Current test system capable of automatically adjusting measuring range

Abstract

The utility model discloses a current test system capable of automatically adjusting a measuring range, comprising an ampere shift channel part, the ampere shift channel part comprises a switch MOSFET Q8, a sampling resistor R17, a resistor R18, a current detection amplifier U5, a push-pull comparator U6, a triode Q9, a diode D6, an anti-reverse diode D7, a triode Q10, a triode Q11, an electrolytic capacitor C2, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25 and a resistor R26; and the milliampere channel part comprises a switch MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) Q4, a sampling resistor R7, a resistor R8, a current detection amplifier U3, a push-pull comparator U4, a triode Q6, a diode D3, an anti-reverse diode D4, a diode D5 and a transistor Q5. According to the current test system capable of automatically switching the measuring range, a logic relation can be formed through current acquisition results of each gear of microampere, milliampere and ampere, and the current detection measuring range can be automatically switched according to the magnitude of an input current value.

Description

TECHNICAL FIELD

[0001] The utility model relates to current test technical field, concretely is a current test system of automatic regulation range. BACKGROUND

[0002] The conventional current test system cannot automatically switch the range, and the switching between microampere (muA), milliamperes (mA) and ampere (A) three grades needs to be set by the knob or the key to switch, or even needs to replace the wire harness interface, otherwise there will be the risk of damaging the equipment. For the automobile controller, part will have the sleep current (or called static current), and the controller is microampere (or milliamperes) order current in the sleep or standby state, and it will return to the ampere order current in the normal mode, so when testing by the conventional current test system, the range needs to be switched to realize the measurement of the current in the two states, which is very inconvenient, therefore it is necessary to study the current test system capable of automatically switching the range. SUMMARY

[0003] The utility model discloses a current test system capable of automatically adjusting the range to solve the problems in the prior art.

[0004] To achieve the above object, the utility model provides the following technical scheme: a current test system capable of automatically adjusting the range, comprising:

[0005] The ampere channel part includes switch MOSFET Q8, sampling resistance R17, resistance R18, current detection amplifier U5, push-pull comparator U6, triode Q9, diode D6, anti-reverse diode D7, triode Q10, triode Q11, electrolytic capacitor C2, resistance R21, resistance R22, resistance R23, resistance R24, resistance R25 and resistance R26.

[0006] The milliamperes channel part includes switch MOSFET Q4, sampling resistance R7, resistance R8, current detection amplifier U3, push-pull comparator U4, triode Q6, diode D3, anti-reverse diode D4, diode D5, transistor Q5, transistor Q7, electrolytic capacitor C1, resistance R11, resistance R12, resistance R13, resistance R14, resistance R15 and resistance R16.

[0007] The microampere channel part includes switch MOSFET Q1, sampling resistance R1, current detection amplifier U1, push-pull comparator U2, transistor Q2, diode D1, transistor Q3, diode D2, resistance R5 and resistance R6.

[0008] Preferably, the capacitances of the electrolytic capacitor C1 and the electrolytic capacitor C2 are 100 mu F.

[0009] Preferably, the resistance of the sampling resistor R17 is 2mR with 1% accuracy; the resistance of the resistor R18 is 10K with 1% accuracy; the resistance of the resistor R22 and the resistor R23 is 4K7 with 1% accuracy; the resistance of the resistor R24 is 2K with 1% accuracy; the resistance of the resistor R25 and the resistor R26 is 47K with 5% accuracy.

[0010] Preferably, the resistance of the sampling resistor R7 is 21mR with 1% accuracy; the resistance of the resistor R8 is 10K with 1% accuracy; the resistance of the resistor R11 is 40K with 1% accuracy; the resistance of the resistor R12 and the resistor R13 is 4K7 with 1% accuracy; the resistance of the resistor R14 is 47K with 5% accuracy; the resistance of the resistor R15 is 4K7 with 1% accuracy; the resistance of the resistor R16 is 10K with 1% accuracy.

[0011] Preferably, the resistance of the sampling resistor R1 is 39R with 1% accuracy; the resistance of the resistor R4 is 130K with 1% accuracy; the resistance of the resistor R5 is 4K7 with 1% accuracy; the resistance of the resistor R6 is 10K with 1% accuracy.

[0012] Compared with the prior art, the current test system with automatic range switching has the beneficial effects that:

[0013] The current test system with automatic range switching can form a logical relationship through the current collection results of each range of microamperes, milliamperes and amperes, and automatically switch the current detection range according to the input current value.

[0014] The microampere, milliamperes and amperes three-range channel switch MOSFET uses different RDS(ON) sizes, so that when two channels are opened at the same time, the current proportion of the channel mainly responsible for outputting the measurement result is much larger than that of the other auxiliary channel, and the output reading accuracy is improved. BRIEF DESCRIPTION OF DRAWINGS

[0015] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, illustrate the present application and are used to explain the present application, and do not constitute a limitation on the present application. In the drawings:

[0016] Figure 1 is a circuit diagram of the present application;

[0017] Figure 2 is a circuit diagram of the ampere range channel part of the present application;

[0018] Figure 3 is a circuit diagram of the milliamperes range channel part of the present application;

[0019] Figure 4Is the circuit diagram of the microampere file passage part of the utility model. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantage of the utility model embodiment clearer, the technical scheme in the utility model embodiment will be clearly and completely described below in conjunction with the drawings in the utility model embodiment. Obviously, the described embodiment is a part of the embodiment of the utility model, rather than all the embodiments. Based on the embodiment in the utility model, all other embodiments obtained by the ordinary skill in the art without creative labor belong to the protection scope of the utility model. Therefore, the following detailed description of the embodiment of the utility model provided in the drawings is not intended to limit the scope of the claimed utility model, but only represents the selected embodiment of the utility model.

[0021] Please refer to Figures 1-4 In the utility model embodiment, a current test system capable of automatically adjusting range comprises:

[0022] The ampere file passage part comprises switch MOSFET Q8, sampling resistor R17, resistor R18, current detection amplifier U5, push-pull comparator U6, triode Q9, diode D6, anti-reverse diode D7, triode Q10, triode Q11, electrolytic capacitor C2, resistor R21, resistor R22, resistor R23, resistor R24, resistor R25 and resistor R26. The resistance of the sampling resistor R17 is 2mR, and the accuracy is 1%. The resistance of the resistor R18 is 10K, and the accuracy is 1%. The resistance of the resistor R22 and the resistor R23 is 4K7, and the accuracy is 1%. The resistance of the resistor R24 is 2K, and the accuracy is 1%. The resistance of the resistor R25 and the resistor R26 is 47K, and the accuracy is 5%.

[0023] The milliamper file passage part comprises switch MOSFET Q4, sampling resistor R7, resistor R8, current detection amplifier U3, push-pull comparator U4, triode Q6, diode D3, anti-reverse diode D4, diode D5, transistor Q5, transistor Q7, electrolytic capacitor C1, resistor R11, resistor R12, resistor R13, resistor R14, resistor R15 and resistor R16. The resistance of the sampling resistor R7 is 21mR, and the accuracy is 1%. The resistance of the resistor R8 is 10K, and the accuracy is 1%. The resistance of the resistor R11 is 40K, and the accuracy is 1%. The resistance of the resistor R12 and the resistor R13 is 4K7, and the accuracy is 1%. The resistance of the resistor R14 is 47K, and the accuracy is 5%. The resistance of the resistor R15 is 4K7, and the accuracy is 1%. The resistance of the resistor R16 is 10K, and the accuracy is 1%.

[0024] Microampere channel part, the microampere channel part includes open light MOSFET Q1, sampling resistance R1, current detection amplifier U1, push-pull comparator U2, transistor Q2, diode D1, transistor Q3, diode D2, resistance R5, resistance R6, the resistance of the sampling resistance R1 is 39R, and the accuracy is 1%;The resistance of the resistance R4 is 130K, and the accuracy is 1%;The resistance of the resistance R5 is 4K7, and the accuracy is 1%;The resistance of the resistance R6 is 10K, and the accuracy is 1%.

[0025] The capacitance of the electrolytic capacitor C1 and the electrolytic capacitor C2 is 100 μF.

[0026] Microampere, milliampere and ampere three-grade channel switch MOSFET, super-precision current detection amplifier, high-speed single-path push-pull comparator, NPN and PNP transistor;

[0027] Microampere, milliampere and ampere three-grade channel switch MOSFET as the switch of each range detection channel;

[0028] Super-precision current detection amplifier as the current collection device of each range detection channel, which can output current measurement results and serve as the logic input of switching range;

[0029] High-speed single-path push-pull comparator as the main device of the hysteresis circuit, which provides a buffer interval for the switching range detection channel;

[0030] NPN and PNP transistor as the logic output switch device of the switching range detection channel;

[0031] One, the current test system needs two power supplies: 5V as the logic power supply of the super-precision current detection amplifier;Charge Pump voltage is used to provide sufficient voltage (VGS(th)) to open the three-grade channel switch MOSFET.

[0032] After the device under test is connected to the current test system that can automatically switch the range, power is turned on, and due to the Charge Pump voltage, the three-stage tube Q9 is turned on by default, the switch MOSFET Q8 of the ampere grade is turned on, and the current detection amplifier U5 starts to collect the voltage across the sampling resistance R17.

[0033] If the input current level of the device under test is ampere (1A-10A current interval), the test system outputs a voltage signal corresponding to the corresponding proportion of 1A-10A current through the output pin of U5;

[0034] If the input current of the measured device exceeds 10A, the hysteresis circuit composed of the push-pull comparator outputs high level when the input reaches 12.5A, the push-pull comparator U6 outputs high level, the transistor Q10 is turned on, and the amperage range switch MOSFET Q8 is closed, so as to achieve the purpose of over-range protection of the test system.

[0035] If the input current of the measured device is less than 1A, the push-pull comparator U6 outputs low level, the microampere range channel MOSFET is turned on through the anti-reverse diode D7, and the transistor Q11 is turned on through the 200ms delay circuit composed of the resistor R24 and the electrolytic capacitor C2, and the amperage range channel MOSFET Q8 is closed, so as to achieve the effect of opening the small current channel first and then closing the large current channel through the delay circuit, and avoid the short circuit of the measurement system output.

[0036] If the input current of the measured device is less than 1A, the push-pull comparator U6 outputs low level, the transistor Q5 is turned on, and finally the microampere range channel MOSFET Q4 is turned on, and the current detection amplifier U3 starts to collect the voltage across the sampling resistor R7.

[0037] If the input current of the measured device is in the amperage range (1mA-1.19A current range), the test system outputs a voltage signal corresponding to the corresponding proportion of 1mA-1.19A current through the output pin of the current detection amplifier U3;

[0038] If the input current of the measured device exceeds 1.19A, the hysteresis circuit composed of the push-pull comparator outputs high level when the input reaches 1.19A, the push-pull comparator U4 outputs high level, the transistor Q6 is turned on through the anti-reverse diode D4, the microampere range channel MOSFET Q4 is closed, the transistor Q7 is turned on, and the amperage range channel MOSFET Q8 is turned on, so as to achieve the purpose of automatic switching of the current range.

[0039] If the input current of the measured device is less than 1mA, the push-pull comparator U4 outputs low level, the microampere range channel MOSFET is turned on through the anti-reverse diode D4, and the amperage range channel MOSFET Q8 is turned on through the 200ms delay circuit composed of the resistor R13 and the electrolytic capacitor C1, and the amperage range channel MOSFET Q4 is closed, so as to achieve the effect of opening the small current channel first and then closing the large current channel through the delay circuit, and avoid the short circuit of the measurement system output.

[0040] If the input current of the measured device is less than 1mA, the push-pull comparator U4 outputs low level, the transistor Q2 is turned on, and finally the microampere range channel MOSFET Q1 is turned on, and the current detection amplifier U1 starts to collect the voltage across the sampling resistor R1.

[0041] If the input current of the measured device is in the range of 1 μA-1.2 mA, the test system outputs a voltage signal corresponding to the proportion of 1 μA-1.2 mA through the output pin of U1;

[0042] If the input current of the measured device exceeds 1.2 mA, when the input reaches 1.2 mA, the push-pull comparator U2 outputs a high level, the transistor Q3 is turned on, and the milliammeter range switch MOSFET Q4 is opened, so as to achieve the purpose of automatic switching of the current range.

[0043] Finally, it should be noted that: the above only for the preferred embodiments of the present application and is not intended to limit the present application, although the foregoing embodiments of the present application have been described in detail, for those skilled in the art, it still can be modified, or part of the technical features of the equivalent replacement. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included within the scope of the present application.

Claims

1. An automatically adjustable range current test system, characterized by, It includes: Ampere channel part, the ampere channel part includes switch MOSFET Q8, sampling resistance R17, resistance R18, current detection amplifier U5, push-pull comparator U6, triode Q9, diode D6, anti-reverse diode D7, triode Q10, triode Q11, electrolytic capacitor C2, resistance R21, resistance R22, resistance R23, resistance R24, resistance R25, resistance R26; Milliampere channel part, the milliampere channel part includes switch MOSFET Q4, sampling resistance R7, resistance R8, current detection amplifier U3, push-pull comparator U4, triode Q6, diode D3, anti-reverse diode D4, diode D5, transistor Q5, transistor Q7, electrolytic capacitor C1, resistance R11, resistance R12, resistance R13, resistance R14, resistance R15, resistance R16; Microampere channel part, the microampere channel part includes switch MOSFET Q1, sampling resistance R1, current detection amplifier U1, push-pull comparator U2, transistor Q2, diode D1, transistor Q3, diode D2, resistance R5, resistance R6.

2. The self-ranging current test system of claim 1, wherein, The capacitances of the electrolytic capacitors C1 and C2 are 100 μF.

3. The self-ranging current test system of claim 1, wherein, The resistance of the sampling resistance R17 is 2 mR, and the accuracy is 1%; the resistance of the resistance R18 is 10K, and the accuracy is 1%; the resistances of the resistances R22 and R23 are 4K7, and the accuracy is 1%; the resistance of the resistance R24 is 2K, and the accuracy is 1%; the resistances of the resistances R25 and R26 are 47K, and the accuracy is 5%.

4. The self-ranging current test system of claim 1, wherein, The resistance of the sampling resistance R7 is 21 mR, and the accuracy is 1%; the resistance of the resistance R8 is 10K, and the accuracy is 1%; the resistance of the resistance R11 is 40K, and the accuracy is 1%; the resistances of the resistances R12 and R13 are 4K7, and the accuracy is 1%; the resistance of the resistance R14 is 47K, and the accuracy is 5%; the resistance of the resistance R15 is 4K7, and the accuracy is 1%; the resistance of the resistance R16 is 10K, and the accuracy is 1%.

5. The self-ranging current test system of claim 1, wherein, The resistance of the sampling resistance R1 is 39R, and the accuracy is 1%; the resistance of the resistance R4 is 130K, and the accuracy is 1%; the resistance of the resistance R5 is 4K7, and the accuracy is 1%; the resistance of the resistance R6 is 10K, and the accuracy is 1%.

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