CN116679187A - PCBA power supply short circuit and power supply voltage automatic detection low-cost test fixture circuit - Google Patents

Abstract

Low-cost test tooling circuit for PCBA power circuit short circuit and voltage automatic detection, small current and low voltage source circuit, is to provide a small current and low voltage path for each power circuit when the main board is not powered on for ADC sampling to determine whether there is a short circuit ; The ADC sampling switching circuit uses ADC sampling to detect the loop impedance to confirm whether the power supply loop is short-circuited by switching, and detects whether the voltage of each power supply loop is normal after the entire board is powered on; After there is no short circuit abnormality in the power circuit, drive the tooling to power on the entire PCBA to be tested through software control and hardware interlocking. The invention patent realizes the low-cost automatic commissioning function of PCBA, which can reduce the false detection and missed detection phenomenon in manual commissioning, and at the same time avoid the discovery of defects after the complete machine is assembled, resulting in the need for complete dismantling and reorganization, resulting in a waste of working time and waste of material.

Description

PCBA power supply short circuit and power supply voltage automatic detection low-cost test tooling circuit

technical field

The invention relates to the technical field of PCBA automatic testing, in particular to a PCBA power circuit short circuit and voltage automatic detection low-cost test tooling circuit.

Background technique

The PCBA production and processing process is complex. During the production and processing process, due to differences in equipment or process conditions of manufacturers, there may be many problems, so that the quality of finished products cannot be guaranteed. Therefore, in order to ensure the high quality and reliability of PCBA, PCBA testing is a necessary process to ensure that each finished PCBA has no quality problems, and the first step of PCBA testing is the short circuit detection of the power circuit and the power supply voltage detection.

For the detection of high-precision products with large batches, manufacturers with a high degree of automation can choose to use ICT online testers, but the cost is quite high, and it is not suitable for the detection of small batches of conventional products of ordinary manufacturers; conventional PCBA detection methods It is manual visual inspection, and then use test leads to carry out relevant tests step by step before and after the whole board is powered on. However, it will consume a lot of labor costs to complete these necessary tasks during the mass production of boards and cards, and it is very prone to missed and false detections. Phenomenon, thus affecting the subsequent production process.

Based on the above unfavorable factors, it is necessary to develop a PCBA power supply short circuit and power supply voltage automatic detection low-cost test tooling circuit to solve the above problems.

Contents of the invention

The purpose of the patent of this invention is to provide PCBA power supply short circuit and power supply voltage automatic detection low-cost test tooling circuit, which can realize automatic power circuit short circuit detection before PCBA is powered on, to ensure that PCBA has no soldering problems, and then power on the entire PCBA board to automatically detect each The power loop voltage ensures that the PCBA has the conditions to flow into the next process.

In order to achieve the above purpose, the patent of the present invention provides a low-cost test tooling circuit for automatic detection of PCBA power supply short circuit and power supply voltage. The circuit includes a small current and low voltage source circuit, ADC sampling switching circuit and PCBA power supply interlocking control circuit. The small current and low voltage source circuit provides a small current and low voltage path for each power circuit when the main board is not powered on for ADC sampling to determine whether there is a short circuit; the ADC sampling switching circuit is through switching Use ADC sampling to detect loop impedance to confirm whether the power supply loop is short-circuited, and check whether the voltage of each power supply loop is normal after detecting that the entire board is powered on; the PCBA power supply interlock control circuit is After confirming that there is no short-circuit abnormality in each power supply loop, through the software The way of control and hardware interlocking drives the tooling to power on the entire PCBA to be tested.

Further in the present invention, in the low-cost test tooling circuit of the above-mentioned PCBA power supply short circuit and power supply voltage automatic detection, it also includes a small current and low voltage source circuit, which can provide a source of about 1V/3mA for each power supply circuit to be tested. It is used to detect the impedance of each power supply circuit under test to determine whether there is a short circuit.

Further in the present invention, in the above-mentioned PCBA power supply short circuit and low-cost test tooling circuit for automatic detection of power supply voltage, it also includes an ADC sampling switching circuit, which can be used to switch and detect the impedance of the power supply circuit to be tested, or after the entire board is powered on. Voltage.

Further, in the low-cost test tooling circuit for automatic detection of PCBA power supply short circuit and power supply voltage, a PCBA power supply interlock control circuit is further included, and the whole board power-on detection is performed after the short circuit detection is completed and there is no abnormality in the detection.

According to claim 2, the PCBA power circuit short-circuit and voltage automatic detection low-cost test tooling circuit is characterized in that the low-current low-voltage source circuit adopts the RY6050 chip.

Further in the present invention, the ADC sampling switching circuit adopts a signal relay HFD4/5 and a MOS tube.

Further in the present invention, the PCBA power supply interlocking control circuit adopts a gate circuit (AND gate) 74LVC1G08 chip.

Further in the present invention, the MOS transistor can be replaced by other types of controllable switch transistors.

Further in the present invention, the MOS tubes can simultaneously drive multiple signal relays to switch ADC signals, and the number is determined by the number of specific power circuits of the PCBA to be tested.

Further in the present invention, the small current and low voltage source circuit can be implemented by other chips, and the test voltage of the power circuit to be tested is not limited to 1V/3mA.

The beneficial effects of the patent of the present invention are:

Compared with the ICT online tester, the cost is lower, and it can maximize the commissioning efficiency of PCBA under the limitation of limited human resources, and can reduce the false detection and missed detection phenomenon in manual commissioning, and can effectively protect the tested At the same time, it can avoid the defects found after the whole machine is assembled, resulting in the need to completely dismantle and reorganize, resulting in waste of working time and waste of materials.

Description of drawings

Fig. 1 is the principle block diagram of the low-cost test tooling circuit of the patent PCBA power supply short circuit and power supply voltage automatic detection of the present invention;

Fig. 2 is the schematic diagram of the low-current low-voltage source circuit in the circuit embodiment of the low-cost test tooling circuit embodiment of the patent PCBA power supply short circuit and power supply voltage automatic detection of the present invention;

Fig. 3 is a schematic diagram of the ADC sampling switching circuit in the embodiment of the patented PCBA power supply short circuit and power supply voltage automatic detection low-cost test tooling circuit of the present invention;

Fig. 4 is a schematic diagram of the PCBA power supply interlocking control circuit in the embodiment of the patented PCBA power supply short circuit and power supply voltage automatic detection low-cost test tooling circuit of the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the patent of the present invention clearer, the patent of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

PCBA power supply short circuit and power supply voltage automatic detection low-cost test tooling circuit embodiment:

This embodiment is shown in Figure 1. This embodiment includes a small current and low voltage source circuit, an ADC sampling switching circuit, and a PCBA power supply interlock control circuit. In the test process, the main control chip controls the ADC sampling switching circuit to first switch to the power Loop short-circuit test mode, the small current and low voltage source circuit provides a source of about 1V/3mA for each power loop, wait for a short period of time to charge and stabilize the capacitors of each power loop, and the main control chip can obtain one of each power loop through ADC sampling. Voltage value, according to the voltage value and the resistance voltage division theorem, an impedance of the power circuit can be calculated and obtained. By comparing the impedance with the set impedance, it can be determined whether there is a short circuit abnormality in the power circuit; after the power circuit detection is completed, The main control chip can control the ADC sampling switching circuit to switch to the voltage detection mode, and at the same time drive the PCBA power supply interlock control circuit to supply power for the whole board. The main control chip can obtain the voltage of each power supply circuit through ADC sampling and determine whether the voltage value of each circuit is normal.

This embodiment is shown in Figure 2. The small current and low voltage source circuit of this embodiment is realized by RY6050 chip. RY6050 chip can not only realize the step-down function but also provide stable output current. See Figure 2 for the peripheral connection circuit of RY6050 chip. The voltage input pin VIN of the RY6050 chip is connected to a DC 3.3V power supply. At the same time, the voltage input pin VIN of the RY6050 chip is also connected to a capacitor filter circuit composed of two capacitors C6 and C7 connected in parallel. The voltage output pin OUT of the RY6050 chip is connected to There is a capacitive filter circuit composed of two capacitors C4 and C5 connected in parallel. FB is connected with a voltage divider feedback circuit composed of two resistors R1 and R4. The resistance of R1 is 24.9k, and the resistance of R4 is 100k. A capacitor C3 is connected in parallel with R1 for filter processing to ensure that the output voltage of VDD_ADC is stable at around 1V.

This embodiment is shown in Figure 3. The ADC sampling switching circuit of this embodiment is realized by signal relay HFD4/5 and MOS tube. HFD4/5 bit double-pole double-throw signal relay, a single relay can switch 2-way ADC sampling, peripheral connection circuit See Figure 3. The COM terminal (pin 3/6) of HFD4/5 is respectively connected to the power circuit probe of the tooling, and connected to the ADC pin of the main control chip. Connect the drive relay to pin 4/5, so that the power circuit of the PCBA to be tested is connected to the low current and low voltage source through the current limiting resistors R2 and R3. After a period of charging, the ADC of the main control chip can read To the voltage value obtained by the power circuit, and then use the law of resistance voltage division to calculate the impedance value of the power circuit to determine whether the circuit is short-circuited; after confirming that there is no short-circuit problem in the power circuit, the main control chip outputs the ARM_RV_SW signal as 0 to control The MOS tube Q1 is turned off, and HFD4/5 is switched back to pin 2/7, so that the power supply of the PCBA to be tested is directly connected to the ADC of the main control chip, and the voltage value of the power circuit can be read, and compared with the value The difference from the actual value can determine whether the power circuit voltage is normal.

The capacitors C1 and C2 in the circuit diagram are energy storage filter capacitors, which can reduce the influence of the instantaneous current on the power system when the relay K1 is turned on; the diode D1 is a freewheeling diode, which can eliminate the reverse voltage generated by the coil when the relay K1 is turned off. Improve system stability.

If the PCBA to be tested has multiple power circuits, you can add corresponding switching relays according to the number of power circuits. The switching relays are all driven by the same MOS tube in parallel. margin.

This embodiment is shown in Figure 4. The PCBA power supply interlock control circuit of this embodiment is implemented by a gate circuit (AND gate) 74LVC1G08 chip. The two inputs of the chip are respectively the power short circuit/voltage sampling switching signal ARM_RV_SW and The entire board power supply control signal ARM_PowerOn is realized by chaining two input signals, and the peripheral connection circuit is shown in Figure 4. It needs to be clear that before powering on the whole board, the short-circuit detection function of the power circuit must be carried out first. After the short-circuit detection is completed and there is no abnormality in the detection, the whole board can be powered on. Therefore, the two signals need to be interlocked by hardware to prevent accidental damage. PCBA to be tested;

When the tooling performs short-circuit detection, the main control chip outputs the ARM_RV_SW signal as 1, so the transistor Q2 is turned on, and the input A of the 74LVC1G08 chip is 0, so no matter what the state of the input B of the chip is, the output Y of the chip is also 0. Transistor Q3 is turned off, relay K2 is turned off and does not supply power to the PCBA to be tested; when the short-circuit detection of the tooling is completed and there is no abnormality, the main control chip outputs the ARM_RV_SW signal as 0, and the transistor Q2 is turned off at this time, and the input A of the 74LVC1G08 chip is 1. The main control chip outputs ARM_PowerOn signal of 1 to test the PCBA power supply, so the input B of the 74LVC1G08 chip is 1, then the output Y of the chip is 1, the transistor Q3 is turned on, and the relay K2 is closed to supply power to the PCBA to be tested.

The capacitors C10 and C11 in the circuit diagram are energy storage filter capacitors, which can reduce the influence of the instantaneous current on the power system when the relay K2 is turned on; the diode D2 is a freewheeling diode, which can eliminate the reverse voltage generated by the coil when the relay K2 is turned off. Improve the stability of the system; capacitors C12, C13, and C14 are energy storage filter capacitors, which can prevent the voltage sag of the power system caused by the high current impact at the moment when the PCBA is powered on.

To sum up, this embodiment can realize the low-cost automatic debugging function of PCBA through the small current and low voltage source circuit, ADC sampling switching circuit and PCBA power supply interlocking control circuit, and can reduce false detection and missed detection in manual debugging. phenomenon, and can effectively protect the tested PCBA, and at the same time, it can avoid the defect discovered after the whole machine is assembled, resulting in the need for complete dismantling and reorganization, resulting in waste of working time and waste of materials.

As another implementation manner, the MOS transistor may be replaced with other types of controllable switch transistors, such as triodes.

As other implementations, the MOS tubes can simultaneously drive multiple signal relays to switch ADC signals, and the number is determined by the number of power circuits of the specific PCBA to be tested.

As other implementation manners, the low-current low-voltage source circuit can be realized by other chips, and the test voltage of the power circuit to be tested is not limited to 1V/3mA.

As other implementation manners, the energy storage filter capacitors, freewheeling diodes, current limiting resistors, and voltage dividing resistors used in the circuit can all be adjusted according to actual needs.

In practical applications, the small current and low voltage source circuit, the ADC sampling switching circuit, and the PCBA power supply interlocking control circuit can be integrated on one PCB, or each device can be fixed through the shell, which is not limited by the patent of the present invention.

The beneficial effects of the patent of the present invention are:

Compared with the ICT online tester, the cost is lower, and it can maximize the commissioning efficiency of PCBA under the limitation of limited human resources, and can reduce the false detection and missed detection phenomenon in manual commissioning, and can effectively protect the tested At the same time, it can avoid the defects found after the whole machine is assembled, resulting in the need to completely dismantle and reorganize, resulting in waste of working time and waste of materials.

The above embodiments do not limit the scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made by those skilled in the art to the technical solution of the present invention shall be included in the claims of the present invention. within the defined scope of protection.

Claims (10)

1. A PCBA power supply loop short circuit and voltage automatic detection low-cost test fixture circuit is characterized in that;

   firstly, automatically detecting a short circuit of a power supply loop before electrifying the PCBA so as to ensure that the PCBA has no welding problem;

   and then electrifying the whole PCBA, automatically detecting the voltage of each power supply loop, and ensuring that the PCBA has the condition of flowing into the next process.
2. 2. The low-cost test fixture circuit for automatically detecting short circuit and voltage of a PCBA power circuit according to claim 1, wherein each power circuit is provided with a low-current low-voltage path for ADC sampling to determine whether there is a short circuit phenomenon when the motherboard is not powered on.
3. 3. The low-cost test fixture circuit for automatically detecting short circuit and voltage of a power circuit of a Printed Circuit Board Assembly (PCBA) according to claim 1, wherein the circuit impedance is detected by means of analog-to-digital converter (ADC) sampling in a switching manner to determine whether the power circuit is short-circuited, and the voltage of each power circuit is detected to be normal after the whole board is electrified.
4. 4. The low-cost test fixture circuit for automatically detecting short circuit and voltage of a power circuit of a Printed Circuit Board Assembly (PCBA) according to claim 2, wherein after confirming that each power circuit has no short circuit abnormality, the whole PCBA board to be tested is electrified through a software control and hardware interlocking driving fixture, and then whether the voltage of each power circuit is normal is detected.
5. 5. The PCBA power supply loop short circuit and voltage automatic detection low cost test fixture circuit of claim 2, wherein the low current low voltage source circuit employs a RY6050 chip.
6. 6. The low-cost test fixture circuit for automatically detecting short circuit and voltage of a PCBA power supply circuit according to claim 3, wherein the ADC sampling switching circuit adopts a signal relay HFD4/5 and a MOS tube.
7. 7. The PCBA power supply loop short circuit and voltage automatic detection low cost test fixture circuit of claim 4, wherein the PCBA power supply interlock control circuit employs a gate circuit (and gate) 74LVC1G08 chip.
8. 8. The PCBA power supply loop short circuit and voltage automatic detection low-cost test fixture circuit of claim 6, wherein the MOS tube can be replaced with other types of controllable switching tubes.
9. 9. The low-cost test fixture circuit for automatically detecting short circuit and voltage of a power circuit of a Printed Circuit Board (PCBA) according to claim 6, wherein the MOS tube can drive the multi-path signal relay to switch ADC signals at the same time, and the number of the MOS tube is determined by the number of the power circuits of the specific PCBA to be detected.
10. 10. The low-cost test fixture circuit for automatically detecting short circuit and voltage of a power circuit of a PCBA according to claim 5, wherein the low-current low-voltage power circuit can be realized by other chips, and the test voltage of the power circuit to be tested is not limited to 1V/3mA.