CN101557092A - Protection circuit and circuit protection method - Google Patents
Protection circuit and circuit protection method Download PDFInfo
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- CN101557092A CN101557092A CNA2009101432923A CN200910143292A CN101557092A CN 101557092 A CN101557092 A CN 101557092A CN A2009101432923 A CNA2009101432923 A CN A2009101432923A CN 200910143292 A CN200910143292 A CN 200910143292A CN 101557092 A CN101557092 A CN 101557092A
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Abstract
The invention discloses a protection circuit and a circuit protection method. The protection circuit comprises a voltage input terminal, a voltage output terminal, a diode, a resistor, a comparator, a power field-effect tube and a control circuit. The invention utilizes the characteristic of the negative temperature coefficient of the diode, i.e., the break-over voltage of the diode decreases as the temperature rises and the comparator reverses and outputs overheat and overcurrent control signal when the highest temperature is achieved. As the temperature coefficient of the diode is relatively constant, the protection circuit can be controlled with high precision and low cost.
Description
Technical field
The present invention relates to communication technical field, particularly a kind of protective circuit and circuit protection method.
Background technology
Excess temperature or current foldback circuit have a large amount of application in hardware system, particularly in the application scenario that needs hot plug, in USB (Universal Serial Bus, USB) interface.Generally be to adopt special chip to provide overcurrent protection function for system, the overtemperature and overcurrent protective circuit that adopts thermistor (being used for thermometric) to become in addition in present hardware designs with power field effect pipe discrete set of devices such as (being used for the control circuit break-make).But when there being many places need carry out temperature when control in the circuit, adopt the scheme cost of special chip higher, and control temperature or current threshold fix, can not change flexibly according to actual conditions.And for thermistor, thermistor is made of metal oxide, and the most frequently used oxide is manganese, nickel, cobalt, iron, copper and titanium, because the difference of manufactured materials causes adopting the overtemperature and overcurrent protective circuit precision of thermistor composition relatively poor.
Summary of the invention
The invention provides a kind of protective circuit and circuit protection method, be used to provide a kind of low cost, temperature control overcurrent and thermal-shutdown circuit accurately.
For achieving the above object, the invention provides a kind of protective circuit, comprise voltage input end, voltage output end, diode, resistance, comparator, power field effect pipe and control circuit;
The positive pole of described diode is connected with described voltage input end by described resistance, and positive pole is connected with an input of described comparator simultaneously; When the temperature of electric current that passes through monitored device or monitored device changes, the turn-on voltage variation of described diode;
Described power field effect pipe, its source electrode is connected with voltage output end with described voltage input end respectively with the leakage level, and grid is connected with described control circuit;
Described comparator, an input is connected with the positive pole of diode, and another input is connected with constant pressure source; Output is connected with described control circuit, is used for the comparative result according to the cathode voltage of the voltage of constant pressure source and diode, to described control circuit output signal;
Described control circuit is connected with the output of described comparator and the grid of described power field effect pipe, is used for the output signal according to described comparator, controls the break-make of described power field effect pipe.
Wherein, described monitored electric current is that described diode is responded to the temperature of described power field effect pipe when flowing through electric current between described voltage input end and the voltage output end; Along with the electric current of flowing through between described voltage input end and the voltage output end increases, the temperature of described power field effect pipe raises, and the temperature that described diode is sensed raises, and the conducting voltage of described diode reduces; The cathode voltage of described diode when the magnitude of voltage of described constant pressure source equals described monitored electric current and reaches maximum permissible value.
Wherein, when being used to detect the temperature of monitored device, described diode is responded to the temperature of described monitored device, and along with the temperature rising of described monitored device, the temperature that described diode is sensed raises, and the conducting voltage of described diode reduces; The cathode voltage of described diode when the temperature that the magnitude of voltage of described constant pressure source equals described monitored device reaches maximum permissible value.
Wherein, described diode is an a plurality of identical diode in parallel, and a plurality of identical diode of described parallel connection is used for the temperature of same device is responded to and/or the temperature of different components is responded to.
The present invention also provides a kind of circuit protection method, be applied in the circuit of voltage input end, voltage output end, diode, resistance, comparator, power field effect pipe and control circuit, the positive pole of described diode is connected with described voltage input end by described resistance, and positive pole is connected with an input of described comparator simultaneously; Described power field effect pipe, its source electrode is connected with voltage output end with described voltage input end respectively with the leakage level, and grid is connected with described control circuit; Described comparator, an input is connected with the positive pole of diode, and another input is connected with constant pressure source; Output is connected with described control circuit; Described control circuit is connected with the output of described comparator and the grid of described power field effect pipe; Described method comprises:
When the temperature of electric current that passes through monitored device or monitored device changes, the turn-on voltage variation of described diode;
Described comparator is according to the comparative result of the cathode voltage of the voltage of constant pressure source and diode, to described control circuit output signal;
Described control circuit is controlled the break-make of described power field effect pipe according to the output signal of described comparator.
Wherein, described monitored electric current is that described diode is responded to the temperature of described power field effect pipe when flowing through electric current between described voltage input end and the voltage output end; Along with the electric current of flowing through between described voltage input end and the voltage output end increases, the temperature of described power field effect pipe raises, and the temperature that described diode is sensed raises, and the conducting voltage of described diode reduces.
Wherein, the cathode voltage of described diode when the magnitude of voltage of described constant pressure source equals described monitored electric current and reaches maximum permissible value,
V
ref＝V
A，C+V
D-C
1*θ
j，c*I
max 2*R
DS(ON)
Wherein, V
RefBe the magnitude of voltage of constant pressure source, V
A, CThe conducting voltage of diode during for normal temperature, V
DBe the cathode voltage of diode, C
1Be the temperature coefficient of diode, θ
J, cBe the hot coefficient of power field effect pipe, I
MaxBe the maximum permissible value of monitored electric current, R
DS (ON)Conducting resistance for power field effect pipe.
Wherein, when being used to detect the temperature of monitored device, described diode is responded to the temperature of described monitored device, and along with the temperature rising of described monitored device, the temperature that described diode is sensed raises, and the conducting voltage of described diode reduces.
Wherein, the cathode voltage of described diode when the temperature that the magnitude of voltage of described constant pressure source equals described monitored device reaches maximum permissible value,
V
ref＝V
A，C+V
D-C
1*(T
max-T
C)
Wherein, V
RefBe the magnitude of voltage of constant pressure source, V
A, CThe conducting voltage of diode during for normal temperature, V
DBe the cathode voltage of diode, C
1Be the temperature coefficient of diode, T
MaxBe the maximum permissible value of the temperature of monitored device, T
CBe normal temperature.
Wherein, described diode is an a plurality of identical diode in parallel, and a plurality of identical diode of described parallel connection is used for the temperature of same device is responded to and/or the temperature of different components is responded to;
In a plurality of identical diode of described parallel connection, the conducting voltage of the diode that temperature is the highest is minimum, and the voltage of the positive pole of a plurality of identical diodes of described parallel connection equals the cathode voltage of the highest diode of described temperature.
Compared with prior art, the present invention has the following advantages:
The present invention utilizes the negative temperature coefficient feature of diode, and when temperature raise, its conducting voltage reduced, and comparator will overturn and export the overtemperature and overcurrent control signal when reaching maximum temperature.Because the temperature coefficient of diode is comparatively constant, so the precision of control protection electric circuit is higher and cost is lower.
Description of drawings
In order to be illustrated more clearly in the technical scheme of the embodiment of the invention, the accompanying drawing of required use is done to introduce simply in will describing embodiment below, apparently, accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.
Fig. 1 is the schematic diagram of the protective circuit that provides in the application scenarios of the present invention;
Fig. 2 is another schematic diagram of the protective circuit that provides in the application scenarios of the present invention;
Fig. 3 is the flow chart of the circuit protection method that provides among the present invention.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment only is a part of embodiment of the present invention, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that is obtained under the creative work prerequisite.
The invention provides a kind of protective circuit, comprise voltage input end, voltage output end, diode, resistance, comparator, power field effect pipe and control circuit;
The positive pole of diode is connected with voltage input end by resistance, and positive pole is connected with an input of comparator simultaneously; When the temperature of electric current that passes through monitored device or monitored device changes, the turn-on voltage variation of diode;
Power field effect pipe, its source electrode is connected with voltage output end with voltage input end respectively with the leakage level, and grid is connected with control circuit;
Comparator, an input is connected with the positive pole of diode, and another input is connected with constant pressure source; Output is connected with control circuit, is used for the comparative result according to the cathode voltage of the voltage of constant pressure source and diode, to the control circuit output signal;
Control circuit is connected with the output of comparator and the grid of power field effect pipe, is used for the output signal according to comparator, the break-make of power controlling field effect transistor.
Wherein, monitored electric current is that diode is responded to the temperature of described power field effect pipe when flowing through electric current between voltage input end and the voltage output end; Along with the electric current of flowing through between voltage input end and the voltage output end increases, the temperature of power field effect pipe raises, and the temperature that diode is sensed raises, and the conducting voltage of diode reduces; The cathode voltage of diode when the magnitude of voltage of constant pressure source equals monitored electric current and reaches maximum permissible value.
Wherein, when being used to detect the temperature of monitored device, diode is responded to the temperature of described monitored device, and along with the temperature rising of monitored device, the temperature that diode is sensed raises, and the conducting voltage of diode reduces; The cathode voltage of diode when the temperature that the magnitude of voltage of constant pressure source equals monitored device reaches maximum permissible value.
Wherein, diode is an a plurality of identical diode in parallel, and a plurality of identical diode in parallel is used for the temperature of same device is responded to and/or the temperature of different components is responded to.
Below in conjunction with a concrete application scenarios, the embodiment of protective circuit among the present invention is described.A kind of protective circuit is provided in the application scenarios of the present invention, its schematic diagram as shown in Figure 1, by diode Q, power field effect pipe M1, comparator C, control circuit K etc. partly form.This protective circuit can be used for single-point overcurrent protection or overheat protector, below the operation principle of protective circuit and the function of each several part is introduced.VIN is an input stage voltage among Fig. 1, and VCC is for supplying with the operating voltage of back level; Later level is used for the USB interface driving and is example, and then VCC is 5V, because the pressure drop of power field effect pipe M1 is very little, so VIN also is about 5V.
M1 is a power field effect pipe, is used to control the VCC switch, and its source electrode is connected with output with the input of protective circuit respectively with the leakage level, and grid is connected with control circuit.
Q is a diode, is used to respond to the temperature (overcurrent protection application) of M1 or the diode of other pyrotoxins (overheat protector application); The positive pole of diode is connected minus earth with the input of comparator one end.
C is a comparator, and the end in the input of comparator is connected with the positive pole of diode Q, the other end of input and reference voltage V
RefConnect; Be used for comparative result,, the break-make of M1 controlled to control circuit K output signal according to the cathode voltage of reference voltage and diode Q.
Control circuit K, an end is connected with the output of comparator, and the other end is connected with the grid of M1, is used for the output according to comparator C, and the break-make of M1 is controlled.
Using as during above-mentioned protective circuit shown in Figure 1, parameters such as Kong Zhi maximum current or maximum temperature according to actual needs are provided with the reference voltage V of input one end of comparator
Ref, when the temperature of pyrotoxin or the electric current that flows through M1 surpassed the maximum of setting, the cathode voltage of diode Q will be less than reference voltage V
Ref, comparator will overturn and export an overtemperature and overcurrent control signal, turn-offs M1 by control circuit K, realizes the overtemperature and overcurrent defencive function.
Concrete, when being used for overcurrent protection, the maximum current that needs control is the electric current of power field effect pipe M1 of flowing through, and this moment, the temperature of diode pair M1 was responded to, when the electric current that flows through M1 reaches maximum current I
MaxThe time, it will reach maximum temperature T
Max, diode need induce this maximum temperature I
MaxWhen the temperature of M1 was responded to, diode Q will try one's best and place near M1, was understandable that, diode Q is the closer to M1, and the temperature of the M1 that senses is accurate more and high more to the sensitivity of the variations in temperature of M1.M1 also can play the effect of control back level work voltage switch simultaneously.
Concrete; when being used for overheat protector; diode need be responded to is the temperature at corresponding pyrotoxin place; diode is placed near monitored device (being pyrotoxin); be understandable that; diode Q is the closer to monitored device, and the temperature of the monitored device of sensing is accurate more and high more to the sensitivity of the variations in temperature of monitored device.M1 only plays the effect of control back level work voltage switch this moment.Certainly also to can be used as a common pyrotoxin applicable cases monitored and overcurrent protection this moment similar for M1.
In conjunction with the applicable cases of overcurrent protection, below circuit is realized that principle is described in detail:
VCC provides the operating voltage to the back level, and for example the driving voltage of USB interface supposes to press the USB code requirement, and allowing the current maxima by it is I
MaxThe conducting resistance of supposing power field effect pipe M1 is R
DS (ON), then the electric current of working as by M1 reaches maximum I
MaxThe time, the maximum power P of the last consumption of M1
MaxFor:
P
max＝I
max 2*R
DS(ON) (1)
For general power field effect pipe, the pass of its power consumption and temperature is
T＝T
C+θ
j，c*P (2)
(2) T in the formula
CBe ambient temperature, θ
J, cBe the hot coefficient of power field effect pipe, P is the power consumption of power field effect pipe.
According to (1) formula and (2) formula, can calculate when electric current and reach maximum I
MaxThe time, the maximum temperature of M1 is:
T
max＝T
C+θ
j，c*P
max＝T
C+θ
j，c*I
max 2*R
DS(ON) (3)
For diode, general diode is a negative temperature coefficient, and its conducting voltage V descends with the rising of temperature, and corresponding relation is:
V＝V
A，C-C
1*(T-T
C) (4)
(4) T in the formula
CBe normal temperature, V
A, CBe normal temperature T
CThe time diode Q conducting voltage, V when being 25 ℃ of example normal temperature with the silicone tube
A, CBe 0.7V.-C
1Be the temperature coefficient of diode, this temperature coefficient is comparatively stable, and for example the temperature coefficient of silicone tube is about-2mV/ ℃, the actual temperature that T senses for diode Q.Because the minus earth of diode Q, therefore when the actual temperature sensed of diode Q is T, the positive pole of diode Q (being the A point among Fig. 1) voltage is the conducting voltage V of diode Q, and (when the negative pole of diode Q was unearthed, the conducting voltage V that the cathode voltage of diode Q should be diode Q added that the cathode voltage of diode is V+V
D).For example when temperature reaches 125 ℃, according to formula (4), its conducting voltage is 0.7-0.002* (125-25)=0.5V, and promptly the positive pole of diode Q (being the A point among Fig. 1) voltage is that (when the negative pole of diode Q was unearthed, the cathode voltage of diode Q should be 0.7+V to 0.5V
D-0.002* (125-25)=0.5+V
D).Along with the rising (for overcurrent protection, promptly the electric current by M1 constantly increases) of T, the conducting voltage V of diode Q is that the cathode voltage of diode Q will constantly descend, when the electric current by M1 reaches maximum I
MaxThe time, the cathode voltage of diode Q reaches minimum value V
Min
One end of the input of comparator directly links to each other the reference voltage V of the other end of the input of comparator with the anodal of diode Q
RefThe electric current of getting by M1 is I
MaxThe time the A voltage V of ordering
MinWhen electric current less than I
MaxThe time, the voltage that A is ordered will be greater than V
Min, the voltage V of comparator electrode input end
Ref(=V
Min) less than the voltage of negative input.When electric current surpasses I
MaxIncrease when causing T to raise, the voltage that A is ordered will further descend again again, at this moment the voltage V of comparator electrode input end
Ref(=V
Min) will be greater than the voltage of negative input, at this moment comparator will overturn, and exports an over-current signal to control circuit K.Control circuit K is according to the over-current signal of comparator output, and output level turn-offs M1 to the grid of M1, thereby cuts off back step voltage VCC, has played the function of overcurrent protection.Control circuit K generally can pass through programmable logic signal, the shutoff of control such as inverter M1.
Based on above-mentioned analysis, for V
RefThe electric current that should get by M1 is I
MaxThe time, the voltage V that A is ordered
Min,, can obtain the maximum constraints electric current I in conjunction with (3) and (4) formula
MaxWith V
RefRelation as follows:
V
ref＝V
min＝V
A，C+V
D-C
1*θ
j，c*I
max 2*R
DS(ON) (5)
This V
RefBe provided with and can should make that the precision of divider resistance is high as far as possible, to guarantee V by the arbitrary constant voltage source in the system is obtained by the divider resistance dividing potential drop
RefAs far as possible accurately.
In the application of overheat protector, diode is placed near monitored device (being pyrotoxin), directly just can draw the highest protection temperature T by (4) formula
MaxAnd V
RefRelation, do not need to convert by (3) formula, the actual temperature of the detected device of sensing as diode Q reaches T
MaxThe time:
V
ref＝V
min＝V
A，C+V
D-C
1*(T
max-T
C) (6)
Can obtain the highest protection temperature T
MaxAnd V
RefRelation, according to the highest protection temperature T
MaxCorresponding V is set
Ref.
Be different from the maximum current and the maximum temperature of being monitored in the special-purpose overtemperature and overcurrent protection integrated chip and can only be fixed value, only need adjust the V of comparator in the protective circuit that the present invention improves according to the variation of maximum current of monitoring and maximum temperature
RefVoltage just can be adjusted the electric current and the temperature of needs monitoring as required flexibly.The parameter difference opposite sex of diode is also little than temperature-sensitive resistance simultaneously, can provide comparatively accurate mistake gentle overcurrent control.
In the application scenarios of the present invention, also provide a kind of protective circuit, be used for multiple spot overcurrent protection or overheat protector, its schematic diagram as shown in Figure 2.
The principle of multiple spot overcurrent protection or overheat protector, identical with the principle of single-point overcurrent protection or overheat protector application, just can monitor multiple spot simultaneously.The multiple spot monitoring has two kinds of application.A kind of is to place a plurality of identical diode in parallel, for example P in Fig. 2 on a monitoring point
APoint has been placed 3 identical diode QA1, QA2 and QA3, avoids a diode monitor sample very little with this, the problem that the monitoring temperature precision is not high, this moment a plurality of identical diodes disperse to be placed on the control point around, place near the control point as far as possible.Second kind of applicable cases has a plurality of points to need monitoring on being, for example among Fig. 1 A is arranged, B, three points of C need monitoring, and the prime operating voltage that offers these three points can be controlled simultaneously by M1 (when the prime operating voltage can not be controlled simultaneously, just need control respectively with a plurality of power field effect pipes), at this moment at P
A, P
B, P
CThree points are respectively placed identical diode, by using a plurality of identical diode in parallel, so just can monitor out P
A, P
B, P
CThe highest point of temperature in three points can realize that multiple spot monitors simultaneously, when increasing a monitoring point, only needs to increase an identical diode and gets final product, thereby can save cost greatly.
When using in parallel a plurality of identical diode, according to formula (4), can know that the cathode voltage of the diode that temperature is the highest is minimum, also be that conducting voltage is minimum, in case after the diode conducting, its internal resistance descends rapidly, almost to 0, the voltage of whole positive terminal in parallel by the highest diode clamp of temperature on the minimum voltage value of conducting voltage decision by it, thereby can induce the highest point of temperature.
In the above-mentioned protective circuit provided by the invention, utilize the negative temperature coefficient feature of diode, when temperature raise, its conducting voltage reduced, and comparator will overturn and export the overtemperature and overcurrent control signal when reaching maximum temperature.The temperature coefficient of diode is comparatively constant, and otherness is less, and control precision is higher.And the temperature threshold of control or current threshold can be according to practical situations, by adjusting V in the comparator
RefVoltage adjust flexibly.At last,, induce the highest point of temperature, both can improve the precision of control, also can monitor multiple spot simultaneously, saved the realization cost by using a plurality of identical diode in parallel.
The present invention also provides a kind of circuit protection method, be applied in the circuit of voltage input end, voltage output end, diode, resistance, comparator, power field effect pipe and control circuit, the positive pole of described diode is connected with described voltage input end by described resistance, and positive pole is connected with an input of described comparator simultaneously; Described power field effect pipe, its source electrode is connected with voltage output end with described voltage input end respectively with the leakage level, and grid is connected with described control circuit; Described comparator, an input is connected with the positive pole of diode, and another input is connected with constant pressure source; Output is connected with described control circuit; Described control circuit is connected with the output of described comparator and the grid of described power field effect pipe.
As shown in Figure 3, this method comprises:
Step s301, when the temperature through monitored electric current or monitored device changes, the turn-on voltage variation of diode;
Step s303, comparator are according to the comparative result of the cathode voltage of the voltage of constant pressure source and diode, to the control circuit output signal;
Step s303, control circuit are according to the output signal of comparator, the break-make of power controlling field effect transistor.
In the above-mentioned method shown in Figure 3, further:
Monitored electric current is when flowing through electric current between voltage input end and the voltage output end, the temperature of diode induced power field effect transistor; Along with the electric current of flowing through between voltage input end and the voltage output end increases, the temperature of power field effect pipe raises, and the temperature that diode is sensed raises, and the conducting voltage of diode reduces.The cathode voltage of diode when the magnitude of voltage of constant pressure source equals monitored electric current and reaches maximum permissible value,
V
ref＝V
A，C+V
D-C
1*θ
j，c*I
max 2*R
DS(ON)
Wherein, V
RefMagnitude of voltage for constant pressure source; V
A, CThe conducting voltage of diode during for normal temperature, V
DBe the cathode voltage of diode, V when the minus earth of diode
D=0, C
1Be the temperature coefficient of diode, θ
J, cBe the hot coefficient of power field effect pipe, I
MaxBe the maximum permissible value of monitored electric current, R
DS (ON)Conducting resistance for power field effect pipe.
When being used to detect the temperature of monitored device, diode is responded to the temperature of monitored device, and along with the temperature rising of monitored device, the temperature that diode is sensed raises, and the conducting voltage of diode reduces.The cathode voltage of diode when the temperature that the magnitude of voltage of constant pressure source equals monitored device reaches maximum permissible value,
V
ref＝V
A，C+V
D-C
1*(T
max-T
C)
Wherein, V
RefMagnitude of voltage for constant pressure source; V
A, CThe conducting voltage of diode during for normal temperature, V
DBe the cathode voltage of diode, V when the minus earth of diode
D=0, C
1Be the temperature coefficient of diode, T
MaxBe the maximum permissible value of the temperature of monitored device, T
CBe normal temperature.
In addition, above-mentioned diode can be a plurality of identical diode of parallel connection, and a plurality of identical diode in parallel is used for the temperature of same device is responded to and/or the temperature of different components is responded to; In a plurality of diode connected in parallel, the conducting voltage of the diode that temperature is the highest is minimum, and the voltage of the positive pole of a plurality of diode connected in parallel equals the conducting voltage of the highest diode of temperature.
In the foregoing circuit guard method provided by the invention, utilize the negative temperature coefficient feature of diode, when temperature raise, its conducting voltage reduced, and comparator will overturn and export the overtemperature and overcurrent control signal when reaching maximum temperature.The temperature coefficient of diode is comparatively constant, and otherness is less, and control precision is higher.And the temperature threshold of control or current threshold can be according to practical situations, by adjusting V in the comparator
RefVoltage adjust flexibly.At last,, induce the highest point of temperature, both can improve the precision of control, also can monitor multiple spot simultaneously, saved the realization cost by with the use in parallel of a plurality of diodes.
Through the above description of the embodiments, those skilled in the art can be well understood to the present invention and can realize by hardware, also can realize by the mode that software adds necessary general hardware platform.Based on such understanding, technical scheme of the present invention can embody with the form of software product, it (can be CD-ROM that this software product can be stored in a non-volatile memory medium, USB flash disk, portable hard drive etc.) in, comprise some instructions with so that computer equipment (can be personal computer, server, the perhaps network equipment etc.) carry out the described method of each embodiment of the present invention.
It will be appreciated by those skilled in the art that accompanying drawing is the schematic diagram of a preferred embodiment, module in the accompanying drawing or flow process might not be that enforcement the present invention is necessary.
It will be appreciated by those skilled in the art that the module in the device among the embodiment can be distributed in the device of embodiment according to the embodiment description, also can carry out respective change and be arranged in the one or more devices that are different from present embodiment.The module of the foregoing description can be merged into a module, also can further split into a plurality of submodules.
The invention described above embodiment sequence number is not represented the quality of embodiment just to description.
More than disclosed only be several specific embodiment of the present invention, still, the present invention is not limited thereto, any those skilled in the art can think variation all should fall into protection scope of the present invention.
Claims (10)
1, a kind of protective circuit is characterized in that, comprises voltage input end, voltage output end, diode, resistance, comparator, power field effect pipe and control circuit;
The positive pole of described diode is connected with described voltage input end by described resistance, and positive pole is connected with an input of described comparator simultaneously; When the temperature of electric current that passes through monitored device or monitored device changes, the turn-on voltage variation of described diode;
Described power field effect pipe, its source electrode is connected with voltage output end with described voltage input end respectively with the leakage level, and grid is connected with described control circuit;
Described comparator, an input is connected with the positive pole of diode, and another input is connected with constant pressure source; Output is connected with described control circuit, is used for the comparative result according to the cathode voltage of the voltage of constant pressure source and diode, to described control circuit output signal;
Described control circuit is connected with the output of described comparator and the grid of described power field effect pipe, is used for the output signal according to described comparator, controls the break-make of described power field effect pipe.
2, protective circuit as claimed in claim 1 is characterized in that, described monitored electric current is that described diode is responded to the temperature of described power field effect pipe when flowing through electric current between described voltage input end and the voltage output end; Along with the electric current of flowing through between described voltage input end and the voltage output end increases, the temperature of described power field effect pipe raises, and the temperature that described diode is sensed raises, and the conducting voltage of described diode reduces; The cathode voltage of described diode when the magnitude of voltage of described constant pressure source equals described monitored electric current and reaches maximum permissible value.
3, protective circuit as claimed in claim 1, it is characterized in that, when being used to detect the temperature of monitored device, described diode is responded to the temperature of described monitored device, temperature rising along with described monitored device, the temperature that described diode is sensed raises, and the conducting voltage of described diode reduces; The cathode voltage of described diode when the temperature that the magnitude of voltage of described constant pressure source equals described monitored device reaches maximum permissible value.
4, as each described protective circuit in the claim 1 to 3; it is characterized in that; described diode is an a plurality of identical diode in parallel, and a plurality of identical diode of described parallel connection is used for the temperature of same device is responded to and/or the temperature of different components is responded to.
5, a kind of circuit protection method, it is characterized in that, be applied in the circuit of voltage input end, voltage output end, diode, resistance, comparator, power field effect pipe and control circuit, the positive pole of described diode is connected with described voltage input end by described resistance, and positive pole is connected with an input of described comparator simultaneously; Described power field effect pipe, its source electrode is connected with voltage output end with described voltage input end respectively with the leakage level, and grid is connected with described control circuit; Described comparator, an input is connected with the positive pole of diode, and another input is connected with constant pressure source; Output is connected with described control circuit; Described control circuit is connected with the output of described comparator and the grid of described power field effect pipe; Described method comprises:
When the temperature of electric current that passes through monitored device or monitored device changes, the turn-on voltage variation of described diode;
Described comparator is according to the comparative result of the cathode voltage of the voltage of constant pressure source and diode, to described control circuit output signal;
Described control circuit is controlled the break-make of described power field effect pipe according to the output signal of described comparator.
6, method as claimed in claim 5 is characterized in that, described monitored electric current is that described diode is responded to the temperature of described power field effect pipe when flowing through electric current between described voltage input end and the voltage output end; Along with the electric current of flowing through between described voltage input end and the voltage output end increases, the temperature of described power field effect pipe raises, and the temperature that described diode is sensed raises, and the conducting voltage of described diode reduces.
7, method as claimed in claim 6 is characterized in that, the cathode voltage of described diode when the magnitude of voltage of described constant pressure source equals described monitored electric current and reaches maximum permissible value,
V
ref＝V
A，C+V
D-C
1*θ
j，c*I
max 2*R
DS(ON)
Wherein, V
RefMagnitude of voltage for constant pressure source; V
A, CThe conducting voltage of diode during for normal temperature, V
DBe the cathode voltage of diode, C
1Be the temperature coefficient of diode, θ
J, cBe the hot coefficient of power field effect pipe, I
MaxBe the maximum permissible value of monitored electric current, R
DS (ON)Conducting resistance for power field effect pipe.
8, method as claimed in claim 5, it is characterized in that, when being used to detect the temperature of monitored device, described diode is responded to the temperature of described monitored device, temperature rising along with described monitored device, the temperature that described diode is sensed raises, and the conducting voltage of described diode reduces.
9, method as claimed in claim 8 is characterized in that, the cathode voltage of described diode when the temperature that the magnitude of voltage of described constant pressure source equals described monitored device reaches maximum permissible value,
V
ref＝V
A，C+V
D-C
1*(T
max-T
C)
Wherein, V
RefMagnitude of voltage for constant pressure source; V
A, CThe conducting voltage of diode during for normal temperature, V
DBe the cathode voltage of diode, C
1Be the temperature coefficient of diode, T
MaxBe the maximum permissible value of the temperature of monitored device, T
CBe normal temperature.
10, as each described method in the claim 5 to 9, it is characterized in that, described diode is an a plurality of identical diode in parallel, and a plurality of identical diode of described parallel connection is used for the temperature of same device is responded to and/or the temperature of different components is responded to;
In a plurality of identical diode of described parallel connection, the conducting voltage of the diode that temperature is the highest is minimum, and the voltage of the positive pole of a plurality of identical diodes of described parallel connection equals the cathode voltage of the highest diode of described temperature.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2009101432923A CN101557092A (en) | 2009-05-22 | 2009-05-22 | Protection circuit and circuit protection method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2009101432923A CN101557092A (en) | 2009-05-22 | 2009-05-22 | Protection circuit and circuit protection method |
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| Publication Number | Publication Date |
|---|---|
| CN101557092A true CN101557092A (en) | 2009-10-14 |
Family
ID=41175090
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA2009101432923A Pending CN101557092A (en) | 2009-05-22 | 2009-05-22 | Protection circuit and circuit protection method |
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|---|---|
| CN (1) | CN101557092A (en) |
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| CN102055169A (en) * | 2009-10-28 | 2011-05-11 | 中国科学院微电子研究所 | Over-temperature protection circuit |
| CN103094887A (en) * | 2011-11-07 | 2013-05-08 | 湖北三环汽车电器有限公司 | Overcurrent and over-temperature protection control circuit |
| CN103795277A (en) * | 2012-10-30 | 2014-05-14 | 康舒科技股份有限公司 | Power supply with output protection function and control method thereof |
| CN104617551A (en) * | 2015-01-13 | 2015-05-13 | 生迪光电科技股份有限公司 | Low-temperature protection circuit and electronic device |
| CN105764004A (en) * | 2016-02-29 | 2016-07-13 | 广东欧珀移动通信有限公司 | Headphone jack protection circuit, headphone jack circuit and mobile device |
| CN105873282A (en) * | 2016-05-30 | 2016-08-17 | 上海晶丰明源半导体有限公司 | Driving power system with temperature control function and temperature control method thereof |
| CN107521364A (en) * | 2017-08-21 | 2017-12-29 | 合肥力正新能源科技有限公司 | A kind of new energy car battery dynamic low-temperature protection method |
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| CN111063329A (en) * | 2020-01-22 | 2020-04-24 | 无锡十顶电子科技有限公司 | Buzzer driving circuit with temperature detection function |
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| CN102055169A (en) * | 2009-10-28 | 2011-05-11 | 中国科学院微电子研究所 | Over-temperature protection circuit |
| CN103094887A (en) * | 2011-11-07 | 2013-05-08 | 湖北三环汽车电器有限公司 | Overcurrent and over-temperature protection control circuit |
| CN103795277A (en) * | 2012-10-30 | 2014-05-14 | 康舒科技股份有限公司 | Power supply with output protection function and control method thereof |
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| CN105764004A (en) * | 2016-02-29 | 2016-07-13 | 广东欧珀移动通信有限公司 | Headphone jack protection circuit, headphone jack circuit and mobile device |
| CN105873282A (en) * | 2016-05-30 | 2016-08-17 | 上海晶丰明源半导体有限公司 | Driving power system with temperature control function and temperature control method thereof |
| CN108572687A (en) * | 2017-03-09 | 2018-09-25 | 华润矽威科技（上海）有限公司 | A kind of excess temperature compensation circuit and method |
| CN108572687B (en) * | 2017-03-09 | 2020-04-28 | 华润矽威科技（上海）有限公司 | Over-temperature compensation circuit and method |
| CN107521364A (en) * | 2017-08-21 | 2017-12-29 | 合肥力正新能源科技有限公司 | A kind of new energy car battery dynamic low-temperature protection method |
| CN111063329A (en) * | 2020-01-22 | 2020-04-24 | 无锡十顶电子科技有限公司 | Buzzer driving circuit with temperature detection function |
| CN113193744A (en) * | 2021-04-12 | 2021-07-30 | 珠海格力电器股份有限公司 | Control device and method for power device in discrete PFC circuit and electric equipment |
| CN113193744B (en) * | 2021-04-12 | 2024-03-29 | 珠海格力电器股份有限公司 | Control device and method for power device in discrete PFC circuit and electrical equipment |
| CN113884208A (en) * | 2021-09-09 | 2022-01-04 | 芯原微电子（成都）有限公司 | High-precision over-temperature detection circuit |
| CN113884208B (en) * | 2021-09-09 | 2023-10-10 | 芯原微电子（成都）有限公司 | High-precision over-temperature detection circuit |
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Application publication date: 20091014 |