply circuit, and comparing the sampling voltage with the constant current voltage threshold value: when the sampling voltage exceeds the constant-current voltage threshold, the constant-current sub-circuit sends a constant-current protection control signal to the control sub-circuit so as to control the power transmission sub-circuit to perform constant-current protection until the sampling voltage is within the constant-current voltage threshold. In the above scheme, the constant current sub-circuit is used for detecting the sampling voltage output by the input sampling sub-circuit, and setting a constant current voltage threshold value through the electronic circuit, and when the sampling voltage output by the input sampling sub-circuit exceeds the constant current voltage threshold value, a constant current protection control signal is sent to the control sub-circuit so as to control the power transmission sub-circuit to perform constant current protection, and the process of controlling power transmission can be realized by detecting the sampling voltage at the input end and comparing the sampling voltage with the set constant current voltage threshold value, thereby realizing the constant current protection of the output current. The circuit combines the constant current sub-circuit with the control sub-circuit positione