CN1948970A - High power digital varistor and testing method thereof - Google Patents

Abstract

The invention relates to high power digital rheostat and testing method. It uses computer and virtual device techniques in electronic equipment testing, increases electronic testing automaticity by digitalizing control, realizes electronic equipment testing load simulation and automatic adjustment in the condition of small load heavy current high power, high precision load regulation by reasonable switching for the load resistance regulating circuit to increase electronic equipment testing precision.

Description

A kind of high power digital varistor and method of testing thereof

Technical field

The invention belongs to the electronic equipment technical field of measurement and test, be specifically related to a kind of high power digital varistor and method of testing thereof.

Background technology

In the electronic equipment test, often need to use the load of rheostat analog operation, and instrument is operated under the rated current, the just test that can stipulate by regulating load.And that the less but rated operational current of some apparatus of load requires is bigger, therefore, must regulate electric current by the high power load of regulating analog meter in the test.And the load regulation of common test instrument generally is made up of disk rheostat and reometer, circuit connection back is by operating personnel's manual adjustments disk rheostat knob and observe the reometer reading, make circuit reach rated current, automaticity is lower, because powerful disk rheostat generally all can not reach very high degree of regulation, add artificial reading error, it is very inaccurate to make rated current regulate.Though the integrated digital potentiometer can reach higher precision, all be that the resistance under the miniwatt condition is regulated automatically, these all are difficult to realize the load adjusting and the current with high accuracy adjusting automatically of little load high-current circuit.

Summary of the invention

The objective of the invention is to overcome the shortcoming of above-mentioned prior art, a kind of Digital Control of passing through is provided, improve the automaticity of Electronic Testing, realize under the high-power condition of the big electric current of little load, high-precision load regulation function, the high power digital varistor and the method for testing thereof of raising electronic equipment measuring accuracy.

For achieving the above object, digital varistor of the present invention comprises control terminal, the digital I/O passage that is connected with the output of control terminal, and the load regulation circuit that links to each other with digital I/O passage output, be characterized in, the output of control terminal is connected with digital I/O passage input, the output terminal of numeral I/O passage is connected with the relay control signal input end of pull-up resistor regulating circuit, the output terminal of input signal channel gating module links to each other with pull-up resistor regulating circuit measured signal input end, the output terminal of pull-up resistor regulating circuit links to each other with the input end of signal collecting device, and the output terminal of the signal collecting device input voltage that will measure that links to each other with the input end of control terminal is delivered to control terminal.

Control terminal of the present invention is main control computer or single-chip microcomputer; It is that ratio is that 2 high-power resistance parallel connection constitutes that the pull-up resistor regulating circuit becomes Geometric Sequence by one group of resistance, and whether controls the relay of this road resistance of gating at each Lu Jiayi.

Method of testing of the present invention is: when carrying out Current Regulation, at first the input end of tested electronic equipment with input signal channel gating module linked to each other, signal collecting device is measured input voltage and is delivered to control terminal, calculate the operating load value that need reach by control terminal, by immediate value in the selected pull-up resistor regulating circuit output resistance of control terminal, and pass through formula $R^{\′}=\frac{R\×2^{n-1}}{N}$ Calculate the value of N, wherein n is a n road resistance, R is the minimum resistance in the resistance of n road, R ' is the circuit output resistance, N is the decimal number that comprises relay on-off state vector information, the result is converted into binary number, and binary code write digital I/O passage, send high-low level by digital I/O passage to pull-up resistor regulating circuit relay drive circuit, the corresponding road of gating resistance carries owing to become band by zero load, subtle change can take place in input voltage, in order to make rated current reach higher accuracy, control terminal repeats above-mentioned adjustment process automatically, till reaching rated current.

The present invention applies to computer technology and virtual instrument technique in the middle of the electronic equipment test, by Digital Control, improves the automaticity of Electronic Testing; The load simulation of electronic equipment test and adjusting have automatically been realized under the high-power condition of the big electric current of little load; Select to have realized the load regulation function of degree of precision to have improved the precision of electronic equipment test by the reasonable break-make of pull-up resistor regulating circuit.

Description of drawings

Fig. 1 is one-piece construction of the present invention and test philosophy synoptic diagram;

Fig. 2 is the structural representation of pull-up resistor regulating circuit 3 of the present invention;

Fig. 3 is a workflow diagram of the present invention.

Embodiment

Below in conjunction with accompanying drawing the present invention is described in further detail.

Referring to Fig. 1, the present invention includes control terminal 1, control terminal 1 is main control computer or single-chip microcomputer, and the digital I/O passage 2 that is connected with the output of control terminal 1, the output terminal of numeral I/O passage 2 is connected with the relay control signal input end of pull-up resistor regulating circuit 3, the output terminal of input signal channel gating module 5 links to each other with pull-up resistor regulating circuit 3 measured signal input ends, the output terminal of pull-up resistor regulating circuit 3 links to each other with the input end of signal collecting device 4, the output terminal of signal collecting device 4 input voltage that will measure that links to each other with the input end of control terminal 1 is delivered to control terminal 1, and tested electronic equipment 6 links to each other with the input end of input signal channel gating module 5.

Referring to Fig. 2, pull-up resistor regulating circuit 3 of the present invention is become by one group of resistance that the resistance of Geometric Sequence (ratio is 2) is in parallel to be constituted, and whether each Lu Jiayi relay control this road resistance of gating.Combination different in parallel by these resistance can obtain a series of different output resistances from low to high.By the way of definite resistance and the resistance of every road resistance, make work system reach desired degree of regulation and range of adjustment.It below is the computing formula of output resistance.

Be provided with n road resistance, minimum resistance is R, and then all resistance can be expressed as R in the circuit, 2R, and 4R ..., 2 ^N-2R, 2 ^N-1R.With a _i(i=1 wherein, 2,3 ..., n) on off operating mode of the every road of expression resistance is promptly worked as a _iRepresented that this road resistance by gating, worked as a at=1 o'clock _iRepresented that resistance was not by gating at=0 o'clock.The on off operating mode of n road resistance can be expressed as Z=(a so ₁, a ₂, a ₃..., a _n), Z is actually one by 0 and 1 unit vector of forming.

If the circuit output resistance is R ',, have according to the parallel circuit computing formula

$R^{\′}=\frac{R\×2^{n-1}}{2^{n-1}\×a_1+2^{n-2}\×a_2+2^{n-3}\×a_3+L+2\×a_{n-1}+1\×a_n}---\left(1\right)$

Make N=2 ^N-1* a ₁+ 2 ^N-2* a ₂+ 2 ^N-3* a ₃+ Λ+2 * a _N-1+ 1 * a _nSo, general computing formula that can adjusted circuit output resistance:

$R^{\′}=\frac{R\×2^{n-1}}{N}---\left(2\right)$

The expression formula of N is represented with vector form, can be obtained

N＝(2 ^n-1，2 ^n-2，2 ^n-3，Λ2，1)Z ^τ (3)

If each the element step-by-step among the on off operating mode vector Z is arranged, then can obtain a binary number, and formula (3) is converted into this binary number decimal numeral result just, after resistance way n determined, the value of N was 1,2,3 as can be known so ..., 2 ⁿ-1, also promptly after n and R determine, can obtain 2 altogether by the break-make combination of controlling each road ⁿ-1 different output resistance R '.When given resistance of need regulating, just can this 2 ⁿSearch the most approaching resistance among-1 R ', using formula (2) calculates the value of N, and through type (3) is tried to achieve on off operating mode vector Z again.Know the on off operating mode of each road resistance, just can use selected control mode to control each road relay on-off, obtained desired resistance.Owing to what obtained by Z is binary number, therefore can write break-make information to digital I/O passage 2 easily, to realize the automatic adjusting of pull-up resistor.

By formula (2) calculate easily when a gating resistance maximum a road time, Z=(0,0,0 ..., 0,1), N=1, this moment, parallel circuit obtained maximum output resistance R ' _Max

R′ _max＝R×2 ^n-1 (4)

When all resistance during all by gating, Z=(1,1,1 ..., 1,1), N=2 ⁿ-1, parallel circuit obtains minimum output resistance R ' _Min

${R^{\′}}_{\min }=\frac{R\×2^{n-1}}{2^n-1}---\left(5\right)$

As can be known by the regulating circuit of n road resistance parallel connection, the scope of output resistance is R ' by formula (4) and formula (5) _Min~ R ' _Max

Here the degree of regulation to circuit carries out following analysis.

If regulating error is ε, then ε can approximate representation be:

$\mathrm{\ϵ}=\frac{R\×2^{n-1}}{2^n-2}-\frac{R\×2^{n-1}}{2^n-1}=R\×\frac{2^{n-1}}{(2^n-2)(2^n-1)}$

As seen the way n of the size of regulating error ε and resistance and minimum resistance R choose relevant, when R one regularly, it is big more that n chooses, then regulating error ε is more little, otherwise ε is big more; And when n one timing, the value that reduces R also can reduce the value of ε.In theory, R ' when n trends towards infinity _Min=0.5R, R ' _Max=∞, ε=0, this moment regulating circuit output resistance (0.5R, adjustable continuously on ∞).But in actual applications, it is infinite that n can not be tending towards, so output resistance and discontinuous.During resistance adjustment, can only be transferred to that output resistance the most approaching with given resistance.

In addition, when n one timing, investigate of the influence of the size of output resistance R ' to precision.Given two resistance value R ' ₁And R ' ₂, make R ' ₁＜R ' ₂, have

${R^{\′}}_1=\frac{R_{\max }}{2^n-n_1}$ ${R^{\′}}_2=\frac{R_{\max }}{2^n-n_2}$ N wherein ₁＞n ₂

Error when regulating these two resistance can be distinguished approximate representation and be

${\mathrm{\ϵ}}_1=\frac{R_{\max }}{2^n-n_1+1}-\frac{R_{\max }}{2^n-n_1}$ ${\mathrm{\ϵ}}_2=\frac{R_{\max }}{2^n-n_2+1}-\frac{R_{\max }}{2^n-n_2}$

Calculate ε ₁＜ε ₂Show one timing as n, in the range of adjustment of formula (2), the more little then degree of regulation of the output resistance that need obtain is high more.For given output resistance, want further to improve degree of regulation, can only increase the value of n so again.

By above analysis as can be known, this digital varistor can realize that the high precision of resistance regulates in theory.During practical application, need take all factors into consideration the size of the desired resistance adjustable extent of system, in this adjustable extent to the requirement of precision, and the cost of system and volume are to determine the value of n and R in the circuit.

Referring to Fig. 3, after the resistance way n of pull-up resistor regulating circuit 3 determined, they were all 2 years old ⁿ-1 output resistance has just determined that also control terminal 1 utilizes calculating formula to calculate all resistance in advance, and the result is stored with the form of database table.When carrying out Current Regulation, at first the input end of tested electronic equipment 6 with input signal channel gating module 5 linked to each other, signal collecting device 4 is measured input voltage and is delivered to control terminal 1, control terminal 1 calculates the load value R ' that actual needs obtains, opening data form then inquires about, find the most output resistance, and pass through formula near R ' $R^{\′}=\frac{R\×2^{n-1}}{N}$ Calculate the value of N, wherein n is a n road resistance, R is the minimum resistance in the resistance of n road, R ' is the circuit output resistance, N is the decimal number that comprises relay on-off state vector information, and the result is converted into binary number, and binary code is write digital I/O passage 2, send high-low level by digital I/O passage 2 to pull-up resistor regulating circuit 3 relay drive circuits, the corresponding road of gating resistance.Carry owing to become band by zero load, subtle change can take place in input voltage, reaches higher accuracy in order to make rated current, and control terminal repeats above-mentioned adjustment process automatically, till reaching rated current.Therefore, need only set the load current value that needs adjustment during use, just can accurately automatically external circuit be adjusted to rated current.

Claims (4)

1, a kind of high power digital varistor, comprise control terminal (1), the digital I/O passage (2) that is connected with the output of control terminal (1), and the load regulation circuit (3) that links to each other with digital I/O passage (2) output, it is characterized in that: the output of control terminal (1) is connected with digital I/O passage (2) input, the output terminal of numeral I/O passage (2) is connected with the relay control signal input end of pull-up resistor regulating circuit (3), the output terminal of input signal channel gating module (5) links to each other with pull-up resistor regulating circuit (3) measured signal input end, the output terminal of pull-up resistor regulating circuit (3) links to each other with the input end of signal collecting device (4), and the output terminal of signal collecting device (4) input voltage that will measure that links to each other with the input end of control terminal (1) is delivered to control terminal (1).

2, high power digital varistor according to claim 1 is characterized in that: said control terminal (1) is main control computer or single-chip microcomputer.

3, high power digital varistor according to claim 1, it is characterized in that: it is that ratio is that 2 high-power resistance parallel connection constitutes that said pull-up resistor regulating circuit (3) becomes Geometric Sequence by one group of resistance, and whether controls the relay of this road resistance of gating at each Lu Jiayi.

4, high power digital varistor method of testing, it is characterized in that: when carrying out Current Regulation, at first the input end of tested electronic equipment (6) with input signal channel gating module (5) linked to each other, signal collecting device (4) is measured input voltage and is delivered to control terminal (1), calculate the operating load value that need reach by control terminal (1), by immediate value in selected pull-up resistor regulating circuit (3) output resistance of control terminal (1), and pass through formula $R^{\′}=\frac{R\×2^{n-1}}{N}$ Calculate the value of N, wherein n is a n road resistance, R is the minimum resistance in the resistance of n road, R ' is the circuit output resistance, N is the decimal number that comprises relay on-off state vector information, the result is converted into binary number, and binary code write digital I/O passage (2), send high-low level by digital I/O passage (2) to pull-up resistor regulating circuit (3) relay drive circuit, the corresponding road of gating resistance carries owing to become band by zero load, subtle change can take place in input voltage, in order to make rated current reach higher accuracy, control terminal repeats above-mentioned adjustment process automatically, till reaching rated current.

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