CN219957737U - 192 channel bridge resistance noise test system based on singlechip control - Google Patents

Abstract

The utility model discloses and provides a 192-channel bridge resistance noise testing system based on single chip microcomputer control, which can solve the problems of large noise error and inaccurate test of a bridge resistance of a 1uV level tested by a common standard instrument, can test a plurality of DUTs and improves the testing efficiency. The utility model comprises a power distribution board, a plurality of test modules, a network switch and an upper computer, wherein the test modules comprise: the device comprises two constant voltage source circuits, a switching circuit, a precise bridge circuit and an MCU. The utility model is applied to the technical field of bridge resistance noise test.

Description

192 channel bridge resistance noise test system based on singlechip control

Technical Field

The utility model relates to a bridge resistance noise test system, in particular to a 192-channel bridge resistance noise test system based on single chip microcomputer control.

Background

At present, the bridge resistance noise measuring mode in the industry is less, and systematic measuring equipment is lacking, wherein one measuring mode is high-precision DMM 34410A (high-performance digital multimeter) measuring by utilizing keysight (De technology (China) Limited), and the precision of 1uV level can be measured. The existing universal meter tests the resistance noise of the bridge at the level of 1uV, the fluctuation and the error are large, and the test requirement cannot be met. If the test requirement is required, a better instrument is required to be selected, so that project cost is greatly increased, project competitiveness is reduced, and meanwhile, a plurality of DUTs are tested, and an external design channel switching board and a control circuit are required, so that circuit design difficulty is increased.

Disclosure of Invention

The utility model aims to solve the technical problems of overcoming the defects of the prior art, and provides a 192-channel bridge resistance noise testing system based on single chip microcomputer control, which can solve the problems of large noise error and inaccurate test of a bridge resistance of a common standard instrument for testing 1uV level, can test a plurality of DUTs and improves the testing efficiency.

The technical scheme adopted by the utility model is as follows: the utility model comprises a power distribution board, a plurality of test modules, a network switch and an upper computer, wherein the test modules comprise:

the input ends of the two paths of constant voltage source circuits are electrically connected with the power distribution board;

the output ends of the two constant voltage source circuits are respectively connected with a switching circuit, and the switching circuit expands the constant voltage source circuits connected with the switching circuits into four constant voltage sources, and each constant voltage source controls four DUTs;

the precise bridge circuit is connected to the test end of the DUT and used for acquiring a bridge resistance noise signal;

and the signal input end of the MCU is connected with the signal output end of the precise bridge circuit, and the MCU is communicated with the upper computer through the network switch.

Further, the constant voltage source circuit employs a linear regulator.

Further, the model of the linear voltage stabilizer is MAX8510.

Further, the switching circuit is a MUX circuit.

Further, the precision bridge circuit is a 6-channel 24-bit ADC MAX11261.

Further, the number of the test modules is 6.

The beneficial effects of the utility model are as follows: the utility model has the following advantages:

1. replacing expensive general-purpose equipment;

2. the noise testing precision of the bridge resistor is improved, and the noise testing error is reduced;

3. the device is convenient to integrate in automation equipment and convenient for automatic large-scale test;

4. the test device has 192-path channel test functions, and can test 6 DUTs at a time, thereby greatly improving the test efficiency.

Drawings

FIG. 1 is a schematic diagram of a bridge resistance noise testing system;

FIG. 2 is a schematic diagram of an actual bridge resistance noise test;

FIG. 3 is a schematic diagram of a constant voltage source switching test;

FIG. 4 is a system block diagram of the present utility model;

FIG. 5 is a circuit diagram of a two-way constant voltage source;

FIG. 6 is a diagram of an alternative measurement switching circuit;

FIG. 7 is a DUT precision bridge circuit diagram;

FIG. 8 is a diagram of a MAX11261 module interface circuit;

term interpretation:

PCB: printed circuit board with improved heat dissipation

Noise bridge resistance Noise

DUT: product(s)

ADC: analog-to-digital converter

DAC: digital-to-analog converter

Gain: amplification gain factor

Vos: the operational amplifier biases the voltage.

Detailed Description

In this embodiment, the micro noise test of the bridge resistor needs to use a constant voltage source and a precise bridge structure, and the measurement in this way has the advantage that noise interference of other elements can be eliminated as much as possible, and the specific principle is shown in fig. 1.

According to the principle of the above diagram, in order to meet the requirement of accurately testing the resistance noise of the bridge, the actual circuit testing principle is as shown in fig. 2:

according to the law of partial pressure: v=r2×vref ≡ (r1+r2)

Vout={（V+）－（V-）}×Gain

It follows that the voltage at the intermediate point of the bridge resistor needs to be acquired. In addition, the reference source Vref can be provided by a constant voltage source circuit, and the actual differential voltage across the bridge resistor can be obtained by dividing the reading of the ADC by Gain.

Because the bridge resistance noise tested by the test system is of the uV level, if the voltage noise of the constant voltage source and the voltage noise of the standard instrument are relatively large, the small voltage can be submerged in the Vos of the amplifier, and the signals and the Vos can not be effectively separated. In order to effectively separate out the signals, the circuit noise interference must be ensured to be small enough, so that an ultra-low noise linear voltage stabilizer MAX8510 and a low noise 6-channel 24-bit ADC MAX11261 are selected in the circuit.

As shown in fig. 3, in order to test multiple DUTs simultaneously, the testing system divides 192 channels into a 6x4x8 architecture, i.e. places the switching circuits together, uses 6 identical modules, and has two constant voltage sources on one module, each constant voltage source is expanded into 4 channels through a switch, and one constant voltage source controls 4 DUTs.

As shown in fig. 4, fig. 4 is a system block diagram of the present utility model.

As shown in fig. 5, U603 and U604 are two constant voltage source chips, C611, C612, C613, C614, C615, C616, C617 and C618 are constant voltage source bypass capacitors for eliminating part of noise interference of input and output.

In fig. 6, two constant voltage sources are respectively divided into 4 paths through one analog electronic switch ADG1612, the switches are controlled by specific IOs, and the constant voltage sources are controlled by specific instructions to be sent to corresponding DUT precision bridge circuits.

As shown in FIG. 7, every 4 DUTs are connected to the constant voltage source signal switched by the ADG1612, bypass capacitors on the circuit are decoupled, external interference is filtered, the voltage of the middle point of the bridge is collected, meanwhile, each DUT is externally connected with a resistor externally connected with the P end and the N end of the bridge, the bridge resistance of the DUT can be calculated through corresponding switch switching, and the testing function is increased.

As shown in fig. 8, the sampled bridge voltage signal is input to MAX11261 via an RC filter circuit for differential and a-D analog-to-digital conversion processing.

Noise validation related data:

when the collected data is processed, considering that the data of the uV level is too small, the single data volume is insufficient to describe bridge resistance Noise, so that the standard deviation concept is introduced, namely, the collected 300 times of data embody Noise by using the standard deviation.

Noise=rms{BridgeOffset_1[]-mean(BridgeOffset_1[])}=STDEVP(BridgeOffset_1[])

Bridgeoffset_1[ ] =vout, and the sample size n=300.

Table 1 below is test data for a portion of the channel.

TABLE 1 partial channel test data

The 192-channel bridge resistance noise testing system based on the single chip microcomputer control can replace expensive general instruments, can improve the noise testing precision of bridge resistance and reduce noise testing errors, is convenient to integrate in automation equipment, is convenient for automatic large-scale testing, has 192-channel testing function, can test 6 DUTs each time, and greatly improves testing efficiency.

While the embodiments of this utility model have been described in terms of practical aspects, they are not to be construed as limiting the meaning of this utility model, and modifications to the embodiments and combinations with other aspects thereof will be apparent to those skilled in the art from this description.

Claims (6)

1. A192 passageway bridge resistance noise test system based on singlechip control, includes power distribution board, a plurality of test module, network switch and host computer, its characterized in that: the test module comprises:

the input ends of the two paths of constant voltage source circuits are electrically connected with the power distribution board;

the output ends of the two constant voltage source circuits are respectively connected with a switching circuit, and the switching circuit expands the constant voltage source circuits connected with the switching circuits into four constant voltage sources, and each constant voltage source controls four DUTs;

the precise bridge circuit is connected to the test end of the DUT and used for acquiring a bridge resistance noise signal;

and the signal input end of the MCU is connected with the signal output end of the precise bridge circuit, and the MCU is communicated with the upper computer through the network switch.

2. The 192-channel bridge resistance noise testing system based on single chip microcomputer control as set forth in claim 1, wherein: the constant voltage source circuit adopts a linear voltage stabilizer.

3. The 192-channel bridge resistance noise testing system based on single chip microcomputer control as set forth in claim 2, wherein: the model of the linear voltage stabilizer is MAX8510.

4. The 192-channel bridge resistance noise testing system based on single chip microcomputer control as set forth in claim 1, wherein: the switching circuit is a MUX circuit.

5. The 192-channel bridge resistance noise testing system based on single chip microcomputer control as set forth in claim 1, wherein: the precision bridge circuit is a 6-channel 24-bit ADC MAX11261.

6. The 192-channel bridge resistance noise testing system based on single chip microcomputer control as set forth in claim 1, wherein: the number of the test modules is 6.