CN100490269C - Resistance output circuit - Google Patents
Resistance output circuit Download PDFInfo
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- CN100490269C CN100490269C CNB2007100900772A CN200710090077A CN100490269C CN 100490269 C CN100490269 C CN 100490269C CN B2007100900772 A CNB2007100900772 A CN B2007100900772A CN 200710090077 A CN200710090077 A CN 200710090077A CN 100490269 C CN100490269 C CN 100490269C
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Abstract
Resistance output circuit includes structures: A-end of over current and over voltage protector (OCOVP) is connected to the output end, and B-end through first protective resistance (PR) is connected to the output end of first operational amplifier (OA); second PR is connected to connection line between inverted input end and output end of OA; connection port of first voltage clamping unit (VCU) is connected to connection line between first PR and first OCOVP; one end of the gain amplifier (GA) is connected to non-invert input end of first OA, and the other end to second OA; non-invert input end of second OA is connected to ground, and the invert input end through second OCOVP is connected to the input end; one end of third PR is connected to input end, and the other end is connected to connection line between fourth PR and GA, and the connection port of second VCU is connected to the connection line. The invention is in use for eliminating influence of internal resistance of OCOVP.
Description
Technical field
The present invention relates to the over-current over-voltage protection technology, more specifically to a kind of electric resistance output circuit of eliminating over-current overvoltage protector spare internal resistance influence.
Background technology
In the electric resistance output circuit design; usually adopt the method for the over-current overvoltage protector of directly in circuit, connecting to come the protective circuit intraware under the situation of overcurrent-overvoltage, not to be damaged; as shown in Figure 1; this circuit comprises input, output, internal circuit and over-current overvoltage protector spare, and this over-current overvoltage protector spare is connected on the connection line between described input and the output.Because over-current overvoltage protector spare itself has certain internal resistance, and its resistance can change along with the variation of circuital current and ambient temperature, thereby influenced the precision of whole electric resistance output circuit.
Summary of the invention
In view of this, the object of the present invention is to provide a kind of electric resistance output circuit circuit that can eliminate over-current overvoltage protector spare internal resistance influence.
The invention provides a kind of electric resistance output circuit, comprise input and output, also comprise:
One end of first over-current overvoltage protector connects described output, and its other end links to each other with the output of first operational amplifier by first protective resistance; On the line between the output of the inverting input of described first operational amplifier and described electric resistance output circuit, be in series with second protective resistance; Described first protective resistance is connected the connectivity port of the first voltage clamp unit with the line between described first over-current overvoltage protector;
The normal phase input end of described first operational amplifier connects an end of gain amplifier; The other end of described gain amplifier connects an end of the 4th protective resistance, and the other end of described the 4th protective resistance connects the output of second operational amplifier; The positive input end grounding of described second operational amplifier; inverting input connects an end of second over-current overvoltage protector; an end that on the line between the inverting input of this second operational amplifier and this second over-current overvoltage protector, is connected the overcurrent onunit; the other end ground connection of this overcurrent onunit; the other end of described second over-current overvoltage protector links to each other with the input of described electric resistance output circuit; the input of described electric resistance output circuit connects an end of the 3rd protective resistance; the other end of described the 3rd protective resistance connects the line between described the 4th protective resistance and the described gain amplifier, also is connected with the connectivity port of the second voltage clamp unit on the line between described the 4th protective resistance and the described gain amplifier.
Preferably, further comprise the tertiary voltage clamp units, the connectivity port of described tertiary voltage clamp units connects the line between the inverting input of described second protective resistance and described first operational amplifier.
Preferably, the described first voltage clamp unit is made up of first positive supply, first negative supply, first diode and second diode, wherein,
The N utmost point of described first diode connects described first positive supply, its P utmost point extremely links to each other with the N of described second diode, any some connectivity port as the described first voltage clamp unit on the line between the P utmost point of described first diode and the N utmost point of described second diode, the P utmost point of described second diode connects described first negative supply.
Preferably, the described second voltage clamp unit is made up of second positive supply, second negative supply, the 3rd diode and the 4th diode, wherein,
The N utmost point of described the 3rd diode connects described second positive supply, its P utmost point extremely links to each other with the N of described the 4th diode, any some connectivity port as the described second voltage clamp unit on the line between the P utmost point of described the 3rd diode and the N utmost point of described the 4th diode, the P utmost point of described the 4th diode connects described second negative supply.
Preferably, described tertiary voltage clamp units is made up of the 3rd positive supply, the 3rd negative supply, the 5th diode and the 6th diode, wherein,
The N utmost point of described the 5th diode connects described positive supply, its P utmost point extremely links to each other with the N of described the 6th diode, any some connectivity port as described tertiary voltage clamp units on the line between the P utmost point of described the 5th diode and the N utmost point of described the 6th diode, the P utmost point of described the 6th diode connects described the 3rd negative supply.
Preferably; described overcurrent onunit is made up of the 7th diode and the 8th diode; the N utmost point of described the 7th diode and the P of described the 8th diode extremely altogether, the P utmost point of described the 7th diode is connected the line between the inverting input of described second over-current overvoltage protector and described second operational amplifier with the N utmost point of described the 8th diode.
Preferably, described gain amplifier is a programmable gain amplifier.
Preferably, described first over-current overvoltage protector is fuse or power resistor.
Preferably, described second over-current overvoltage protector is fuse or power resistor.
By technique scheme as can be known; the present invention utilizes the clamp down on effect of voltage clamp unit to voltage; and utilized empty short, the empty disconnected principle of operational amplifier, and make and when operate as normal, eliminate over-current overvoltage protector internal resistance influence, improve the precision of output resistance.
Description of drawings
Fig. 1 is the prior art constructions schematic diagram;
Fig. 2 is the structural representation of the embodiment one of electric resistance output circuit of the present invention;
Fig. 3 is the structural representation of the embodiment two of electric resistance output circuit of the present invention;
Fig. 4 is the structural representation of the embodiment three of electric resistance output circuit of the present invention.
Embodiment
Using over-current overvoltage protector through regular meeting in circuit design is not damaged under with the situation of protective circuit intraware at over-voltage and over-current; all be the over-current overvoltage protector of directly in circuit, connecting generally speaking; but which kind of over-current overvoltage protector spare itself all exists certain inherent resistance; and its resistance can change along with the variation of circuital current and ambient temperature; influence the output accuracy of circuit, this has become crucial restraining factors of precision resister designing circuitry.
Basic thought of the present invention is exactly to utilize the clamp down on effect of voltage clamp unit to voltage, and has utilized empty short, the empty disconnected principle of operational amplifier to eliminate the internal resistance influence of over-current overvoltage protector.
Please refer to Fig. 2, be the structural representation of the embodiment one of electric resistance output circuit of the present invention;
A kind of electric resistance output circuit, comprise input and output, also comprise: first protective circuit 100, second protective circuit 200 and gain amplifier 300, described first protective circuit comprises: first over-current overvoltage protector 101, first operational amplifier 102, first protective resistance 103, second protective resistance 104 and the first voltage clamp unit 105; The A end of described first over-current overvoltage protector 101 connects described output, its B end links to each other with the output of described first operational amplifier 102 by described first protective resistance 103, on the inverting input of described first operational amplifier 102 and the line between the described output, be in series with second protective resistance 104, the connectivity port of the described first voltage clamp unit 105 connects the line between described first protective resistance 103 and described first over-current overvoltage protector 101, and the normal phase input end of described first operational amplifier 102 connects an end of gain amplifier 300; Described second overcurrent-overvoltage protecting circuit 200 comprises: second over-current overvoltage protector 201, second operational amplifier 202, overcurrent onunit 203, the 3rd protective resistance 204, the 4th protective resistance 205 and the second voltage clamp unit 206; The other end of described gain amplifier 300 connects an end of described the 4th protective resistance 205; the other end of described the 4th protective resistance 205 connects the output of described second operational amplifier 202; the positive input end grounding of described second operational amplifier 202; its inverting input connects the B end of second over-current overvoltage protector 201; the A end of described second over-current overvoltage protector 201 links to each other with described input; described input connects an end of the 3rd protective resistance 204; the other end of described the 3rd protective resistance 204 connects the line between the 4th protective resistance 205 and the described gain amplifier 300, and the connectivity port of the described second voltage clamp unit 206 connects the line between described the 4th protective resistance 205 and the described gain amplifier 300.
The operation principle of this circuit is:
In operate as normal, according to the disconnected principle of the void of operational amplifier, the inverting input voltage of described first operational amplifier 102 is identical with the voltage of the A end of described first over-current overvoltage protector 101; According to the short principle of the void of operational amplifier; the normal phase input end of first operational amplifier 102 and the voltage of inverting input equate; so the voltage of the A of described first over-current overvoltage protector 101 end is identical with the normal phase input end voltage of described first operational amplifier 102, thereby the resistance of having eliminated on described first over-current overvoltage protector 101 influences.
According to the short principle of the void of operational amplifier, the inverting input of described second operational amplifier 202 has identical voltage with in-phase input end, because the voltage of the normal phase input end of described second operational amplifier 202 is 0V, so the voltage of the inverting input of described second operational amplifier 202 also is 0V.The voltage of the B end of second over-current overvoltage protector 201 is 0V; According to the disconnected principle of the void of operational amplifier; the inverting input of described second operational amplifier 202 does not have electric current to flow through; so do not have electric current to flow through on described second over-current overvoltage protector 201, owing to there is not electric current to flow through, the voltage of the A end of described second over-current overvoltage protector 201 also is 0V.Thereby offset the influence of the inherent resistance of described second over-current overvoltage protector 201 when having reached this protective circuit operate as normal.
The case of external drive current is I; enter this circuit from input; this electric current I is in the circuit rated current; this electric current is by the pressure drop of a V1=I*R1 of place, connectivity port generation of the second voltage clamp unit 206 in second protective circuit 200; described R1 is the resistance value of the 3rd protective resistance 204; behind gain amplifier 300; produce the voltage drop of a voltage V2=X*I*R1 at the normal phase input end place of described first operational amplifier 102; wherein X is the multiplication factor of described gain amplifier; this gain amplifier can be programmable gain amplifier (PGA); circuit output end voltage is identical with the normal phase input end voltage of described first operational amplifier 102; so the output resistance of the output of electric resistance output circuit is R=V2/I=PGA*R1, that is to say that the output resistance of electric resistance output circuit depends on the multiplication factor of gain amplifier 300 and the resistance of the 3rd protection electricity group 204.
This circuit can also comprise tertiary voltage clamp units 106, as shown in Figure 3, is the structural representation of the embodiment two of electric resistance output circuit of the present invention; The connectivity port of described tertiary voltage clamp units 106 connects the inverting input of described first operational amplifier 102 and the connection line between described second protective resistance 104.
When circuit breaks down, when input flows into excessive electric current, because described the 3rd protective resistance 204 has very high resistance value, so it is less to flow through the electric current of the 3rd protective resistance 204; This moment, most electric currents flow through described second over-current overvoltage protector 201 and overcurrent onunit 203, and these electric currents cause described second over-current overvoltage protector 201 to open circuit very soon, thereby cut off circuit loop, thereby have guaranteed the safety of the components and parts in the circuit.
Because the existence of described the 3rd protective resistance 204; having certain residual current exists; the voltage that described electric resistance output circuit inserts still can act on the output of described second operational amplifier 202; at this moment because the voltage clamp function that the second voltage clamp unit 206 has in this circuit; make it can clamp down on the voltage that the 3rd protective resistance 204 and described the 4th protective resistance 205 tie points are stated in the residence in this case; again because the existence of the 4th protective resistance 205; fault current is limited within the current range that described second operational amplifier 202 can bear, protects described second operational amplifier 202 not to be damaged.
When circuit breaks down; when output occurs exceeding the voltage of supply voltage scope; described first over-current overvoltage protector 101 is fused very fast meeting; after the fusing; have only second protective resistance 104 to be connected in the whole loop; because the resistance very big (10k Ω) of described second protective resistance 104, and because the voltage clamp effect of tertiary voltage clamp units 106, thereby reach the function of over-current over-voltage protection.
Below by object lesson the present invention is further described in detail.
The described first voltage clamp unit 105 or the second voltage clamp unit 206 or tertiary voltage clamp units 106 can be made up of positive supply, negative supply, first diode and second diode, please refer to Fig. 4, be the structural representation of the embodiment three of electric resistance output circuit of the present invention; As shown in the figure, the N utmost point of diode 1053 connects described positive supply 1051, its P utmost point extremely links to each other with the N of described diode 1054, the P utmost point of described diode 1054 connects described negative supply 1052, same, the N utmost point of diode 2063 connects described positive supply 2061, its P utmost point extremely links to each other with the N of described diode 2064, the P utmost point of diode 2064 connects described negative supply 2064, equally, the N utmost point of diode 1063 connects described positive supply 1061, and its P utmost point extremely links to each other with the N of described diode 1064, and the P utmost point of described diode 1064 connects described negative supply 1062.
Described overcurrent onunit 203 is made up of diode 2031 and diode 2032; the P utmost point of described diode 2031 and the N of described diode 2032 extremely altogether, the N utmost point of described diode 2031 and the P utmost point of described diode 2032 are connected the connection line between described second over-current overvoltage protector 201 and described second operational amplifier, 202 inverting inputs.
Suppose among Fig. 4, first over-current overvoltage protector 101 and second over-current overvoltage protector 201 all are fuse, its rated current is 50mA, described first protective resistance 103 is 200 Ω, described second protective resistance 104 is 10k Ω, and to be 100V/1A, positive supply 1051 and positive supply 1051 be-5V for+5V, negative supply 1061 and negative supply 1062 for diode 1053, diode 1054, diode 1063, diode 1064; The 3rd protective resistance 204 for 1k Ω/10W, described the 4th protective resistance 205 be 200 Ω/1W, diode 2031, diode 2032, diode 2063, diode 2064 be 100V/1A, positive supply VCC2061 for+5V, power supply VSS2062 be-5V.
On the structure as can be seen; first protective circuit 100 is voltage buffering output circuits; in the circuit operate as normal; disconnected, the empty short principle of void according to operational amplifier; described first operational amplifier, 102 positive output end voltages are identical with the voltage of the A end of described first over-current overvoltage protector 101, thereby eliminated the internal resistance influence of described first over-current overvoltage protector 101.
Described second operational amplifier 202 works in magnifying state, and the voltage of the A end of described second over-current overvoltage protector 201 is clamped at 0V.
When the case of external drive current is 2mA, this electric current is by the pressure drop of a V1=I*R1 of place, connectivity port generation of the second voltage clamp unit 206 in second protective circuit 200, and described R1 is the resistance value of the 3rd protective resistance 204, R1=1k Ω, by gain amplifier 300 with its amplification, herein, described gain amplifier 300 can be programmable gain amplifier PGA, its multiplication factor X, X=2,3,4,5; Produce the voltage drop of a voltage V2=X*I*R1 at the normal phase input end place of described first operational amplifier 102, so the output resistance of the output of final electric resistance output circuit is R=V2/I=X*1k Ω, the output resistance that is to say electric resistance output circuit just depends on the multiplication factor of gain amplifier 300.Reach the internal resistance influence of eliminating over-current overvoltage protector, improve the purpose of the precision of output resistance.
The embodiment of the invention is utilized the clamp down on effect of voltage clamp unit to voltage; and the principle of having utilized the empty weak point of operational amplifier, void to break; make electric resistance output circuit when operate as normal, eliminate over-current overvoltage protector internal resistance influence, improve the precision of circuit output resistance.
Suppose because misoperation; the false voltage of 20V appears in output; suppose the described first not fusing of over-current overvoltage protector 101; because false voltage (20V) has exceeded the supply voltage scope; so will cause diode 1053 works; the voltage of the P utmost point of diode 1053 will be clamped to+5.7V about; at this moment; will there be the voltage about 20V-5.7V=14.3V on described first over-current overvoltage protector 101; because the resistance of described first over-current overvoltage protector 101 generally has only several Ω; so described first over-current overvoltage protector 101 is fused very fast meeting; after the fusing; have only second protective resistance 104 to be connected in the whole loop; because the resistance very big (10k Ω) of described second protective resistance 104; and because the clamping action of diode 1063, the electric current that flows through on described second protective resistance 104 is approximately 1.4mA, thereby reaches the function of over-current over-voltage protection.
Suppose for a certain reason; input flows to the fault current of 20mA; suppose that over-current overvoltage protector 201 does not damage; so all electric currents will flow through the 3rd protective resistance 204; the voltage drop that on described the 3rd protective resistance 204, will produce 20V; because diode 2063; the clamping action of diode 2064; described the 3rd protective resistance 204 connects diode 2063; the voltage of diode 2064 those ends will be limited in+5.7V about; the voltage that so described the 3rd protective resistance 204 connects described second over-current overvoltage protector, 201 those ends will be 20+5.7=25.7V; this voltage acts directly on described over-current overvoltage protector 201 and diode 2031; on the diode 2032; because diode 2031; the voltage drop of diode 2032 is generally 0.7V; so the voltage of nearly 25V will act on the described over-current overvoltage protector 201, described second over-current overvoltage protector 201 will cut off circuit loop very soon.Cut off only remaining the 3rd protective resistance 204 in the inside, whole loop, back and be connected in the whole loop, because the resistance of described the 3rd protective resistance 204 has 1k Ω, the residual current of entire circuit is very little, thereby reaches the function of overcurrent protection.Described the 4th protective resistance 205 can limit the output current of described second operational amplifier 202 within its scope that can bear.
Described first over-current overvoltage protector 101 or second over-current overvoltage protector 201 can be fuse or power resistor; it generally only has several ohm, and when circuit flow was crossed big electric current, its very fast meeting was fused; thereby the cut-out circuit loop reaches the purpose of protective circuit.
More than disclosed only be preferred implementation of the present invention; but the present invention is not limited thereto; any those skilled in the art can think do not have a creationary variation, and, all should drop in protection scope of the present invention not breaking away from some improvements and modifications of being done under the principle of the invention prerequisite.
Claims (9)
1, a kind of electric resistance output circuit comprises input and output, it is characterized in that, also comprises:
One end of first over-current overvoltage protector connects described output, and its other end links to each other with the output of first operational amplifier by first protective resistance; On the line between the output of the inverting input of described first operational amplifier and described electric resistance output circuit, be in series with second protective resistance; Described first protective resistance is connected the connectivity port of the first voltage clamp unit with the line between described first over-current overvoltage protector;
The normal phase input end of described first operational amplifier connects an end of gain amplifier; The other end of described gain amplifier connects an end of the 4th protective resistance, and the other end of described the 4th protective resistance connects the output of second operational amplifier; The positive input end grounding of described second operational amplifier; inverting input connects an end of second over-current overvoltage protector; an end that on the line between the inverting input of this second operational amplifier and this second over-current overvoltage protector, is connected the overcurrent onunit; the other end ground connection of this overcurrent onunit; the other end of described second over-current overvoltage protector links to each other with the input of described electric resistance output circuit; the input of described electric resistance output circuit connects an end of the 3rd protective resistance; the other end of described the 3rd protective resistance connects the line between described the 4th protective resistance and the described gain amplifier, also is connected with the connectivity port of the second voltage clamp unit on the line between described the 4th protective resistance and the described gain amplifier.
2, electric resistance output circuit as claimed in claim 1; it is characterized in that; further comprise the tertiary voltage clamp units, the connectivity port of described tertiary voltage clamp units connects the line between the inverting input of described second protective resistance and described first operational amplifier.
3, electric resistance output circuit as claimed in claim 1 is characterized in that, the described first voltage clamp unit is made up of first positive supply, first negative supply, first diode and second diode, wherein,
The N utmost point of described first diode connects described first positive supply, its P utmost point extremely links to each other with the N of described second diode, any some connectivity port as the described first voltage clamp unit on the line between the P utmost point of described first diode and the N utmost point of described second diode, the P utmost point of described second diode connects described first negative supply.
4, electric resistance output circuit as claimed in claim 1 is characterized in that, the described second voltage clamp unit is made up of second positive supply, second negative supply, the 3rd diode and the 4th diode, wherein,
The N utmost point of described the 3rd diode connects described second positive supply, its P utmost point extremely links to each other with the N of described the 4th diode, any some connectivity port as the described second voltage clamp unit on the line between the P utmost point of described the 3rd diode and the N utmost point of described the 4th diode, the P utmost point of described the 4th diode connects described second negative supply.
5, electric resistance output circuit as claimed in claim 2 is characterized in that, described tertiary voltage clamp units is made up of the 3rd positive supply, the 3rd negative supply, the 5th diode and the 6th diode, wherein,
The N utmost point of described pentode connects described the 3rd positive supply, its P utmost point extremely links to each other with the N of described the 6th diode, any some connectivity port as described tertiary voltage clamp units on the line between the P utmost point of described the 5th diode and the N utmost point of described the 6th diode, the P utmost point of described the 6th diode connects described the 3rd negative supply.
6, electric resistance output circuit as claimed in claim 1; it is characterized in that; described overcurrent onunit is made up of the 7th diode and the 8th diode; the N utmost point of described the 7th diode and the P of described the 8th diode extremely altogether, the P utmost point of described the 7th diode is connected the line between the inverting input of described second over-current overvoltage protector and described second operational amplifier with the N utmost point of described the 8th diode.
7, as any described electric resistance output circuit among the claim 1-6, it is characterized in that described gain amplifier is a programmable gain amplifier.
8, electric resistance output circuit as claimed in claim 7 is characterized in that, described first over-current overvoltage protector is fuse or power resistor.
9, electric resistance output circuit as claimed in claim 7 is characterized in that, described second over-current overvoltage protector is fuse or power resistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2007100900772A CN100490269C (en) | 2007-03-26 | 2007-03-26 | Resistance output circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2007100900772A CN100490269C (en) | 2007-03-26 | 2007-03-26 | Resistance output circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101026300A CN101026300A (en) | 2007-08-29 |
| CN100490269C true CN100490269C (en) | 2009-05-20 |
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| Application Number | Title | Priority Date | Filing Date |
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| CNB2007100900772A Expired - Fee Related CN100490269C (en) | 2007-03-26 | 2007-03-26 | Resistance output circuit |
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| CN (1) | CN100490269C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| DE102010002695A1 (en) | 2010-03-09 | 2011-09-15 | Robert Bosch Gmbh | Method for evaluating an analog signal |
| CN102914973B (en) * | 2012-10-22 | 2015-06-17 | 南京航空航天大学 | Electronic combined resistor for engine controller object in loop simulation test |
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Granted publication date: 20090520 Termination date: 20180326 |