PCBA working current detection circuit

Abstract

The utility model discloses a PCBA working current detection circuit comprising a sampling circuit, an amplification circuit, a filter circuit, a window comparator circuit and a state display circuit, and the sampling circuit is electrically connected with a load P1. The input end of the amplifying circuit is electrically connected with the sampling circuit, and the output end is electrically connected with the input end of the window comparator circuit. And the output end of the window comparator circuit is electrically connected with the state display circuit. The window comparator circuit comprises an operational amplifier U1B and an operational amplifier U1A, and outputs a high level or a low level by comparing two threshold levels with an output voltage signal. The state display circuit comprises a light-emitting diode D2 and a light-emitting diode D3, and only the light-emitting diode D2 is lightened when the level is high, and NG does not pass. And when the low level is output, only the light-emitting diode D3 is lightened, and the PASS passes through the light-emitting diode D3. Whether the lamp bead works normally or not is determined according to the current range when the PCBA works normally, and the detection result is presented through the two light-emitting diodes.

Description

Technical Field

[0001] The utility model relates to the technical field of PCBA detection, in particular to a PCBA working current detection circuit. Background Art

[0002] Lamp beads are involved in many PCBAs. It is very important to detect whether the lamp beads are functioning well. Currently, most conventional testing methods are manual visual inspection or machine recognition. The former relies on human eyes, which will cause errors in large-scale inspections, and will also cause eye fatigue and errors when measuring large quantities. Each person's subjective observation opinions are also different. For the latter, the current machine equipment costs are generally high and there will be color deviations. Utility Model Content

[0003] In order to overcome the above shortcomings, the purpose of the utility model is to provide a PCBA working current detection circuit to solve the problem of inconvenient detection of lamp bead functions in PCBA proposed in the above background technology.

[0004] In order to achieve the above purpose, the technical solution adopted by the utility model is a PCBA working current detection circuit, including a sampling circuit, an amplification circuit, a filtering circuit, a window comparator circuit and a status display circuit, wherein:

[0005] The sampling circuit is electrically connected to the load P1 to generate an output voltage signal. The input end of the amplifier circuit is electrically connected to the sampling circuit, and the output end is electrically connected to the input end of the window comparator circuit to amplify the output voltage signal and remove noise. The output end of the window comparator circuit is electrically connected to the status display circuit.

[0006] The window comparator circuit includes an operational amplifier U1B and an operational amplifier U1A, and is used to compare the threshold level of the operational amplifier U1B and the threshold level of the operational amplifier U1A with the output voltage signal respectively, and output a high level or a low level.

[0007] The state display circuit includes a light emitting diode D2 and a light emitting diode D3, and is used for when the window comparator outputs a high level, only the light emitting diode D2 is lit, indicating NG failure. When the window comparator outputs a low level, only the light emitting diode D3 is lit, indicating PASS.

[0008] Furthermore, the sampling circuit includes a resistor R10. One end of the resistor R10 is connected to the load P1, and the other end is grounded GND.

[0009] Further, the amplification circuit includes an operational amplifier U2A, a resistor R8, a resistor R12, a resistor R16, a resistor R5, a capacitor C2, a capacitor C4 and a capacitor C5. The positive input terminal of the operational amplifier U2A is connected to the node between the resistor R10 and the load P1 through the resistor R12, and is grounded GND through the resistor R16, the negative input terminal is connected to the other end of the resistor R10 through the resistor R8, and is grounded GND through the capacitor C2, the positive power supply terminal is connected to a 5V power supply, and the negative power supply terminal is grounded GND. The capacitor C4 is connected in parallel to the two ends of the resistor R16. The two ends of the resistor R5 are respectively connected to the negative input terminal and the output terminal of the operational amplifier U2A. The positive terminal of the capacitor C5 is connected to the positive power supply terminal of the operational amplifier U2A, and the negative terminal is grounded.

[0010] Furthermore, the PCBA working current detection circuit also includes a filter circuit, which includes a resistor R9 and a capacitor C3. One end of the resistor R9 is connected to the output end of the operational amplifier U2A, and the other end is electrically connected to the input end of the window comparator circuit, and is grounded GND through the capacitor C3.

[0011] Further, the window comparator circuit includes a first integrated operational amplifier circuit. The first integrated operational amplifier circuit includes the operational amplifier U1B, resistor R6, resistor R1, resistor R2, resistor R3 and capacitor C1. The positive input terminal of the operational amplifier U1B is connected to the resistor R9 through the resistor R6, the negative input terminal is grounded GND through the resistor R1, and the 5V power supply is connected through the resistor R2, and the output terminal is connected to one end of the resistor R3. The capacitor C1 is connected in parallel to both ends of the resistor R1.

[0012] Further, the window comparator circuit includes a second integrated operational amplifier circuit. The second integrated operational amplifier circuit includes the operational amplifier U1A, a resistor R14, a resistor R17, a resistor R18, a resistor R19, a capacitor C6 and a capacitor C7. The negative input terminal of the operational amplifier U1A is connected to the resistor R9 through the resistor R14, the positive input terminal is grounded to GND through the resistor R18, and the 5V power supply is connected to the resistor R19, the output terminal is connected to one end of the resistor R17, the positive power supply terminal is connected to the 5V power supply, and the negative power supply terminal is grounded to GND. The capacitor C7 is connected in parallel to both ends of the resistor R1. The positive terminal of the capacitor C6 is connected to the positive power supply terminal of the operational amplifier U1A, and the negative terminal is grounded to GND.

[0013] Furthermore, the first integrated operational amplifier circuit further comprises a diode D1, wherein the positive terminal of the diode D1 is connected to the other end of the resistor R3. The second integrated operational amplifier circuit further comprises a diode D4, wherein the positive terminal of the diode D4 is connected to the other end of the resistor R17.

[0014] Furthermore, the state display circuit also includes a resistor R11, a resistor R15, a resistor R4, a resistor R7, a resistor R13, a transistor Q2 and a transistor Q1. The base of the transistor Q2 is connected to the two negative ends of the diode D1 and the diode D4 respectively through the resistor R11, the emitter is grounded GND, and the collector is connected to the negative end of the light-emitting diode D2. The base of the transistor Q1 is connected to the collector of the transistor Q2 through the resistor R7, the emitter is grounded GND through the resistor R13, and the collector is connected to a 5V power supply. The positive end of the light-emitting diode D2 is connected to the 5V power supply through the resistor R4, the positive end of the light-emitting diode D3 is connected to the collector of the transistor Q1, and the negative end is connected to the emitter of the transistor Q1.

[0015] Furthermore, the transistor Q2 is an NPN transistor, and the transistor Q2 is a PNP transistor.

[0016] Compared with the prior art, the beneficial effects of the utility model are as follows: the PCBA working current detection circuit provided in the present application confirms whether the lamp beads are working normally through the current range when the PCBA is working normally. First, compared with manual visual inspection, the accuracy of the detection results can be greatly improved; second, the test results are displayed using only two light-emitting diodes of different colors, which is not easy to mismeasure; third, compared with existing machine recognition, this design has lower cost and is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The utility model is a circuit schematic diagram of an embodiment of a PCBA working current detection circuit. DETAILED DESCRIPTION

[0018] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0019] refer to Figure 1 , Figure 1 A circuit schematic diagram of a PCBA working current detection circuit provided by an embodiment of the utility model is shown.

[0020] like Figure 1As shown, the technical solution adopted by the utility model is a PCBA working current detection circuit, including a sampling circuit, an amplifying circuit, a filtering circuit, a window comparator circuit and a status display circuit, wherein:

[0021] The sampling circuit is electrically connected to the load P1 to generate an output voltage signal. The input end of the amplifier circuit is electrically connected to the sampling circuit, and the output end is electrically connected to the input end of the window comparator circuit to amplify the output voltage signal and remove noise. The output end of the window comparator circuit is electrically connected to the status display circuit.

[0022] The window comparator circuit includes an operational amplifier U1B and an operational amplifier U1A, and is used to compare the threshold level of the operational amplifier U1B and the threshold level of the operational amplifier U1A with the output voltage signal respectively, and output a high level or a low level.

[0023] The status display circuit includes a light-emitting diode D2 and a light-emitting diode D3. When the window comparator outputs a high level, only the light-emitting diode D2 is lit, indicating NG. When the window comparator outputs a low level, only the light-emitting diode D3 is lit, indicating PASS.

[0024] The PCBA working current detection circuit provided in this application confirms whether the lamp beads are working normally through the current range when the PCBA is working normally, uses a window comparator circuit to compare and judge the voltage signal of the load P1, and presents the detection results through two light-emitting diodes. For example, the light-emitting diode D2 is a red light, and the light-emitting diode D3 is a street light, which makes it faster and more intuitive to distinguish and interpret the detection results.

[0025] In some embodiments, reference Figure 1 The sampling circuit includes a resistor R10. One end of the resistor R10 is connected to the load P1, and the other end is grounded GND.

[0026] The amplifier circuit includes an operational amplifier U2A, a resistor R8, a resistor R12, a resistor R16, a resistor R5, a capacitor C2, a capacitor C4 and a capacitor C5. The positive input terminal of the operational amplifier U2A is connected to the node between the resistor R10 and the load P1 through the resistor R12, and is grounded to GND through the resistor R16. The negative input terminal is connected to the other end of the resistor R10 through the resistor R8, and is grounded to GND through the capacitor C2. The positive power supply terminal is connected to a 5V power supply, and the negative power supply terminal is grounded to GND. The capacitor C4 is connected in parallel to the two ends of the resistor R16. The two ends of the resistor R5 are respectively connected to the negative input terminal and the output terminal of the operational amplifier U2A. The positive terminal of the capacitor C5 is connected to the positive power supply terminal of the operational amplifier U2A, and the negative terminal is grounded.

[0027] In some embodiments, reference Figure 1The PCBA working current detection circuit also includes a filter circuit, which includes a resistor R9 and a capacitor C3. One end of the resistor R9 is connected to the output end of the operational amplifier U2A, and the other end is electrically connected to the input end of the window comparator circuit and grounded GND through the capacitor C3.

[0028] In some embodiments, reference Figure 1 The window comparator circuit includes a first integrated operational amplifier circuit. The first integrated operational amplifier circuit includes an operational amplifier U1B, a resistor R6, a resistor R1, a resistor R2, a resistor R3 and a capacitor C1. The positive input terminal of the operational amplifier U1B is connected to the resistor R9 through the resistor R6, the negative input terminal is grounded to GND through the resistor R1, and the 5V power supply is connected through the resistor R2, and the output terminal is connected to one end of the resistor R3. The capacitor C1 is connected in parallel to both ends of the resistor R1.

[0029] The window comparator circuit includes a second integrated operational amplifier circuit. The second integrated operational amplifier circuit includes an operational amplifier U1A, a resistor R14, a resistor R17, a resistor R18, a resistor R19, a capacitor C6 and a capacitor C7. The negative input terminal of the operational amplifier U1A is connected to the resistor R9 through the resistor R14, the positive input terminal is connected to the ground GND through the resistor R18, and the 5V power supply is connected through the resistor R19, the output terminal is connected to one end of the resistor R17, the positive power supply terminal is connected to the 5V power supply, and the negative power supply terminal is connected to the ground GND. The capacitor C7 is connected in parallel to both ends of the resistor R1. The positive terminal of the capacitor C6 is connected to the positive power supply terminal of the operational amplifier U1A, and the negative terminal is connected to the ground GND.

[0030] The first integrated operational amplifier circuit also includes a diode D1, a positive terminal of the diode D1 and the other end of the resistor R3. The second integrated operational amplifier circuit also includes a diode D4, a positive terminal of the diode D4 and the other end of the resistor R17.

[0031] In some embodiments, reference Figure 1 The state display circuit also includes a resistor R11, a resistor R15, a resistor R4, a resistor R7, a resistor R13, a transistor Q2 and a transistor Q1. The base of the transistor Q2 is connected to the two negative ends of the diode D1 and the diode D4 respectively through the resistor R11, the emitter is grounded GND, and the collector is connected to the negative end of the light-emitting diode D2. The base of the transistor Q1 is connected to the collector of the transistor Q2 through the resistor R7, the emitter is grounded GND through the resistor R13, and the collector is connected to a 5V power supply. The positive end of the light-emitting diode D2 is connected to the 5V power supply through the resistor R4, the positive end of the light-emitting diode D3 is connected to the collector of the transistor Q1, and the negative end is connected to the emitter of the transistor Q1.

[0032] Further, the transistor Q2 is an NPN transistor, and the transistor Q2 is a PNP transistor.

[0033] The working principle of the PCBA working current detection circuit provided in this application is as follows:

[0034] One end of the sampling resistor R10 is connected to the resistor R8, and the other end is connected to the resistor R12. Resistor R8, resistor R12, capacitor C2, capacitor C4, resistor R5, capacitor C5, and operational amplifier U2A form a differential amplifier circuit. Resistor R9 and capacitor C3 form an RC filter circuit. Resistor R6, resistor R14, capacitor C1, capacitor C6, capacitor C7, resistor R1, resistor R2, resistor R18, resistor R19, resistor R17, operational amplifier U1A, operational amplifier U1B, diode D1, and diode D4 form a window comparator, in which resistor R1 and resistor R2 are the voltage divider resistors of operational amplifier U1B, and resistor R18 and resistor R19 are the voltage divider resistors of operational amplifier U2B. Diodes D1 and D2 act as isolation to prevent the upper and lower loops from affecting each other.

[0035] The normal working current of the load will output the voltage to the differential amplifier circuit through the sampling resistor R10. For example, if the load current setting range is 60-75ma, then according to the formula: U=IR, it can be concluded that the differential voltage range is between 0.03V and 0.0375V, and then the voltage is amplified by the differential amplifier circuit. According to the formula: Vout=(R5 / R8)*Vin, the output voltage range is calculated to be between 3-3.75V, and then it is input into the window comparator after filtering. At the same time, the voltage is divided by resistors R1 and R2, so that the voltage of the operational amplifier U1B is controlled at 3.75V. Similarly, the voltage is divided by resistors R18 and R19 to control the voltage of the operational amplifier U1A at 3V. When the output voltage is higher than this range, a high level will be output, so that the NPN transistor Q2 is turned on, and the red light D2 is lit. The PNP transistor Q1 is turned on at a low level, and the green light D3 is not lit. When the output voltage is within this range, both NPN transistors Q2 and Q1 are not conducting, and the green light D3 is on.

[0036] For example, when the amplified voltage is 3.8V, the operational amplifier U1B outputs a high level, the operational amplifier U1A outputs a low level, and finally the window comparator outputs a high level. At this time, the NPN transistor Q2 is turned on, the red light D2 is on, and at the same time, the PNP transistor Q1 is turned on at a low level so that the green light D3 is not on, that is, the overall display detection result is poor, and the test ends at this time.

[0037] For example, when the amplified voltage is 3.5V, the operational amplifier U1B outputs a low level, the operational amplifier U1A outputs a low level, and finally the window comparator outputs a low level. At this time, the NPN transistor Q2 is not conducting, the red light D2 is not on, and at the same time, the PNP transistor Q1 is not conducting at a high level. At this time, the green light D3 is on, that is, the overall display detection result is good, and the test ends at this time.

[0038] For example, when the amplified voltage is 2.8V, the operational amplifier U1B outputs a low level, the operational amplifier U1A outputs a high level, and finally the window comparator outputs a high level. At this time, the NPN transistor Q2 is turned on, the resistor D2 lights up as a red light, and the PNP transistor Q1 is turned on at a low level. At this time, the green light D3 is not on, that is, the overall display detection result is poor, and the test ends at this time.

[0039] The above implementation modes are only for illustrating the technical concept and features of the utility model, and their purpose is to allow people familiar with this technology to understand the content of the utility model and implement it. It cannot be used to limit the protection scope of the utility model. Any equivalent changes or modifications made according to the spirit of the utility model should be included in the protection scope of the utility model.

Claims

1. A PCBA working current detection circuit, characterized in that: It includes a sampling circuit, an amplifying circuit, a filtering circuit, a window comparator circuit and a status display circuit, wherein: The sampling circuit is electrically connected to the load P1 to generate an output voltage signal; the input end of the amplifier circuit is electrically connected to the sampling circuit, and the output end is electrically connected to the input end of the window comparator circuit to amplify the output voltage signal and remove noise; the output end of the window comparator circuit is electrically connected to the status display circuit; The window comparator circuit includes an operational amplifier U1B and an operational amplifier U1A, which is used to compare the output voltage signal with the threshold level of the operational amplifier U1B and the threshold level of the operational amplifier U1A respectively, and output a high level or a low level; The status display circuit includes a light-emitting diode D2 and a light-emitting diode D3, and is used for lighting only the light-emitting diode D2 when the window comparator outputs a high level, indicating NG failure; when the window comparator outputs a low level, only the light-emitting diode D3 is lit, indicating PASS.

2. The PCBA working current detection circuit according to claim 1, characterized in that: The sampling circuit includes a resistor R10; one end of the resistor R10 is connected to the load P1, and the other end of the resistor R10 is grounded GND.

3. The PCBA working current detection circuit according to claim 2, characterized in that: The amplification circuit includes an operational amplifier U2A, a resistor R8, a resistor R12, a resistor R16, a resistor R5, a capacitor C2, a capacitor C4 and a capacitor C5; the positive input terminal of the operational amplifier U2A is connected to the node between the resistor R10 and the load P1 through the resistor R12, and is grounded GND through the resistor R16, the negative input terminal is connected to the other end of the resistor R10 through the resistor R8, and is grounded GND through the capacitor C2, the positive power supply terminal is connected to a 5V power supply, and the negative power supply terminal is grounded GND; the capacitor C4 is connected in parallel to the two ends of the resistor R16; the two ends of the resistor R5 are respectively connected to the negative input terminal and the output terminal of the operational amplifier U2A; the positive terminal of the capacitor C5 is connected to the positive power supply terminal of the operational amplifier U2A, and the negative terminal is grounded.

4. The PCBA working current detection circuit according to claim 3, characterized in that: It also includes a filtering circuit, which includes a resistor R9 and a capacitor C3; one end of the resistor R9 is connected to the output end of the operational amplifier U2A, and the other end is electrically connected to the input end of the window comparator circuit, and is grounded GND through the capacitor C3.

5. The PCBA working current detection circuit according to claim 4, characterized in that: The window comparator circuit includes a first integrated operational amplifier circuit; the first integrated operational amplifier circuit includes the operational amplifier U1B, resistor R6, resistor R1, resistor R2, resistor R3 and capacitor C1; the positive input end of the operational amplifier U1B is connected to the resistor R9 through the resistor R6, the negative input end is grounded GND through the resistor R1, and is connected to a 5V power supply through the resistor R2, and the output end is connected to one end of the resistor R3; the capacitor C1 is connected in parallel to the two ends of the resistor R1.

6. The PCBA working current detection circuit according to claim 5, characterized in that: The window comparator circuit includes a second integrated operational amplifier circuit; the second integrated operational amplifier circuit includes the operational amplifier U1A, resistor R14, resistor R17, resistor R18, resistor R19, capacitor C6 and capacitor C7; the negative input terminal of the operational amplifier U1A is connected to the resistor R9 through the resistor R14, the positive input terminal is grounded GND through the resistor R18, and is connected to a 5V power supply through the resistor R19, the output terminal is connected to one end of the resistor R17, the positive power supply terminal is connected to the 5V power supply, and the negative power supply terminal is grounded GND; the capacitor C7 is connected in parallel to the two ends of the resistor R1; the positive terminal of the capacitor C6 is connected to the positive power supply terminal of the operational amplifier U1A, and the negative terminal is grounded GND.

7. The PCBA working current detection circuit according to claim 6, characterized in that: The first integrated operational amplifier circuit further includes a diode D1, a positive terminal of the diode D1 and the other end of the resistor R3; the second integrated operational amplifier circuit further includes a diode D4, a positive terminal of the diode D4 and the other end of the resistor R17.

8. The PCBA working current detection circuit according to claim 7, characterized in that: The state display circuit also includes a resistor R11, a resistor R15, a resistor R4, a resistor R7, a resistor R13, a transistor Q2 and a transistor Q1; the base of the transistor Q2 is connected to the two negative ends of the diode D1 and the diode D4 respectively through the resistor R11, the emitter is grounded GND, and the collector is connected to the negative end of the light-emitting diode D2; the base of the transistor Q1 is connected to the collector of the transistor Q2 through the resistor R7, the emitter is grounded GND through the resistor R13, and the collector is connected to a 5V power supply; the positive end of the light-emitting diode D2 is connected to the 5V power supply through the resistor R4, the positive end of the light-emitting diode D3 is connected to the collector of the transistor Q1, and the negative end is connected to the emitter of the transistor Q1.

9. The PCBA working current detection circuit according to claim 8, characterized in that: The transistor Q2 is an NPN transistor, and the transistor Q2 is a PNP transistor.

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