CN112462241A - Short circuit detection circuit and short circuit detection method for detecting mainboard - Google Patents
Short circuit detection circuit and short circuit detection method for detecting mainboard Download PDFInfo
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- CN112462241A CN112462241A CN202011437716.XA CN202011437716A CN112462241A CN 112462241 A CN112462241 A CN 112462241A CN 202011437716 A CN202011437716 A CN 202011437716A CN 112462241 A CN112462241 A CN 112462241A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/28—Testing of electronic circuits, e.g. by signal tracer
- G01R31/2801—Testing of printed circuits, backplanes, motherboards, hybrid circuits or carriers for multichip packages [MCP]
- G01R31/281—Specific types of tests or tests for a specific type of fault, e.g. thermal mapping, shorts testing
- G01R31/2812—Checking for open circuits or shorts, e.g. solder bridges; Testing conductivity, resistivity or impedance
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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Abstract
The invention relates to the technical field of short circuit detection, in particular to a short circuit detection circuit and a short circuit detection method for detecting a mainboard, which comprise a driving circuit, an AND gate circuit, a detection point circuit, a relay circuit and a comparator circuit, wherein the relay circuit is respectively and electrically connected with the detection point circuit, the AND gate circuit and the comparator circuit, the AND gate circuit is respectively and electrically connected with the driving circuit and the comparator circuit, the driving circuit is electrically connected with a GPIO port of an external control system, the driving circuit outputs a non-short circuit state and a short circuit state to an external control system, the control system can judge whether the mainboard to be detected is in the non-short circuit state or the short circuit state by detecting the difference of the level, thereby determining whether the next step of power-on functional test of the mainboard to be detected is carried out, the whole process can be controlled automatically without human intervention, thereby realizing the purpose of automatic production, greatly improving the production efficiency.
Description
Technical Field
The invention relates to the technical field of short circuit detection, in particular to a short circuit detection circuit and a short circuit detection method for detecting a mainboard.
Background
At present, the short circuit test before the power-on of a tested mainboard is subjected to the function test usually needs to be manually detected by using a universal meter firstly, or a station is independently arranged, and the short circuit test equipment in a professional field is used for detecting. After the short circuit test is passed, the next mainboard functional test can be entered, so as to prevent the tested mainboard from further damage due to short circuit or damage the test equipment. The influence brought by the prior art scheme is that the production efficiency is low, the labor and the working hour investment cannot be reduced, the production cost is difficult to compress, and the industrial production automation development trend is not met.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: a short circuit detection circuit and a short circuit detection method for detecting a motherboard are provided.
In order to solve the above technical problems, a first technical solution adopted by the present invention is:
a short circuit detection circuit for detecting a mainboard comprises a driving circuit, an AND gate circuit, a detection point circuit, a relay circuit and a comparator circuit, wherein the relay circuit is electrically connected with the detection point circuit, the AND gate circuit and the comparator circuit respectively, the AND gate circuit is electrically connected with the driving circuit and the comparator circuit respectively, and the driving circuit is electrically connected with a GPIO port of a peripheral control system.
The second technical scheme adopted by the invention is as follows:
a short circuit detection method for detecting a short circuit detection circuit of a main board includes the steps of:
the comparator circuit outputs low level, the AND gate circuit outputs low level and the drive circuit outputs low level;
the control system judges whether the GPIO port detects low level;
if yes, the tested mainboard is judged to be in a short-circuit state.
The invention has the beneficial effects that:
the ground of the detection circuit is connected with the ground of the tested mainboard, and in addition, the detection circuit is connected with any test point on the tested mainboard through the detection point circuit; through the relay circuit, after the short circuit test of the tested mainboard is completed, the electrical connection between the test point of the tested mainboard and the detection circuit can be timely disconnected, and the next step of power-on functional test of the tested mainboard is not influenced, so that the aim of automatic production is fulfilled; the test point of the tested mainboard is in a non-short circuit state and a short circuit state, the most obvious characteristic is that the difference of the impedance value of the test point to the ground is obvious, the impedance value is smaller in the short circuit state, generally below 100 omega, the impedance value is larger in the non-short circuit state, generally larger than 1k omega, therefore, the short circuit and the non-short circuit can be accurately identified and distinguished through the comparator circuit; the signal output by the comparator circuit is converted through the AND gate circuit, so that the anti-interference capability of the circuit can be improved; through drive circuit, with two kinds of state signal levels of non-short circuit and short circuit output to the control system of peripheral hardware, control system detects the difference of this level, just can judge whether the mainboard that is surveyed is in non-short circuit or short circuit state to whether the decision is surveyed the mainboard and is gone up the functional test on next step, whole flow can automated control completely, need not artificial intervention, thereby realizes automated production's purpose, improves production efficiency greatly.
Drawings
Fig. 1 is a connection block diagram of a short detection circuit for detecting a main board according to the present invention;
FIG. 2 is a schematic circuit diagram of a probing point circuit of a short circuit detection circuit for testing a motherboard according to the present invention;
fig. 3 is a schematic circuit diagram of a relay circuit and an and circuit of a short circuit detection circuit for detecting a main board according to the present invention;
FIG. 4 is a schematic circuit diagram of a comparator circuit for detecting a short circuit detection circuit of a motherboard according to the present invention;
fig. 5 is a schematic circuit diagram of a driving circuit for detecting a short circuit detection circuit of a main board according to the present invention;
FIG. 6 is a flowchart illustrating the steps of a short detection method for detecting a short detection circuit of a motherboard according to the present invention;
fig. 7 is a detection flowchart of a short detection method for detecting a short detection circuit of a main board according to the present invention;
description of reference numerals:
1. a control system; 2. a drive circuit; 3. an AND gate circuit; 4. a detection point circuit; 5. a relay circuit; 6. a comparator circuit.
Detailed Description
In order to explain technical contents, achieved objects, and effects of the present invention in detail, the following description is made with reference to the accompanying drawings in combination with the embodiments.
Referring to fig. 1, a technical solution provided by the present invention:
a short circuit detection circuit for detecting a mainboard comprises a driving circuit, an AND gate circuit, a detection point circuit, a relay circuit and a comparator circuit, wherein the relay circuit is electrically connected with the detection point circuit, the AND gate circuit and the comparator circuit respectively, the AND gate circuit is electrically connected with the driving circuit and the comparator circuit respectively, and the driving circuit is electrically connected with a GPIO port of a peripheral control system.
From the above description, the beneficial effects of the present invention are:
the ground of the detection circuit is connected with the ground of the tested mainboard, and in addition, the detection circuit is connected with any test point on the tested mainboard through the detection point circuit; through the relay circuit, after the short circuit test of the tested mainboard is completed, the electrical connection between the test point of the tested mainboard and the detection circuit can be timely disconnected, and the next step of power-on functional test of the tested mainboard is not influenced, so that the aim of automatic production is fulfilled; the test point of the tested mainboard is in a non-short circuit state and a short circuit state, the most obvious characteristic is that the difference of the impedance value of the test point to the ground is obvious, the impedance value is smaller in the short circuit state, generally below 100 omega, the impedance value is larger in the non-short circuit state, generally larger than 1k omega, therefore, the short circuit and the non-short circuit can be accurately identified and distinguished through the comparator circuit; the signal output by the comparator circuit is converted through the AND gate circuit, so that the anti-interference capability of the circuit can be improved; through drive circuit, with two kinds of state signal levels of non-short circuit and short circuit output to the control system of peripheral hardware, control system detects the difference of this level, just can judge whether the mainboard that is surveyed is in non-short circuit or short circuit state to whether the decision is surveyed the mainboard and is gone up the functional test on next step, whole flow can automated control completely, need not artificial intervention, thereby realizes automated production's purpose, improves production efficiency greatly.
Further, the detection point circuit comprises a resistor R11, one end of the resistor R11 is electrically connected with the relay circuit, and the other end of the resistor R11 is connected with the first test point TP 1.
As can be seen from the above description, the first test point TP1 is generally a test point of a signal network or a power network, and is determined by the tested motherboard; the resistor R11 is arranged for current limiting or reserved voltage division, and a proper resistance value needs to be selected according to an actual tested mainboard.
Further, the relay circuit comprises a resistor R1, a resistor R2, a resistor R6, a field effect transistor Q1, a field effect transistor Q2 and a relay U2, a first pin of the relay U2 is electrically connected with the drain electrode of the field effect transistor Q1, a second pin of the relay U2 is respectively and electrically connected with one end of a resistor R6 and a comparator circuit, the other end of the resistor R6 is connected with a power supply, the third pin of the relay U2 is electrically connected with a detection point circuit, the eighth pin of the relay U2 is grounded, the grid of the field effect transistor Q1 is electrically connected with one end of the resistor R2 and the drain of the field effect transistor Q2 respectively, the source electrode of the field effect transistor Q1 is electrically connected with one end of a resistor R1, the other end of the resistor R1 is connected with a power supply, the grid electrode of the field effect transistor Q2 is electrically connected with an AND gate circuit, the source electrode of the field effect transistor Q2 is grounded, and the other end of the resistor R2 is connected with a power supply.
As can be seen from the above description, at the beginning, the relay U2 is in the default state, the second pin and the third pin of the relay U2 are in contact conduction, so that the resistor R6 connected to the second pin of the relay U2, the test point circuit, and the test point-to-ground resistor R form a series voltage dividing circuit to divide the voltage of the power supply "VDD _ 5V"; if the tested mainboard is in a non-short circuit state, the resistance value R to the ground of a detection point of the tested mainboard is larger, so that the voltage divided by a second pin 'Test _ OUT' node of the relay U2 is larger; if the tested mainboard is in a short-circuit state, the ground resistance value R of the detection point of the tested mainboard is smaller, so that the voltage of the node of the second pin 'Test _ OUT' of the relay U2 is smaller.
Meanwhile, a signal level of 'Gate _ OUT' is obtained after the processing of the AND Gate circuit, if a detection point of the tested mainboard is IN a non-short-circuit state, the 'Gate _ OUT' is IN a high level, the field effect tube Q2 is conducted, the drain electrode of the field effect tube Q2 is changed into a low level, the field effect tube Q1 is conducted, the first pin of the relay U2 obtains a power supply voltage 'VDD _ 5V', the relay U2 is switched to a state that the second pin is disconnected with the third pin, and the third pin is connected with the fourth pin, so that the 'Test _ IN' and the 'Test _ OUT' are disconnected, the Test point of the tested mainboard is electrically disconnected with the detection circuit, and the detection circuit is prevented from influencing a functional Test to be carried OUT next by the tested mainboard.
Further, the and circuit includes a resistor R3, a resistor R4, a resistor R5, a capacitor C1, and a chip U1, wherein a first pin of the chip U1 is electrically connected to one end of a resistor R3, one end of the resistor R5, and one end of the capacitor C1, the other end of the capacitor C1 is grounded, the other end of the resistor R5 is grounded, the other end of the resistor R3 is connected to a power supply, a second pin of the chip U1 is electrically connected to the comparator circuit, a third pin of the chip U1 is grounded, a fourth pin of the chip U1 is electrically connected to one end of the resistor R4 and the relay circuit, the other end of the resistor R4 is grounded, and a fifth pin of the chip U1 is connected to the power supply.
As can be seen from the above description, the resistor R3, the resistor R5, and the capacitor C1 are arranged to perform the functions of serial voltage division and RC delay, and the divided voltage is output to the first pin of the and gate chip U1 as an input voltage of the and gate, so that the advantage of reducing the influence on the and gate judgment caused by voltage instability at the moment of power supply conduction through the RC delay is achieved; the output end (fourth pin) of the and gate chip U1 is connected with a resistor R4 to ground, which plays a role in enhancing signal stability; meanwhile, an output signal 'Gate _ OUT' is connected to the relay circuit, and the 'Gate _ OUT' signal is used for judging whether a test point of the tested mainboard is in a short-circuit state or not; when the Gate _ OUT is at a high level, it indicates that the test point of the tested motherboard is in a non-short-circuit state, otherwise, it is in a short-circuit state.
Further, the comparator circuit comprises a resistor R9, a resistor R10, a resistor R13 and a comparator U3, a first pin of the comparator U3 is electrically connected with one end of the resistor R10 and an AND gate circuit respectively, the other end of the resistor R10 is electrically connected with a power supply, a second pin of the comparator U3 is electrically connected with one end of the resistor R9 and one end of the resistor R13 respectively, the other end of the resistor R9 is electrically connected with the power supply, the other end of the resistor R13 is grounded, a third pin of the comparator U3 is electrically connected with a relay circuit, a fourth pin of the comparator U3 is grounded, and an eighth pin of the comparator U3 is electrically connected with the power supply.
As can be seen from the above description, the resistor R9 and the resistor R13 together form a serial voltage divider circuit, which divides the power voltage "VDD _ 5V", and the divided voltage level "Vref" is connected to the second pin of the comparator U3 as the reference voltage of the comparator circuit; the third pin of the comparator U3 is connected to the 'Test _ OUT' node of the relay circuit and serves as the positive input end of the comparator; the first pin of the comparator U3 is connected with 1 pull-up resistor R10 and is also connected with a 'Compare _ OUT' node of an AND gate circuit to be used as the output end of the comparator; when the Test point of the tested mainboard is short-circuited, the voltage value of the "Test _ OUT" node is lower than the reference voltage "Vref", so that the output terminal "Compare _ OUT" is at a low level. On the contrary, when the Test point of the tested motherboard is not short-circuited, the voltage value of the "Test _ OUT" node is higher than the reference voltage "Vref", so that the output terminal "Compare _ OUT" is at a high level.
Further, the driving circuit comprises a resistor R7, a resistor R8, a resistor R14, a light emitting diode D1, a field effect transistor Q3 and a field effect transistor Q4, wherein a gate of the field effect transistor Q3 is electrically connected to one end of the resistor R7 and a drain of the field effect transistor Q4, a source of the field effect transistor Q3 is electrically connected to the other end of the resistor R7 and a source of the field effect transistor Q3 and the other end of the resistor R7 are both connected to a power supply, a drain of the field effect transistor Q3 is electrically connected to one end of the resistor R8, the other end of the resistor R8 is electrically connected to an anode of the light emitting diode D1, a cathode of the light emitting diode D1 is grounded, a gate of the field effect transistor Q4 is electrically connected to one end of the resistor R14 and an and gate circuit, a source of the field effect transistor Q4 is electrically connected to the other end of the resistor R14 and a drain of.
As can be seen from the above description, the pull-down resistor R14 plays a role in stabilizing the gate of the field-effect transistor Q4, so as to avoid being in a suspended state when no input is performed, and improve the anti-interference capability; the grid electrode of the field effect transistor Q4 is connected to a 'Gate _ OUT' node of the AND Gate circuit, the source electrode of the field effect transistor Q4 is grounded, the drain electrode of the field effect transistor Q4 is connected to the grid electrode of the field effect transistor Q3, the source electrode of the field effect transistor Q3 is connected with a power supply and is connected to the grid electrode of the field effect transistor Q7 through a resistor R, and the drain electrode of the field effect transistor Q3 serves as the output end of the driving circuit and outputs a 'Check _ OUT' signal; the resistor R7 plays a role of pulling the gate of the field effect transistor Q3 high when in an idle state, so that the field effect transistor Q3 is in a non-conduction state; the output end 'Check _ OUT' is connected to a GPIO port of a peripheral control system and is used as an identification for judging whether a test point of a tested mainboard is in a short-circuit state or not by a system end, meanwhile, the 'Check _ OUT' is also connected to a resistor R8 of a driving circuit, and the resistor R8 and a light-emitting diode D1 are connected in series and then connected to the ground, so that the purpose that the high and low level change of a 'Check _ OUT' signal can be reflected by the on and off of the light-emitting diode D1, and a visual prompt effect is achieved.
Referring to fig. 6, another technical solution provided by the present invention:
a short circuit detection method for detecting a short circuit detection circuit of a main board includes the steps of:
the comparator circuit outputs low level, the AND gate circuit outputs low level and the drive circuit outputs low level;
the control system judges whether the GPIO port detects low level;
if yes, the tested mainboard is judged to be in a short-circuit state.
Further, the method also comprises the following steps:
the comparator circuit outputs high level, the AND gate circuit outputs high level and the drive circuit outputs high level;
the control system judges whether the GPIO port detects high level;
if yes, the tested mainboard is judged to be in a non-short circuit state.
Referring to fig. 1 to 5, a first embodiment of the present invention is:
referring to fig. 1, the short circuit detection circuit for detecting a motherboard includes a driving circuit 2, an and circuit 3, a detection point circuit 4, a relay circuit 5 and a comparator circuit 6, where the relay circuit 5 is electrically connected to the detection point circuit 4, the and circuit 3 and the comparator circuit 6, the and circuit 3 is electrically connected to the driving circuit 2 and the comparator circuit 6, and the driving circuit 2 is electrically connected to a GPIO port of a peripheral control system 1.
The control system 1 can be an embedded computer, a single chip microcomputer control system and the like, and is generally used as an upper computer end for production automation control.
Referring to fig. 2, the probing point circuit 4 includes a resistor R11 (with a resistance of 100 Ω), one end of the resistor R11 is electrically connected to the relay circuit 5, and the other end of the resistor R11 is connected to the first testing point TP1 through a contact pin.
Referring to fig. 3, the relay circuit 5 includes a resistor R1 (having a resistance of 0 Ω), a resistor R2 (having a resistance of 1K Ω), a resistor R6 (having a resistance of 300 Ω), a fet Q1 (model IRLML640), a fet Q2 (model BSS138), and a relay U2 (model HFD4), a first pin of the relay U2 is electrically connected to a drain of the fet Q1, a second pin of the relay U2 is electrically connected to one end of the resistor R6 and the comparator circuit 6, respectively, the other end of the resistor R6 is electrically connected to a power supply, a third pin of the relay U2 is electrically connected to the detection point circuit 4, an eighth pin of the relay U2 is grounded, a gate of the fet Q1 is electrically connected to one end of the resistor R2 and a drain of the fet Q2, a source of the fet Q1 is electrically connected to one end of the resistor R1, and the other end of the resistor R1 is electrically connected to the power supply, the grid electrode of the field effect transistor Q2 is electrically connected with the AND circuit 3, the source electrode of the field effect transistor Q2 is grounded, and the other end of the resistor R2 is connected with a power supply.
Referring to fig. 3, the and circuit 3 includes a resistor R3 (having a resistance of 1K Ω), a resistor R4 (having a resistance of 10K Ω), a resistor R5 (having a resistance of 2K Ω), a capacitor C1 (having a capacitance of 100 μ F), and a chip U1 (having a model of 74LVC1G08 of NXP corporation), a first pin of the chip U1 is electrically connected to one end of the resistor R3, one end of the resistor R5, and one end of the capacitor C1, the other end of the capacitor C1 is grounded, the other end of the resistor R5 is grounded, the other end of the resistor R3 is connected to the power supply, a second pin of the chip U1 is electrically connected to the comparator circuit 6, a third pin of the chip U1 is grounded, a fourth pin of the chip U1 is electrically connected to one end of the resistor R4 and the relay circuit 5, the other end of the resistor R4 is grounded, and a fifth pin of the chip U1 is connected to the power supply.
Referring to fig. 4, the comparator circuit 6 includes a resistor R9 (with a resistance value of 1K Ω), a resistor R10 (with a resistance value of 1K Ω), a resistor R13 (with a resistance value of 1K Ω), and a comparator U3 (with a model number of LM393), a first pin of the comparator U3 is electrically connected to one end of the resistor R10 and the and circuit 3, another end of the resistor R10 is connected to the power supply, a second pin of the comparator U3 is electrically connected to one end of the resistor R9 and one end of the resistor R13, another end of the resistor R9 is connected to the power supply, another end of the resistor R13 is grounded, a third pin of the comparator U3 is electrically connected to the relay circuit 5, a fourth pin of the comparator U3 is grounded, and an eighth pin of the comparator U3 is connected to the power supply.
Referring to fig. 5, the driving circuit 2 includes a resistor R7 (with a resistance of 10K Ω), a resistor R8 (with a resistance of 1K Ω), a resistor R14 (with a resistance of 10K Ω), a light emitting diode D1 (with a model of 523SYGD for hundred million lights), a field effect transistor Q3 (with a model of IRLML6401), and a field effect transistor Q4 (with a model of BSS138), a gate of the field effect transistor Q3 is electrically connected to one end of the resistor R7 and a drain of the field effect transistor Q4, a source of the field effect transistor Q3 is electrically connected to the other end of the resistor R7, a source of the field effect transistor Q3 and the other end of the resistor R7 are both connected to a power source, a drain of the field effect transistor Q3 is electrically connected to one end of the resistor R8, the other end of the resistor R8 is electrically connected to an anode of the light emitting diode D1, a cathode of the light emitting diode D1 is grounded, a gate of the field effect transistor Q, the source electrode of the field effect transistor Q4 is electrically connected with the other end of the resistor R14, and the drain electrode of the field effect transistor Q4 and the other end of the resistor R14 are both grounded.
The working principle of the short circuit detection circuit for detecting the mainboard is as follows:
the detection point circuit 4 consists of a test point and a resistor, and if the number of detection points needs to be increased, the corresponding resistor and the test point only need to be correspondingly increased; a test point circuit corresponds to a test point on a tested mainboard, and the test point is usually a signal network node or a power network node and is determined by the tested mainboard; the resistor R11 is arranged for current limiting or reserved voltage division, and a proper resistance value needs to be selected according to an actual tested mainboard.
At the beginning, the relay U2 is in a default state, the second pin and the third pin of the relay U2 are in contact conduction, so that the second pin connecting resistor R6 of the relay U2 forms a series voltage dividing circuit with the resistor R11 of the test point circuit and the test point-to-ground resistor R due to the contact conduction, voltage division is performed on the power supply voltage "VDD _ 5V", and a voltage division level V (test out) is obtained at the second pin of the relay U2; if the tested mainboard is in a non-short circuit state, the ground resistance R of the detection point of the tested mainboard is larger, so that the voltage division level obtained by the second pin of the relay U2 is higher; if the tested mainboard is in a short-circuit state, the ground resistance R of the detection point of the tested mainboard is relatively low, so that the voltage division level obtained by the second pin of the relay U2 is relatively low.
Meanwhile, the divided voltage level V (Test _ OUT) is converted into a Compare-OUT level signal after being processed by the comparator circuit 6, and is converted into a 'Gate _ OUT' signal level after being processed by the AND circuit 3, if the detection point of the detected mainboard is in a non-short circuit state, then "Gate _ OUT" is high, fet Q2 is turned on, the drain of fet Q2 goes low, the field effect transistor Q1 is turned on, and the first pin of the relay U2 obtains the power voltage "VDD _ 5V", so that the relay U2 switches the connection state, namely, the second pin and the third pin of the relay U2 are disconnected, the third pin and the fourth pin of the relay U2 are connected, therefore, the 'Test _ IN' and the 'Test _ OUT' are disconnected, the Test point of the tested mainboard is disconnected with the detection circuit, and the circuit is prevented from influencing the next functional Test of the tested mainboard.
The resistor R3, the resistor R5 and the capacitor C1 are arranged to play a role in series voltage division and RC time delay, and the voltage after voltage division is output to a first pin of a chip U1 of the AND gate circuit 3 and serves as an input end electrode of an AND gate; an output pin (a fourth pin) of the chip U1 of the AND circuit 3 is connected with a resistor R4 to the ground, so that the pull-down effect is achieved, and the signal stability is enhanced; a fourth pin of the Gate circuit U1 outputs a 'Gate _ OUT' signal to the relay circuit 5, wherein the 'Gate _ OUT' signal is used for judging whether a test point of the tested mainboard is in a short-circuit state or not; when the 'Gate _ OUT' is in a high level state, it indicates that the test point of the tested mainboard is in a non-short-circuit state, otherwise, the test point is in a short-circuit state.
The resistor R9 and the resistor R13 jointly form a series voltage dividing circuit, the voltage dividing circuit divides the power supply voltage VDD _5V, and the level Vref after voltage division is input to a second pin of the comparator U3 to be used as the reference voltage of the comparator circuit 6; the third pin of the comparator U3 is a positive input terminal, is connected to the output terminal of the relay circuit 5, and receives the "Test _ OUT" signal level from the relay circuit 5; the first pin of the comparator U3 is the output terminal, and is connected with a pull-up resistor R10 and the 'Compare _ OUT' node of the AND gate circuit 3, and the output level Compare _ OUT of the comparator is transmitted to the input terminal of the AND gate circuit 3; when the Test point of the tested motherboard is short-circuited, the level value of the "Test _ OUT" node is lower than the reference voltage "Vref", so that the output terminal "Compare _ OUT" is at a low level. On the contrary, when the Test point of the tested motherboard is not short-circuited, the level value of the "Test _ OUT" node is higher than the reference voltage "Vref", so that the output terminal "Compare _ OUT" is at a high level.
The pull-down resistor R14 has the function of stabilizing the grid of the field effect transistor Q4, so that the grid of the field effect transistor Q4 is prevented from being in a suspended state when no input is carried out, and the anti-jamming capability is improved; the grid of the field effect transistor Q4 is connected with the output end 'Gate _ OUT' node of the AND circuit 3, the source of the field effect transistor Q4 is grounded, the drain of the field effect transistor Q4 is connected with the grid of the field effect transistor Q3, the source of the field effect transistor Q3 is connected with a power supply and is connected with the grid of the field effect transistor Q7 through a resistor R7, and the drain of the field effect transistor Q3 is used as the output end of the drive circuit 2 to output a 'Check _ OUT' signal; the resistor R7 plays a role of pulling the gate of the field effect transistor Q3 high when in an idle state, so that the field effect transistor Q3 is in a non-conduction state; the output end "Check _ OUT" is connected to a GPIO port of the peripheral control system 1, and is used as an identifier for a system end to determine whether a test point of a tested motherboard is in a short-circuit state, and meanwhile, the "Check _ OUT" is also connected to a resistor R8 of the driving circuit 2, and the resistor R8 and the light emitting diode D1 are connected in series and then connected to the ground, so that a purpose that a high-low level change of the "Check _ OUT" output is reflected by turning on and off of the light emitting diode D1 to play a visual prompting role, where D1 is on to indicate that the test point is normal, and D1 is off to indicate that the test point is short-.
Whether the test point of the tested mainboard is short-circuited or not is directly reflected as the ground resistance value of the test point; if the test point of the tested mainboard is in a short-circuit state, the resistance value to the ground is small and is usually less than 100 omega; if the test point of the tested mainboard is in a non-short circuit state, the resistance value to ground is large, and is usually larger than 1K omega.
According to the principle of serial partial pressure calculation, V (Test _ OUT) ═ VDD _5V × (R + R11)/(R6+ R11+ R), where R denotes the resistance to ground of the Test points, where R6 takes 300 Ω and R11 takes 100 Ω, according to the formula, if the Test points of the tested motherboard are short-circuited, and if R is 100 Ω, V (Test _ OUT) ═ 5V × (100+100)/(300+ 100) ═ 2V; if the Test points of the tested motherboard are not short-circuited, if R is 1k Ω, V (Test _ OUT) is 5V (1000+100)/(300+100+1000) is 3.93V.
The resistor R9 and the resistor R13 both take 1K Ω, and therefore Vref is 5V × 1/2 is 2.5V; if the Test point of the tested mainboard is short-circuited, V (Test _ OUT) is 2V < 2.5V, and according to the comparator principle, the output of the comparator circuit 6 is low level, that is, V (Compare _ OUT) is 0V; if the Test point of the tested motherboard is not short-circuited, V (Test _ OUT) is 3.93V > 2.5V, and the comparator circuit 6 outputs a high level, i.e., V (Compare _ OUT) is 5V according to the comparator principle.
Since the resistor R3 is 1K Ω, the resistor R5 is 2K Ω, and the capacitor C1 is 100 μ F, the level value V1 of the first pin of the and chip U1 is VDD _5V R5/(R3+ R5) is 5V 2/(1+2) 3.3V, and the voltage is high for the and chip U1; therefore, if the test point of the tested main board is short-circuited and V (Compare _ OUT) is 0V, the output is low level, that is, V (Gate _ OUT) is 0V according to the chip principle of the and circuit 3; if the test point of the tested main board is not short-circuited and V (Compare _ OUT) is 5V, the output is high level, that is, V (Gate _ OUT) is 5V according to the chip principle of the and circuit 3.
According to the conduction principle of MOS, if a test point of the tested motherboard is short-circuited and V (Gate _ OUT) is 0V, the fet Q4 is not turned on, the Gate voltage of the fet Q3 is high, and the fet Q3 is not turned on, so that V (Check _ OUT) is 0V, the led D1 is not lit, and the level value detected by the control system 1 is low; if the test point of the tested main board is not short-circuited and V (Gate _ OUT) is 5V, the fet Q4 is turned on, the Gate voltage of the fet Q3 is low, and the fet Q3 is turned on, so that V (Check _ OUT) is 5V, the led D1 lights up, and the level value detected by the control system 1 is high.
According to the description of the driving circuit 2, if the level value received by the control system 1 is a low level, it is determined that the tested mainboard is in a short-circuit state; if the level value received by the control system 1 is a high level, judging that the tested mainboard is in a non-short circuit state;
according to the MOS conduction principle and the relay working principle, if a test point of a tested mainboard is short-circuited, V (Gate _ OUT) is 0V, a field effect tube Q2 is not conducted, the grid of the field effect tube Q1 is at a high level, the field effect tube Q1 is not conducted, a first pin of a relay U2 is not supplied with power, the relay U2 does not act and is in a default state, and a second pin and a third pin of a relay U2 are in contact connection; if the test point of the tested mainboard is not short-circuited, V (Gate _ OUT) ═ 5V, the field effect transistor Q2 is turned on, the Gate of the field effect transistor Q1 is at a low level, the field effect transistor Q1 is turned on, the first pin of the relay U2 is powered on, the relay U2 acts in a working state, and the third pin and the second pin of the relay U2 are disconnected, so that the test point of the tested mainboard is electrically disconnected from the test point of the tested mainboard, and the influence of the test circuit is avoided when the tested mainboard is in a non-short-circuited state and is subjected to next functional test.
Referring to fig. 6 and 7, a second embodiment of the present invention is:
referring to fig. 6, a short circuit detection method for detecting a short circuit detection circuit of a motherboard includes the following steps:
the comparator circuit 6 outputs low level, the AND gate circuit 3 outputs low level and the drive circuit 2 outputs low level;
the control system 1 judges whether the GPIO port detects a low level;
if yes, the tested mainboard is judged to be in a short-circuit state.
Further comprising the steps of:
the comparator circuit 6 outputs high level, the AND gate circuit 3 outputs high level and the drive circuit 2 outputs high level;
the control system 1 judges whether the GPIO port detects a high level;
if yes, the tested mainboard is judged to be in a non-short circuit state.
Referring to fig. 7, the short circuit detection method for detecting the short circuit detection circuit of the motherboard includes the following specific embodiments:
whether the test point of the tested mainboard is short-circuited or not;
if the test point of the tested mainboard is short-circuited, the impedance value of the test point to the ground is small, and the voltage value after serial voltage division is low;
if the comparator circuit, the AND gate circuit and the driving circuit all output low levels, the control system judges whether the GPIO port detects the low levels;
if the GPIO port detects low level and the light emitting diode is extinguished, the detected mainboard is judged to be in a short circuit state.
If the test point of the tested mainboard is not short-circuited, the impedance value of the test point to the ground is larger, and the voltage value after serial voltage division is higher;
if the comparator circuit, the AND gate circuit and the driving circuit all output high levels, the control system judges whether the GPIO port detects the high levels;
and if the GPIO port detects high level and the light-emitting diode is lightened, judging that the detected mainboard is in a non-short-circuit state.
In summary, according to the short circuit detection circuit and the short circuit detection method for detecting a motherboard provided by the present invention, the ground of the detection circuit is connected to the ground of the tested motherboard, and in addition, any test point on the tested motherboard is connected through the detection point circuit; through the relay circuit, after the short circuit test of the tested mainboard is completed, the electrical connection between the test point of the tested mainboard and the detection circuit can be timely disconnected, and the next step of power-on functional test of the tested mainboard is not influenced, so that the aim of automatic production is fulfilled; the test point of the tested mainboard is in a non-short circuit state and a short circuit state, the most obvious characteristic is that the difference of the impedance value of the test point to the ground is obvious, the impedance value is smaller in the short circuit state, generally below 100 omega, the impedance value is larger in the non-short circuit state, generally larger than 1k omega, therefore, the short circuit and the non-short circuit can be accurately identified and distinguished through the comparator circuit; the signal output by the comparator circuit is converted through the AND gate circuit, so that the anti-interference capability of the circuit can be improved; through drive circuit, with two kinds of state signal levels of non-short circuit and short circuit output to the control system of peripheral hardware, control system detects the difference of this level, just can judge whether the mainboard that is surveyed is in non-short circuit or short circuit state to whether the decision is surveyed the mainboard and is gone up the functional test on next step, whole flow can automated control completely, need not artificial intervention, thereby realizes automated production's purpose, improves production efficiency greatly.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes made by using the contents of the present specification and the drawings, or applied directly or indirectly to the related technical fields, are included in the scope of the present invention.
Claims (8)
1. The short-circuit detection circuit for detecting the mainboard is characterized by comprising a driving circuit, an AND gate circuit, a detection point circuit, a relay circuit and a comparator circuit, wherein the relay circuit is respectively and electrically connected with the detection point circuit, the AND gate circuit and the comparator circuit, the AND gate circuit is respectively and electrically connected with the driving circuit and the comparator circuit, and the driving circuit is electrically connected with a GPIO port of a peripheral control system.
2. The short circuit detection circuit for detecting a main board according to claim 1, wherein the detection point circuit comprises a resistor R11, one end of the resistor R11 is electrically connected to the relay circuit, and the other end of the resistor R11 is connected to the first test point TP 1.
3. The short circuit detection circuit for detecting a main board according to claim 1, wherein the relay circuit includes a resistor R1, a resistor R2, a resistor R6, a FET Q1, a FET Q2 and a relay U2, a first pin of the relay U2 is electrically connected to a drain of the FET Q1, a second pin of the relay U2 is electrically connected to one end of a resistor R6 and the comparator circuit, respectively, another end of the resistor R6 is connected to a power supply, a third pin of the relay U2 is electrically connected to the detection point circuit, an eighth pin of the relay U2 is grounded, a gate of the FET Q1 is electrically connected to one end of the resistor R2 and a drain of the FET Q2, a source of the FET Q1 is electrically connected to one end of the resistor R1, another end of the resistor R1 is connected to the power supply, a gate of the FET Q2 is electrically connected to an AND gate circuit, the source electrode of the field effect transistor Q2 is grounded, and the other end of the resistor R2 is connected with a power supply.
4. The short circuit detection circuit for detecting the mainboard of claim 1, wherein the and circuit comprises a resistor R3, a resistor R4, a resistor R5, a capacitor C1 and a chip U1, a first pin of the chip U1 is electrically connected with one end of a resistor R3, one end of a resistor R5 and one end of a capacitor C1 respectively, the other end of the capacitor C1 is grounded, the other end of the resistor R5 is grounded, the other end of the resistor R3 is connected with a power supply, a second pin of the chip U1 is electrically connected with a comparator circuit, a third pin of the chip U1 is grounded, a fourth pin of the chip U1 is electrically connected with one end of the resistor R4 and the relay circuit respectively, the other end of the resistor R4 is grounded, and a fifth pin of the chip U1 is connected with the power supply.
5. The short circuit detection circuit for detecting the mainboard of claim 1, wherein the comparator circuit comprises a resistor R9, a resistor R10, a resistor R13 and a comparator U3, a first pin of the comparator U3 is electrically connected with one end of the resistor R10 and an AND gate circuit respectively, another end of the resistor R10 is connected with a power supply, a second pin of the comparator U3 is electrically connected with one end of the resistor R9 and one end of the resistor R13 respectively, another end of the resistor R9 is connected with the power supply, another end of the resistor R13 is connected with the ground, a third pin of the comparator U3 is electrically connected with a relay circuit, a fourth pin of the comparator U3 is connected with the ground, and an eighth pin of the comparator U3 is connected with the power supply.
6. The short detection circuit for detecting a motherboard according to claim 1, the driving circuit comprises a resistor R7, a resistor R8, a resistor R14, a light-emitting diode D1, a field-effect tube Q3 and a field-effect tube Q4, the grid electrode of the field effect transistor Q3 is respectively and electrically connected with one end of a resistor R7 and the drain electrode of the field effect transistor Q4, the source electrode of the field effect transistor Q3 is electrically connected with the other end of the resistor R7, the source electrode of the field effect transistor Q3 and the other end of the resistor R7 are both connected with a power supply, the drain electrode of the field effect transistor Q3 is electrically connected with one end of a resistor R8, the other end of the resistor R8 is electrically connected with the anode of a light emitting diode D1, the cathode of the light emitting diode D1 is grounded, the grid of the field effect transistor Q4 is respectively and electrically connected with one end of the resistor R14 and the AND circuit, the source electrode of the field effect transistor Q4 is electrically connected with the other end of the resistor R14, and the drain electrode of the field effect transistor Q4 and the other end of the resistor R14 are both grounded.
7. A short-circuit detection method for detecting a short-circuit detection circuit of a main board according to claim 1, comprising the steps of:
the comparator circuit outputs low level, the AND gate circuit outputs low level and the drive circuit outputs low level;
the control system judges whether the GPIO port detects low level;
if yes, the tested mainboard is judged to be in a short-circuit state.
8. The short circuit detection method of the short circuit detection circuit for detecting the main board according to claim 7, further comprising the steps of:
the comparator circuit outputs high level, the AND gate circuit outputs high level and the drive circuit outputs high level;
the control system judges whether the GPIO port detects high level;
if yes, the tested mainboard is judged to be in a non-short circuit state.
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| CN202011437716.XA CN112462241A (en) | 2020-12-07 | 2020-12-07 | Short circuit detection circuit and short circuit detection method for detecting mainboard |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113219320A (en) * | 2021-04-16 | 2021-08-06 | 深圳市安仕新能源科技有限公司 | BMS circuit board checking method, system, readable storage medium and terminal equipment |
| CN115656876A (en) * | 2022-11-21 | 2023-01-31 | 上海海栎创科技股份有限公司 | Micro short circuit test circuit and test method |
| CN116540146A (en) * | 2023-05-25 | 2023-08-04 | 深圳市航顺芯片技术研发有限公司 | GPIO short circuit detection method and GPIO short circuit detection system |
-
2020
- 2020-12-07 CN CN202011437716.XA patent/CN112462241A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113219320A (en) * | 2021-04-16 | 2021-08-06 | 深圳市安仕新能源科技有限公司 | BMS circuit board checking method, system, readable storage medium and terminal equipment |
| CN113219320B (en) * | 2021-04-16 | 2023-03-10 | 深圳市安仕新能源科技有限公司 | BMS circuit board checking method, system, readable storage medium and terminal equipment |
| CN115656876A (en) * | 2022-11-21 | 2023-01-31 | 上海海栎创科技股份有限公司 | Micro short circuit test circuit and test method |
| CN116540146A (en) * | 2023-05-25 | 2023-08-04 | 深圳市航顺芯片技术研发有限公司 | GPIO short circuit detection method and GPIO short circuit detection system |
| CN116540146B (en) * | 2023-05-25 | 2024-03-22 | 深圳市航顺芯片技术研发有限公司 | GPIO short circuit detection method and GPIO short circuit detection system |
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