CN104198783A - Power detection circuit with temperature compensation characteristic and powered device - Google Patents
Power detection circuit with temperature compensation characteristic and powered device Download PDFInfo
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- CN104198783A CN104198783A CN201410481905.5A CN201410481905A CN104198783A CN 104198783 A CN104198783 A CN 104198783A CN 201410481905 A CN201410481905 A CN 201410481905A CN 104198783 A CN104198783 A CN 104198783A
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Abstract
The invention provides a power detection circuit with a temperature compensation characteristic and a powered device. The power detection circuit comprises a voltage-to-current conversion circuit and a micro-current source. An input end of the voltage-to-current conversion circuit is connected with a supply voltage input end, supply voltages can be converted into first currents, second currents and third currents by the voltage-to-current conversion circuit, each second current is equal to the sum of the corresponding first current and the corresponding third current and is outputted via a first output end, and the third currents are outputted via a second output end; an input end of the micro-current source receives the second currents, and fourth currents are generated at an output end of the micro-current source; the third currents are compared to the fourth currents to generate comparison signals. The power detection circuit and the powered device have the advantages that reference voltages, band-gap reference and comparators can be omitted, and accordingly the power detection circuit and the powered device are favorable for reducing the areas of chips.
Description
Technical field
The present invention relates to power supply detection technique, relate in particular to a kind of power receiving equipment that there is the power sense circuit of temperature compensation characteristic and comprise this power sense circuit.
Background technology
In ic power managing chip, particularly be applied to POE (PoE, Power over Ethernet) power receiving equipment (PD in system, Power Device) time, in the time that power-supply unit (PSE, Power Source Equipment) detects power receiving equipment, can provide the supply voltage in particular range to power receiving equipment, power receiving equipment must detect this supply voltage, and circuit is switched to detected state.Or be while being applied to the circuit such as under-voltage protection (UVLO, Under Voltage Lock Out), when detecting that supply voltage sends enable signal while dropping in normal range, ensure that circuit working is under safe and reliable supply voltage.
As shown in Figure 1, traditional power sense circuit is by supply voltage V by voltage comparator 12
inthe reference voltage V producing with band-gap reference 11
refrelatively realize.Wherein, supply voltage V
inthrough resistance R
1and resistance R
2after step-down, input to comparer 12, when the voltage after step-down is greater than reference voltage V
reftime, the output level upset of comparer 12, for system provides enable signal.Reference voltage V
refproduced by band-gap reference 11, ensured reference voltage V
refthere is low-temperature coefficient.The threshold voltage that above-mentioned control method can make power supply detect has that precision is high, temperature is floated little characteristic, but its circuit design scheme complexity, need additional designs band-gap reference 11 and comparer 12, cause chip area to increase, and extra module needs power-on time, cause detection time elongated, even detect unsuccessfully.
Summary 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, can save band-gap reference and comparer, is conducive to reduce chip area.
For solving the problems of the technologies described above, the invention provides a kind of power sense circuit with temperature compensation characteristic, comprising:
Voltage turns current circuit, its input end connects supply voltage incoming end, described voltage turns current circuit supply voltage is converted to the first electric current, the second electric current and the 3rd electric current, the second electric current equals the first electric current and the second electric current sum, described the second electric current is exported via the first output terminal, and described the 3rd electric current is exported via the second output terminal;
Micro-current source, its input end receives described the second electric current, and its output terminal produces the 4th electric current;
Wherein, described the 3rd electric current and the 4th electric current generation comparison signal of comparing.
According to one embodiment of present invention, described voltage turns current circuit and comprises:
The one PNP triode, its emitter connects described supply voltage incoming end to receive described supply voltage, and its base stage connects the collector of a described PNP triode;
The 2nd PNP triode, its emitter connects described supply voltage incoming end, and its base stage connects the base stage of a described PNP triode, and its collector turns the second output terminal of current circuit as described voltage;
The first resistance, its first end connects described supply voltage incoming end, and its second end connects the collector of a described PNP triode;
The second resistance, its first end connects the collector of a described PNP triode, and its second end turns the first output terminal of current circuit as described voltage;
Wherein, the electric current of described the first resistance of flowing through is described the first electric current, and the electric current of described the second resistance of flowing through is described the second electric current, and the electric current of the collector of described the 2nd PNP triode is described the 3rd electric current.
According to one embodiment of present invention, described micro-current source comprises:
The one NPN triode, its collector connects the second end of described the second resistance, and its base stage connects the collector of a described NPN triode, its grounded emitter;
The 2nd NPN triode, its collector connects the collector of described the 2nd PNP triode, its base stage connects the base stage of a described NPN triode, the collector output comparison signal of described the 2nd NPN triode, and the electric current of the collector of described the 2nd NPN triode is described the 4th electric current;
The 3rd resistance, its first end connects the emitter of described the 2nd NPN triode, its second end ground connection.
According to one embodiment of present invention, this power sense circuit also comprises: level shifting circuit, is converted to digital level by described comparison signal.
According to one embodiment of present invention, this power sense circuit also comprises:
The 4th resistance, the second end of described the second resistance connects the collector of a described NPN triode via the 4th resistance;
The 6th switching tube, its first end connects the first end of described the 4th resistance, and its second end connects the second end of described the 4th resistance, and its control end receives described digital level.
According to one embodiment of present invention, described level shifting circuit comprises:
Schmitt inverter, its input end receives described comparison signal;
Phase inverter, its input end connects the output terminal of described schmitt inverter, and its output terminal is exported described digital level.
According to one embodiment of present invention, when described supply voltage rises to first threshold voltage from low to high, described digital level overturns; When described supply voltage drops to Second Threshold voltage from high to low, described digital level overturns, and described first threshold voltage is greater than described Second Threshold voltage.
According to one embodiment of present invention, described first threshold voltage is:
Described Second Threshold voltage is:
Wherein, R
1for the resistance value of described the first resistance, R
2for the resistance value of described the second resistance, R
3for the resistance value of described the 3rd resistance, R
4for the resistance value of described the 4th resistance, V
befor the base-emitter voltage of a described PNP triode, the 2nd PNP triode and a NPN triode, V
t=kT/q, k is Boltzmann constant, and T is temperature, and q is electron charge constant, and n is the dimension scale of described the 2nd NPN triode and a NPN triode.
According to one embodiment of present invention, the collector of described the 2nd NPN triode connects the collector of described the 2nd PNP triode via the 4th switching tube, wherein, the first end of described the 4th switching tube connects the collector of described the 2nd PNP triode, the second end of described the 4th switching tube connects the collector of described the 2nd NPN triode, and the control end of described the 4th switching tube receives the bias voltage that biasing circuit provides.
According to one embodiment of present invention, described biasing circuit comprises:
The 6th resistance, its first end connects described supply voltage incoming end;
Voltage stabilizing diode, its negative electrode connects the second end of described the 6th resistance, its plus earth.
In order to address the above problem, the present invention also provides a kind of power receiving equipment, and this power receiving equipment comprises the power sense circuit of the temperature compensation characteristic described in above any one.
Compared with prior art, the present invention has the following advantages:
The power sense circuit of the embodiment of the present invention utilizes voltage to turn current circuit supply voltage is converted to the 3rd electric current, the 4th electric current that the 3rd electric current and micro-current source produce compares to produce comparison signal, this comparison signal has been indicated the scope of supply voltage, the power sense circuit of the embodiment of the present invention is without reference circuit, thereby save band-gap reference and comparer, be conducive to reduce chip area; And can realize temperature compensation by the resistance in regulating circuit, reduce the temperature of threshold voltage and floated.
Furthermore, the power sense circuit of the embodiment of the present invention can also comprise lag function, can prevent comparison signal and enable signal saltus step with the shake of supply voltage of output.
In addition, the power sense circuit of the embodiment of the present invention also limits collector-emitter pressure reduction of a PNP triode, the 2nd PNP triode, a NPN triode, the 2nd NPN triode by the 4th switching tube and biasing circuit, reduced the error that Early effect is introduced to threshold voltage.
Brief description of the drawings
Fig. 1 is the electrical block diagram of a kind of power sense circuit in prior art;
Fig. 2 is according to the electrical block diagram of the power sense circuit of first embodiment of the invention;
Fig. 3 is according to the electrical block diagram of the power sense circuit of second embodiment of the invention;
Fig. 4 is according to the electrical block diagram of the power sense circuit of third embodiment of the invention;
Fig. 5 is according to the electrical block diagram of the power sense circuit of fourth embodiment of the invention;
Fig. 6 A and Fig. 6 B are the signal waveform schematic diagram of power sense circuit shown in Fig. 5.
Embodiment
Below in conjunction with specific embodiments and the drawings, the invention will be further described, but should not limit the scope of the invention with this.
The first embodiment
With reference to figure 2, the power sense circuit with temperature compensation characteristic of the present embodiment comprises that voltage turns current circuit 21 and micro-current source 22.
Wherein, voltage turns current circuit 21 for by supply voltage V
inbe converted to electric current, and compare with the electric current that micro-current source 22 is exported, produce the comparison signal of instruction comparative result.Furthermore, voltage turns current circuit 21 by supply voltage V
inbe converted to the first electric current I
1, the second electric current I
2with the 3rd electric current I
3, wherein, the second electric current I
2equal the first electric current I
1with the 3rd electric current I
3sum; The input end of micro-current source 22 receives the second electric current I
2, the output terminal of micro-current source 22 produces the 4th electric current I
4, the 4th electric current I
4with the 3rd electric current I
3can flow to same node and compare, to produce comparison signal V
1.Turn resistance and the ratio of each resistance in current circuit 21 and micro-current source 22 by regulation voltage, size and temperature coefficient that can adjusting threshold voltage, can be in harmonious proportion the temperature compensation function of threshold voltage thereby realize threshold voltage.
As a preferred embodiment, voltage turns current circuit 21 can comprise PNP triode Q
1, PNP triode Q
2, resistance R
1and resistance R
2; Micro-current source 22 can comprise NPN triode Q
3, NPN triode Q
4and resistance R
3.
Wherein, PNP triode Q
1emitter connect supply voltage incoming end to receive supply voltage V
in, its base stage connects the collector of self; PNP triode Q
2emitter connect supply voltage incoming end, its base stage connects PNP triode Q
1base stage; Resistance R
1first end connect supply voltage incoming end, its second end connects a PNP triode Q
1collector; Resistance R
2first end connect PNP triode Q
1collector; NPN triode Q
3collector connect the second resistance R
2the second end, its base stage connects the collector of self, its grounded emitter; NPN triode Q
4collector connect PNP triode Q
2collector, its base stage connects NPN triode Q
3base stage, NPN triode Q
4collector output comparison signal V
1.
Wherein, the described resistance R of flowing through
1electric current be the first electric current I
1, second resistance R of flowing through
2electric current be the second electric current I
2, PNP triode Q
2the electric current of collector be the 3rd electric current I
3, NPN triode Q
4the electric current of collector be the 4th electric current I
4.
Wherein, set NPN triode Q
3with NPN triode Q
4dimension scale be 1:n (n is positive number, for example, n=4), can obtain the 4th electric current I 4 that this micro-current source 22 produces as follows:
wherein, V
be3for NPN triode Q
3base-emitter voltage, V
be4for NPN triode Q
4base-emitter voltage, V
t=kT/q, k is Boltzmann constant, and T is temperature, and q is electron charge constant, R
3for resistance R
3resistance value.
PNP triode Q
1with PNP triode Q
2form current mirror, PNP triode Q
2collector produce the 3rd electric current I
3, as can be seen from Figure 2, the resistance R of flowing through
2the second electric current I
2it is the first electric current I
1with the 3rd electric current I
3and, wherein the first electric current I
1it is the resistance R of flowing through
1electric current.
The 3rd electric current I
3expression formula as follows:
wherein, V
infor input voltage V
inmagnitude of voltage, V
be3for NPN triode Q
3base-emitter voltage, V
be1for PNP triode Q
1base-emitter voltage, R
2for resistance R
2resistance value, R
4for resistance R
4resistance value, R
1for resistance R
1resistance value.
Conventionally can think PNP triode Q
1, PNP triode Q
2and NPN triode Q
3base-emitter voltage approximately equal, be V
be, electric current I so
3and electric current I
4transfer to same node and be equivalent to form current comparator, both difference between currents are:
Therefore ， ⊿ I is and supply voltage V
inthe function ， being directly proportional in the time of ⊿ I zero passage, comparison signal V
1can upset.Input voltage V
inrise from low to high, cause comparison signal V
1there is the supply voltage V of upset
infirst threshold voltage be designated as V
tH1; Input voltage V
indecline from high to low, cause comparison signal V
1there is the supply voltage V of upset
insecond Threshold voltage be designated as V
tH2, there is following relation:
Wherein
typical first compensation phase band-gap reference expression formula,
for scale-up factor, by regulating resistance R
1, R
2resistance value can regulate this scale-up factor, thereby can obtain needed different threshold voltage, can also pass through in addition regulating resistance R
3resistance value can realize single order temperature compensation.
The second embodiment
With reference to figure 3, Fig. 3 shows the circuit structure of the power sense circuit of the second embodiment, and it has increased level shifting circuit 23 on the basis of the first embodiment, and the input end of this level shifting circuit 23 receives comparison signal V
1, this comparison signal is converted to digital level V
2.
Comparison signal V
1the result of indicator current comparison, normally simulating signal, level shifting circuit 23 is converted into digital logic signal, is also digital level V
2.It should be noted that comparison signal V
1itself can indicate supply voltage V
invariation, level shifting circuit 23 is converted into digital level V
2, mainly can for other adjunct circuit compatibilities, for example can utilize digital level V
2control other adjunct circuit.
The 3rd embodiment
With reference to figure 4, Fig. 4 shows the circuit structure of the power sense circuit of the 3rd embodiment, and it has increased level shifting circuit 23, biasing circuit 24, resistance R on the basis of the first embodiment
4, switching tube M
6and switching tube M
4.The input end of this level shifting circuit 23 receives comparison signal V
1, this comparison signal is converted to digital level V
2; The second resistance R
2the second end via the 4th resistance R
4connect NPN triode Q
3collector, the first end contact resistance R of switching tube M6
4first end, its second end contact resistance R
4the second end, its control end receives digital level V
2; NPN triode Q
2collector via switching tube M
4connect PNP triode Q
4collector, wherein, switching tube M
4first end connect PNP triode Q
2collector, switching tube Q
4the second end connect NPN triode Q
4collector, the control end of switching tube M4 receives the bias voltage V that biasing circuit 24 provides
b.
Wherein, resistance R
4with switching tube M
6be used for introducing sluggish effect.Particularly, supply voltage V
inrise to from low to high first threshold voltage V
tH1time, digital level V
2overturn; Supply voltage V
indrop to from high to low Second Threshold voltage V
tH2time, digital level V
2overturn, first threshold voltage V
tH1be greater than Second Threshold voltage V
tH2.
Furthermore, at supply voltage V
inthe process rising from low-voltage toward high voltage, electric current I
4first be greater than electric current I
3, make comparison signal V
1first in low level, corresponding digital level V
2also in logic low, make switching tube M
6(supposition switching tube M
6for nmos pass transistor) be turned off; As supply voltage V
inrise to first threshold voltage V
tH1time, comparison signal V
1with digital level V
2upset, for high level, makes switching tube M
6conducting.At supply voltage V
inwhen high voltage declines toward low-voltage, electric current I
4first be less than electric current I
3, make comparison signal V
1first in high level, corresponding digital level V
2also in logic high, switching tube M
6conducting; As supply voltage V
indrop to Second Threshold voltage V
tH2time, comparison signal V
1with digital level V
2upset, for low level, makes switching tube M
6turn-off.
Switching tube M
4can be by comparison signal V
1high level be restricted to the highest V
b-V
gs4thereby, level shift circuit 23 is formed to protection, play the effect of clamper protection, wherein V
bfor bias voltage V
bmagnitude of voltage, V
gs4for switching tube M
4gate source voltage.In addition, switching tube M
4the collector emitter voltage that can limit PNP triode Q1 and PNP triode Q2, NPN triode Q3 and NPN triode Q4 is poor, thereby reduces the error that strategic point profit (Early) effect is introduced to threshold voltage.
The 4th embodiment
With reference to figure 5, Fig. 5 shows the circuit structure of the power sense circuit of the 4th embodiment, and its general structure is identical with the 3rd embodiment shown in Fig. 4, and difference is only the particular circuit configurations that the 4th embodiment has provided level shifting circuit 23 and biasing circuit 24.
With reference to figure 5, level shifting circuit 23 comprises: schmitt inverter S
1, its input end receives comparison signal V
1; Phase inverter N
1, its input end connects schmitt inverter S
1output terminal, its output terminal output digital level V
2.Biasing circuit 24 comprises: the 6th resistance R
6, its first end connects supply voltage incoming end to receive supply voltage V
in; Voltage stabilizing diode D
1, its negative electrode connects the 6th resistance R
6the second end, its plus earth.
In biasing circuit 24, resistance R
6with voltage stabilizing diode D
1form current path, produce bias voltage V at the negative electrode of voltage stabilizing diode
b, this bias voltage V
btransfer to switching tube M
4control end, be switching tube M
4biasing is provided.
Fig. 6 A shows supply voltage Vin in the time rising from low-voltage to high voltage, the 3rd electric current I
3, the 4th electric current I
4, comparison signal V
1and digital level V
2with supply voltage V
inchange curve.In conjunction with Fig. 5 and Fig. 6 A, at supply voltage V
inthe process rising from low-voltage toward high voltage, electric current I
4first be greater than electric current I
3, make comparison signal V
1first in low level, through schmitt inverter S
1with phase inverter N
1after, digital level V
2for low level signal, make switching tube M
6(supposition switching tube M
6for nmos pass transistor) be turned off, therefore electric current I
3expression formula as follows:
wherein, V
infor input voltage V
inmagnitude of voltage, V
be3for NPN triode Q
3base-emitter voltage, V
be1for PNP triode Q
1base-emitter voltage, R
2for resistance R
2resistance value, R
4for resistance R
4resistance value, R
1for resistance R
1resistance value.
Conventionally can think PNP triode Q
1, PNP triode Q
2and NPN triode Q
3base-emitter voltage approximately equal, be V
be, electric current I so
3and electric current I
4transfer to same node and be equivalent to form current comparator, both difference between currents are:
Therefore ， ⊿ I is and supply voltage V
inthe function ， being directly proportional in the time of ⊿ I zero passage, comparison signal V
1can upset.Therefore input voltage V
inwhile rising, cause comparison signal V from low to high
1there is the first threshold voltage V of reversion
tH1for:
Also be input voltage V
inrise and reach this first threshold voltage V from low to high
tH1time, comparison signal V
1to overturn, wherein
typical first compensation phase band-gap reference expression formula,
for scale-up factor, by regulating resistance R
1, R
2, R
4resistance value can regulate this scale-up factor, thereby can obtain needed different threshold voltage, can also pass through in addition regulating resistance R
3resistance value can realize single order temperature compensation.
Fig. 6 B shows supply voltage V
inin the time declining from high voltage to low-voltage, the 3rd electric current I
3, the 4th electric current I
4, comparison signal V
1and digital level V
2with supply voltage V
inchange curve, it should be noted that, in order to meet drawing convention, the horizontal ordinate V in Fig. 6 B
inremain from small to large and to change, when therefore the horizontal ordinate of Fig. 6 B is checked from right to left, embodied input voltage V
invariation tendency from high to low.In conjunction with Fig. 5 and Fig. 6 B, as supply voltage V
inrise to first threshold voltage V
tH1when above, comparison signal V
1be high level by low level upset, through schmitt inverter S
1with phase inverter N
1after, make switching tube M
6(in the present embodiment, being for example NMOS pipe) switched to open-minded by shutoff.Afterwards, if supply voltage V
inwhile decline from high voltage to low-voltage, when dropping to Second Threshold voltage V
tH2time, comparison signal V1, digital level can overturn, with first threshold voltage V
tH1in like manner can obtain this Second Threshold voltage V
tH2for:
Obviously, V
tH1>V
tH2, thereby can realize sluggish effect.Particularly, supply voltage V
inwhile rising from low to high, reaching larger first threshold voltage V
tH1time comparison signal V
1can overturn, and as supply voltage V
inwhile decline from high to low, reaching lower Second Threshold voltage V
tH2time, comparison signal V
1just can overturn, can prevent that like this comparison signal V1, digital level V2 are at supply voltage V
inwhen shake, there is saltus step.
It should be noted that, " high voltage " " low-voltage " " high level " " low level " of mentioning in above-mentioned each embodiment is only relative concept, for example high-tension voltage range is higher than the voltage range of low-voltage, the voltage range of high level is higher than low level voltage range, and is limited to specific voltage range.
In sum, the invention provides a kind of power sense circuit with temperature compensation characteristic, in the time detecting that supply voltage reaches threshold voltage, comparison signal overturns.This power sense circuit does not need reference voltage, has saved band-gap reference and comparer; Can realize temperature compensation by the resistance in regulating circuit, reduce the temperature of threshold voltage and floated; This power sense circuit can also have lag function, can prevent comparison signal and enable signal saltus step with the shake of supply voltage of output; In addition, by switching tube M
4can also limit triode to Q with biasing circuit
1with Q
2and Q
3with Q
4collector emitter voltage poor, reduced the error that Early effect is introduced to threshold voltage.
The power sense circuit of the embodiment of the present invention can be applied to various power receiving equipments, is particularly useful for the power receiving equipment of POE.
The above, be only preferred embodiment of the present invention, not the present invention done to any pro forma restriction.Therefore, every content that does not depart from technical solution of the present invention, just according to technical spirit of the present invention to any simple amendment made for any of the above embodiments, the conversion that is equal to, all still belong in the protection domain of technical solution of the present invention.
Claims (11)
1. a power sense circuit with temperature compensation characteristic, is characterized in that, comprising:
Voltage turns current circuit, its input end connects supply voltage incoming end, described voltage turns current circuit supply voltage is converted to the first electric current, the second electric current and the 3rd electric current, the second electric current equals the first electric current and the second electric current sum, described the second electric current is exported via the first output terminal, and described the 3rd electric current is exported via the second output terminal;
Micro-current source, its input end receives described the second electric current, and its output terminal produces the 4th electric current;
Wherein, described the 3rd electric current and the 4th electric current generation comparison signal of comparing.
2. the power sense circuit with temperature compensation characteristic according to claim 1, is characterized in that, described voltage turns current circuit and comprises:
The one PNP triode, its emitter connects described supply voltage incoming end to receive described supply voltage, and its base stage connects the collector of a described PNP triode;
The 2nd PNP triode, its emitter connects described supply voltage incoming end, and its base stage connects the base stage of a described PNP triode, and its collector turns the second output terminal of current circuit as described voltage;
The first resistance, its first end connects described supply voltage incoming end, and its second end connects the collector of a described PNP triode;
The second resistance, its first end connects the collector of a described PNP triode, and its second end turns the first output terminal of current circuit as described voltage;
Wherein, the electric current of described the first resistance of flowing through is described the first electric current, and the electric current of described the second resistance of flowing through is described the second electric current, and the electric current of the collector of described the 2nd PNP triode is described the 3rd electric current.
3. the power sense circuit with temperature compensation characteristic according to claim 2, is characterized in that, described micro-current source comprises:
The one NPN triode, its collector connects the second end of described the second resistance, and its base stage connects the collector of a described NPN triode, its grounded emitter;
The 2nd NPN triode, its collector connects the collector of described the 2nd PNP triode, its base stage connects the base stage of a described NPN triode, the collector output comparison signal of described the 2nd NPN triode, and the electric current of the collector of described the 2nd NPN triode is described the 4th electric current;
The 3rd resistance, its first end connects the emitter of described the 2nd NPN triode, its second end ground connection.
4. the power sense circuit with temperature compensation characteristic according to claim 3, is characterized in that, also comprises:
Level shifting circuit, is converted to digital level by described comparison signal.
5. the power sense circuit with temperature compensation characteristic according to claim 4, is characterized in that, also comprises:
The 4th resistance, the second end of described the second resistance connects the collector of a described NPN triode via the 4th resistance;
The 6th switching tube, its first end connects the first end of described the 4th resistance, and its second end connects the second end of described the 4th resistance, and its control end receives described digital level.
6. according to the power sense circuit with temperature compensation characteristic described in claim 4 or 5, it is characterized in that, described level shifting circuit comprises:
Schmitt inverter, its input end receives described comparison signal;
Phase inverter, its input end connects the output terminal of described schmitt inverter, and its output terminal is exported described digital level.
7. the power sense circuit with temperature compensation characteristic according to claim 5, is characterized in that, when described supply voltage rises to first threshold voltage from low to high, described digital level overturns; When described supply voltage drops to Second Threshold voltage from high to low, described digital level overturns, and described first threshold voltage is greater than described Second Threshold voltage.
8. the power sense circuit with temperature compensation characteristic according to claim 7, is characterized in that, described first threshold voltage is:
Described Second Threshold voltage is:
Wherein, R
1for the resistance value of described the first resistance, R
2for the resistance value of described the second resistance, R
3for the resistance value of described the 3rd resistance, R
4for the resistance value of described the 4th resistance, V
befor the base-emitter voltage of a described PNP triode, the 2nd PNP triode and a NPN triode, V
t=kT/q, k is Boltzmann constant, and T is temperature, and q is electron charge constant, and n is the dimension scale of described the 2nd NPN triode and a NPN triode.
9. the power sense circuit with temperature compensation characteristic according to claim 3, it is characterized in that, the collector of described the 2nd NPN triode connects the collector of described the 2nd PNP triode via the 4th switching tube, wherein, the first end of described the 4th switching tube connects the collector of described the 2nd PNP triode, the second end of described the 4th switching tube connects the collector of described the 2nd NPN triode, and the control end of described the 4th switching tube receives the bias voltage that biasing circuit provides.
10. the power sense circuit with temperature compensation characteristic according to claim 9, is characterized in that, described biasing circuit comprises:
The 6th resistance, its first end connects described supply voltage incoming end;
Voltage stabilizing diode, its negative electrode connects the second end of described the 6th resistance, its plus earth.
11. 1 kinds of power receiving equipments, this power receiving equipment, by POE, is characterized in that, this power receiving equipment comprises the power sense circuit with temperature compensation characteristic described in any one in claim 1 to 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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|---|---|---|---|
| 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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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104991125A (en) * | 2015-06-15 | 2015-10-21 | 许昌学院 | Ethernet power equipment power supply detection circuit |
| CN105548680A (en) * | 2015-12-05 | 2016-05-04 | 许昌学院 | Ethernet electric equipment power level detection circuit |
| CN107193315A (en) * | 2017-07-27 | 2017-09-22 | 居水荣 | A kind of multi thresholds low-voltage detection circuit |
| CN111682503A (en) * | 2020-06-17 | 2020-09-18 | 苏州纳芯微电子股份有限公司 | Undervoltage protection circuit |
| CN112714002A (en) * | 2020-12-04 | 2021-04-27 | 杭州士兰微电子股份有限公司 | Power receiving control device, power receiving end equipment and Ethernet power supply system |
| CN113268099A (en) * | 2021-04-27 | 2021-08-17 | 深圳市至正电子有限责任公司 | Solid-state direct-current voltage reference circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104991125A (en) * | 2015-06-15 | 2015-10-21 | 许昌学院 | Ethernet power equipment power supply detection circuit |
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| CN113268099A (en) * | 2021-04-27 | 2021-08-17 | 深圳市至正电子有限责任公司 | Solid-state direct-current voltage reference circuit |
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