CN102053198B - Voltage detection circuit, method and electronic system - Google Patents
Voltage detection circuit, method and electronic system Download PDFInfo
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Abstract
The invention discloses a voltage detection circuit which is used for detecting an input voltage and comprises a voltage-current converter used for generating a monitoring current changing with the input voltage and a current comparator coupled to the voltage-current converter and used for comparing the monitoring current with a threshold current and generating a detection signal representing the state of the input voltage according to the compared result, wherein the threshold current is proportional to the temperature of the voltage detection circuit. Compared with the under voltage detection circuit in the prior art, the voltage detection circuit has less current branches; and the voltage threshold related to the input voltage and provided by the detection circuit is a band gap voltage and can have a delaying function, therefore, the wafer size and the energy consumption of the voltage detection circuit can be reduced and the accuracy and the stability of the voltage detection circuit can be improved.
Description
Technical field
The present invention relates to a kind of voltage detecting technology, particularly relate to a kind of detection potential circuit, method and electronic system.
Background technology
When the voltage of power supply was lower than predetermined threshold value, electronic equipment can not be worked normally.Figure 1 shows that the circuit diagram of a kind of undervoltage detection circuit 100 of the prior art.Undervoltage detection circuit 100 comprises band-gap circuit 102, voltage comparator 104 and voltage divider 106.Band-gap circuit 102 can produce unaffected by temperature fluctuations and keep the constant bandgap voltage reference of essence.Voltage divider 106 receives input voltage VIN, and provides induced voltage proportional to input voltage VIN at node 108.Voltage comparator 104 is induced voltage and bandgap voltage references relatively, when induced voltage during less than bandgap voltage reference, produce the detection signal UVA of expression under-voltage condition.Yet current value and the input voltage VIN of the electric current of the voltage divider 106 of flowing through are proportional, and therefore when input voltage VIN increased, the energy consumption of undervoltage detection circuit 100 can increase.
The circuit diagram of another kind of undervoltage detection circuit 200 of the prior art shown in Figure 2.Undervoltage detection circuit 200 comprises electric current maker 208 and voltage comparator 204.Electric current maker 208 produce to the temperature of undervoltage detection circuit 200 (for example: absolute temperature) proportional electric current.The the first band gap voltage maker that is comprised of bipolar transistor Q2 and resistance R 3 can receive this electric current, and the first band gap voltage is provided accordingly.In like manner, the second band gap voltage maker that is comprised of bipolar transistor Q6 and resistance R 2 can receive this electric current, and the second band gap voltage is provided accordingly.Therefore, obtain induced voltage at node 202, this induced voltage equals input voltage VIN and deducts the first band gap voltage; Obtain threshold voltage at node 201, this threshold voltage equals the second band gap voltage.When induced voltage during less than threshold voltage, voltage comparator 204 produces the detection signal UVA of expression under-voltage conditions.
Yet, voltage comparator, for example: voltage comparator 104 or 204 can increase complexity and the cost of undervoltage detection circuit 100 or 200.In addition, undervoltage detection circuit 100 or 200 may produce vibration.For example, owing to being subject to the impact of the noise of undervoltage detection circuit, induced voltage promptly is increased to greater than threshold voltage within the relatively short time and drops to less than threshold voltage again, and detection signal UVA can vibrate between two states (for example: high level and low level).Therefore, undervoltage detection circuit 100 or 200 stability also can reduce.
Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of voltage detecting circuit and method thereof with less chip size and low energy consumption.
The invention provides a kind of voltage detecting circuit, for detection of input voltage, it comprises: voltage-current converter, for generation of the monitoring current that changes according to input voltage; And be coupled in the current comparator of voltage-current converter, be used for monitoring current relatively and with the size of threshold current, the temperature of wherein said threshold current and described input voltage detection circuit is proportional, and produces the detection signal of the state of expression input voltage according to result relatively.
The present invention also provides a kind of voltage detection method, and for detection of input voltage, it comprises: produce the monitoring current that changes according to input voltage; Relatively monitoring current and to the size of the proportional threshold current of temperature; Reach the detection signal that produces the state of expression input voltage according to result relatively.
The present invention also provides a kind of electronic system, and it comprises: load and testing circuit.This load is driven by the electric energy with input voltage.Testing circuit is coupled in load, is used for comparing the size of input voltage and voltage threshold., it comprises: voltage-current converter and current comparator.Wherein, voltage-current converter is for generation of the monitoring current that changes according to input voltage, and band gap voltage is provided; Current comparator is coupled in voltage-current converter, is used for comparing the size of monitoring current and threshold current, and produces detection signal according to result relatively, and wherein, voltage threshold is determined by band gap voltage.
Compare with undervoltage detection circuit of the prior art, voltage detecting circuit of the present invention has current branch still less, and the voltage threshold relevant with input voltage that this testing circuit provides is band gap voltage and can has lag function.Therefore, chip size and the energy consumption of voltage detecting circuit can be reduced, and the precision and stability of voltage detecting circuit can be improved.
Below in conjunction with the drawings and specific embodiments technical scheme of the present invention is described in detail, so that characteristic of the present invention and advantage are more obvious.
Description of drawings
Figure 1 shows that the circuit diagram of a kind of undervoltage detection circuit of the prior art;
The circuit diagram of another kind of undervoltage detection circuit of the prior art shown in Figure 2;
Fig. 3 A is depicted as the according to an embodiment of the invention structured flowchart of voltage detecting circuit;
Fig. 3 B is depicted as according to the present invention the sequential chart of the signal that the voltage detecting circuit 300 of embodiment as shown in Figure 3A receives and produce;
Fig. 3 C is depicted as according to the present invention another sequential chart of the signal that the voltage detecting circuit 300 of embodiment as shown in Figure 3A receives and produce;
Fig. 3 D is depicted as according to the present invention another sequential chart of the signal that the voltage detecting circuit 300 of embodiment as shown in Figure 3A receives and produce;
Figure 4 shows that according to the present invention the as shown in Figure 3A circuit diagram of the voltage detecting circuit 300 of embodiment;
Figure 5 shows that according to the present invention the as shown in Figure 3A circuit diagram of the band gap voltage maker 308 of embodiment;
Figure 6 shows that according to the present invention the as shown in Figure 3A another kind of circuit diagram of the band gap voltage maker 308 of embodiment;
Figure 7 shows that another sequential chart of the signal that voltage detecting circuit 300 according to an embodiment of the invention receives and produces;
Figure 8 shows that according to the present invention the as shown in Figure 3A circuit diagram of the current comparator 304 of embodiment;
Figure 9 shows that the according to an embodiment of the invention operational flowchart of voltage detecting circuit 300; And
Figure 10 shows that the according to an embodiment of the invention structured flowchart of electronic system.
Embodiment
Below will provide detailed explanation to embodiments of the invention.Although the present invention sets forth in connection with some embodiments and illustrates, it should be noted that the present invention not merely is confined to these embodiments.On the contrary, the modification that the present invention is carried out or be equal to replacement all should be encompassed in the middle of the claim scope of the present invention.
In addition, for better explanation the present invention, provided numerous details in the embodiment hereinafter.It will be understood by those skilled in the art that does not have these details, and the present invention can implement equally.In the other example, method, flow process, element and the circuit known for everybody are not described in detail, so that highlight purport of the present invention.
Embodiments of the invention provide a kind of voltage detecting circuit, for detection of the state of input voltage.Voltage detecting circuit of the present invention comprises voltage-current converter and current comparator.Wherein, voltage-current converter produces the monitoring current that changes according to input voltage; Current comparator compares the size of monitoring current and threshold current, and produces the detection signal VA of the state of expression input voltage according to result relatively.Detection signal VA can represent whether input voltage is greater than or less than predetermined threshold value.Compare with undervoltage detection circuit of the prior art, its advantage is, voltage-current converter of the present invention and current comparator have current branch still less.Therefore, can reduce chip size and the energy consumption of voltage detecting circuit.
Fig. 3 A is depicted as the according to an embodiment of the invention structured flowchart of voltage detecting circuit 300.In the present embodiment, voltage detecting circuit 300 comprises electric current maker 302, current comparator 304, voltage-current converter 306 and voltage sense circuit 310.Voltage sense circuit 310 is used for receiving input voltage VIN, and produces the induced signal 332 of expression input voltage VIN.The voltage-current converter 306 that is coupled in voltage sense circuit 310 is used for receiving induced signal 332, and produces the monitoring current 314 that changes according to induced signal 332.Electric current maker 302 is for generation of threshold current 312.The current comparator 304 that is coupled in electric current maker 302 and voltage-current converter 306 is used for comparing the size of monitoring current 314 and threshold current 312, and produces detection signal VA according to result relatively.Detection signal VA represents the state of input voltage VIN, and for example: whether input voltage VIN is greater than or less than predetermined threshold value.Therefore, in one embodiment, voltage detecting circuit 300 can be used for detecting overvoltage condition.In another embodiment, voltage detecting circuit 300 also can be used for detecting under-voltage condition.
In one embodiment, the temperature of the threshold current 312 of electric current maker 302 generations and voltage detecting circuit 300 (for example: absolute temperature) roughly proportional.The band gap voltage maker adopts threshold current 312 to keep the constant band gap voltage of essence to produce unaffected by temperature fluctuations.For example, because threshold current 312 is roughly proportional with temperature, when threshold current 312 was flowed through resistance, the voltage of this resistance had positive temperature coefficient (PTC).Therefore, if the electronic component (for example: mos field effect transistor or bipolar junction transistor) with negative temperature coefficient is connected with this resistance, then the total voltage of this resistance and this electronic component is temperature independent, namely produces unaffected by temperature fluctuations and keeps the constant band gap voltage of essence.
In one embodiment, voltage sense circuit 310 receive threshold electric currents 312.In the example of Fig. 3 A, voltage sense circuit 310 is coupled in electric current maker 302, and shares the current branch of threshold currents 312 with electric current maker 302.In another embodiment, voltage sense circuit 310 has respectively different current branch with electric current maker 302, for example: the image current of voltage sense circuit 310 receive threshold electric currents 312.Therefore, flow through simultaneously electric current maker 302 and voltage sense circuit 310 of threshold current 312.
Voltage-current converter 306 receives the induced signal 332 of expression input voltage VIN, and produces monitoring current 314 according to induced signal 332.In one embodiment, voltage-current converter 306 comprises (being not limited to) voltage controlled current source, is used for producing monitoring current 314 according to induced signal 332.Therefore, monitoring current 314 changes according to input voltage VIN.For example, when input voltage VIN increased, monitoring current 314 also increased thereupon.Yet the present invention is not limited thereto, and in other embodiment, when input voltage VIN increased, monitoring current 314 reduced.
Compare with the voltage comparator (for example: the voltage comparator 104 among Fig. 1 or the voltage comparator 204 among Fig. 2) in the undervoltage detection circuit of the prior art, voltage-current converter 306 of the present invention and current comparator 304 have current branch still less, and for example: voltage-current converter 306 and current comparator 304 are shared the current branch of a monitoring current 314.Therefore, reduce chip size and the energy consumption of voltage detecting circuit 300.
In one embodiment, voltage-current converter 306 produces the second band gap voltage VB2, and according to this second band gap voltage VB2 voltage threshold VTH1 and VTH2 is set.Voltage-current converter 306 comprises amplifier 305, is used for according to induced signal 332 control monitoring currents 314, and the second band gap voltage VB2 is provided.In particular, when monitoring current 314 equaled threshold current 312, monitoring current 314 was substantially proportional with temperature.Therefore, when monitoring current 314 equals threshold current 312, provide the second band gap voltage VB2 by voltage-current converter 306.In one embodiment, voltage threshold VTH1 can be by the second band gap voltage VB2 decision, and for example: VTH1 equals VB2.
In the embodiment shown in Fig. 3 A, voltage-current converter 306 also comprises the band gap voltage maker 308 that is coupled in amplifier 305, for generation of the 3rd band gap voltage VB3.Thus, voltage threshold VTH1 can be determined by the second band gap voltage VB2 and the 3rd band gap voltage VB3.Its advantage is, voltage threshold VTH1 can be set to larger than the value of VB2, for example: VTH1=VB2+VB3; Voltage threshold VTH2 can be set to corresponding band gap voltage, and for example: when VTH2 equaled VTH1, VTH2 equaled VB2 or VB2+VB3; Or when VTH2 equaled VTH1 ± VB1, VTH2 equaled VB2 ± VB1 or VB2+VB3 ± VB1.Therefore, improve the precision of voltage threshold VTH1 and VTH2.The detailed operation of voltage threshold VTH2 and monitoring current 314 will be described in Fig. 3 B.
Its advantage is in the present embodiment, and voltage-current converter 306 has lag function, and namely the different conditions according to input voltage VIN makes voltage threshold VTH2 have different magnitudes of voltage, for example: magnitude of voltage V1 and magnitude of voltage V2.In particular, the band gap voltage that is provided by voltage-current converter 306 changes according to the state of input voltage VIN.In one embodiment, the 3rd band gap voltage VB3 that produces of band gap voltage maker 308 has the magnitude of voltage of selecting from least magnitude of voltage VB3_1 and magnitude of voltage VB3_2.For example, when detection signal VA had the expression input voltage VIN greater than the first state of voltage threshold VTH2, it was VB3_1 that the 3rd band gap voltage VB3 has magnitude of voltage; When VA had the expression input voltage VIN less than the second state of voltage threshold VTH2, it was VB3_2 that the 3rd band gap voltage VB3 has magnitude of voltage.Simultaneously, voltage-current converter 306 is regulated monitoring current 314 according to voltage threshold VTH2.As seen, it can alleviate or eliminate the vibration of voltage detecting circuit 300 in below in conjunction with the detailed description of carrying out such as Fig. 3 C, thereby further improves the stability of voltage detecting circuit 300.
Perhaps, for being provided at the voltage threshold VTH2 that has different magnitudes of voltage under the different voltage statuss, can be according to the status adjustment threshold current 312 of input voltage VIN.For example, electric current maker 302 provides offset current proportional to temperature with compensation threshold current 312 under a voltage status.Therefore, as seen, it can alleviate or eliminate the vibration of voltage detecting circuit 300 in the detailed description of carrying out in below in conjunction with Fig. 3 D, thereby further improves the stability of voltage detecting circuit 300.
Fig. 3 B is depicted as according to the present invention the sequential chart 400 of the signal that the voltage detecting circuit 300 among the embodiment as shown in Figure 3A receives and produce.Fig. 3 B is described in connection with Fig. 3 A.Sequential chart 400 has been described the state of detection signal VA, threshold current 312, monitoring current 314 and input voltage VIN.
In Fig. 3 B, input voltage VIN increases during to t3 at time t1, and reduces during to t7 at time t3.Monitoring current 314 changes according to input voltage VIN.Therefore, monitoring current 314 increases during to t3 at time t1, and reduces during to t7 at time t3.
In Fig. 3 B, voltage threshold VTH2 can not change according to the state of input voltage VIN.Time t1 to t2 and t5 in the time interval of t7, monitoring current 314 is less than threshold current 312.Therefore, current comparator 304 can produce and have the first state (for example: detection signal VA low level), in order to represent that input voltage VIN is less than voltage threshold VTH2.In the time interval of t5, monitoring current 314 is greater than threshold current 312 at time t2.Therefore, current comparator 304 can produce and have the second state (for example: detection signal VA high level), in order to represent that input voltage VIN is greater than voltage threshold VTH2.
At moment t2 or t5, monitoring current 314 equals threshold current 312, and the expression input voltage VIN equals voltage threshold VTH2.Its advantage is in the present embodiment, and voltage threshold VTH2 is set to band gap voltage, for example: VB2.Therefore, improve the precision of voltage threshold VTH2.
Fig. 3 C is depicted as another sequential chart 400 ' of the signal that receives and produce according to the voltage detecting circuit 300 among the embodiment as shown in Figure 3A.Fig. 3 C is described in connection with Fig. 3 A.Sequential chart 400 ' has been described the state of detection signal VA, threshold current 312, monitoring current 314 and input voltage VIN.
In Fig. 3 C, voltage threshold VTH2 changes according to the state of input voltage VIN.In particular, (for example: in the time of low level), voltage threshold VTH2 (for example: VB2+VB3_1) equals magnitude of voltage V1 when detection signal VA has the first state.(for example: in the time of high level), voltage threshold VTH2 (for example: VB2+VB3_2) equals magnitude of voltage V2 when detection signal VA has the second state.
In the time interval of t2, detection signal VA is that low level represents that input voltage VIN is less than voltage threshold VTH2 (VTH2=V1) at t1.At moment t2, input voltage VIN equals magnitude of voltage V1.Therefore, monitoring current 314 changes to threshold current 312.Thus, since moment t2, the state of detection signal VA is transformed into high level.In case the state variation of detection signal VA is to high level, voltage threshold VTH2 changes magnitude of voltage V2 into.In one embodiment, can regulate monitoring current 314 according to voltage threshold VTH2.Shown in Fig. 3 C, at moment t2, monitoring current 314 is increased to greater than current value I 1.Its advantage is in the present embodiment, although the noise of voltage detecting circuit 300 may cause input voltage VIN or monitoring current 314 slight jitter, monitoring current 314 can not be reduced to threshold current 312.So detection signal VA can remain on high level.In other words, by suitable selection current value I 1, can ignore the input voltage that caused by the noise of voltage detecting circuit 300 or the variation of monitoring current, and can not affect detection signal VA.Therefore, alleviate or eliminate the vibration of detection signal VA, thereby improve the stability of voltage detecting circuit 300.
At moment t6 ', input voltage VIN is reduced to magnitude of voltage V2.Therefore, monitoring current 314 is reduced to threshold current 312.Thus, since moment t6 ', the state of detection signal VA can be switched to low level.In case the state variation of detection signal VA is to low level, voltage threshold VTH2 changes magnitude of voltage V1 into.In like manner, monitoring current 314 is reduced to less than current value I 2.Its advantage is in the present embodiment, although the noise of voltage detecting circuit 300 may cause input voltage VIN or monitoring current 314 slight jitter, monitoring current 314 can not be increased to threshold current 312.So detection signal VA can remain on low level.In other words, by suitable selection current value I 2, can ignore input voltage that the noise by voltage detecting circuit 300 causes or the variation of monitoring current, and can not affect detection signal VA.Therefore, can alleviate or eliminate the vibration of detection signal VA, thereby improve the stability of voltage detecting circuit 300.
Fig. 3 D is depicted as according to the present invention another sequential chart 400 of the signal that the voltage detecting circuit 300 among the embodiment as shown in Figure 3A receives and produce ".Fig. 3 D is described in connection with Fig. 3 A.Sequential chart 400 " state of detection signal VA, threshold current 312, monitoring current 314 and input voltage VIN described.
In Fig. 3 D, threshold current 312 changes according to the state of input voltage VIN.In particular, in the present embodiment, (for example: in the time of low level), electric current maker 302 affords redress electric current with compensation threshold current 312 when detection signal VA is in the first state.Thus, when detection signal VA had the first state, threshold current 312 equaled current value I 3.When detection signal VA had the second state, threshold current 312 equaled current value I 4.Wherein, current value I 4 is less than current value I 3.
In the time interval of t2, detection signal VA is that low level represents that input voltage VIN is less than voltage threshold VTH2 (VTH2=V1) at t1.So electric current maker 302 provides offset current proportional to temperature with compensation threshold current 312.Therefore, threshold current 312 equals current value I 3.In moment t2, input voltage VIN equals V1.Therefore, monitoring current 314 changes to and equals current value I 3.Thus, since moment t2, the state of detection signal VA is transformed into high level.In case the state variation of detection signal VA is to high level, electric current maker 302 stops the electric current that affords redress.Therefore, threshold current 312 is reduced to and equals current value I 4.Its advantage is in the present embodiment, although the noise of voltage detecting circuit 300 may cause input voltage VIN or monitoring current 314 slight jitter, monitoring current 314 can not be reduced to threshold current 312.So detection signal VA can remain on high level.In other words, by suitable selection current value I 4, can ignore input voltage that the noise by voltage detecting circuit 300 causes or the variation of monitoring current, and can not affect detection signal VA.Therefore, can alleviate or eliminate the vibration of detection signal VA.
Because voltage threshold VTH2 can change according to the variation of threshold current 312, voltage threshold VTH2 can change to magnitude of voltage V2 ' from magnitude of voltage V1, and wherein, V2 ' is less than V1.
At moment t6 " in, input voltage VIN drops to magnitude of voltage V2 '.Therefore, monitoring current 314 is reduced to current value I 4.Thus, since moment t6 ", the state of detection signal VA is transformed into low level.In case the state variation of detection signal VA is to low level, threshold current 312 is adjusted to and equals current value I 3.In like manner, voltage threshold VTH2 can change to accordingly and equal magnitude of voltage V1.Its advantage is in the present embodiment, although the noise of voltage detecting circuit 300 may cause input voltage VIN or monitoring current 314 slight jitter, monitoring current 314 can not be increased to threshold current 312.So detection signal VA can remain on low level.In other words, by suitable selection current value I 3, can ignore input voltage that the noise by voltage detecting circuit 300 causes or the variation of monitoring current, and can not affect detection signal VA.Therefore, can alleviate or eliminate the vibration of detection signal VA, thereby improve the stability of voltage detecting circuit 300.
Although in Fig. 3 B, Fig. 3 C and Fig. 3 D, provided concrete waveform, but the signal that voltage detecting circuit 300 receives and produces still can have other waveform according to the electrical equipment that voltage detecting circuit 300 contains, and is not limited to the example that Fig. 3 B, Fig. 3 C and Fig. 3 D provide.For example, the level of monitoring current 314 can reduce with the rising of input voltage VIN.In addition, the waveform of monitoring current 314 can be linearity curve according to the electrical equipment that voltage detecting circuit 300 contains, for example: the straight line that increases or reduce.
Figure 4 shows that according to the present invention the circuit diagram of the voltage detecting circuit 300 among the embodiment as shown in Figure 3A.Fig. 4 is described in connection with Fig. 3 A and Fig. 3 B.Element identical with Fig. 3 A label among Fig. 4 has identical function.
In Fig. 4, electric current maker 302 comprises open circuit 402, transistor 404,406,410 and 412 and resistance 408 and 414.When voltage detecting circuit 300 was opened, open circuit 402 produced start signal (for example: digital 1 signal or simulating signal).
Electric current maker 302 is for generation of threshold current 312 proportional to temperature.In one embodiment, transistor 410 and 412 is P-type mos field effect (P-type metal-oxide semiconductor field effect, PMOS) transistor, transistor 404 and 406 is N-type metal oxide semiconductor field-effect (N-type metal-oxide semiconductor field effect, NMOS) transistor.Transistor 410 and 412 intercouples, and consists of current mirror, is used for producing according to the threshold current 312 of the transistor 412 of flowing through the image current 450 of the transistor 410 of flowing through.Therefore, image current 450 approximates threshold current 312.
In addition, the grid with transistor 404 of diode connected mode is coupled in the grid of transistor 406, and resistance 408 is connected with transistor 406.Therefore, the gate source voltage V_gs2 that the gate source voltage V_gs1 of transistor 404 can equal transistor 406 adds the voltage on the resistance 408, namely
V_gs1＝V_gs2+I*R， (1)
Wherein, I represent the to flow through current value of threshold current 312 of transistor 406 and resistance 408, R represents the resistance of resistance 408.According to formula (1), the current value of threshold current 312 is:
I＝(V_gs1-V_gs2)/R. (2)
In one embodiment, transistor 404 and 406 can be operated in sub-threshold region.At this moment, the difference between gate source voltage V_gs1 and the gate source voltage V_gs2 is:
(V_gs1-V_gs2)＝n*K*T*In(S)/q， (3)
Wherein, n represents slope factor, and K represents Boltzmann constant, and T represents the absolute temperature of voltage detecting circuit 300, S represents that the size of transistor 404 and 406 is than (for example: the ratio between the breadth length ratio of the breadth length ratio of transistor 404 and transistor 406), and q represents electron charge.If n*K*In (S)/q represents with a constant A, formula (2) can be expressed as:
I＝(A/R)*T. (4)
Shown in formula (4), threshold current 312 is approximately proportional with absolute temperature.Its advantage is, when transistor 406 was operated in sub-threshold region, threshold current 312 reduced.In addition, according to formula (4), threshold current 312 is not subjected to the impact of input voltage VIN.Therefore, can reduce the energy consumption of voltage detecting circuit 300.
In Fig. 4, the voltage sense circuit 310 that is comprised of transistor 412 and resistance 414 is included in the electric current maker 302.Electric current maker 302 is used transistor 412 and is produced threshold current 312.In one embodiment, voltage sense circuit 310 provides the first band gap voltage VB1, and produces induced signal 332 according to the first band gap voltage VB1 and input voltage VIN.
In particular, transistor 412 and resistance 414 can be used as the band gap voltage maker, and adopt threshold current 312 to produce the first band gap voltage VB1.The threshold current 312 of resistance 414 roughly is directly proportional with absolute temperature owing to flowing through, and the voltage of resistance 414 can have positive temperature coefficient (PTC).In addition, because the energy gap of silicon has negative temperature characteristic in CMOS technique, the gate source voltage of transistor 412 has negative temperature coefficient.Therefore, the gate source voltage sum of the voltage of resistance 414 and transistor 412 is that unaffected by temperature fluctuations keeps the first constant band gap voltage VB1 of essence.Induced signal 332 can be by the difference between input voltage VIN and the band gap voltage VB1 (for example: V_SENSE=VIN-VB1) represent, and can be used for representing input voltage VIN.
As the description of carrying out in conjunction with Fig. 3 A, when monitoring current 314 equaled threshold current 312, the induced voltage V_SENSE of expression induced signal 332 equaled voltage threshold VTH1, and input voltage VIN equals voltage threshold VTH2.In Fig. 4, because V_SENSE=VIN-VB1, VTH2 equals VTH1 and adds VB1, i.e. VTH2=VTH1+VB1.Electric current maker 302 and voltage sense circuit 310 also can have other structures, and are not limited to example shown in Figure 4.
In one embodiment, band gap voltage maker 308 comprises the resistance 432 of mutual series connection and the transistor 434 with diode connected mode.The monitoring current 314 band gap voltage maker 308 of can flowing through.Similar with voltage sense circuit 310, when monitoring current 314 equaled threshold current 312, band gap voltage maker 308 produced the 3rd band gap voltage VB3.
Band gap voltage maker 308 also can have other assemblies, and is not limited to example shown in Figure 4.For example, band gap voltage maker 308 has the bandgap cell of a plurality of mutual series connection, and each bandgap cell comprises the resistance of mutual series connection and the transistor with diode connected mode.Therefore, the 3rd band gap voltage VB3 can determine by a plurality of band gap voltages, and for example: the 3rd band gap voltage VB3 can equal the summation of the band gap voltage that a plurality of bandgap cell produce.In addition, band gap voltage maker 308 can comprise a plurality of bipolar transistors and resistance, and is not limited to the MOS transistor in the example shown in Figure 4.
In particular, in one embodiment, when VIN＜VTH2, induced voltage V_SENSE is less than voltage threshold VTH1, and transistor 428 is operated in cut-off region.Therefore, monitoring current 314 is less than threshold current 312, thereby makes transistor 426 be operated in linear zone.Therefore, the source-drain voltage of transistor 426 drops to less than predetermined threshold value, for example: the voltage threshold of transistor 436, and to turn-off transistor 436.Therefore, the output terminal of current comparator 304 is connected to ground by transistor 438.Thus, detection signal VA has low level, and the expression input voltage VIN is less than voltage threshold VTH2.
When VIN=VTH2, induced voltage V_SENSE equals voltage threshold VTH1, and transistor 428 is operated in sub-threshold region.Because transistor 426 produces the monitoring current 314 of mirror image according to threshold current 312, this monitoring current 314 equals threshold current 312.Similar with band gap voltage maker 308, transistor 428 and resistance 430 produce the second band gap voltage VB2.Thus, voltage threshold VTH1 is set equal to VB2+VB3; Voltage threshold VTH2 is set equal to VB1+VB2+VB3.
When VIN＞VTH2, induced voltage V_SENSE is greater than voltage threshold VTH1, and transistor 428 is operated in linear zone.Monitoring current 314 reaches maximal value, for example: threshold current 312, thus make transistor 426 be operated in the saturation region.The source-drain voltage of transistor 426 is greater than the voltage threshold of transistor 436, thereby opens transistor 436.Therefore, the output terminal of current comparator 304 produces the detection signal VA of high level, is used for the expression input voltage VIN greater than voltage threshold VTH2.Current comparator 304 and voltage-current converter 306 also can have other structures, and are not limited to the example of Fig. 4.
The advantage of the present embodiment is, voltage comparator (for example: the voltage comparator 104 among Fig. 1 and the voltage comparator 204 among Fig. 2) is replaced by the catabiotic voltage-current converter 306 of current branch and the current comparator 304 that have still less, reduces chip size and the energy consumption of voltage detecting circuit 300.In addition, because voltage threshold VTH2 is unaffected by temperature fluctuations and the constant band gap voltage of maintenance essence, thereby improve the accuracy of detection of voltage detecting circuit 300.
Figure 5 shows that according to the present invention the circuit diagram of the band gap voltage maker 308 among the embodiment as shown in Figure 3A.Fig. 5 is described in connection with Fig. 3 A and Fig. 4.Element identical with Fig. 4 label with Fig. 3 A among Fig. 5 has identical function.
In Fig. 5, band gap voltage maker 308 has lag function.The 3rd band gap voltage VB3 has a plurality of magnitudes of voltage, for example: magnitude of voltage VB3_1 and magnitude of voltage VB3_2.In one embodiment, band gap voltage maker 308 comprises bandgap cell 501, bandgap cell 502 and switch 504.The bandgap cell 501 if monitoring current 314 is flowed through, bandgap cell 501 can produce four-tape gap voltage VB4.Bandgap cell 502 is connected with bandgap cell 501.The bandgap cell 502 if monitoring current 314 is flowed through, bandgap cell 502 can produce the 5th band gap voltage VB5.In one embodiment, switch 504 can receive the detection signal VA of the state of expression input voltage VIN, and can control accordingly bandgap cell 502.
The 3rd band gap voltage that band gap voltage maker 308 produces changes according to detection signal VA.In particular, if detection signal VA has the expression input voltage VIN less than the first state of voltage threshold VTH2, for example: low level, switch 504 disconnects.Monitoring current 314 flow through simultaneously bandgap cell 501 and bandgap cell 502.Therefore, the 3rd band gap voltage VB3 has magnitude of voltage VB3_1, wherein, and VB3_1=VB4+VB5.Thus, voltage threshold VTH2 can be set to VB1+VB2+VB3_1, i.e. VTH2=VB1+VB2+VB4+VB5.
If detection signal VA has the expression input voltage VIN greater than the second state of voltage threshold VTH2, for example: high level, switch 504 closures.Monitoring current 314 flow through bandgap cell 501 and switch 504.Therefore, the 3rd band gap voltage VB3 has magnitude of voltage VB3_2, wherein, and VB3_2=VB4.In one embodiment, magnitude of voltage VB3_2 is less than magnitude of voltage VB3_1.Thus, voltage threshold VTH2 can be set to VB1+VB2+VB3_2, i.e. VTH2=VB1+VB2+VB4.
Figure 6 shows that according to the present invention the another kind of circuit diagram of the band gap voltage maker 308 among the embodiment as shown in Figure 3A.Fig. 6 is described in connection with Fig. 3 A and Fig. 4.Element identical with Fig. 4 label with Fig. 3 A among Fig. 6 has identical function.
In the example of Fig. 6, band gap voltage maker 308 also has lag function.Band gap voltage VB3 has a plurality of magnitudes of voltage, for example: magnitude of voltage VB3_1 and magnitude of voltage VB3_2.In one embodiment, band gap voltage maker 308 comprises bandgap cell 602, bandgap cell 604 and switch 606.Switch 606 is connected with bandgap cell 604.Switch 606 and bandgap cell 604 are in parallel with bandgap cell 602.The bandgap cell 602 if monitoring current 314 is flowed through, bandgap cell 602 can produce the 6th band gap voltage VB6.The bandgap cell 604 if monitoring current 314 is flowed through, bandgap cell 604 can produce the 7th band gap voltage VB7.Switch 606 can receive detection signal VA, and can control accordingly bandgap cell 602 and bandgap cell 604.
The 3rd band gap voltage that band gap voltage maker 308 produces changes according to detection signal VA.In particular, if detection signal VA has the expression input voltage VIN less than the first state of voltage threshold VTH2, for example: low level, switch 606 disconnects.Monitoring current 314 bandgap cell 602 of flowing through.The 3rd band gap voltage VB3 has magnitude of voltage VB3_1, wherein, and VB3_1=VB6.Thus, voltage threshold VTH2 can be set to VB1+VB2+VB3_1, i.e. VTH2=VB1+VB2+VB6.
If detection signal VA has the expression input voltage VIN greater than the second state of voltage threshold VTH2, for example: high level, switch 504 closures.Compare with bandgap cell 604, bandgap cell 602 has more transistor and resistance, so need higher operating voltage ability conducting.Therefore, but the transistor automatic cutout of bandgap cell 602.So, monitoring current 314 can flow through bandgap cell 604 and switch 606.Therefore, the 3rd band gap voltage VB3 has magnitude of voltage VB3_2, wherein, and VB3_2=VB7.Magnitude of voltage VB3_2 is less than magnitude of voltage VB3_1.Thus, voltage threshold VTH2 can be set to VB1+VB2+VB3_2, i.e. VTH2=VB1+VB2+VB7.Band gap voltage maker 308 also can have other structure, and is not limited to the example among Fig. 4, Fig. 5 and Fig. 6.
Figure 7 shows that the sequential chart 700 of the signal that voltage detecting circuit 300 according to an embodiment of the invention receives and produces.Sequential chart 700 reflected voltage detecting circuit 300 adopt Fig. 5 or embodiment illustrated in fig. 6 in the situation of band gap voltage maker.Fig. 7 is described in connection with the example of Fig. 3 C, Fig. 4, Fig. 5 and Fig. 6.Sequential chart 700 has been described the state of detection signal VA, threshold current 312, monitoring current 314 and input voltage VIN.
At moment t2, monitoring current 314 reaches maximal value.In one embodiment, this maximal value equals threshold current 312.In moment t2, the 3rd band gap voltage VB3 changes to magnitude of voltage VB3_2 from magnitude of voltage VB3_1.Therefore, voltage threshold VTH2 changes to magnitude of voltage V2 from magnitude of voltage V1.At this moment, transistor 428 is operated in sub-threshold region.Since moment t2, transistor 428 is operated in linear zone until input voltage VIN drops to voltage threshold VTH2, for example: at moment t6 '.That is to say, monitoring current 314 continue to equal threshold current 312 until input voltage VIN less than magnitude of voltage V2.Thus, although the noise of voltage detecting circuit 300 may cause the slight jitter of input voltage VIN, monitoring current 314 equals threshold current 312, and can not drop to less than threshold current 312.Therefore, can alleviate or eliminate the vibration of detection signal VA.
In moment t6 ', input voltage VIN is reduced to voltage threshold VTH2.Therefore, monitoring current 314 is reduced to the current value I 2 less than threshold current 312.Thus, voltage threshold VTH2 changes magnitude of voltage V1 into from magnitude of voltage V2.Since moment t6 ', the gate source voltage of transistor 428 reduces.Transistor 428 can be operated in cut-off region.Therefore, can alleviate or eliminate the vibration of detection signal VA.
Figure 8 shows that according to the present invention the circuit diagram of the current comparator 304 among the embodiment as shown in Figure 3A.Fig. 8 is described in connection with Fig. 3 A, Fig. 3 D and Fig. 4.Element identical with Fig. 4 label with Fig. 3 A among Fig. 8 has identical function.
In Fig. 8, current comparator 304 comprises current compensator 802, is used for affording redress electric current with compensation threshold current 312 according to the state of input voltage VIN.Thus, threshold current 312 changes according to the state of input voltage VIN, thereby supports that voltage-current converter 306 provides lag function.
In particular, in one embodiment, current compensator 802 can comprise transistor 804 and switch 806.The grid of transistor 804 is coupled in the grid 452 of the transistor 412 among Fig. 4.Transistor 804 and transistor 412 have consisted of current mirror, are used for producing the image current with current value I 5 according to threshold current 312.Thus, image current also can be roughly proportional with temperature.Switch 806 receives detection signal VA, and controls accordingly image current.
Illustrate, if detection signal VA has the expression input voltage VIN less than the first state of voltage threshold VTH2, for example: low level, switch 806 closures.Transistor 426 and transistor 412 produce image current I4 according to threshold current 312.Transistor 804 and transistor 412 produce image current I5 with compensation threshold current 312 according to threshold current 312.Thus, by monitoring current 314 relatively with have size between the threshold current 312 of current value I 3 (I3=I4+I5), current comparator 304 can determine the state of detection signal VA.For example, when monitoring current 314 equaled current value I 3, current value I 3 was greater than current value I 4, and detection signal VA can switch to the second state from the first state.
If detection signal VA has the expression input voltage VIN greater than the second state of voltage threshold VTH2, for example: high level, switch 806 disconnects.Transistor 426 and transistor 412 produce image current I4 according to threshold current 312.Therefore, by monitoring current 314 relatively with have size between the threshold current 312 of current value I 4, current comparator 304 can determine the state of detection signal VA.For example, when monitoring current 314 equaled current value I 4, VA can switch to the first state from the second state.
Thus, voltage threshold VTH2 can regulate according to threshold current 312.For example: if VA is in the first state, voltage threshold VTH2 equals magnitude of voltage V1.If detection signal VA is in the second state, voltage threshold VTH2 equals magnitude of voltage V2 '.Current compensator 802 also can have other structures, and is not limited to the example of Fig. 8.For example, current compensator 802 electric current that can when detection signal VA has high level, afford redress.
Its advantage of voltage detecting circuit of the present invention is, by using the current comparator 304 among Fig. 8, and the resistance in the voltage-current converter 306, for example: resistance 430 and 432, can have relatively little resistance provides band gap voltage VB2+VB3.Therefore, can reduce chip size and the cost of voltage detecting circuit 300.In addition, voltage threshold VTH2 changes according to threshold current 312.Therefore, can alleviate or eliminate the vibration of voltage detecting circuit 300, thereby improve the stability of voltage detecting circuit 300.
Figure 9 shows that the according to an embodiment of the invention operational flowchart 900 of voltage detecting circuit 300.Fig. 9 is described in connection with Fig. 3 A～Fig. 8.The concrete operation step that Fig. 9 is contained is as just example.That is to say, the present invention is suitable for other rational operating processes or Fig. 9 is carried out improved operation steps.
In step 902, (for example: the monitoring current that input voltage VIN) changes (for example: monitoring current 314) according to input voltage in generation.In one embodiment, voltage sense circuit 310 provides the first band gap voltage VB1, and produces the induced signal 332 that represents input voltage VIN according to the first band gap voltage VB1 and input voltage VIN.Wherein, monitoring current 314 produces according to induced signal 332.
In step 904, relatively monitoring current and threshold current are (for example: size threshold current 312).
In step 906, produce according to the result of this comparison this input voltage of expression state detection signal (for example: detection signal VA).
In step 908, (for example: the voltage threshold that VB1+VB2+VB3) input voltage is set (for example: voltage threshold VTH2) according to band gap voltage.When monitoring current equaled threshold current, input voltage equaled this voltage threshold.In one embodiment, if input voltage VIN greater than voltage threshold VTH2, this band gap voltage is set to the first magnitude of voltage, for example: VB1+VB2+VB3_2.If input voltage VIN is less than voltage threshold VTH2, this band gap voltage is set to the second voltage value, for example: VB1+VB2+VB3_1.In one embodiment, according to voltage threshold VTH2 monitoring current 314 is set.
In step 910, according to the state of input voltage threshold current is set.In one embodiment, if input voltage VIN greater than voltage threshold VTH2, is set to the first current value with threshold current 312, for example: I4.If input voltage less than voltage threshold VTH2, is set to the second current value with threshold current 312, for example: I3.
Figure 10 shows that the according to an embodiment of the invention structured flowchart of electronic system 1000.In Figure 10, electronic system 1000 comprises power supply 1002, voltage detecting circuit 300 and load 1004.Power supply 1002, for example: battery can provide the electric energy with voltage VIN with driving voltage testing circuit 300 and load 1004.Load 1004 (for example: electric automobile or computing machine) can receive this electric energy, and can carry out various functions.Voltage detecting circuit 300 can adopt Fig. 3 A～structure shown in Figure 8.Voltage detecting circuit 300 can detect this voltage VIN, and produces the detection signal VA of the state of expression voltage VIN.Load 1004 can be controlled this electric energy according to detection signal VA.For example: when detection signal VA represents voltage VIN greater than predetermined threshold value, for example: overvoltage condition, but load 1004 automatic cut-off powers.Perhaps, when detection signal VA represents voltage VIN less than predetermined threshold value, for example: under-voltage condition, open the light source in the load 1004, for example: light emitting diode, charge to power supply 1002 with reminding user.
Above embodiment and accompanying drawing only are the present invention's embodiment commonly used.Obviously, under the prerequisite that does not break away from the present invention's spirit that claims define and invention scope, can have and variously augment, revise and replace.It should be appreciated by those skilled in the art that the present invention can change aspect form, structure, layout, ratio, material, element, assembly and other to some extent according to concrete environment and job requirement in actual applications under the prerequisite that does not deviate from the invention criterion.Therefore, only be illustrative rather than definitive thereof at the embodiment of this disclosure, the present invention's scope is defined by appended claim and legal equivalents thereof, and is not limited to description before this.
Claims (21)
1. a voltage detecting circuit for detection of input voltage, is characterized in that, described voltage detecting circuit comprises:
Voltage-current converter is for generation of the monitoring current that changes according to described input voltage; And
Be coupled in the current comparator of described voltage-current converter, the size that is used for more described monitoring current and threshold current, and produce the detection signal of the state of the described input voltage of expression according to the result of described comparison, wherein, the temperature of described threshold current and described voltage detecting circuit is proportional.
2. voltage detecting circuit according to claim 1 is characterized in that, described voltage detecting circuit also comprises:
Be coupled in the voltage sense circuit of described voltage-current converter, be used for providing the first band gap voltage, and produce the induced signal of the described input voltage of expression according to described the first band gap voltage and described input voltage, wherein, described voltage-current converter produces described monitoring current according to described induced signal.
3. voltage detecting circuit according to claim 1, it is characterized in that, described voltage detecting circuit also comprises mos field effect transistor, and wherein, described mos field effect transistor is operated in sub-threshold region to produce described threshold current.
4. voltage detecting circuit according to claim 1 is characterized in that, described voltage detecting circuit also comprises:
Be coupled in the electric current maker of described current comparator, for generation of described threshold current, wherein, described electric current maker determines the maximal value of described monitoring current according to described threshold current.
5. voltage detecting circuit according to claim 1, it is characterized in that, described voltage-current converter provides the second band gap voltage, and according to described the second band gap voltage voltage threshold is set, when described monitoring current equaled described threshold current, described input voltage equaled described voltage threshold.
6. voltage detecting circuit according to claim 5 is characterized in that, described the second band gap voltage changes according to the state of described input voltage.
7. voltage detecting circuit according to claim 6 is characterized in that, regulates described monitoring current according to described voltage threshold.
8. voltage detecting circuit according to claim 5, it is characterized in that, described the second band gap voltage has the magnitude of voltage of selecting from least the first magnitude of voltage and second voltage value, wherein, if described input voltage is greater than described voltage threshold, described the second band gap voltage has described the first magnitude of voltage; And if described input voltage is less than described voltage threshold, described the second band gap voltage has described second voltage value.
9. voltage detecting circuit according to claim 5, it is characterized in that, described threshold current has the current value of selecting from least the first current value and the second current value, wherein, if described input voltage is greater than described voltage threshold, described threshold current has described the first current value; And if described input voltage is less than described voltage threshold, described threshold current has described the second current value.
10. voltage detecting circuit according to claim 1 is characterized in that, described threshold current changes according to the state of described input voltage.
11. a voltage detection method for detection of input voltage, is characterized in that, described voltage detection method comprises:
The monitoring current that generation changes according to described input voltage;
More described monitoring current and to the size of the proportional threshold current of temperature; And
Produce the detection signal of the state of the described input voltage of expression according to the result of described comparison.
12. voltage detection method according to claim 11 is characterized in that, the step that produces described monitoring current also comprises:
Produce the induced signal that represents described input voltage according to the first band gap voltage and described input voltage; And
Produce described monitoring current according to described induced signal.
13. voltage detection method according to claim 11 is characterized in that, described voltage detection method also comprises:
The second band gap voltage is provided; And
According to described the second band gap voltage voltage threshold is set, wherein, when described monitoring current equaled described threshold current, described input voltage equaled described voltage threshold.
14. voltage detection method according to claim 13 is characterized in that, described voltage detection method also comprises:
If described input voltage is greater than described voltage threshold, described the second band gap voltage is set to the first magnitude of voltage; And
If described input voltage is less than described voltage threshold, described the second band gap voltage is set to the second voltage value.
15. voltage detection method according to claim 13 is characterized in that, described the second band gap voltage changes according to the state of described input voltage, and described voltage detection method also comprises:
Regulate described monitoring current according to described voltage threshold.
16. voltage detection method according to claim 11 is characterized in that, described voltage detection method also comprises:
If described input voltage is greater than voltage threshold, described threshold current is set to the first current value; And
If described input voltage is less than described voltage threshold, described threshold current is set to the second current value.
17. an electronic system is characterized in that, described electronic system comprises:
Load by the electric energy driving with input voltage; And
Be coupled in the voltage detecting circuit of described load, be used for the size of more described input voltage and voltage threshold, described voltage detecting circuit comprises:
Voltage-current converter for generation of the monitoring current that changes according to described input voltage, and provides band gap voltage; And
Be coupled in the current comparator of described voltage-current converter, be used for the size of more described monitoring current and threshold current, and produce detection signal according to the result of described comparison, wherein, described voltage threshold is determined by described band gap voltage.
18. electronic system according to claim 17 is characterized in that, described voltage-current converter according to the described band gap voltage of the status adjustment of described input voltage to change described voltage threshold.
19. electronic system according to claim 18, it is characterized in that, described band gap voltage has the magnitude of voltage of selecting from least the first magnitude of voltage and second voltage value, wherein, if described input voltage is greater than described voltage threshold, described band gap voltage has described the first magnitude of voltage; And if described input voltage is less than described voltage threshold, described band gap voltage has described second voltage value.
20. electronic system according to claim 17 is characterized in that, described testing circuit according to the described threshold current of the status adjustment of described input voltage to change described voltage threshold.
21. electronic system according to claim 20, it is characterized in that, described threshold current has the current value of selecting from least the first current value and the second current value, wherein, if described input voltage is greater than described voltage threshold, described threshold current has described the first current value; And if described input voltage is less than described voltage threshold, described threshold current has described the second current value.
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| CN103308752A (en) * | 2012-03-08 | 2013-09-18 | 扬州稻源微电子有限公司 | High voltage detection circuit and radio frequency identification label chip using high voltage detection circuit |
| CN103809014B (en) * | 2012-11-15 | 2016-12-21 | 凹凸电子（武汉）有限公司 | A kind of detector unit, testing circuit and detection method |
| CN103853228A (en) * | 2012-12-07 | 2014-06-11 | 上海华虹集成电路有限责任公司 | Reference voltage generating circuit |
| US9634653B2 (en) * | 2014-12-11 | 2017-04-25 | Texas Instruments Incorporated | Method and apparatus for a brown out detector |
| CN109245206B (en) * | 2018-09-17 | 2021-10-15 | 上海空间电源研究所 | High-voltage lithium ion battery pack charging control signal generation circuit |
| CN109739710B (en) * | 2019-01-04 | 2022-07-12 | 华大半导体有限公司 | Undervoltage detection circuit and undervoltage detection method |
| CN109917176B (en) * | 2019-04-04 | 2023-12-15 | 上海东软载波微电子有限公司 | Drive overcurrent detection circuit |
| CN111987754A (en) * | 2019-05-24 | 2020-11-24 | 凹凸电子（武汉）有限公司 | Mobile device and control method for supplying power to load |
| CN112068634B (en) * | 2019-06-11 | 2022-08-30 | 瑞昱半导体股份有限公司 | Reference voltage generating device |
| US11199565B1 (en) * | 2020-07-17 | 2021-12-14 | Novatek Microelectronics Corp. | Undervoltage detection circuit |
| CN111879999B (en) * | 2020-07-31 | 2023-03-14 | 东南大学 | Low-temperature coefficient rapid voltage detection circuit |
| CN113608008A (en) * | 2021-08-30 | 2021-11-05 | 深圳赫飞物联科技有限公司 | Power supply voltage detection circuit and application thereof |
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