CN104198783B - Power sense circuit and power receiving equipment with temperature compensation characteristic - Google Patents
Power sense circuit and power receiving equipment with temperature compensation characteristic Download PDFInfo
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- CN104198783B CN104198783B CN201410481905.5A CN201410481905A CN104198783B CN 104198783 B CN104198783 B CN 104198783B CN 201410481905 A CN201410481905 A CN 201410481905A CN 104198783 B CN104198783 B CN 104198783B
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Abstract
The present invention provides a kind of power sense circuit and parasite power supplier with temperature compensation characteristic, and the power sense circuit includes：Voltage-current conversion circuit, its input connects supply voltage incoming end, supply voltage is converted to the first electric current, the second electric current and the 3rd electric current by the Voltage-current conversion circuit, second electric current is equal to the first electric current and the second electric current sum, second electric current is exported via the first output end, and the 3rd electric current is exported via the second output end；Micro-current source, its input receives second electric current, and its output end produces the 4th electric current；Wherein, the 3rd electric current and the 4th electric current compare generation comparison signal.The present invention can save band-gap reference and comparator without reference voltage, be conducive to reducing chip area.
Description
Technical field
The present invention relates to power detecting technology, more particularly to a kind of power sense circuit with temperature compensation characteristic and
Power receiving equipment comprising the power sense circuit.
Background technology
In ic power managing chip, POE (PoE, Power over is especially applicable to
During power receiving equipment (PD, Power Device) Ethernet) in system, as power supply unit (PSE, Power Source
When Equipment) detecting power receiving equipment, supply voltage particular range in can be provided power receiving equipment, and power receiving equipment must then be examined
The supply voltage is surveyed, and switches the circuit to detection state.Or it is to be applied to under-voltage protection (UVLO, Under Voltage
Lock Out) etc. circuit when, send enable signal when detecting supply voltage and falling in normal range (NR), it is ensured that circuit is operated in
Under safe and reliable supply voltage.
As shown in figure 1, traditional power sense circuit is by supply voltage V by voltage comparator 12inWith band-gap reference
11 reference voltage Vs producedrefCompare and realize.Wherein, supply voltage VinBy resistance R1With resistance R2Inputted after decompression to
Comparator 12, voltage after decompression is more than reference voltage VrefWhen, the output level upset of comparator 12, being provided for system makes
Can signal.Reference voltage VrefProduced by band-gap reference 11, it is ensured that reference voltage VrefWith low-temperature coefficient.Above-mentioned controlling party
Method can make the threshold voltage of power detecting have a characteristic that precision is high, temperature drift is small, but its circuit design it is complicated, it is necessary to
Additional designs band-gap reference 11 and comparator 12, cause chip area to increase, and extra module needs power-on time, cause inspection
The survey time is elongated, or even detection failure.
The content of the invention
The problem to be solved in the present invention is to provide a kind of power sense circuit and power receiving equipment with temperature compensation characteristic,
Without reference voltage, band-gap reference and comparator can be saved, is conducive to reducing chip area.
In order to solve the above technical problems, the invention provides a kind of power sense circuit with temperature compensation characteristic, bag
Include：
Voltage-current conversion circuit, its input connection supply voltage incoming end, the Voltage-current conversion circuit is electric by power supply
Pressure is converted to the first electric current, the second electric current and the 3rd electric current, and the second electric current is equal to the first electric current and the 3rd electric current sum, and described the
Two electric currents are exported via the first output end, and the 3rd electric current is exported via the second output end；
Micro-current source, its input receives second electric current, and its output end produces the 4th electric current；
Wherein, the 3rd electric current and the 4th electric current compare generation comparison signal.
According to one embodiment of present invention, the Voltage-current conversion circuit includes：
First PNP triode, its emitter stage connects the supply voltage incoming end to receive the supply voltage, its base stage
Connect the colelctor electrode of first PNP triode；
Second PNP triode, its emitter stage connects the supply voltage incoming end, and its base stage connects the first PNP tri-
The base stage of pole pipe, its colelctor electrode as the Voltage-current conversion circuit the second output end；
First resistor, its first end connects the supply voltage incoming end, and its second end connects first PNP triode
Colelctor electrode；
Second resistance, its first end connects the colelctor electrode of first PNP triode, and its second end turns as the voltage
First output end of current circuit；
Wherein, the electric current for flowing through the first resistor is first electric current, and it is institute to flow through the electric current of the second resistance
The second electric current is stated, the electric current of the colelctor electrode of second PNP triode is the 3rd electric current.
According to one embodiment of present invention, the micro-current source includes：
First NPN triode, its colelctor electrode connects the second end of the second resistance, and its base stage connects the first NPN
The colelctor electrode of triode, its grounded emitter；
Second NPN triode, its colelctor electrode connects the colelctor electrode of second PNP triode, its base stage connection described the
The base stage of one NPN triode, the colelctor electrode output comparison signal of second NPN triode, the collection of second NPN triode
The electric current of electrode is the 4th electric current；
3rd resistor, its first end connects the emitter stage of second NPN triode, its second end ground connection.
According to one embodiment of present invention, the power sense circuit also includes：Level shifting circuit, compares letter by described
Number be converted to digital level.
According to one embodiment of present invention, the power sense circuit also includes：
4th resistance, the second end of the second resistance connects the collection of first NPN triode via the 4th resistance
Electrode；
6th switching tube, its first end connects the first end of the 4th resistance, and its second end connects the 4th resistance
The second end, its control end receives the digital level.
According to one embodiment of present invention, the level shifting circuit includes：
Schmitt inverter, its input receives the comparison signal；
Phase inverter, its input connects the output end of the schmitt inverter, and its output end exports the digital level.
According to one embodiment of present invention, it is described when the supply voltage rises to first threshold voltage from low to high
Digital level is overturn；When the supply voltage drops to second threshold voltage from high to low, the digital level is turned over
Turn, the first threshold voltage is more than the second threshold voltage.
According to one embodiment of present invention, the first threshold voltage is：
The second threshold voltage is：
Wherein, R1For the resistance value of the first resistor, R2For the resistance value of the second resistance, R3For the described 3rd electricity
The resistance value of resistance, R4For the resistance value of the 4th resistance, VbeFor first PNP triode, the second PNP triode and
The base emitter voltage of one NPN triode, VT=kT/q, k are Boltzmann constant, and T is temperature, and q is that electron charge is normal
Number, n is the dimension scale of second NPN triode and the first NPN triode.
According to one embodiment of present invention, the colelctor electrode of second NPN triode connects institute via the 4th switching tube
The colelctor electrode of the second PNP triode is stated, wherein, the first end of the 4th switching tube connects the collection of second PNP triode
Electrode, the second end of the 4th switching tube connects the colelctor electrode of second NPN triode, the control of the 4th switching tube
End receives the bias voltage that biasing circuit is provided.
According to one embodiment of present invention, the biasing circuit includes：
6th resistance, its first end connects the supply voltage incoming end；
Voltage-regulator diode, its negative electrode connects the second end of the 6th resistance, its plus earth.
In order to solve the above problems, present invention also offers a kind of power receiving equipment, the power receiving equipment includes any of the above
The power sense circuit of described temperature compensation characteristic.
Compared with prior art, the present invention has advantages below：
Supply voltage is converted to the 3rd electric current by the power sense circuit of the embodiment of the present invention using Voltage-current conversion circuit,
The 4th electric current that 3rd electric current is produced with micro-current source is compared to produce comparison signal, and the comparison signal indicates power supply
The scope of voltage, the power sense circuit of the embodiment of the present invention is without reference circuit, so that band-gap reference and comparator are eliminated,
Be conducive to reducing chip area；And temperature-compensating can be realized by adjusting the resistance in circuit, reduce threshold voltage
Temperature drift.
Furthermore, the power sense circuit of the embodiment of the present invention can also include lag function, can prevent output
Comparison signal and enable signal saltus step with the shake of supply voltage.
In addition, the power sense circuit of the embodiment of the present invention also limits the first PNP by the 4th switching tube and biasing circuit
Triode, the second PNP triode, the first NPN triode, colelctor electrode-emitter stage pressure difference of the second NPN triode, reduce strategic point
The error that sharp effect is introduced to threshold voltage.
Brief description of the drawings
Fig. 1 is a kind of electrical block diagram of power sense circuit in the prior art；
Fig. 2 is the electrical block diagram of power sense circuit according to a first embodiment of the present invention；
Fig. 3 is the electrical block diagram of power sense circuit according to a second embodiment of the present invention；
Fig. 4 is the electrical block diagram of power sense circuit according to a third embodiment of the present invention；
Fig. 5 is the electrical block diagram of power sense circuit according to a fourth embodiment of the present invention；
Fig. 6 A and Fig. 6 B are the signal waveform schematic diagrames of power sense circuit shown in Fig. 5.
Embodiment
With reference to specific embodiments and the drawings, the invention will be further described, but the guarantor of the present invention should not be limited with this
Protect scope.
First embodiment
With reference to Fig. 2, the power sense circuit with temperature compensation characteristic of the present embodiment includes Voltage-current conversion circuit 21
With micro-current source 22.
Wherein, Voltage-current conversion circuit 21 is used for supply voltage VinBe converted to electric current, and exported with micro-current source 22
Electric current is compared, and produces the comparison signal for indicating comparative result.Furthermore, Voltage-current conversion circuit 21 is by supply voltage
VinBe converted to the first electric current I1, the second electric current I2With the 3rd electric current I3, wherein, the second electric current I2Equal to the first electric current I1With the 3rd
Electric current I3Sum；The input of micro-current source 22 receives the second electric current I2, the 4th electric current I of output end generation of micro-current source 224,
4th electric current I4With the 3rd electric current I3Same node can be flowed to be compared, to produce comparison signal V1.Turned by adjusting voltage
The resistance and ratio of each resistance in current circuit 21 and micro-current source 22, can be with the size of adjusting threshold voltage and temperature system
Number, so as to realize that threshold voltage can reconcile the temperature compensation function of threshold voltage.
As a preferred embodiment, Voltage-current conversion circuit 21 can include PNP triode Q1, PNP triode Q2、
Resistance R1With resistance R2；Micro-current source 22 can include NPN triode Q3, NPN triode Q4And resistance R3。
Wherein, PNP triode Q1Emitter stage connection supply voltage incoming end to receive supply voltage Vin, the connection of its base stage
The colelctor electrode of itself；PNP triode Q2Emitter stage connection supply voltage incoming end, its base stage connection PNP triode Q1Base
Pole；Resistance R1First end connection supply voltage incoming end, its second end connect the first PNP triode Q1Colelctor electrode；Resistance R2
First end connection PNP triode Q1Colelctor electrode；NPN triode Q3Colelctor electrode connection second resistance R2The second end, its base
Pole connects the colelctor electrode of itself, its grounded emitter；NPN triode Q4Colelctor electrode connection PNP triode Q2Colelctor electrode, its
Base stage connection NPN triode Q3Base stage, NPN triode Q4Colelctor electrode output comparison signal V1。
Wherein, the resistance R is flowed through1Electric current be the first electric current I1, flow through second resistance R2Electric current be the second electric current
I2, PNP triode Q2Colelctor electrode electric current be the 3rd electric current I3, NPN triode Q4Colelctor electrode electric current be the 4th electric current I4。
Wherein, setting NPN triode Q3With NPN triode Q4Dimension scale be 1：N (n is positive number, for example, n=4), can
It is as follows with the 4th electric current I4 for obtaining the micro-current source 22 generation：
Wherein, Vbe3For NPN triode Q3Base emitter voltage, Vbe4For NPN tri-
Pole pipe Q4Base emitter voltage, VT=kT/q, k are Boltzmann constant, and T is temperature, and q is electron charge constant, R3For
Resistance R3Resistance value.
PNP triode Q1With PNP triode Q2Form current mirror, PNP triode Q2Colelctor electrode produce the 3rd electric current
I3, from figure 2 it can be seen that flowing through resistance R2The second electric current I2It is the first electric current I1With the 3rd electric current I3Sum, wherein first
Electric current I1It is to flow through resistance R1Electric current.
3rd electric current I3Expression formula it is as follows：
Wherein, VinFor input voltage VinMagnitude of voltage, Vbe3For the poles of NPN tri-
Pipe Q3Base emitter voltage, Vbe1For PNP triode Q1Base emitter voltage, R2For resistance R2Resistance value, R4For
Resistance R4Resistance value, R1For resistance R1Resistance value.
Generally it can be thought that PNP triode Q1, PNP triode Q2And NPN triode Q3Base emitter voltage it is near
Patibhaga-nimitta etc., is Vbe, then electric current I3With electric current I4Transmit to same node equivalent to formation current comparator, both electric currents
Difference is：
Therefore , ⊿ I are and supply voltage VinThe function , being directly proportional is when ⊿ I zero passages, comparison signal V1It can overturn.
Input voltage VinRise from low to high, cause comparison signal V1The supply voltage V overturninFirst threshold voltage be designated as
VTH1；Input voltage VinDecline from high to low, cause comparison signal V1The supply voltage V overturninSecond threshold voltage note
For VTH2, then have following relation：
WhereinIt is typical first compensation phase band-gap reference expression formula,For proportionality coefficient, lead to
Overregulate resistance R1、R2Resistance value can adjust the proportionality coefficient, it is hereby achieved that required different threshold voltages,
It can in addition contain by adjusting resistance R3Resistance value can realize single order temperature-compensating.
Second embodiment
With reference to Fig. 3, Fig. 3 shows the circuit structure of the power sense circuit of second embodiment, and it is in first embodiment
On the basis of add level shifting circuit 23, the input of the level shifting circuit 23 receives comparison signal V1, this is compared into letter
Number be converted to digital level V2。
Comparison signal V1Indicator current result of the comparison, typically analog signal, level shifting circuit 23 are converted into
Digital logic signal, namely digital level V2.It should be noted that comparison signal V1Itself it can indicate supply voltage Vin
Change, level shifting circuit 23 is converted into digital level V2, primarily can be used for it is compatible with other adjunct circuits, for example
Digital level V can be utilized2To control other adjunct circuits.
3rd embodiment
With reference to Fig. 4, Fig. 4 shows the circuit structure of the power sense circuit of 3rd embodiment, and it is in first embodiment
On the basis of add level shifting circuit 23, biasing circuit 24, resistance R4, switching tube M6And switching tube M4.Level conversion electricity
The input on road 23 receives comparison signal V1, the comparison signal is converted into digital level V2；Second resistance R2The second end via
4th resistance R4Connect NPN triode Q3Colelctor electrode, switching tube M6 first end connection resistance R4First end, its second end
Connect resistance R4The second end, its control end receives digital level V2；NPN triode Q2Colelctor electrode via switching tube M4Connection
PNP triode Q4Colelctor electrode, wherein, switching tube M4First end connection PNP triode Q2Colelctor electrode, switching tube Q4
Two ends connection NPN triode Q4Colelctor electrode, switching tube M4 control end receives the bias voltage V that biasing circuit 24 is providedb。
Wherein, resistance R4With switching tube M6For introducing hysteresis effect.Specifically, supply voltage VinRise from low to high
To first threshold voltage VTH1When, digital level V2Overturn；Supply voltage VinSecond threshold voltage is dropped to from high to low
VTH2When, digital level V2Overturn, first threshold voltage VTH1More than second threshold voltage VTH2。
Furthermore, in supply voltage VinDuring rising from low-voltage toward high voltage, electric current I4It is more than electricity first
Flow I3So that comparison signal V1It is first in low level, corresponding digital level V2It is also at logic low so that switching tube
M6(it is assumed that switching tube M6For nmos pass transistor) it is turned off；As supply voltage VinRise to first threshold voltage VTH1When, compare letter
Number V1With digital level V2Overturn as high level so that switching tube M6Conducting.In supply voltage VinHigh voltage declines toward low-voltage
When, electric current I4It is less than electric current I first3So that comparison signal V1It is first in high level, corresponding digital level V2It is also at and patrols
Collect high level, switching tube M6Conducting；As supply voltage VinDrop to second threshold voltage VTH2When, comparison signal V1With numeral electricity
Flat V2Overturn as low level so that switching tube M6Shut-off.
Switching tube M4Can be by comparison signal V1High level be limited to highest Vb-Vgs4, so as to level shift circuit 23
Protection is formed, plays a part of clamper protection, wherein VbFor bias voltage VbMagnitude of voltage, Vgs4For switching tube M4Grid source electricity
Pressure.In addition, switching tube M4PNP triode Q1 and PNP triode Q2, NPN triode Q3 and NPN triode Q4 collection can be limited
Electrode-transmitter pole tension is poor, so as to reduce the error that sharp (Early) effect in distress is introduced to threshold voltage.
Fourth embodiment
With reference to Fig. 5, Fig. 5 shows the circuit structure of the power sense circuit of fourth embodiment, its general structure and Fig. 4 institutes
Show that 3rd embodiment is identical, difference is only the physical circuit that fourth embodiment gives level shifting circuit 23 and biasing circuit 24
Structure.
With reference to Fig. 5, level shifting circuit 23 includes：Schmitt inverter S1, its input reception comparison signal V1；It is anti-phase
Device N1, its input connection schmitt inverter S1Output end, its output end output digital level V2.Biasing circuit 24 includes：
6th resistance R6, its first end connects supply voltage incoming end to receive supply voltage Vin；Voltage-regulator diode D1, the connection of its negative electrode
6th resistance R6The second end, its plus earth.
In biasing circuit 24, resistance R6With voltage-regulator diode D1Current path is formed, is produced in the negative electrode of voltage-regulator diode inclined
Put voltage Vb, bias voltage VbTransmit to switching tube M4Control end, be switching tube M4Biasing is provided.
Fig. 6 A show supply voltage Vin when rising from low-voltage to high voltage, the 3rd electric current I3, the 4th electric current I4, ratio
Compared with signal V1And digital level V2With supply voltage VinChange curve.With reference to Fig. 5 and Fig. 6 A, in supply voltage VinFrom low electricity
Press during rising toward high voltage, electric current I4It is more than electric current I first3So that comparison signal V1Low level is first in, is passed through
Schmitt inverter S1With phase inverter N1Afterwards, digital level V2For low level signal so that switching tube M6(it is assumed that switching tube M6For
Nmos pass transistor) it is turned off, therefore electric current I3Expression formula it is as follows：
Wherein, VinFor input voltage VinMagnitude of voltage, Vbe3For the poles of NPN tri-
Pipe Q3Base emitter voltage, Vbe1For PNP triode Q1Base emitter voltage, R2For resistance R2Resistance value, R4For
Resistance R4Resistance value, R1For resistance R1Resistance value.
Generally it can be thought that PNP triode Q1, PNP triode Q2And NPN triode Q3Base emitter voltage it is near
Patibhaga-nimitta etc., is Vbe, then electric current I3With electric current I4Transmit to same node equivalent to formation current comparator, both electric currents
Difference is：
Therefore , ⊿ I are and supply voltage VinThe function , being directly proportional is when ⊿ I zero passages, comparison signal V1It can overturn.
Therefore input voltage VinWhen rising from low to high, cause comparison signal V1The first threshold voltage V invertedTH1For：
Namely input voltage VinRise from low to high and reach first threshold voltage VTH1When, comparison signal V1It will turn over
Turn, whereinIt is typical first compensation phase band-gap reference expression formula,For ratio system
Number, by adjusting resistance R1、R2、R4Resistance value can adjust the proportionality coefficient, it is hereby achieved that required different thresholds
Threshold voltage, it can in addition contain by adjusting resistance R3Resistance value can realize single order temperature-compensating.
Fig. 6 B show supply voltage VinWhen declining from high voltage to low-voltage, the 3rd electric current I3, the 4th electric current I4, ratio
Compared with signal V1And digital level V2With supply voltage VinChange curve, it is necessary to explanation, in order to meet drawing convention, figure
Abscissa V in 6BinIt is still to change from small to large, therefore Fig. 6 B abscissa when checking from right to left, embodies input
Voltage VinVariation tendency from high to low.With reference to Fig. 5 and Fig. 6 B, as supply voltage VinRise to first threshold voltage VTH1More than
When, comparison signal V1It is high level by low level upset, by schmitt inverter S1With phase inverter N1Afterwards, switching tube M is made6(this
In embodiment be, for example, NMOS tube) switched to by shut-off it is open-minded.Afterwards, if supply voltage VinDecline from high voltage to low-voltage
When, when dropping to second threshold voltage VTH2When, comparison signal V1, digital level can be overturn, with first threshold voltage VTH1
It can similarly obtain, second threshold voltage VTH2For：
Obviously, VTH1>VTH2, thus hysteresis effect can be realized.Specifically, supply voltage VinWhen rising from low to high,
Reaching larger first threshold voltage VTH1When comparison signal V1It can overturn, and as supply voltage VinDecline from high to low
When, reaching relatively low second threshold voltage VTH2When, comparison signal V1It can just overturn, can so prevent comparison signal
V1, digital level V2 are in supply voltage VinSaltus step occurs during shake.
It should be noted that " high voltage " " low-voltage " " high level " " low level " mentioned in each above-mentioned embodiment is only
It is relative concept, such as high-tension voltage range is higher than the voltage range of low-voltage, and the voltage range of high level is higher than low
The voltage range of level, and be not to be limited to specific voltage range.
In summary, the invention provides a kind of power sense circuit with temperature compensation characteristic, when detecting power supply
Comparison signal is overturn when voltage reaches threshold voltage.The power sense circuit does not need reference voltage, eliminates band gap base
Accurate and comparator；Temperature-compensating can be realized by the resistance adjusted in circuit, reduce the temperature drift of threshold voltage；The power supply is examined
Slowdown monitoring circuit can also have lag function, can prevent the comparison signal of output and enable signal to jump with the shake of supply voltage
Become；In addition, passing through switching tube M4Triode can also be limited to Q with biasing circuit1With Q2And Q3With Q4Colelctor electrode-emitter stage
Voltage difference, reduces the error that Early effect is introduced to threshold voltage.
The power sense circuit of the embodiment of the present invention can apply to various power receiving equipments, and be particularly suitable for use in POE
Power receiving equipment.
The above described is only a preferred embodiment of the present invention, not making any formal limitation to the present invention.Cause
This, every content without departing from technical solution of the present invention, simply the technical spirit according to the present invention is to made for any of the above embodiments
Any simple modification, equivalent conversion, are still within the scope of the technical scheme of the invention.
Claims (11)
1. a kind of power sense circuit with temperature compensation characteristic, it is characterised in that including：
Voltage-current conversion circuit, its input connection supply voltage incoming end, the Voltage-current conversion circuit turns supply voltage
The first electric current, the second electric current and the 3rd electric current are changed to, the second electric current is equal to the first electric current and the 3rd electric current sum, second electricity
Flow through and exported by the first output end, the 3rd electric current is exported via the second output end；
Micro-current source, its input receives second electric current, and its output end produces the 4th electric current；
Wherein, the 3rd electric current and the 4th electric current compare generation comparison signal.
2. the power sense circuit according to claim 1 with temperature compensation characteristic, it is characterised in that the voltage turns
Current circuit includes：
First PNP triode, its emitter stage connects the supply voltage incoming end to receive the supply voltage, the connection of its base stage
The colelctor electrode of first PNP triode；
Second PNP triode, its emitter stage connects the supply voltage incoming end, and its base stage connects first PNP triode
Base stage, its colelctor electrode as the Voltage-current conversion circuit the second output end；
First resistor, its first end connects the supply voltage incoming end, and its second end connects the collection of first PNP triode
Electrode；
Second resistance, its first end connects the colelctor electrode of first PNP triode, and its second end turns electric current as the voltage
First output end of circuit；
Wherein, the electric current for flowing through the first resistor is first electric current, and it is described the to flow through the electric current of the second resistance
Two electric currents, the electric current of the colelctor electrode of second PNP triode is the 3rd electric current.
3. the power sense circuit according to claim 2 with temperature compensation characteristic, it is characterised in that the micro-current
Source includes：
First NPN triode, its colelctor electrode connects the second end of the second resistance, and its base stage connects the poles of the first NPN tri-
The colelctor electrode of pipe, its grounded emitter；
Second NPN triode, its colelctor electrode connects the colelctor electrode of second PNP triode, and its base stage connects the first NPN
The base stage of triode, the colelctor electrode output comparison signal of second NPN triode, the colelctor electrode of second NPN triode
Electric current be the 4th electric current；
3rd resistor, its first end connects the emitter stage of second NPN triode, its second end ground connection.
4. the power sense circuit according to claim 3 with temperature compensation characteristic, it is characterised in that also include：
Level shifting circuit, digital level is converted to by the comparison signal.
5. the power sense circuit according to claim 4 with temperature compensation characteristic, it is characterised in that also include：
4th resistance, the second end of the second resistance connects the colelctor electrode of first NPN triode via the 4th resistance；
6th switching tube, its first end connects the first end of the 4th resistance, and its second end connects the of the 4th resistance
Two ends, its control end receives the digital level.
6. the power sense circuit with temperature compensation characteristic according to claim 4 or 5, it is characterised in that the electricity
Flat change-over circuit includes：
Schmitt inverter, its input receives the comparison signal；
Phase inverter, its input connects the output end of the schmitt inverter, and its output end exports the digital level.
7. the power sense circuit according to claim 5 with temperature compensation characteristic, it is characterised in that the power supply electricity
When pressure rises to first threshold voltage from low to high, the digital level is overturn；The supply voltage declines from high to low
During to second threshold voltage, the digital level is overturn, and the first threshold voltage is more than the second threshold voltage.
8. the power sense circuit according to claim 7 with temperature compensation characteristic, it is characterised in that first threshold
Threshold voltage is：
The second threshold voltage is：
Wherein, R1For the resistance value of the first resistor, R2For the resistance value of the second resistance, R3For the 3rd resistor
Resistance value, R4For the resistance value of the 4th resistance, VbeFor first PNP triode, the second PNP triode and first
The base emitter voltage of NPN triode, VT=kT/q, k are Boltzmann constant, and T is temperature, and q is electron charge constant, n
For second NPN triode and the dimension scale of the first NPN triode.
9. the power sense circuit according to claim 3 with temperature compensation characteristic, it is characterised in that described second
The colelctor electrode of NPN triode connects the colelctor electrode of second PNP triode via the 4th switching tube, wherein, the described 4th opens
The first end for closing pipe connects the colelctor electrode of second PNP triode, the second end connection described second of the 4th switching tube
The colelctor electrode of NPN triode, the control end of the 4th switching tube receives the bias voltage that biasing circuit is provided.
10. the power sense circuit according to claim 9 with temperature compensation characteristic, it is characterised in that the biasing
Circuit includes：
6th resistance, its first end connects the supply voltage incoming end；
Voltage-regulator diode, its negative electrode connects the second end of the 6th resistance, its plus earth.
11. a kind of power receiving equipment, the power receiving equipment is by POE, it is characterised in that the power receiving equipment includes claim 1
To the power sense circuit with temperature compensation characteristic any one of 10.
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| CN201410481905.5A CN104198783B (en) | 2014-09-19 | 2014-09-19 | Power sense circuit and power receiving equipment with temperature compensation characteristic |
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| CN104991125A (en) * | 2015-06-15 | 2015-10-21 | 许昌学院 | Ethernet power equipment power supply detection circuit |
| CN105548680B (en) * | 2015-12-05 | 2020-05-05 | 许昌学院 | Ethernet consumer power level detection circuit |
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| CN104198783A (en) | 2014-12-10 |
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