Power supply polarity detection circuit

Abstract

The utility model relates to a power supply polarity detection circuit. The circuit comprises a first resistor, a second resistor, a bias branch and a voltage measuring device, the first input end of the detection circuit is connected to the first end of the first resistor, the second input end of the detection circuit corresponds to the first end of the second resistor, and the second end of the first resistor is connected with the second end of the second resistor; the positive input ends of the bias branch and the voltage measuring device are connected between the first resistor and the second resistor; the cathode input end of the voltage measuring device and the first electrode of the to-be-measured power supply are common reference points of the detection circuit; the potential difference of the positive pole input end of the voltage measuring device relative to the common reference point is to-be-measured voltage, and the voltage measuring device is used for judging the power supply polarity of the to-be-measured power supply through the to-be-measured voltage. The method has the effect of improving the accuracy of power supply polarity detection.

Description

Technical Field

[0001] The present application relates to the technical field of power supply detection, and in particular to a power supply polarity detection circuit. Background Art

[0002] In circuits, the polarity of the DC input signal must be distinguished to prevent circuit malfunctions caused by reversed polarity. For example, a battery charger can be damaged if the battery being charged is connected to the charger with reverse polarity. Therefore, the polarity of the connected battery must be determined. Only when the polarity is correct can the charger enter operation and charge the battery.

[0003] The detection circuit in the related art requires the design of a circuit with a specific structure to implement. It is implemented by using a voltage comparator or a complex circuit with multiple detection or control ports. For example, the two poles of the power supply to be tested are connected to the positive input and negative input of the voltage comparator respectively. If the output terminal is high, the power supply to be tested is connected to the detection circuit in the positive direction, that is, the positive input terminal corresponds to the positive pole of the power supply to be tested, and the negative input terminal corresponds to the negative pole of the power supply to be tested. If the output terminal is low, the power supply to be tested is connected to the detection circuit in the negative direction, that is, the positive input terminal corresponds to the negative pole of the power supply to be tested, and the negative input terminal corresponds to the positive pole of the power supply to be tested.

[0004] Regarding the above-mentioned related technologies, the applicant believes that if the power supply to be tested is not connected to the detection circuit, the output terminal of the related technologies will be low level; if the circuit to be tested is connected to the detection circuit in reverse, the output terminal of the related technologies will also be low level. As a result, the related technologies cannot accurately distinguish the polarity of the power supply. Utility Model Content

[0005] In order to improve the accuracy of power supply polarity detection, the present application provides a power supply polarity detection circuit.

[0006] This application provides a power polarity detection circuit, which adopts the following technical solution:

[0007] A power supply polarity detection circuit includes: a first resistor, a second resistor, a bias branch, and a voltage measuring device;

[0008] The first input terminal of the detection circuit is connected to the first end of the first resistor, the second input terminal of the detection circuit corresponds to the first end of the second resistor, and the second end of the first resistor is connected to the second end of the second resistor;

[0009] The bias branch and the positive input terminal of the voltage measuring device are connected between the first resistor and the second resistor;

[0010] The negative input terminal of the voltage measuring device and the first pole of the power supply to be measured are common reference points of the detection circuit;

[0011] The potential difference between the positive input terminal of the voltage measuring device and the common reference point is the voltage to be measured. The voltage measuring device is used to determine the power polarity of the power supply to be measured through the voltage to be measured.

[0012] By adopting the above technical solution, it is only necessary to add a bias branch between the first resistor and the second resistor as the voltage divider network to determine the power polarity of the power supply to be tested and distinguish between the three situations of forward connection, reverse connection and no connection. In addition, the structure of the detection circuit is simple and easy to implement.

[0013] Optionally, the bias branch includes a bias resistor, a diode, and a bias voltage source;

[0014] The first end of the bias resistor is connected between the first resistor and the second resistor;

[0015] The second end of the bias resistor is connected to the cathode of the diode;

[0016] The anode of the diode is connected to the positive terminal of the bias voltage source.

[0017] By adopting the above technical solution, a bias power supply, a bias resistor and a diode are added to the bias branch. Under different conditions of the power supply to be tested (correct connection, no connection, and reverse polarity connection), the voltage measuring device can output three different readings to determine the actual connection method of the power supply to be tested.

[0018] Optionally, when the first input terminal and the second input terminal are not connected to the power supply to be measured, the voltage to be measured is a first voltage, and the first voltage is not zero.

[0019] By adopting the above technical solution, when the power supply to be tested is not connected, the voltage to be tested is not 0 and the voltage value can be read.

[0020] Optionally, when the first input terminal is connected to the negative pole of the power supply to be measured and the second input terminal is connected to the positive pole of the power supply to be measured, the voltage to be measured is a second voltage, and the second voltage is not equal to the first voltage.

[0021] By adopting the above technical solution, the reverse connection of the power supply to be tested and the non-connection of the power supply to be tested are distinguished by the voltage value of the voltage to be tested.

[0022] Optionally, when the first input terminal is connected to the positive pole of the power supply to be tested and the second input terminal is connected to the negative pole of the power supply to be tested, the voltage to be tested is a third voltage, the third voltage is not equal to the first voltage, and the third voltage is not equal to the second voltage.

[0023] By adopting the above technical solution, three situations of forward access, reverse access and no access can be distinguished.

[0024] Optionally, the resistance of the bias resistor is greater than the resistance of the first resistor.

[0025] By adopting the above technical solution, a bias resistor is used to increase the voltage on both sides of the bias resistor.

[0026] Optionally, the resistance of the bias resistor is greater than the resistance of the second resistor.

[0027] By adopting the above technical solution, a bias resistor is used to increase the voltage on both sides of the bias resistor.

[0028] Optionally, the voltage measuring device is a microprocessor unit MCU.

[0029] By adopting the above technical solution, the voltage to be measured is measured using MCU.

[0030] Optionally, the voltage measuring device is provided with an analog-to-digital conversion module, and the analog-to-digital conversion module is used to convert the voltage to be measured into an analog-to-digital output.

[0031] By adopting the above technical solution, the MCU can output the analog-to-digital output corresponding to the voltage to be measured, thereby distinguishing the polarity of the power supply to be measured.

[0032] Optionally, the positive input terminal of the voltage measuring device is an input port of the analog-to-digital conversion module.

[0033] By adopting the above technical solution, the influence of the internal resistance of the MCU is reduced through the analog-to-digital conversion module.

[0034] In summary, this application includes at least one of the following beneficial technical effects:

[0035] 1. Simply adding a bias branch between the first and second resistors in the voltage divider network can determine the polarity of the power supply under test and distinguish between forward connection, reverse connection, and no connection. The detection circuit has a simple structure and is easy to implement.

[0036] 2. Add bias resistors and diodes in the bias branch so that the polarity of the power supply under test can be determined by the different states of the diodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the structure of a power supply polarity detection circuit disclosed in an embodiment of the present application.

[0038] Description of the accompanying symbols: bias branch 11; voltage measuring device 12; first resistor R1; second resistor R2; bias resistor R3; power supply to be measured VS1; bias voltage source V1; diode D1. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of this application more clear, the following Figure 1It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0040] The present application embodiment discloses a power supply polarity detection circuit. Figure 1 The detection circuit includes: a first resistor R1, a second resistor R2, a bias branch 11 and a voltage measuring device 12.

[0041] A first resistor R1 and a second resistor R2 are connected in series, a first input terminal of the detection circuit corresponds to the first resistor R1, and a second input terminal of the detection circuit corresponds to the second resistor R2;

[0042] The positive input terminal of the bias branch 11 and the voltage measuring device 12 is connected between the first resistor R1 and the second resistor R2;

[0043] The negative input terminal of the voltage measuring device 12 and the first pole of the power supply VS1 to be measured are common reference points of the detection circuit;

[0044] The potential difference of the positive input terminal of the voltage measuring device 12 relative to the common reference point is the voltage to be measured V0 , and the voltage measuring device is used to determine the power polarity of the power supply to be measured VS1 through the voltage to be measured V0 .

[0045] In an optional embodiment of the present application, the bias branch 11 includes a bias resistor R3, a diode D1, and a bias voltage source V1. The first end of the bias resistor R3 is connected between the first resistor R1 and the second resistor R2; the second end of the bias resistor R3 is connected to the cathode of the diode D1; and the anode of the diode D1 is connected to the anode of the bias voltage source V1.

[0046] Optionally, the voltage measuring device 12 is a MCU (MicroController Unit).

[0047] Optionally, the voltage measuring device 12 is provided with an analog-to-digital conversion module (A / D conversion module), which is used to convert the measured voltage V0 into an analog-to-digital output. For example, when the measured voltage V0 is 1.09V, the analog-to-digital output of the A / D conversion module is 0x5B.

[0048] Optionally, the positive input terminal of the voltage measuring device 12 is an input port of the analog-to-digital conversion module.

[0049] Optionally, the negative terminal of the bias voltage source V1 is connected to the common reference point.

[0050] Optionally, the common reference point is grounded, and the potential of the common reference point is 0.

[0051] Optionally, the resistance of the bias resistor R3 is greater than the resistance of the first resistor R1. Optionally, the resistance of the bias resistor R3 is greater than the resistance of the second resistor R2. Exemplarily, the resistance of the bias resistor R3 is 5 MΩ, while the resistance of the first resistor R1 is 100 kΩ and the resistance of the second resistor R2 is 10 kΩ. Exemplarily, the resistance of the bias resistor R3 is at least 50 times greater than the resistance of the first resistor R1.

[0052] Optionally, the voltage of the power supply under test VS1 may be greater than or less than the voltage of the bias voltage source V1. For example, the voltage of the bias voltage source V1 is 3.3V, and the voltage of the power supply under test VS1 is 10V or 12V; or, the voltage of the bias voltage source V1 is 3.3V, and the voltage of the power supply under test VS1 is 3.0V.

[0053] Optionally, when the power supply VS1 to be tested is not connected to the first input terminal and the second input terminal, the diode D1 is in a conducting state, and the voltage to be tested V0 is a first voltage, which is not 0. When the power supply VS1 to be tested is not connected to the first input terminal and the second input terminal, only the bias voltage source V1 provides power in the detection circuit, and therefore the diode D1 is in a conducting state.

[0054] Optionally, when the first input terminal is connected to the negative electrode of the power supply VS1 to be measured and the second input terminal is connected to the positive electrode of the power supply VS1 to be measured, the voltage to be measured V0 is a second voltage, and the second voltage is not equal to the first voltage.

[0055] Optionally, when the first input terminal is connected to the positive pole of the power supply VS1 to be tested and the second input terminal is connected to the negative pole of the power supply VS1 to be tested, the voltage to be tested V0 is a third voltage, the third voltage is not equal to the first voltage, and the third voltage is not equal to the second voltage.

[0056] In some other embodiments, the positive input terminal of the voltage measuring device 12 is further provided with an overcurrent protection element ( Figure 1 (Not shown) An overcurrent protection element (OCP) is connected at one end to the positive input terminal of the voltage measuring device 12, and at the other end between the first resistor R1 and the second resistor R2. The OCP prevents excessive current from flowing through the voltage measuring device 12. When the current flowing through the voltage measuring device 12 exceeds the upper current limit of the MCU, the OCP trips the circuit. The upper current limit of the voltage measuring device 12 is factory-set. For example, the OCP can be a fuse or a circuit breaker.

[0057] In summary, by adopting the above technical solution, it is only necessary to add a bias branch between the first resistor and the second resistor as the voltage divider network to determine the power polarity of the power supply to be tested, and distinguish between the three situations of forward connection, reverse connection and no connection. Moreover, the structure of the detection circuit is simple and easy to implement.

[0058] This application Figure 1 Implementation principle 1 of the illustrated embodiment:

[0059] First, let the voltage of the power supply under test, VS1, be 12V, the voltage of the bias voltage source be 3.3V, the resistance of the first resistor be 100kΩ, the resistance of the second resistor be 10kΩ, and the resistance of the bias resistor be 5MΩ. To simplify the analysis, diode D1 is considered an ideal diode and its forward voltage drop is ignored. Thus,

[0060] 1. Not connected: The power supply to be tested is not connected to the detection circuit;

[0061] At this time, the diode D1 is in the on state, and the bias voltage source V1, the second resistor R2, and the bias resistor R3 form a loop. The second resistor R2 and the bias resistor R3 are connected in series. Therefore, V0 only includes the divided voltage provided by the bias voltage source V1, and then:

[0062] V0=(V1×R2) / (R3+R2)

[0063] =(3.3V×10000Ω) / (5000000Ω×10000Ω)=6.58mV;

[0064] When the MCU detects that the voltage to be measured V0 is 6.58mV, its analog-to-digital output is 0X8.

[0065] 2. Forward connection: The positive pole of the power supply to be tested is connected to the first input terminal, and the negative pole is connected to the second input terminal;

[0066] At this time, diode D1 is in the on state. The bias voltage source V1, the second resistor R2, and the bias resistor R3 form a loop, with the second resistor R2 and the bias resistor R3 connected in series; the target power supply VS1, the first resistor R1, and the second resistor R2 form another loop, with the first resistor R1 and the second resistor R2 connected in series. Therefore, V0 includes the divided voltage provided by the bias voltage source V1 and the divided voltage provided by the target power supply VS1, and then:

[0067] V0=(VS1×R2) / (R1+R2)+(V1×R2) / (R3+R2)

[0068] =(12V×10000Ω) / (100000Ω+10000Ω)+(3.3V×10000Ω) / (5000000Ω×10000Ω)

[0069] =1090.9mV+6.58mV=1097.48mV≈1.09V;

[0070] When the MCU detects that the measured voltage V0 is 1097.48mV, its analog-to-digital output is 0X5B. Because the error introduced by the 6.58mV bias voltage is minimal and can be compensated for using the MCU's internal algorithm, it does not affect the actual measurement accuracy.

[0071] 3. Reverse connection: the positive pole of the power supply to be tested is connected to the second input terminal, and the negative pole is connected to the first input terminal;

[0072] At this time, the diode D1 is in the on state. Then:

[0073] V0=-(VS1×R2) / (R1+R2)+(V1×R2) / (R3+R2)

[0074] =-(12V×10000Ω) / (100000Ω+10000Ω)+(3.3V×10000Ω) / (5000000Ω+10000Ω)

[0075] =-1090.9mV+6.58mV=-1084.32mV≈-1.08V;

[0076] When the MCU detects that the voltage to be measured V0 is -1.08V, its analog-to-digital output is 0.

[0077] This application Figure 1 Implementation principle 2 of the illustrated embodiment:

[0078] First, let the voltage of the power supply under test, VS1, be 3V, the voltage of the bias voltage source be 3.3V, the resistance of the first resistor be 100kΩ, the resistance of the second resistor be 10kΩ, and the resistance of the bias resistor be 5MΩ. To simplify the analysis, diode D1 is considered an ideal diode and its forward voltage drop is ignored. Thus,

[0079] 1. Not connected: The power supply to be tested is not connected to the detection circuit;

[0080] At this time, the diode D1 is in the on state, and the bias voltage source V1, the second resistor R2, and the bias resistor R3 form a loop. The second resistor R2 and the bias resistor R3 are connected in series. Therefore, V0 only includes the divided voltage provided by the bias voltage source V1, and then:

[0081] V0=(V1×R2) / (R2+R3)

[0082] =(3.3V×10000Ω) / (5000000Ω×10000Ω)=6.58mV;

[0083] When the MCU detects that the voltage to be measured V0 is 6.58mV, its analog-to-digital output is 0X8.

[0084] 2. Forward connection: The positive pole of the power supply to be tested is connected to the first input terminal, and the negative pole is connected to the second input terminal;

[0085] At this time, diode D1 is in the on state. The bias voltage source V1, the second resistor R2, and the bias resistor R3 form a loop, with the second resistor R2 and the bias resistor R3 connected in series; the target power supply VS1, the first resistor R1, and the second resistor R2 form another loop, with the first resistor R1 and the second resistor R2 connected in series. Therefore, V0 includes the divided voltage provided by the bias voltage source V1 and the divided voltage provided by the target power supply VS1, and then:

[0086] V0=(VS1×R2) / (R1+R2)+(V1×R2) / (R3+R2)

[0087] =(3V×10000Ω) / (100000Ω+10000Ω)+(3.3V×10000Ω) / (5000000Ω×10000Ω)

[0088] =272.72mV+6.58mV=279.3mV≈0.279V;

[0089] When the MCU detects that the measured voltage V0 is 279.3mV, its analog-to-digital output is 0X5B. Because the error introduced by the 6.58mV bias voltage is minimal and can be compensated for using the MCU's internal algorithm, it does not affect the actual measurement accuracy.

[0090] 3. Reverse connection: the positive pole of the power supply to be tested is connected to the second input terminal, and the negative pole is connected to the first input terminal;

[0091] At this time, the diode D1 is in the on state, so:

[0092] V0=-(VS1×R2) / (R1+R2)+(V1×R2) / (R3+R2)

[0093] =-(3V×10000Ω) / (100000Ω+10000Ω)+(3.3V×10000Ω) / (5000000Ω+10000Ω)

[0094] =-272.27mV+6.58mV=-265.69mV≈-0.266V;

[0095] When the MCU detects that the voltage to be measured V0 is -0.266V, its analog-to-digital output is 0.

[0096] This application Figure 1 Implementation principle 3 of the illustrated embodiment:

[0097] First, let the voltage of the power supply under test, VS1, be 3V, the voltage of the bias voltage source be 3.3V, the resistance of the first resistor be 10kΩ, the resistance of the second resistor be 100kΩ, and the resistance of the bias resistor be 5MΩ. To simplify the analysis, diode D1 is considered an ideal diode and its forward voltage drop is ignored. Thus,

[0098] 1. Not connected: The power supply to be tested is not connected to the detection circuit;

[0099] At this time, the diode D1 is in the on state, and the bias voltage source V1, the second resistor R2, and the bias resistor R3 form a loop. The second resistor R2 and the bias resistor R3 are connected in series. Therefore, V0 only includes the divided voltage provided by the bias voltage source V1, and then:

[0100] V0=(V1×R2) / (R2+R3)

[0101] =(3.3V×1000Ω) / (5000000Ω×1000Ω)=64.7mV;

[0102] When the MCU detects that the voltage to be measured V0 is 64.7mV, its analog-to-digital output is 0X8.

[0103] 2. Forward connection: The positive pole of the power supply to be tested is connected to the first input terminal, and the negative pole is connected to the second input terminal;

[0104] At this time, diode D1 is in the on state. The bias voltage source V1, the second resistor R2, and the bias resistor R3 form a loop, with the second resistor R2 and the bias resistor R3 connected in series; the target power supply VS1, the first resistor R1, and the second resistor R2 form another loop, with the first resistor R1 and the second resistor R2 connected in series. Therefore, V0 includes the divided voltage provided by the bias voltage source V1 and the divided voltage provided by the target power supply VS1, and then:

[0105] V0=(VS1×R2) / (R1+R2)+(V1×R2) / (R3+R2)

[0106] =(3V×100000Ω) / (100000Ω+10000Ω)+(3.3V×100000Ω) / (5000000Ω×100000Ω)

[0107] =2727.27mV+64.7mV=2791.97mV≈2.79V;

[0108] When the MCU detects that the measured voltage V0 is 2791.97mV, its analog-to-digital output is 0X5B. Because the error introduced by the 64.7mV bias voltage is minimal and can be compensated for using the MCU's internal algorithm, it does not affect the actual measurement accuracy.

[0109] 3. Reverse connection: the positive pole of the power supply to be tested is connected to the second input terminal, and the negative pole is connected to the first input terminal;

[0110] V0=(VS1×R2) / (R1+R2)+(V1×R2) / (R3+R2)

[0111] =(-3V×10000Ω) / (100000Ω+10000Ω)+(3.3V×100000Ω) / (5000000Ω×100000Ω)

[0112] =-2727.27mV+64.7mV=-2662.57mV≈-2.66V;

[0113] When the MCU detects that the voltage to be measured V0 is -2662.57mV, its analog-to-digital output is 0.

[0114] Therefore, through the explanation of the above three situations, the three access states of the power supply to be tested can be judged according to the analog-to-digital output of the MCU: not connected, forward connected, and reverse connected. Especially for the judgment of the two access states of not connected and reverse connected. If the power supply to be tested is not connected to the detection circuit, the analog-to-digital output of this application is 0x8; if the circuit to be tested is reversely connected to the detection circuit, the analog-to-digital output of this application is 0. Compared with the relevant technology, this application can clearly distinguish whether the power supply to be tested is not connected to the detection circuit or is reversely connected to the detection circuit.

[0115] The above are all preferred embodiments of the present application and are not intended to limit the scope of protection of this application. Unless otherwise stated, any feature disclosed in this specification (including the abstract and drawings) may be replaced by other equivalent or similar features. In other words, unless otherwise stated, each feature is merely an example of a series of equivalent or similar features.

Claims

1. A power supply polarity detection circuit, characterized in that: include: a first resistor, a second resistor, a bias branch, and a voltage measuring device; The first input end of the detection circuit is connected to the first end of the first resistor, the second input end of the detection circuit corresponds to the first end of the second resistor, and the second end of the first resistor is connected to the second end of the second resistor; The bias branch and the positive input terminal of the voltage measuring device are connected between the first resistor and the second resistor; The negative input terminal of the voltage measuring device and the first pole of the power supply to be measured are common reference points of the detection circuit; The potential difference of the positive input terminal of the voltage measuring device relative to the common reference point is the voltage to be measured, and the voltage measuring device is used to determine the power polarity of the power supply to be measured through the voltage to be measured.

2. The power supply polarity detection circuit according to claim 1, characterized in that: The bias branch includes a bias resistor, a diode and a bias voltage source; The first end of the bias resistor is connected between the first resistor and the second resistor; The second end of the bias resistor is connected to the cathode of the diode; The anode of the diode is connected to the anode of the bias voltage source.

3. The power supply polarity detection circuit according to claim 2, characterized in that: When the first input terminal and the second input terminal are not connected to the power supply to be measured, the voltage to be measured is a first voltage, and the first voltage is not zero.

4. The power supply polarity detection circuit according to claim 3, characterized in that: When the first input terminal is connected to the negative electrode of the power supply to be measured and the second input terminal is connected to the positive electrode of the power supply to be measured, the voltage to be measured is a second voltage, and the second voltage is not equal to the first voltage.

5. The power polarity detection circuit according to claim 4, characterized in that: When the first input terminal is connected to the positive electrode of the power supply to be measured and the second input terminal is connected to the negative electrode of the power supply to be measured, the voltage to be measured is a third voltage, the third voltage is not equal to the first voltage, and the third voltage is not equal to the second voltage.

6. The power supply polarity detection circuit according to claim 2, characterized in that: The resistance of the bias resistor is greater than the resistance of the first resistor.

7. The power supply polarity detection circuit according to claim 2, characterized in that: The resistance of the bias resistor is greater than the resistance of the second resistor.

8. The power polarity detection circuit according to claim 1, characterized in that: The voltage measuring device is a microprocessor unit MCU.

9. The power polarity detection circuit according to claim 8, characterized in that: The voltage measuring device is provided with an analog-to-digital conversion module, and the analog-to-digital conversion module is used to convert the voltage to be measured into an analog-to-digital output.

10. The power polarity detection circuit according to claim 9, characterized in that: The positive input terminal of the voltage measuring device is the input port of the analog-to-digital conversion module.

Images