CN213633551U

CN213633551U - Current monitoring circuit

Info

Publication number: CN213633551U
Application number: CN202022209387.5U
Authority: CN
Inventors: 唐剑奇
Original assignee: Kunshan Luxshare RF Technology Co Ltd
Current assignee: Suzhou Lixun Technology Co ltd
Priority date: 2020-09-30
Filing date: 2020-09-30
Publication date: 2021-07-06
Anticipated expiration: 2030-09-30

Abstract

The application discloses a current monitoring circuit, which comprises a power supply conversion circuit, a first voltage conversion circuit and a second voltage conversion circuit, wherein the first voltage is converted into a second voltage which provides a voltage of a current monitoring circuit system; the power supply switching circuit receives a first voltage and provides the power supply current corresponding to the first voltage to the current sampling circuit; the current sampling circuit is used for providing power supply current to the element to be tested, sampling the power supply current of the power switch circuit and outputting sampling voltage; the voltage follower circuit outputs a follower voltage according to the sampling voltage; the voltage comparison circuit is used for comparing the sampling voltage corresponding to the current sampling circuit with the reference voltage so as to output a comparison voltage and feed back the comparison voltage to the power switch circuit; when the power supply current exceeds a first default value, the power supply switch circuit stops providing the power supply current to the element to be tested, and the power supply conversion circuit continuously provides the voltage of the current monitoring circuit system.

Description

Current monitoring circuit

Technical Field

The present application relates to a current monitoring circuit, and more particularly, to a current monitoring circuit for current monitoring or overcurrent protection.

Background

The supply voltage range of the antenna control unit (RCU) is wide, and is usually 10V to 30V. In addition, the aging test of the whole machine electrification is carried out at the early stage of the production of the antenna control unit. In order to prevent the antenna control units from being damaged by large current caused by the reverse connection of the anode and the cathode of the power supply or the short circuit of the circuit board during testing, a current monitoring circuit is required to be configured at the power supply input port of each antenna control unit during testing so as to monitor the tested current.

SUMMERY OF THE UTILITY MODEL

In order to solve the test problem of the prior art to the antenna control unit, the application discloses a current monitoring circuit for monitoring the test current of an element to be tested.

According to the current monitoring circuit disclosed by the embodiment, the power supply circuit is used for monitoring the power supply current of an element to be tested, the power supply conversion circuit receives a first voltage and converts the first voltage into a second voltage, the voltage value of the second voltage is different from that of the first voltage, and the second voltage provides the voltage of the current monitoring circuit system; the power supply switching circuit receives a first voltage and provides the power supply current corresponding to the first voltage to the current sampling circuit; the current sampling circuit is electrically connected with the power switch circuit, is used for providing the power supply current to the element to be tested, is used for sampling the power supply current of the power switch circuit and outputs sampling voltage; the voltage following circuit is electrically connected with the current sampling circuit and outputs following voltage according to the sampling voltage; the voltage comparison circuit is electrically connected with the current sampling circuit and used for comparing the sampling voltage corresponding to the current sampling circuit with a reference voltage so as to output a comparison voltage and feed back the comparison voltage to the power switch circuit; when the power supply current exceeds a first default value, the power supply switch circuit stops providing the power supply current to the element to be tested, and the power supply conversion circuit continuously provides the system voltage of the current monitoring circuit.

In the testing process, in order to prevent the damage to the product caused by the large current caused by the reverse connection of the anode and the cathode of the power supply or the short circuit of the circuit board, the application provides the current monitoring circuit which is used for monitoring the testing current of the element to be tested so as to cut off and lock the power switch and give an alarm when the testing current is overlarge, and then the overcurrent protection is carried out on the element to be tested. When the overcurrent protection is started, the power supply switch circuit stops providing the power supply current to the element to be tested, the overcurrent protection is only operated on the power supply switch circuit, and the power supply conversion circuit continuously provides the system voltage of the current monitoring circuit, so that the protection action is continuously locked after the overcurrent.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

FIG. 1 is a block diagram of an embodiment of the present application; and

fig. 2 is a detailed circuit of an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is described as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. Other words used to describe relationships between components may be similarly interpreted, such as "between" and "directly between," or "adjacent" and "directly adjacent," etc.

Fig. 1 is a block diagram of an embodiment of the present application. The current monitoring circuit shown in the figure is used for monitoring the supply current of the device to be tested, for example, in the application of an antenna control unit (RCU) burn-in test, and is used for current monitoring and overcurrent protection, so as to cut off and lock the power switch to perform overcurrent protection on the device to be tested when the test current is too large.

The current monitoring circuit includes a power conversion circuit 100, a power switch circuit 200, a current sampling circuit 300, a voltage follower circuit 400, a voltage comparator circuit 500 and an indicator circuit 600. The power conversion circuit 100 receives a first voltage and converts the first voltage into a second voltage, which has a different voltage value from the first voltage. The second voltage provides the current monitoring circuitry voltage. The power switching circuit 200 receives the first voltage and provides a supply current corresponding to the first voltage to the current sampling circuit 300. The current sampling circuit 300 is electrically connected to the power switch circuit 200, the current sampling circuit 300 receives the supply current and provides the supply current to the device to be tested, and the current sampling circuit 300 is configured to provide the supply current to the device to be tested, and in addition, the current sampling circuit 300 further samples the supply current provided by the power switch circuit 200 and outputs a sampling voltage. The voltage follower circuit 400 is electrically connected to the current sampling circuit 300, and the voltage follower circuit 400 outputs a follower voltage according to the sampled voltage. The voltage comparison circuit 500 is electrically connected to the current sampling circuit 300, and the voltage comparison circuit 500 is configured to compare the sampled voltage corresponding to the current sampling circuit 300 with a reference voltage to output a comparison voltage, and feed back the comparison voltage to the power switch circuit 200. When the supply current exceeds a first default value, the power switch circuit 200 stops providing the supply current to the element to be tested, and performs overcurrent protection on the element to be tested. Specifically, the overcurrent protection is only operated in the power switch circuit 200, and the power conversion circuit 100 continuously provides the system voltage of the current monitoring circuit, so that the protection operation after overcurrent is continuously locked.

The power conversion circuit 100 and the power switch circuit 200 are electrically connected to an input port 710, and the first voltage is input to the power conversion circuit 100 and the power switch circuit 200 through the input port 710. The supply current output by the current sampling circuit 300 is provided to the device under test through the output port 720.

The indication circuit 600 is electrically connected to the voltage follower circuit 400, powered by the second voltage provided by the power conversion circuit, and the indication circuit 600 is configured to respond to the follower voltage output by the voltage follower circuit 400 and the comparison voltage output by the voltage comparison circuit 500 to indicate whether the supply current of the device to be tested exceeds the first default value or does not exceed the second default value. When the supply current of the device to be tested is too high, i.e. exceeds the first default value, the control signal is fed back to the power switch circuit, and the power conversion circuit is used for supplying power and providing reference voltage for the power switch circuit 200, the current sampling circuit 300, the voltage follower circuit 400, the voltage comparison circuit 500 and the indication circuit 600. Therefore, in the present application, the overcurrent protection is only operated on the power switch circuit, and the power of the power conversion circuit is not cut off, so that the protection operation is continuously locked after the overcurrent.

Fig. 2 is a detailed circuit according to an embodiment of the present application, which shows a detailed composition of each circuit in fig. 1, and each circuit is described below.

The power conversion circuit 100 receives a first voltage and converts the first voltage into a second voltage having a different voltage value from the first voltage, the second voltage providing the current monitoring circuitry voltage. Specifically, the power conversion circuit 100 converts a wide range of input voltages from dc to a stable system voltage to power the indication circuit 600 of the monitoring circuit and the control circuit or other circuits in the monitoring circuit, such as the power switch circuit 200, the current sampling circuit 300, the voltage follower circuit 400, the voltage comparator circuit 500, etc. The input voltage is the first voltage, which generally ranges from 10 volts to 30 volts, while the system voltage is the second voltage, which is typically 5 volts. In some cases, 3.3 volts may also be used. The power conversion circuit 100 may employ a conventional dc-to-dc voltage conversion module, such as an XL1509 dc power step-down module, whose composition and related circuit configuration are common knowledge of those skilled in the art, and therefore detailed description of the power conversion circuit 100 is not repeated herein.

The power switch circuit 200 may include a mosfet and an NPN transistor for switching the back-stage power. Specifically, the power switch circuit 200 may include a first mosfet 210, a first NPN transistor 220, and a second NPN transistor 230.

The first mosfet 210 has a gate, a source and a drain, the gate of the first mosfet 210 receives the first voltage, and the drain of the first mosfet 210 is electrically connected to the current sampling circuit 300.

The first NPN transistor 220 has an emitter, a base, and a collector, the collector of the first NPN transistor 220 is electrically connected to the source of the first mosfet 210, and the emitter of the first NPN transistor 220 is electrically connected to the ground.

The second NPN transistor 230 has an emitter, a base, and a collector, the collector of the second NPN transistor 230 is electrically connected to the base of the first NPN transistor 220, the base of the second NPN transistor 230 is electrically connected to the output terminal of the voltage comparing circuit 500, and the emitter of the second NPN transistor 230 is electrically connected to the ground terminal.

The current monitoring circuit of the present application further includes a reset switch circuit 240 for resetting the power switch circuit. The reset switch circuit 240 is electrically connected between the input port 710 and the base of the first NPN transistor 220. The reset switch circuit 240 may be a dial switch circuit for resetting the power supply and restarting the current monitoring circuit when the power switch circuit is locked. A resistor 241 may be disposed between the reset switch circuit 240 and the input port 710, and a resistor 242 may be disposed between the reset switch circuit 240 and the ground.

The current sampling circuit 300 includes a first PNP transistor 310, a second PNP transistor 320, and a third PNP transistor 330.

The first PNP transistor 310 has an emitter, a base, and a collector, the emitter of the first PNP transistor 310 is electrically connected to the power switch circuit 200, and the base of the first PNP transistor 310 is electrically connected to the collector of the first PNP transistor 310.

In addition, a first resistor 311 may be disposed between the collector of the first PNP transistor 310 and the ground. A second resistor 312 may be disposed between the emitter of the first PNP transistor 310 and the power switch circuit 200.

The second PNP transistor 320 has an emitter, a base, and a collector, the emitter of the second PNP transistor 320 is electrically connected to the power switch circuit 200, and the base of the second PNP transistor 320 is electrically connected to the base of the first PNP transistor 310.

In addition, a third resistor 321 can be disposed between the collector of the second PNP transistor 320 and the ground. A fourth resistor 322 may be disposed between the emitter of the second PNP transistor 320 and the power switch circuit 200.

The third PNP transistor 330 has an emitter, a base, and a collector, the emitter of the third PNP transistor 330 is electrically connected to the emitter of the first PNP transistor 310, the base of the third PNP transistor 330 is electrically connected to the collector of the second PNP transistor 320, and the collector of the third PNP transistor 330 is electrically connected to the voltage follower circuit 400.

In addition, a fifth resistor 331 may be disposed between the collector of the third PNP transistor 330 and the ground.

The current sampling circuit 300 can complete current sampling by using three triodes and five resistors, and the design of the current sampling circuit is simplified.

The voltage follower circuit 400 is used to isolate the current sample output voltage of the current sampling circuit 300 to control the on and off of the indicator element in the indicator circuit. The voltage follower circuit 400 includes a first amplifier 410, a positive input terminal of the first amplifier 410 is electrically connected to the current sampling circuit 300, and a negative input terminal of the first amplifier 410 is electrically connected to an output terminal of the first amplifier 410. More specifically, the positive input terminal of the first amplifier 410 is electrically connected to the collector of the third PNP transistor 330.

The voltage comparison circuit 500 includes a first diode 510 and a second amplifier 520, wherein an anode terminal of the first diode 510 is electrically connected to the current sampling circuit 300, a positive input terminal of the second amplifier 520 is electrically connected to a cathode terminal of the first diode 510, a negative input terminal of the second amplifier 520 receives a reference voltage, and an output terminal of the second amplifier 520 is electrically connected to a positive input terminal of the second amplifier 520. A resistor 530 may be disposed between the output of the second amplifier 520 and the positive input of the second amplifier 520.

More specifically, the negative input terminal of the second amplifier 520 receives the reference voltage, when the sampling voltage is greater than the reference voltage, the second amplifier 520 outputs the high-level comparison voltage, and a negative feedback is introduced between the output terminal and the positive input terminal of the second amplifier 520, so that the second amplifier 520 can always output the high-level comparison voltage to maintain the indicating element in the indicating circuit in the first color state, for example, when a light emitting diode is used, the red color can be displayed as an alarm. When the second amplifier 520 outputs a low level of comparison voltage, it indicates that the test current is normal, so the indicating element in the indicating circuit maintains the second color state, for example, when a light emitting diode is used, it may display green.

The indication circuit 600 is electrically connected to the voltage follower circuit 400, and the indication circuit 600 is used for responding to the follower voltage output by the voltage follower circuit 400 and the comparison voltage output by the voltage comparison circuit 500 to indicate whether the supply current of the device to be tested exceeds the first default value or does not exceed the second default value. The indication circuit 600 includes a light emitting indication element 610, a first switch 611 and a second switch 612. The light-emitting indication device 610 can be configured with two light-emitting diodes of different colors, which can be respectively defined as a first light-emitting diode and a second light-emitting diode, the first light-emitting diode is electrically connected to the current sampling circuit 300 and the first switch 611, and the second light-emitting diode is electrically connected to the voltage comparison circuit 500 and the second switch 612. With such a configuration, when the second amplifier 520 outputs a high-level comparison voltage, the second led is driven to turn on, so that the second led emits light, which indicates that the current test current exceeds the first default value. When the supply current does not exceed the second default value, the second switch 612 is not turned on, and the first switch 611 is turned on, so that the first led emits light, indicating that the current test current exceeds the first default value. In conjunction with the foregoing description, the first led may use blue light to indicate that the current power supply current is normal, and the second led may use red light to indicate that the current power supply current is overcurrent.

The power switching circuit 200, the current sampling circuit 300, the voltage follower circuit 400, and the voltage comparator circuit 500 constitute a reusable unit circuit, so that when the number of detected elements is large, the unit circuit can be duplicated, and the power conversion circuit 100 supplies power to the plurality of reusable unit circuits.

In the testing process, in order to prevent the damage to the product caused by the large current caused by the reverse connection of the anode and the cathode of the power supply or the short circuit of the circuit board, the application provides the current monitoring circuit which is used for monitoring the testing current of the element to be tested so as to cut off and lock the power switch and give an alarm when the testing current is overlarge, and then the overcurrent protection is carried out on the element to be tested. In addition, the power switch circuit, the current sampling circuit, the voltage follower circuit and the voltage comparison circuit form a reusable unit circuit, so that when the number of detected elements is large, the unit circuit can be copied, and the test configuration is simplified.

The foregoing description shows and describes several preferred embodiments of the present application, but as aforementioned, it is to be understood that the application is not limited to the forms disclosed herein, but is not to be construed as excluding other embodiments and is capable of use in various other combinations, modifications, and environments and is capable of changes within the scope of the novel concepts as expressed herein, either by the above teachings or by the skill or knowledge of the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the application, which is to be protected by the claims appended hereto.

Claims

1. A current monitoring circuit for monitoring a supply current of an element to be tested, comprising:

the power supply conversion circuit receives a first voltage and converts the first voltage into a second voltage, wherein the second voltage is different from the first voltage in voltage value and provides the current monitoring circuit system voltage;

a power switching circuit receiving the first voltage and providing the supply current corresponding to the first voltage;

the current sampling circuit is electrically connected with the power switch circuit, receives the power supply current, provides the power supply current for the element to be tested, and samples the power supply current of the power switch circuit to output sampling voltage;

the voltage following circuit is electrically connected with the current sampling circuit and outputs following voltage according to the sampling voltage;

the voltage comparison circuit is electrically connected with the current sampling circuit and used for comparing the sampling voltage corresponding to the current sampling circuit with a reference voltage so as to output a comparison voltage and feed back the comparison voltage to the power switch circuit;

when the power supply current exceeds a first default value, the power supply switch circuit stops providing the power supply current to the element to be tested, and the power supply conversion circuit continuously provides the system voltage of the current monitoring circuit.

2. The current monitoring circuit of claim 1, wherein the power switching circuit comprises:

the first metal-oxide-semiconductor field effect transistor is provided with a grid electrode, a source electrode and a drain electrode, the grid electrode receives the first voltage, and the drain electrode of the first metal-oxide-semiconductor field effect transistor is electrically connected with the current sampling circuit;

a first NPN transistor having an emitter, a base and a collector, wherein the collector of the first NPN transistor is electrically connected to the source of the first MOSFET, and the emitter of the first NPN transistor is electrically connected to a ground terminal;

the collector of the second NPN type transistor is electrically connected with the base of the first NPN type transistor, the base of the second NPN type transistor is electrically connected with the output end of the voltage comparison circuit, and the emitter of the second NPN type transistor is electrically connected with the grounding end.

3. The current monitoring circuit of claim 1, further comprising an indication circuit electrically connected to the voltage follower circuit, powered by the second voltage provided by the power conversion circuit, for indicating whether the supply current exceeds the first default value or does not exceed a second default value in response to the follower voltage and the comparison voltage.

4. The current monitoring circuit of claim 1, further comprising a reset switch circuit for resetting the power switch circuit.

5. The current monitoring circuit of claim 1, wherein the current sampling circuit comprises:

a first PNP transistor having an emitter, a base, and a collector, the emitter of the first PNP transistor being electrically connected to the power switch circuit, the base of the first PNP transistor being electrically connected to the collector of the first PNP transistor;

a second PNP transistor having an emitter, a base, and a collector, the emitter of the second PNP transistor being electrically connected to the power switch circuit, the base of the second PNP transistor being electrically connected to the base of the first PNP transistor;

a third PNP type transistor having an emitter, a base, and a collector, the emitter of the third PNP type transistor electrically connected to the emitter of the first PNP type transistor, the base of the third PNP type transistor electrically connected to the collector of the second PNP type transistor, the collector of the third PNP type transistor electrically connected to the voltage follower circuit.

6. The current monitoring circuit of claim 5, wherein the current sampling circuit further comprises:

the first resistor is electrically connected between the collector electrode of the first PNP type transistor and a ground terminal;

the second resistor is electrically connected between the emitting electrode of the first PNP type transistor and the power switch circuit;

a third resistor electrically connected between the collector of the second PNP transistor and the ground terminal;

a fourth resistor electrically connected between the emitter of the second PNP transistor and the power switch circuit;

and the fifth resistor is electrically connected between the collector of the third PNP type transistor and the grounding terminal.

7. The current monitoring circuit of claim 1, wherein the voltage follower circuit comprises a first amplifier, a positive input of the first amplifier is electrically connected to the current sampling circuit, and a negative input of the first amplifier is electrically connected to an output of the first amplifier.

8. The current monitoring circuit of claim 1, wherein the voltage comparator circuit comprises a first diode and a second amplifier, an anode of the first diode is electrically connected to the current sampling circuit, a positive input of the second amplifier is electrically connected to a cathode of the first diode, a negative input of the second amplifier receives a reference voltage, and an output of the second amplifier is electrically connected to the positive input of the second amplifier.

9. The current monitoring circuit according to claim 1, wherein the power switch circuit, the current sampling circuit, the voltage follower circuit, and the voltage comparator circuit are respectively provided in plurality.