CN102510056A - High-precision signal source output overvoltage protection circuit - Google Patents
High-precision signal source output overvoltage protection circuit Download PDFInfo
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- CN102510056A CN102510056A CN2011104326923A CN201110432692A CN102510056A CN 102510056 A CN102510056 A CN 102510056A CN 2011104326923 A CN2011104326923 A CN 2011104326923A CN 201110432692 A CN201110432692 A CN 201110432692A CN 102510056 A CN102510056 A CN 102510056A
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Abstract
The invention provides a high-precision signal source output overvoltage protection circuit which is mainly applied to high-precision signal source equipment and a protection circuit requiring high-precision signal source output and high reliability. The high-precision signal source output overvoltage protection circuit comprises an operational amplifier module, a first voltage clamping unit, a first overcurrent and overvoltage protection unit and a feedback unit, wherein a normal-phase input end of the operational amplifier module is used for receiving the input voltage; a reversed-phase input end of the operational amplifier module is electrically connected with a second end of the first overcurrent and overvoltage protection unit through the feedback unit; an output end of the operational amplifier module is electrically connected with a first end of the first overcurrent and overvoltage protection unit; a connection port of the first voltage clamping unit is electrically connected with the output end of the operational amplifier module; the first overcurrent and overvoltage protection unit further comprises a first light-controlled field effect tube; and the first light-controlled field effect tube is a protection device with quick self cutoff of overcurrent detection.
Description
Technical field
The invention relates to a kind of output over-voltage protection circuit, particularly a kind of high-precision signal source output over-voltage protection circuit.
Background technology
In the product use, artificial operate miss appears through regular meeting, and particularly the output circuit misoperation causes damage to system.For example with output misconnection high pressure (220V alternating current etc.), perhaps with output misconnection input, the signal source that perhaps inserts surpasses the measuring range of system itself etc., the protective capacities of output circuit generally all very a little less than, can't reach very strong overvoltage protection ability.
Conventional guard method is employed in the method that adds over-current overvoltage protector spare on the connection line between circuit input end or the signal source output; As shown in Figure 1; This circuit comprises input 91, output 92, internal circuit 93 and over-current overvoltage protector spare 94; This over-current overvoltage protector spare is generally fuse or power resistor; This over-current overvoltage protector spare is connected on the connection line between said input and the output, this over-current overvoltage protector spare can guarantee circuit when input or output insert big voltage or electric current, eliminate to internal circuit in the infringement of assembly.
Because the over-current overvoltage protector spare in the foregoing circuit comprises internal resistance, supposes that the input of circuit and the voltage range between the output are 0 ~ 100mV, the internal resistance of said over-current overvoltage protector spare is 1 ohm; If drive the load of 1mA, then over-current overvoltage protector spare will produce the 1mV voltage drop, if at the higher circuit of required precision; In signal source circuit; The output error of circuit can reach 1%, and obviously, the internal resistance of said over-current overvoltage protector spare produces very big influence to the precision of circuit; Owing to have over-current overvoltage protector spare in the circuit; Be equivalent to increase the internal resistance of circuit, made the circuit load ability drop directly to cause the output accuracy of circuit to reduce.For signal source circuit, all be low-power level signal, required precision is than higher, and is only limited through conventional over-current overvoltage protector spare protective capability, and influences the reliability of signal source.
Summary of the invention
In order to overcome the defective that above-mentioned prior art exists; The purpose of this invention is to provide a kind of high-precision signal source output over-voltage protection circuit; Be mainly used in the high-precision signal source device, and some need high-precision signal output and need in the overvoltage crowbar of high reliability.Utilize this high-precision signal source output over-voltage protection circuit to carry out over-current detection automatically; Certainly turn-off fast during overcurrent; Voltage is limited in the scope that device can bear, thereby realizes the over-pressure protective capability, do not influence the output accuracy of signal source simultaneously; It is low to have solved conventional output over-voltage protection circuit protection ability, influences the technical problem of signal source precision.
Based on above-mentioned purpose, the present invention provides a kind of high-precision signal source output over-voltage protection circuit, comprising: operational amplifier module, the first voltage clamp unit, first over-current over-voltage protection unit and the feedback unit, wherein:
The normal phase input end of said operational amplifier module is used to receive input voltage; The inverting input of said operational amplifier module is electrically connected at second end of the said first over-current over-voltage protection unit via said feedback unit; The output of said operational amplifier module is electrically connected at first end of the said first over-current over-voltage protection unit; On the connection line between second end of said feedback unit and the said first over-current over-voltage protection unit is output a bit arbitrarily, is used for output voltage;
The connectivity port of the said first voltage clamp unit is electrically connected at the output of said operational amplifier module;
The said first over-current over-voltage protection unit further comprises the first photo field effect pipe.
Preferably, the said first over-current over-voltage protection unit also comprises a switch control unit, is used to control the ON/OFF of the said first photo field effect pipe, and said switch control unit comprises an anodal and negative pole; The said first photo field effect pipe comprises first end, second end, the 3rd end and the 4th end, wherein:
The positive pole of said switch control unit is electrically connected at second end of the first photo field effect pipe; The negative pole of said switch control unit is electrically connected at first end of the first photo field effect pipe; The 3rd end of the said first photo field effect pipe is electrically connected at the inverting input of said operational amplifier module via said feedback unit, and the 4th end of the said first photo field effect pipe is electrically connected at the output of said operational amplifier module.
Preferably, the said first voltage clamp unit comprises positive supply, negative supply, first diode, second diode, first Zener diode and second Zener diode, wherein:
The N utmost point of said first Zener diode and the N utmost point of said first diode are electrically connected at the A point; The P utmost point of said first Zener diode is electrically connected at earth terminal; The P utmost point of said second Zener diode and the P utmost point of said second diode are electrically connected at the B point, and the N utmost point of said second Zener diode is electrically connected at earth terminal; The A point be on the connection line of the N utmost point of the N utmost point and said first diode of said first Zener diode more arbitrarily, the B point be on the connection line of the P utmost point of the P utmost point and said second diode of said second Zener diode more arbitrarily.
Said positive supply is electrically connected at the A point between the N utmost point of the N utmost point and said first Zener diode of said first diode, and said negative supply is electrically connected at the B point between the P utmost point of the P utmost point and said second Zener diode of said second diode;
The P utmost point of said first diode and the N utmost point of said second diode electrically connect, any some connectivity port as the said first voltage clamp unit on the connection line between the P utmost point of said first diode and the N utmost point of said second diode.
Preferably, said feedback unit is first protective resistance, and said first protective resistance is electrically connected between the 3rd end of inverting input and the said first photo field effect pipe of said operational amplifier module.
As further improvement of the present invention; Said feedback unit comprises the second over-current over-voltage protection unit and the second voltage clamp unit; The said second over-current over-voltage protection unit is electrically connected between the 3rd end of inverting input and the said first photo field effect pipe of said operational amplifier module, and the connectivity port of the said second voltage clamp unit is electrically connected at the inverting input of said operational amplifier module.
Preferably, the said second over-current over-voltage protection unit comprises the second photo field effect pipe, and the said second photo field effect pipe comprises first end, second end, the 3rd end and the 4th end, wherein:
The 3rd end of the said second photo field effect pipe is electrically connected at the inverting input of said operational amplifier module; The 4th end of the said second photo field effect pipe is electrically connected at the 3rd end of the said first photo field effect pipe, and first end of the said second photo field effect pipe and second end are electrically connected between the positive pole of second end and switch control unit of the said first photo field effect pipe.
Preferably; The said second voltage clamp unit comprises the 3rd diode and the 4th diode; The N utmost point of said the 3rd diode is electrically connected at the A point between the N utmost point of the N utmost point and said first Zener diode of said first diode; The P utmost point of said the 4th diode is electrically connected at the B point between the P utmost point of the P utmost point and said second diode of said second Zener diode; The P utmost point of the 3rd diode is electrically connected at the N utmost point of the 4th diode, any some connectivity port as the said second voltage clamp unit on the connection line between the P utmost point of said the 3rd diode and the N utmost point of said the 4th diode.
As further improvement of the present invention, said high-precision signal source output over-voltage protection circuit also comprises first current-limiting resistance, and said first current-limiting resistance is electrically connected between the output and the said first voltage clamp unit of said operational amplifier module.
As further improvement of the present invention, said high-precision signal source output over-voltage protection circuit also comprises second current-limiting resistance, and said second current-limiting resistance is electrically connected between the inverting input and the said second voltage clamp unit of said operational amplifier module.
Preferably, the said first voltage clamp unit also comprises the 5th diode and the 6th diode, and said the 5th diode electrically is connected between said positive supply and the A point, and said the 6th diode electrically is connected between said negative supply and the B point, wherein:
The P utmost point of said the 5th diode is electrically connected at said positive supply, and the N utmost point of said the 5th diode and the N utmost point of first diode are electrically connected at the A point;
The N utmost point of said the 6th diode is electrically connected at said negative supply, and the P utmost point of said the 6th diode and the P utmost point of second diode are electrically connected at the B point.
The photo field effect pipe and the second photo field effect pipe all are that the band over-current detection is fast from the protection device that turn-offs.
The present invention provides a kind of high-precision signal source output over-voltage protection circuit; Utilize operational amplifier, diode, Zener diode, current-limiting resistance, carry the over-current detection ability, from photo field effect pipe of turn-off characteristic and low internal resistance characteristic etc.; Realized high-precision overvoltage protection ability; Can not influence the output accuracy of signal, both satisfy the requirement of reliability, satisfy the requirement of practicality again.Compared with prior art, the present invention has the following advantages:
1, utilizes photo field effect pipe inner band over-current detection and the ability of turn-offing certainly and the clamp function of diode and Zener diode, improved the output over-voltage protection ability greatly.
2, utilize the low internal resistance characteristic of photo field effect pipe, improved the load capacity of signal source output over-voltage protection circuit greatly, and then improved output accuracy.
3, in feedback circuit, also take the overvoltage protection measure, utilize photo field effect pipe and diode further to improve the precision of signal source output over-voltage protection circuit.
4, between power supply and Zener diode, increase diode; Utilize the reverse cut-off characteristics of diode to cut off the clamping voltage after Zener diode punctures; Make supply voltage can not change, need not select the more operational amplifier of high working voltage, thereby practice thrift cost.
5, on the basis of photo field effect pipe, Zener diode, through increasing current-limiting resistance, make the electric current that flows through operational amplifier further obtain restriction, let operational amplifier be in a safe condition all the time, significantly improved the reliability of entire circuit.
Description of drawings
Fig. 1 is the prior art constructions sketch map;
Fig. 2 is first kind of structural representation of a kind of high-precision signal of the present invention source output over-voltage protection circuit;
Fig. 3 is the circuit topological structure figure of first embodiment of a kind of high-precision signal of the present invention source output over-voltage protection circuit;
Fig. 4 is second kind of structural representation of a kind of high-precision signal of the present invention source output over-voltage protection circuit;
Fig. 5 is the circuit topological structure figure of second embodiment of a kind of high-precision signal of the present invention source output over-voltage protection circuit;
Fig. 6 is the circuit topological structure figure of the 3rd embodiment of a kind of high-precision signal of the present invention source output over-voltage protection circuit;
Fig. 7 is the 4th kind of structural representation of a kind of high-precision signal of the present invention source output over-voltage protection circuit;
Fig. 8 is the circuit topological structure figure of the 4th embodiment of a kind of high-precision signal of the present invention source output over-voltage protection circuit.
Embodiment
In the middle of specification and above-mentioned claim, used some vocabulary to censure specific assembly.Comprise that common knowledge the knowledgeable should understand in the affiliated field, same assembly may be called with different nouns by manufacturer.This specification and above-mentioned claim are not used as distinguishing the mode of assembly with the difference of title, but the benchmark that is used as distinguishing with the difference of assembly on function.Be to be an open term mentioned " comprising " in the middle of specification and the above-mentioned right request terms in the whole text, so should be construed to " comprise but be not limited to ".In addition, " electric connection " speech is to comprise any indirect means that are electrically connected that directly reach at this.Therefore, be electrically connected at one second device, then represent this first device can be directly connected in this second device, or be connected to this second device through other device or the intersegmental ground connection of connection hand if describe one first device in the literary composition.
For making the object of the invention, technical scheme and advantage more obviously understandable, hereinafter is special lifts specific embodiment, and conjunction with figs. makes detailed description, same or similar assembly or the step of same numeral indication wherein, but following embodiment is used to limit the present invention.In addition, for the purpose of simplicity of illustration, some known habitual structures and assembly will illustrate with the mode of simple signal in graphic.
In circuit design, use over-current overvoltage protector through regular meeting; Be used for protecting internal circuit under the situation of over-voltage and over-current, not to be damaged; All be the over-current overvoltage protector of directly in circuit, connecting generally speaking, as shown in Figure 1, this over-current overvoltage protector is generally fuse or power resistor; But all there is certain inherent resistance in which kind of over-current overvoltage protector spare itself; Reduced the output circuit load capacity thus, and then the output accuracy of image circuit, be even more important for signal source circuit.
First embodiment
The present invention provides a kind of high-precision signal source output over-voltage protection circuit; Fig. 2 is first kind of structural representation of a kind of high-precision signal of the present invention source output over-voltage protection circuit; Please, comprising: operational amplifier module 10, the first voltage clamp unit 20, the first over-current over-voltage protection unit 30 and feedback unit 40 with reference to Fig. 2; The first voltage clamp unit 20 is used for voltage clamp; The first over-current over-voltage protection unit 30 turn-offs when being used for overcurrent-overvoltage certainly, thereby the protection internal circuit is without prejudice; Wherein:
First kind of high-precision signal source output over-voltage protection circuit utilizes the effect of clamping down on of the 20 pairs of voltages in the first voltage clamp unit; The band over-current detection of utilizing the first photo field effect pipe is fast from turn-off characteristic; And the very little characteristic of the internal resistance of the first photo field effect pipe; The principle of also utilizing operational amplifier imaginary short, void to open circuit realizes over-pressure protection and the influence of eliminating the internal resistance of output over-voltage protection circuit, for high-precision signal source circuit provides reliable guarantee.
Fig. 3 please merge with reference to Fig. 2 and Fig. 3 for the circuit topological structure figure of first embodiment of a kind of high-precision signal of the present invention source output over-voltage protection circuit.
A kind of high-precision signal source output over-voltage protection circuit comprises: operational amplifier module 10, the first voltage clamp unit 20, the first over-current over-voltage protection unit 30 and feedback unit 40.
The first over-current over-voltage protection unit 30 comprises the first photo field effect pipe 300 and a switch control unit (figure does not show), and the first photo field effect pipe 300 comprises first end, second end, the 3rd end and the 4th end.Said switch control unit is used to control the ON/OFF of the said first photo field effect pipe, and said switch control unit comprises an anodal and negative pole.The first photo field effect pipe, 300 inside have the over-current detection ability; When electric current reaches setting; This first photo field effect pipe 300 will turn-off fast certainly, and the internal resistance of the first photo field effect pipe is lower, can too much not influence the load capacity of signal source output circuit.Said switch control unit is used to control the ON/OFF of the first photo field effect pipe 300, and this switch control unit can be resistance of a voltage source series connection, also can be a current source, and present embodiment is an example with current source 301, but is not limited thereto.Current source 301 comprises an anodal and negative pole, the positive pole and the negative pole of corresponding switch control unit respectively.
The first voltage clamp unit 20 comprises positive supply 210, negative supply 211, first diode 201, second diode 202, first Zener diode 221 and second Zener diode 222.
The positive input of operational amplifier 100 is used to receive input voltage vin as the input of high-precision signal source output over-voltage protection circuit; The inverting input of operational amplifier 100 is electrically connected at the 3rd end of the first photo field effect pipe 300 via first protective resistance 400; The output of operational amplifier 100 is electrically connected at the 4th end of the first photo field effect pipe 300; The positive power source terminal of operational amplifier 100 is electrically connected at positive supply 210, and the magnitude of voltage of positive supply 210 is VCC, and the negative power end of operational amplifier 100 is electrically connected at negative supply 211, and the magnitude of voltage of negative supply 211 is VSS.
The N utmost point of the N utmost point of first Zener diode 221 and first diode 201 is electrically connected at the A point; The P utmost point of first Zener diode 221 is electrically connected at earth terminal; The P utmost point of the P utmost point of second Zener diode 222 and second diode 202 is electrically connected at the B point, and the N utmost point of second Zener diode 222 is electrically connected at earth terminal.Here it is to be noted; The A point be on the connection line of the N utmost point of the N utmost point and first diode 201 of first Zener diode 221 more arbitrarily; The B point be on the connection line of the P utmost point of the P utmost point and said second diode 202 of said second Zener diode 222 more arbitrarily; Define A point and B point just for convenience, can not think qualification claims and specification.
The positive pole of current source 301 is electrically connected at second end of the first photo field effect pipe 300; The negative pole of current source 301 is electrically connected at first end of the first photo field effect pipe 300; The 3rd end of the first photo field effect pipe 300 is electrically connected at the inverting input of operational amplifier 100 via first protective resistance 400, and the 4th end of the first photo field effect pipe 300 is electrically connected at the output of operational amplifier 100.
Any some output end vo ut as this high-precision signal source output over-voltage protection circuit on the connection line between the 3rd end of the first photo field effect pipe 300 and first protective resistance 400 also is an output over-voltage protection point of the present invention.
The operation principle of first kind of high-precision signal source output over-voltage protection circuit is:
From circuit structure, can find out; This circuit is a voltage buffering follower, and input Vin receives input voltage, and output end vo ut is an output voltage; The purpose of this circuit cushions input voltage exactly and follows; Make output voltage V out equal input voltage vin, wherein, current source 301 is switch controlling signals of the first photo field effect pipe 300.
When operate as normal, according to the void of the operational amplifier principle that opens circuit, no current flows through on first protective resistance 400, and the inverting input voltage of operational amplifier 100 is identical with the voltage of the 3rd end of the first photo field effect pipe 300; Imaginary short principle according to operational amplifier; The normal phase input end of operational amplifier 100 and the voltage of inverting input equate; So the voltage of the first photo field effect pipe 300 the 3rd end is identical with the voltage of the normal phase input end of operational amplifier 100, thereby offset the influence of the resistance on the first photo field effect pipe 300.
When output end vo ut misconnection is to high pressure; Because the clamping action of first diode 201, second diode 202, first Zener diode 221 and second Zener diode 222; The high pressure of misconnection almost all is applied on the first photo field effect pipe 300, and the electric current that flows through the first photo field effect pipe 300 will increase fast; Because the photo field effect pipe is that the band over-current detection is fast from the protection device that turn-offs; The first photo field effect pipe, 300 inside carry the over-current detection ability; When detecting circuit above predetermined value, fast from shutoff, thereby disengagement failure voltage reaches the purpose of protection internal circuit.Because the input impedance of operational amplifier is generally all very high; So the resistance value and the power of first protective resistance 400 can be designed as suitable higher value; Even too high like this voltage is applied on first protective resistance 400 and the operational amplifier 100 through output end vo ut, also can not produce damage to first protective resistance 400 and operational amplifier 100.
Utilize the low internal resistance characteristic of the first photo field effect pipe 300, can not influence the load capacity of signal source output circuit, so just realized under the prerequisite that does not influence the signal source output accuracy, increased forceful electric power overvoltage protection ability.
Enumerate concrete data below the present invention is done further detailed description.
The first photo field effect pipe 300 adopts the photo field effect pipe that can buy on the market; GU PhotoMOS such as Panasonic company; During conducting internal resistance be 30
; The unlatching and the shutoff of current source 301 control photo field effect pipes; Photo field effect pipe inside carries current sense function, automatically shuts down when electric current reaches 170mA; Operational amplifier 100 is common operational amplifier; Its input impedance is 50M
, rated current 10mA; First diode 201, second diode 202 be 100V/1A; First Zener diode 221 and second Zener diode, 222 puncture voltages are 6.2V; The magnitude of voltage of positive supply 210 is VCC=+5V; The magnitude of voltage of negative supply 211 is VSS=-5V, first protective resistance 400 be 100
.
In the circuit operate as normal; Operation principle as above-mentioned is said; According to imaginary short, the void of the operational amplifier principle that opens circuit; This circuit input end Vin is identical with the voltage of output end vo ut, has offset the influence of the internal resistance of the first photo field effect pipe 300 to circuit, and output voltage range is-5V ~+5V.
The voltage of a 200V of having supposed output end vo ut misconnection, false voltage head and shoulders above the scope of supply voltage, will cause first diode 201, second diode 202, first Zener diode 221 and 222 clamping actions of second Zener diode.First Zener diode 221 punctures fast; A point current potential is clamped to about 6.2V; The P pole tension of first diode 201 is clamped to about 6.2V+0.7V=6.9V; At this moment, flow through on the first photo field effect pipe 300 and will have the voltage about 200V-6.9V=193.1V, about the electric current 193.1V/30 that flows through
=6.4A; The first photo field effect pipe, 300 inside carry the electric circuit inspection function; To automatically shut down when electric current surpasses 170mA when detecting, and, protect internal circuit not to be damaged so the first photo field effect pipe 300 will soon automatically shut down.Have only first protective resistance 400 to be connected in the whole loop this moment; The resistance value of first protective resistance 400 be 100
; The electric current that flows through is approximately 200V/100
=2mA; Make the operational amplifier safe condition, reached the function of over-current over-voltage protection.
Because the voltage that A is ordered is clamped at about 6.2V, the magnitude of voltage of positive supply 210 is VCC=+5V, so the magnitude of voltage of positive supply raises to some extent, therefore needs the bigger operational amplifier of selection work voltage.
Second embodiment
As further improvement of the present invention, on the basis of first kind of high-precision signal source output over-voltage protection circuit, upgrade, feedback unit has also been taked the overvoltage protection measure.Fig. 4 is for second kind of structural representation of a kind of high-precision signal of the present invention source output over-voltage protection circuit, please with reference to Fig. 4.For the difference of clear relatively present embodiment and the foregoing description, the assembly identical with first embodiment is to use identical label.
Please merge with reference to Fig. 3 and Fig. 4, feedback unit 40 has been taked the overvoltage protection measure equally, so just can omit first protective resistance 400.The infinite height of the input impedance of operational amplifier under theoretical state; But input impedance is not infinite height under the actual conditions; Especially high precision operating amplifier, its input impedance is not very high, second kind of high-precision signal source output over-voltage protection circuit omitted first protective resistance 400; Can further improve the precision of signal output, sort circuit is particularly useful for required precision than higher occasion.
Fig. 5 please merge with reference to Fig. 4 and Fig. 5 for the circuit topological structure figure of second embodiment of a kind of high-precision signal of the present invention source output over-voltage protection circuit.
Second kind of high-precision signal source output over-voltage protection circuit; Comprise: operational amplifier module 10, the first voltage clamp unit 20, the first over-current over-voltage protection unit 30 and feedback unit 40, feedback unit 40 comprises the second over-current over-voltage protection unit 41 and the second voltage clamp unit 42.
The first over-current over-voltage protection unit 30 comprises that the first photo field effect pipe 300 and a current source 301, the first photo field effect pipes 300 comprise first end, second end, the 3rd end and the 4th end.The first photo field effect pipe, 300 inside have the over-current detection ability; When electric current reaches setting; This first photo field effect pipe 300 will turn-off fast certainly, and the internal resistance of the first photo field effect pipe is lower, can too much not influence the load capacity of signal source output circuit.
The second over-current over-voltage protection unit 41 comprises the second photo field effect pipe 410; The internal structure of the said second photo field effect pipe 410 and the first photo field effect pipe 300 are identical, and the second photo field effect pipe 410 comprises first end, second end, the 3rd end and the 4th end.
The first voltage clamp unit 20 comprises positive supply 210, negative supply 211, first diode 201, second diode 202, first Zener diode 221 and second Zener diode 222.
The second voltage clamp unit 42 comprises the 3rd diode 421 and the 4th diode 422.
The positive input of operational amplifier 100 is used to receive input voltage vin as the input of high-precision signal source output over-voltage protection circuit; The inverting input of operational amplifier 100 is electrically connected at the 3rd end of the second photo field effect pipe 410; The output of operational amplifier 100 is electrically connected at the 4th end of the first photo field effect pipe 300; The positive power source terminal of operational amplifier 100 is electrically connected at positive supply 210, and the magnitude of voltage of positive supply 210 is VCC, and the negative power end of operational amplifier 100 is electrically connected at negative supply 211, and the magnitude of voltage of negative supply 211 is VSS.
The N utmost point of the N utmost point of first Zener diode 221 and first diode 201 is electrically connected at the A point; The P utmost point of first Zener diode 221 is electrically connected at earth terminal; The P utmost point of the P utmost point of second Zener diode 222 and second diode 202 is electrically connected at the B point, and the N utmost point of second Zener diode 222 is electrically connected at earth terminal.Here it is to be noted equally; The A point be on the connection line of the N utmost point of the N utmost point and first diode 201 of first Zener diode 221 more arbitrarily; The B point be on the connection line of the P utmost point of the P utmost point and said second diode 202 of said second Zener diode 222 more arbitrarily; Define A point and B point just for convenience, can not think qualification claims and specification.
First end of the first photo field effect pipe 300 is electrically connected at the negative pole of current source 301; The 3rd end of the first photo field effect pipe 300 is electrically connected at the 4th end of the second photo field effect pipe 410; The 4th end of the first photo field effect pipe 300 is electrically connected at the output of operational amplifier 100; First end of the second photo field effect pipe 410 and second end are electrically connected between the positive pole of second end and current source 301 of the first photo field effect pipe 300; That is: second end of the first photo field effect pipe 300 is electrically connected at first end of the second photo field effect pipe 410, and second end of the second photo field effect pipe 410 is electrically connected at the positive pole of current source 301.
The N utmost point of the N utmost point of the 3rd diode 421 and first diode 201 is electrically connected at the A point; The P utmost point of the P utmost point of the 4th diode 422 and second diode 202 is electrically connected at the B point; The P utmost point of the 3rd diode 421 is electrically connected at the N utmost point of the 4th diode 422, any some connectivity port as the second voltage clamp unit 42 on the connection line between the N utmost point of the P utmost point of the 3rd diode 421 and the 4th diode 422.The connectivity port of the second voltage clamp unit 42 is electrically connected at the inverting input of operational amplifier 100.
Any some output end vo ut as this high-precision signal source output over-voltage protection circuit on the connection line between the 4th end of the 3rd end of the first photo field effect pipe 300 and the second photo field effect pipe 410 also is an output over-voltage protection point of the present invention.
The operation principle of second kind of high-precision signal source output over-voltage protection circuit is:
From circuit structure, can find out; This circuit is a voltage buffering follower equally, and input Vin receives input voltage, and output end vo ut is an output voltage; The purpose of this circuit cushions input voltage exactly and follows; Make output voltage V out equal input voltage vin, wherein, current source 301 is switch controlling signals of the first photo field effect pipe 300 and the second photo field effect pipe.
When operate as normal, according to the void of the operational amplifier principle that opens circuit, no current flows through on the second photo field effect pipe 410, and the inverting input voltage of operational amplifier 100 is identical with the voltage of the 3rd end of the first photo field effect pipe 300; Imaginary short principle according to operational amplifier; The normal phase input end of operational amplifier 100 and the voltage of inverting input equate; So the voltage of the first photo field effect pipe 300 the 3rd end is identical with the voltage of the normal phase input end of operational amplifier 100, thereby offset the influence of the resistance on the first photo field effect pipe 300.
When output end vo ut misconnection is to high pressure; Because the clamping action of first diode 201, second diode 202, first Zener diode 221 and second Zener diode 222; The high pressure of misconnection almost all is applied on the first photo field effect pipe 300, and the electric current that flows through the first photo field effect pipe 300 will increase fast; Because the photo field effect pipe is that the band over-current detection is fast from the protection device that turn-offs; The first photo field effect pipe, 300 inside carry the over-current detection ability; When detecting electric current above predetermined value, fast from shutoff, thereby disengagement failure voltage reaches the purpose of protection internal circuit.
Because in fact the input impedance of high precision operating amplifier be not very high; When too high voltage is applied to the second photo field effect pipe 410 and 100 last times of operational amplifier through output end vo ut; Because the clamping action of the 3rd diode 421, the 4th diode 422, first Zener diode 221 and second Zener diode 222; High pressure almost all is applied on the second photo field effect pipe 410, and the electric current that flows through the second photo field effect pipe 410 will increase fast; Because the photo field effect pipe is that the band over-current detection is fast from the protection device that turn-offs; The second photo field effect pipe, 410 inside carry the over-current detection ability; When detecting circuit above predetermined value; Certainly turn-off fast, thereby disengagement failure voltage reaches the purpose of protection internal circuit, especially makes operational amplifier 100 be in a safe condition.
The 3rd embodiment
As further improvement of the present invention, on the basis of first kind of high-precision signal source output over-voltage protection circuit and second kind of high-precision signal source output over-voltage protection circuit, upgrade, improvement has been made in the first voltage clamp unit.Fig. 6 is the circuit topological structure figure of the 3rd embodiment of a kind of high-precision signal of the present invention source output over-voltage protection circuit; The electrical block diagram of present embodiment is identical with second embodiment; Please merge with reference to Fig. 4 and Fig. 6; For the difference of clear relatively present embodiment and the foregoing description, identical assembly is to use identical label.
Compared to the first voltage clamp unit 20 of first embodiment and second embodiment, the first voltage clamp unit 20 in the third high-precision signal source output over-voltage protection circuit also comprises the 5th diode 205 and the 6th diode 206.
The 5th diode 205 is electrically connected between positive supply 210 and the A point; The 6th diode 206 is electrically connected between negative supply 211 and the B point; Wherein: the P utmost point of the 5th diode 205 is electrically connected at the N utmost point of positive supply 210, the five diodes 205 and the N utmost point of first diode 201 is electrically connected at the A point; The N utmost point of the 6th diode 206 is electrically connected at the P utmost point of negative supply 211, the six diodes 206 and the P utmost point of second diode is electrically connected at the B point.The something in common of the present embodiment and second embodiment repeats no more here.
The operation principle of the third high-precision signal source output over-voltage protection circuit and second kind of high-precision signal source output over-voltage protection circuit are basic identical, and difference is:
The effect of the 5th diode 205 and the 6th diode 206 is: under the overvoltage malfunction, cut off the clamping voltage after first Zener diode 221 punctures through the reverse cut-off characteristics of the 5th diode 205; Cut off the clamping voltage after second Zener diode 222 punctures through the reverse cut-off characteristics of the 6th diode 206.
Those skilled in the art have common knowledge the knowledgeable and know: generally; The puncture voltage design load of first Zener diode 221 and second Zener diode 222 is higher than VCC and VSS; As described in first embodiment; The puncture voltage of first Zener diode 221 and second Zener diode 222 is 6.2V, VCC=+5V, VSS=-5V.Under overvoltage condition; Because the clamping action of first Zener diode 221 and second Zener diode 222; Positive supply VCC value and negative supply VSS value among the embodiment that wins are slightly raise; Described in concrete the giving an example of first embodiment, then just need select the more operational amplifier of high working voltage for use, thus cause the significantly rising of cost.Present embodiment is through increasing the 5th diode 205 and the 6th diode 206; Utilize the reverse cut-off characteristics of diode; Make the voltage of positive supply 210 and negative supply 211 can not rise with the puncture voltage of Zener diode; Thereby solved this problem, need not increase cost and buy the higher operational amplifier of operating voltage.Even output end vo ut misconnection high pressure can not cause the variation of positive supply VCC value and negative supply VSS value yet, thereby practice thrift cost.
The 4th embodiment
As further improvement of the present invention, on second kind of basis with the third high-precision signal source output over-voltage protection circuit, upgrade, through increasing the reliability that current-limiting resistance promotes entire circuit.Fig. 7 is for the 4th kind of structural representation of a kind of high-precision signal of the present invention source output over-voltage protection circuit, and please with reference to Fig. 7, for the difference of clear relatively present embodiment and the foregoing description, identical assembly is to use identical label.
Compared to the electrical block diagram (Fig. 4) of second embodiment and the 3rd embodiment, the 4th kind of high-precision signal source output over-voltage protection circuit also comprises first current-limiting resistance 51 and second current-limiting resistance 52.First current-limiting resistance 51 is electrically connected between the output and the first voltage clamp unit 20 of operational amplifier module 10, and second current-limiting resistance 52 is electrically connected between the inverting input and the second voltage clamp unit 42 of operational amplifier module 10.The something in common of this electrical block diagram and the second and the 3rd embodiment repeats no more here.
Fig. 8 is the circuit topological structure figure of the 4th embodiment of a kind of high-precision signal of the present invention source output over-voltage protection circuit; Please merge with reference to Fig. 7 and Fig. 8; Give an example for ease; Fig. 8 has increased by first current-limiting resistance 51 and second current-limiting resistance 52 on the basis of Fig. 6, but is not limited thereto, and can also on the basis of Fig. 5, increase.
First current-limiting resistance 51 is electrically connected between the connectivity port of output and the first voltage clamp unit 20 of operational amplifier 100, and second current-limiting resistance 52 is electrically connected between the connectivity port of inverting input and the second voltage clamp unit 42 of operational amplifier 100.The something in common of this circuit topological structure figure and the 3rd embodiment repeats no more here.
The operation principle of the 4th kind of high-precision signal source output over-voltage protection circuit and the third high-precision signal source output over-voltage protection circuit are basic identical, and difference is:
The effect of first current-limiting resistance 51 and second current-limiting resistance 52 is: under the overvoltage malfunction, the electric current of operational amplifier 100 is flow through in restriction.
Those skilled in the art have common knowledge the knowledgeable and know; The input of operational amplifier and output pin all have overvoltage preferably, overcurrent protection ability, and the technical scheme through first, second, third embodiment can solve the technical problem in the output over-voltage protection circuit of the overwhelming majority.If desired more reliably during circuit protection; Especially high-precision operational amplifier; Input impedance is lower than common operational amplifier, through increasing by first current-limiting resistance 51 and second current-limiting resistance 52, makes the electric current that flows through operational amplifier 100 further obtain restriction; Let operational amplifier be in a safe condition better, thereby significantly improve the reliability of entire circuit.
In sum; The present invention provides a kind of high-precision signal source output over-voltage protection circuit; Utilize operational amplifier, diode, Zener diode, current-limiting resistance, carry the over-current detection ability, from photo field effect pipe of turn-off characteristic and low internal resistance characteristic etc., realized high-precision overvoltage protection ability, can not influence the output accuracy of signal; Both satisfied the requirement of reliability; Satisfy the requirement of practicality again, be particularly useful for the high-precision signal source device, and some circuit that need high-precision signal output and need high reliability.Compared with prior art, the present invention has the following advantages:
1, utilizes photo field effect pipe inner band over-current detection and the ability of turn-offing certainly and the clamp function of diode and Zener diode, improved the output over-voltage protection ability greatly.
2, utilize the low internal resistance characteristic of photo field effect pipe, improved the load capacity of high-precision signal source output over-voltage protection circuit greatly.
3, in feedback circuit, also take the overvoltage protection measure, utilize photo field effect pipe and diode further to improve the precision of signal source output over-voltage protection circuit.
4, between power supply and Zener diode, increase diode; Utilize the reverse cut-off characteristics of diode to cut off the clamping voltage after Zener diode punctures; Make supply voltage can not change, need not select the more operational amplifier of high working voltage, thereby practice thrift cost.
5, on the basis of photo field effect pipe, Zener diode, through increasing current-limiting resistance, make the electric current that flows through operational amplifier further obtain restriction, let operational amplifier be in a safe condition all the time, significantly improved the reliability of entire circuit.
Though the present invention with embodiment openly as above; Right its is not in order to limit the present invention; Has common knowledge the knowledgeable in the technology neck under any; Do not breaking away from the spirit and scope of the present invention, when can doing various variations and retouching, so protection scope of the present invention is as the criterion when looking above-mentioned the claim scope person of defining.
Claims (10)
1. a high-precision signal source output over-voltage protection circuit is characterized in that, comprising: operational amplifier module, the first voltage clamp unit, first over-current over-voltage protection unit and the feedback unit, wherein:
The normal phase input end of said operational amplifier module is used to receive input voltage; The inverting input of said operational amplifier module is electrically connected at second end of the said first over-current over-voltage protection unit via said feedback unit; The output of said operational amplifier module is electrically connected at first end of the said first over-current over-voltage protection unit; On the connection line between second end of said feedback unit and the said first over-current over-voltage protection unit is output a bit arbitrarily, is used for output voltage;
The connectivity port of the said first voltage clamp unit is electrically connected at the output of said operational amplifier module;
The said first over-current over-voltage protection unit further comprises the first photo field effect pipe.
2. high-precision signal as claimed in claim 1 source output over-voltage protection circuit; It is characterized in that; The said first over-current over-voltage protection unit also comprises a switch control unit, is used to control the ON/OFF of the said first photo field effect pipe, and said switch control unit comprises an anodal and negative pole; The said first photo field effect pipe comprises first end, second end, the 3rd end and the 4th end, wherein:
The positive pole of said switch control unit is electrically connected at second end of the first photo field effect pipe; The negative pole of said switch control unit is electrically connected at first end of the first photo field effect pipe; The 3rd end of the said first photo field effect pipe is electrically connected at the inverting input of said operational amplifier module via said feedback unit, and the 4th end of the said first photo field effect pipe is electrically connected at the output of said operational amplifier module.
3. according to claim 1 or claim 2 high-precision signal source output over-voltage protection circuit; It is characterized in that; The said first voltage clamp unit comprises positive supply, negative supply, first diode, second diode, first Zener diode and second Zener diode, wherein:
The N utmost point of said first Zener diode and the N utmost point of said first diode are electrically connected at the A point; The P utmost point of said first Zener diode is electrically connected at earth terminal; The P utmost point of said second Zener diode and the P utmost point of said second diode are electrically connected at the B point, and the N utmost point of said second Zener diode is electrically connected at earth terminal;
Said positive supply is electrically connected at the A point between the N utmost point of the N utmost point and said first Zener diode of said first diode, and said negative supply is electrically connected at the B point between the P utmost point of the P utmost point and said second Zener diode of said second diode;
The P utmost point of said first diode and the N utmost point of said second diode electrically connect, any some connectivity port as the said first voltage clamp unit on the connection line between the P utmost point of said first diode and the N utmost point of said second diode.
4. high-precision signal as claimed in claim 2 source output over-voltage protection circuit; It is characterized in that; Said feedback unit is first protective resistance, and said first protective resistance is electrically connected between the 3rd end of inverting input and the said first photo field effect pipe of said operational amplifier module.
5. high-precision signal as claimed in claim 3 source output over-voltage protection circuit; It is characterized in that; Said feedback unit comprises the second over-current over-voltage protection unit and the second voltage clamp unit; The said second over-current over-voltage protection unit is electrically connected between the 3rd end of inverting input and the said first photo field effect pipe of said operational amplifier module, and the connectivity port of the said second voltage clamp unit is electrically connected at the inverting input of said operational amplifier module.
6. high-precision signal as claimed in claim 5 source output over-voltage protection circuit; It is characterized in that; The said second over-current over-voltage protection unit comprises the second photo field effect pipe, and the said second photo field effect pipe comprises first end, second end, the 3rd end and the 4th end, wherein:
The 3rd end of the said second photo field effect pipe is electrically connected at the inverting input of said operational amplifier module; The 4th end of the said second photo field effect pipe is electrically connected at the 3rd end of the said first photo field effect pipe, and first end of the said second photo field effect pipe and second end are electrically connected between the positive pole of second end and switch control unit of the said first photo field effect pipe.
7. high-precision signal as claimed in claim 5 source output over-voltage protection circuit; It is characterized in that; The said second voltage clamp unit comprises the 3rd diode and the 4th diode; The N utmost point of said the 3rd diode is electrically connected at the A point between the N utmost point of the N utmost point and said first Zener diode of said first diode; The P utmost point of said the 4th diode is electrically connected at the B point between the P utmost point of the P utmost point and said second diode of said second Zener diode; The P utmost point of the 3rd diode is electrically connected at the N utmost point of the 4th diode, any some connectivity port as the said second voltage clamp unit on the connection line between the P utmost point of said the 3rd diode and the N utmost point of said the 4th diode.
8. high-precision signal as claimed in claim 5 source output over-voltage protection circuit; It is characterized in that; Said high-precision signal source output over-voltage protection circuit also comprises first current-limiting resistance, and said first current-limiting resistance is electrically connected between the output and the said first voltage clamp unit of said operational amplifier module.
9. high-precision signal as claimed in claim 5 source output over-voltage protection circuit; It is characterized in that; Said high-precision signal source output over-voltage protection circuit also comprises second current-limiting resistance, and said second current-limiting resistance is electrically connected between the inverting input and the said second voltage clamp unit of said operational amplifier module.
10. high-precision signal as claimed in claim 3 source output over-voltage protection circuit; It is characterized in that; The said first voltage clamp unit also comprises the 5th diode and the 6th diode; Said the 5th diode electrically is connected between said positive supply and the A point, and said the 6th diode electrically is connected between said negative supply and the B point, wherein:
The P utmost point of said the 5th diode is electrically connected at said positive supply, and the N utmost point of said the 5th diode and the N utmost point of first diode are electrically connected at the A point;
The N utmost point of said the 6th diode is electrically connected at said negative supply, and the P utmost point of said the 6th diode and the P utmost point of second diode are electrically connected at the B point.
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| CN201110432692.3A CN102510056B (en) | 2011-12-21 | 2011-12-21 | High-precision signal source output overvoltage protection circuit |
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| CN105226605A (en) * | 2015-10-22 | 2016-01-06 | 江苏绿扬电子仪器集团有限公司 | A kind of high-precision signal source output overvoltage protection circuit |
| CN109921400A (en) * | 2019-04-03 | 2019-06-21 | 昆山通达测科电子科技有限公司 | High-speed high-power surge voltage-suppressing circuit |
| CN111313365A (en) * | 2020-03-30 | 2020-06-19 | 福州京东方光电科技有限公司 | Overvoltage protection circuit, overvoltage protection method and display device |
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| CN109921400A (en) * | 2019-04-03 | 2019-06-21 | 昆山通达测科电子科技有限公司 | High-speed high-power surge voltage-suppressing circuit |
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| CN111313365A (en) * | 2020-03-30 | 2020-06-19 | 福州京东方光电科技有限公司 | Overvoltage protection circuit, overvoltage protection method and display device |
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| CN102510056B (en) | 2015-01-21 |
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