CN114825563B - Circuit structure with temperature protection - Google Patents

Circuit structure with temperature protection Download PDF

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Publication number
CN114825563B
CN114825563B CN202210754525.9A CN202210754525A CN114825563B CN 114825563 B CN114825563 B CN 114825563B CN 202210754525 A CN202210754525 A CN 202210754525A CN 114825563 B CN114825563 B CN 114825563B
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circuit
switching tube
resistor
temperature
current
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CN114825563A (en
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不公告发明人
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Suzhou Baker Microelectronics Co Ltd
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Suzhou Baker Microelectronics Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
    • H02J7/00309—Overheat or overtemperature protection
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
    • H02J7/0031—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits using battery or load disconnect circuits

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Protection Of Static Devices (AREA)

Abstract

The invention discloses a circuit structure with temperature protection, which comprises: the temperature measuring circuit, the first circuit and the comparison circuit; the current of the temperature measuring circuit is positively correlated with the temperature; the current on the first circuit is equal to the current of the temperature measuring circuit, and the first circuit comprises a first switching tube; the comparison circuit comprises a first resistor, M first switching tubes and a comparison unit, wherein the M first switching tubes are connected in parallel and then connected in series with the first resistor to form a second circuit, the output end of the first circuit and the output end of the second circuit are grounded or grounded through a preset circuit unit, the controlled end of each first switching tube is connected, the comparison unit is used for comparing the current on the first circuit and the current on the second circuit and outputting a comparison result signal, and the comparison result signal is used for indicating whether the temperature is greater than a preset threshold value or not. The invention reduces the complexity of the battery power supply circuit applying the temperature protection circuit, reduces the volume of the battery power supply circuit, and also reduces the fault rate caused by the influence of temperature.

Description

Circuit structure with temperature protection
Technical Field
The invention relates to the technical field of battery power supply, in particular to a circuit structure with temperature protection.
Background
In the related art, a power supply circuit is usually used for charging a battery load, but when the operating temperature of the battery power supply circuit is too high, not only can the performance and parameters of the battery power supply circuit be greatly affected, but also the service life of the battery power supply circuit can be shortened, and meanwhile, the battery load at the rear end can be damaged by the power supply circuit.
However, in the related art, the temperature protection circuit in the power supply circuit usually needs to input the reference voltage, and therefore, the temperature protection circuit usually has a reference voltage generation circuit, and the arrangement of the reference voltage generation circuit obviously increases the circuit volume and increases the circuit complexity. Meanwhile, the output of the common reference voltage generating circuit is greatly influenced by temperature, so that the output error of the reference voltage generating circuit is larger in a high-temperature environment, the reliability of the temperature protection circuit is reduced, and the failure rate of the power supply circuit in the high-temperature environment is greatly improved.
Disclosure of Invention
In view of this, embodiments of the present invention provide a circuit structure with temperature protection, so as to solve the problems that a reference voltage generating circuit in an existing temperature protection circuit increases a circuit volume, increases a circuit complexity, and is greatly affected by temperature, resulting in low reliability.
An embodiment of the present invention provides a circuit structure with temperature protection, including: the temperature measuring circuit comprises a temperature measuring circuit, a first circuit and a comparison circuit;
the current of the temperature measuring circuit is positively correlated with the temperature;
the current on the first circuit is equal to the current of the temperature measuring circuit, and the first circuit comprises a first switching tube;
the comparison circuit comprises a first resistor, M first switching tubes and a comparison unit, wherein the M first switching tubes are connected in parallel and then connected in series with the first resistor to form a second circuit, the input end of the first circuit and the input end of the second circuit are connected with a preset voltage, the output end of the first circuit and the output end of the second circuit are grounded or grounded through a preset circuit unit, the comparison circuit and the controlled end of each first switching tube in the first circuit are connected, the voltage of the controlled end of each first switching tube is reduced along with the increase of the current of the temperature measurement circuit, the comparison unit is used for comparing the current of the first circuit with the current of the second circuit and outputting a comparison result signal, and the comparison result signal is used for indicating whether the temperature is larger than a preset threshold value or not.
Optionally, the first switch tube is a triode or a field effect tube.
Optionally, the preset circuit unit includes a second resistor and a third resistor, the second resistor is connected in series with the output end of the first circuit and then grounded, and the third resistor is connected in series with the output end of the second circuit and then grounded;
the second resistor and the third resistor have the same resistance value;
two input ends of the comparison unit are respectively connected with the first end of the second resistor and the first end of the third resistor, and the first end of the second resistor and the first end of the third resistor are both the other ends except a grounding end.
Optionally, the temperature measuring circuit includes a first component, the first component is a diode, a triode with a collector connected to a base, or a field effect transistor with a gate connected to a drain, and a voltage drop across the first component is positively correlated to a temperature when an input voltage is constant.
Optionally, the temperature measuring circuit further includes an isolation module, a fourth resistor, a second switching tube, and a third switching tube;
the input ends of the second switching tube and the third switching tube are connected with the preset voltage; the controlled ends of the second switching tube and the third switching tube are connected with the controlled end of the first switching tube and are connected with the output end of one of the second switching tube and the third switching tube, and the currents on the third switching tube and the second switching tube are the same;
the number of the first elements is N +1, and the parameters are the same; the input end of one of the first components is connected with the output end of the second switching tube through the isolation module, and the output end of the first component is grounded; the rest N first components are connected in parallel, the input ends of the N first components are connected with the output end of the third switching tube sequentially through the fourth resistor and the isolation module, and the output ends of the N first components are grounded.
Optionally, the isolation module includes a fourth switching tube and a fifth switching tube, the controlled end of the fourth switching tube is connected to the controlled end of the fifth switching tube, and is connected to the input end of one of the fourth switching tube and the fifth switching tube, and parameters of the fourth switching tube and the fifth switching tube are the same; the input end of the fifth switch tube is connected with the output end of the second switch tube, the output end of the fifth switch tube is connected with the input end of the first component, the input end of the fourth switch tube is connected with the output end of the third switch tube, and the output end of the fourth switch tube is connected with the input end of the N first component through the fourth resistor.
Optionally, the circuit structure with temperature protection further includes a control module;
and the control module is used for outputting a corresponding control signal according to the comparison result signal, and the control signal is used for controlling the functional circuit to work or stop working.
The embodiment of the invention also provides a power supply circuit with temperature protection, which comprises a battery charging circuit and any one of the circuit structures with temperature protection, wherein a comparison result signal output by the circuit structure with temperature protection is used for controlling the battery charging circuit to work or stop working.
Optionally, the battery charging circuit includes a boost chopper circuit.
Optionally, the boost chopper circuit includes an inductor, a sixth switching tube, and a diode, one end of the inductor is connected to a power supply, the other end of the inductor is connected to an anode of the diode, a cathode of the diode is an output end of the boost chopper circuit, the other end of the inductor is grounded through the sixth switching tube, and on/off of the sixth switching tube is controlled by the control module.
Optionally, the power supply circuit with temperature protection further comprises a power frequency transformer and a rectification filter circuit, wherein the power frequency transformer, the rectification filter circuit and the battery charging circuit are sequentially connected in series.
The circuit structure with temperature protection and the power supply circuit provided by the embodiment of the invention do not need to be provided with a reference voltage generating circuit, so that the circuit structure is simple, the number of components is small, the complexity of the circuit is further reduced, and the volume of the circuit is reduced. In addition, the temperature protection and adjustment in the embodiment of the invention are convenient.
Drawings
The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and not to be construed as limiting the invention in any way, and in which:
fig. 1 is a schematic diagram of a circuit structure with temperature protection according to an embodiment of the present invention;
FIG. 2 is a diagram illustrating the relationship between current ic and current i4 with temperature according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of another circuit structure with temperature protection according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of another circuit structure with temperature protection according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a battery charging circuit according to an embodiment of the present invention;
fig. 6 is a block diagram of an internal circuit of a control chip according to an embodiment of the present invention;
fig. 7 is a circuit block diagram of a power supply circuit with temperature protection according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.
It should be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising a," "8230," "8230," or "comprising" does not exclude the presence of other like elements in a process, method, article, or apparatus comprising the element. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the following examples, "plurality" means two or more unless specifically limited otherwise.
Referring to fig. 1, an embodiment of the invention provides a circuit structure with temperature protection, including: a temperature measuring circuit 101, a first circuit 102 and a comparison circuit 103;
the current of the temperature measuring circuit 101 is positively correlated with the temperature;
the current on the first circuit 102 is equal to the current of the temperature measuring circuit 101, and the first circuit 102 comprises a first switching tube Q7;
the comparison circuit 103 includes a first resistor r2, M first switching tubes Q7 and a comparison unit, the M first switching tubes Q7 are connected in parallel and then connected in series with the first resistor r2 to form a second circuit 1031, and an input end of the first circuit 102 and an input end of the second circuit 1031 are connected with a preset voltage V dd The output terminal of the first circuit 102 and the output terminal of the second circuit 1031 are both grounded or are grounded through a preset circuit unit (not shown in fig. 1), the comparison circuit 103 and the controlled terminal of each first switch Q7 in the first circuit 102 are both connected, and the voltage of the controlled terminal of the first switch Q7 decreases as the current of the temperature measuring circuit 101 increases, the comparison unit (not shown in fig. 1) is configured to compare the current of the first circuit 102 with the current of the second circuit 1031 and output a comparison result signal, and the comparison result signal is configured to indicate whether the temperature is greater than a preset threshold value or not.
Specifically, the preset voltage is constant. One end of the first resistor r2 is connected to the input ends of the M parallel first switching tubes Q7, and the other end is connected to the preset voltage, that is, the first resistor r2 is disposed between the power supply and the M parallel first switching tubes Q7. The circuit structure may further include a control module, where the control module is configured to output a corresponding control signal according to the comparison result signal, and the control signal may be configured to control the related circuit to operate (close) or stop operating (open).
The circuit structure with the temperature protection function provided by the embodiment of the invention does not need to be provided with a reference voltage generating circuit, so that the circuit structure is simple, the number of components is small, the complexity of the circuit is further reduced, and the volume of the circuit is reduced. In addition, the temperature protection and adjustment in the embodiment of the invention are convenient.
The circuit structure with temperature protection provided by the embodiment of the invention can be applied to a power supply circuit, such as a power supply circuit for charging a battery.
In some specific embodiments, the first switching transistor Q7 is a triode or a field effect transistor (MOS). Specifically, the first switch Q7 is a PNP transistor (see fig. 1 and 3) or a P-channel MOS transistor (see fig. 4, although the first switch Q7 is a transistor in fig. 3 and the first switch Q7 is a field effect transistor in fig. 4, they are the first switch, and therefore the same reference numerals are used to indicate that the second switch, the third switch, the fourth switch, the fifth switch and the first component are all referred to hereinafter). When the first switch tube Q7 is a PNP type triode, an emitter of the first switch tube Q7 is an input terminal, an emitter of the first switch tube Q7 in the first circuit 102 is also an input terminal of the first circuit 102, a collector of the first switch tube Q7 is an output terminal, a collector of the first switch tube Q7 in the first circuit 102 is also an output terminal of the first circuit 102, and a base of the first switch tube Q7 is a controlled terminal. When the first switching tube Q7 is a P-channel MOS tube, a source of the first switching tube Q7 is an input end, a source of the first switching tube Q7 in the first circuit 102 is also an input end of the first circuit 102, a drain of the first switching tube Q7 is an output end, a drain of the first switching tube Q7 in the first circuit 102 is also an output end of the first circuit 102, and a gate of the first switching tube Q7 is a controlled end.
The working principle of the embodiment of the present invention is described below by taking the first switching tube Q7 as a PNP type triode as an example:
when the temperature is low to a certain degree (for example, 0 Kelvin), the current ic of the temperature measurement circuit 101 is 0, because the current i3 of the first circuit 102 and the current of the temperature measurement circuit 101The currents ic are equal, so that i3 is 0, and at this time, the first switch Q7 in the first circuit 102 and the M parallel first switch Q7 in the comparison circuit 103 are all in the off state, so that the voltage difference between the base and the emitter of each first switch Q7 is 0V, and therefore, the base voltage of each first switch Q7 is equal to the preset voltage V dd 。
As the temperature rises, ic gradually increases from 0, and at this time, the voltage difference between the base and the emitter of the first switch Q7 in the first circuit 102 and the first switch Q7 in the comparison circuit 103 gradually increases, since the emitter voltage of the first switch Q7 in the first circuit 102 is always at the preset voltage V dd Therefore, the base voltage of the first switch Q7 in the first circuit 102 will gradually decrease. Since the base voltages of the first switch tube Q7 in the first circuit 102 and the first switch tube Q7 in the comparison circuit 103 are equal, the base voltage of the first switch tube Q7 in the comparison circuit 103 is also from V as the temperature rises dd The current i4 is generated in the M parallel first switch tubes Q7 in the comparison circuit 103. At a lower temperature, the voltage difference V between the base and the emitter of the first switch tube Q7 in the first circuit 102 be7 At this time, it can be considered that voltage differences between bases and emitters of the first switch tube Q7 in the first circuit 102 and the first switch tube Q7 in the comparison circuit 103 are almost the same, so that the current i4 in the M parallel first switch tubes Q7 in the comparison circuit 103 is approximately equal to M times of the current i3 in the first switch tube Q7 in the first circuit 102, so that i4 is approximately equal to M times of the current i3 in the first switch tube Q7 in the first circuit 102, and thus i3 is also small in the current i3 in the first switch tube Q7 in the first circuit 102, and at this time, the voltage in the first resistor r2 is negligible>i3, i4>ic；
If the first resistor r2 is not present, the voltage difference V between the base and the emitter of the first switching tube Q7 in the first circuit 102 be7 Is always equal to the voltage difference V between the base and the emitter of the first switch tube Q7 in the comparison circuit 103 be8 The current i4 on the M parallel first switching tubes Q7 in the comparison circuit 103 is always M times the current i3 on the first switching tube Q7.
However, since the first resistor r2 is provided in the embodiment of the present invention, the voltage difference V between the base and the emitter of the M parallel first switching tubes Q7 in the comparison circuit 103 be8 Is always higher than the voltage difference V between the base and the emitter of the first switching tube Q7 in the first circuit 102 be7 Small r2 x i4. At this time, when the temperature is gradually increased from a lower level, ic is increased, so that the voltage difference V between the base and the emitter of the first switching tube Q7 in the first circuit 102 is increased be7 Increase, therefore, the base voltage V b Decreasing, i4 increases, so the voltage difference V between the base and emitter of the M parallel first switching tubes Q7 in the comparison circuit 103 be8 Compared with the voltage difference V between the base and the emitter of the first switch tube Q7 in the first circuit 102 be7 It becomes smaller and smaller. Since the current of the transistor increases exponentially as the voltage difference between the base and the emitter increases, V be7 And V be8 The influence of the difference between the first and second switching tubes Q7 and Q7 on the current is gradually greater than the influence of the difference between the first switching tube Q7 in the first circuit 102 and the first switching tube Q7 in the comparison circuit 103 on the current, so that i3 is caused to occur after the temperature rises to a certain point Tx>i4, i.e. ic>i4。
From the above analysis, a graph of the current ic and the current i4 as a function of temperature can be obtained, as shown in fig. 2. As can be seen from fig. 2, ic < i4 when the temperature is below Tx; when the temperature is equal to Tx, ic = i4; when the temperature is above Tx, ic > i4. From the above analysis, increasing the value of M or decreasing the resistance of the first resistor r2 can increase the value of the current i4, so as to move the temperature critical point Tx in fig. 2 to the right, i.e. increase the temperature value of the temperature critical point Tx; conversely, decreasing the value of M or increasing the resistance of the first resistor r2 decreases the temperature value of the temperature threshold Tx.
When the first switch tube Q7 is a P-channel MOS tube, the working principle is the same as that when the first switch tube Q7 is a PNP-type triode, and details are not repeated here.
In some specific embodiments, the first circuit may include only the first switch Q7, where the input terminal of the first switch Q7 is the input terminal of the first circuit, and the output terminal of the first switch Q7 is the output terminal of the first circuit.
In some specific embodiments, referring to fig. 3 and fig. 4, the preset circuit unit includes a second resistor rs1 and a third resistor rs2, the second resistor rs1 is connected in series with an output terminal of the first circuit 102 (when the first circuit includes only the first switch Q7, the output terminal of the first circuit 102 is the output terminal of the first switch Q7) and then grounded, and the third resistor rs2 is connected in series with the output terminal of the second circuit 1031 and then grounded;
the resistance values of the second resistor rs1 and the third resistor rs2 are the same;
two input ends of the comparing unit (specifically, may be the comparator A1 in fig. 3 and 4) are respectively connected to the first end of the second resistor rs1 and the first end of the third resistor rs2, and both the first end of the second resistor rs1 and the first end of the third resistor rs2 are the other ends except for the ground end.
In the embodiment of the present invention, since the resistances of the second resistor rs1 and the third resistor rs2 are the same, the voltage magnitude relationship between the first end of the second resistor rs1 and the first end of the third resistor rs2 represents the current magnitude relationship between the second resistor rs1 and the third resistor rs 2. Specifically, the comparing unit may be a comparator A1, and the second resistor rs1 and the third resistor rs2 serve as current detection resistors. Referring to fig. 3 and 4, the current ic and the current i4 respectively flow into the second resistor rs1 and the third resistor rs2, and the resistance values of the second resistor rs1 and the third resistor rs2 are both rs, so that the comparison voltage V is respectively generated at the positive input end and the negative input end of the comparator A1 s1 And V s2 And V is s1 =rs*ic，V s2 = rs = i4; therefore, when ic<i4, V s1 <V s2 Output V of comparator A1 c Low, at which time the circuit temperature is lower than Tx; when ic>i4, V s1 >V s2 Output V of comparator A1 c High, at which time the circuit temperature is too high, above Tx.
In other optional specific embodiments, currents on the first circuit and the second circuit may be respectively collected by using other current sampling manners, and then the currents are input to the comparison unit to compare magnitudes of the currents.
In some specific embodiments, the temperature measuring circuit 101 includes a first component, which is a diode, a triode with a collector connected to a base, or a field effect transistor with a gate connected to a drain, and a voltage drop across the first component is positively correlated to a temperature under a constant input voltage.
When the first component is a triode, the triode can be an NPN type triode specifically; when the first component is a field effect transistor, the first component may be an N-channel field effect transistor.
In other alternative embodiments, the first component may be another component than the above components, as long as the voltage drop across the component is positively correlated with the temperature, such as a thermistor.
In some specific embodiments, referring to fig. 3, the temperature measuring circuit 101 further includes an isolation module, a fourth resistor r1, a second switch tube Q5, and a third switch tube Q6;
the input terminals of the second switch tube Q5 and the third switch tube Q6 are connected to the preset voltage, specifically, the input terminals of the second switch tube Q5 and the third switch tube Q6 may be connected to the same power supply as the input terminals of the first circuit 102 and the second circuit 1031; controlled ends of the second switching tube Q5 and the third switching tube Q6 are both connected with a controlled end of the first switching tube Q7 and are connected with an output end of one of the second switching tube Q5 and the third switching tube Q6, the controlled ends of the second switching tube Q5 and the third switching tube Q6 may be specifically connected with an output end of the third switching tube Q6, and currents on the third switching tube Q6 and the second switching tube Q5 are the same;
the number of the first elements is N +1, and the parameters are the same; the input end of one of the first components is connected with the output end of the second switching tube Q5 through the isolation module, and the output end of the first component is grounded; the rest N first components are connected in parallel, the input ends of the N first components are connected with the output end of the third switching tube Q6 sequentially through the fourth resistor r1 and the isolation module, and the output ends of the N first components are grounded.
The second switching tube Q5 and the third switching tube Q6 may be transistors or field effect tubes. Referring to fig. 3, when the second switching tube Q5 and the third switching tube Q6 are triodes, they may be specifically PNP triodes, and the base is a controlled terminal, the emitter is an input terminal, and the collector is an output terminal. At this time, the first switching tube Q7 should also be a triode, specifically, a PNP-type triode, with a base being a controlled terminal, an emitter being an input terminal, and a collector being an output terminal. Referring to fig. 4, when the second switching tube Q5 and the third switching tube Q6 are field effect tubes, they may be P-channel field effect tubes, and the gate is a controlled end, the source is an input end, and the drain is an output end. At this time, the first switching tube Q7 should also be a field effect tube, specifically, a P-channel field effect tube, with the gate being the controlled end, the source being the input end, and the drain being the output end.
The second switching tube Q5, the third switching tube Q6 and the first switching tube Q7 in the first circuit 102 constitute a current mirror circuit, and the parameters of the three are completely the same, and the currents of the three are also the same.
In some specific embodiments, the isolation module includes a fourth switching tube Q3 and a fifth switching tube Q4, the controlled terminals of the fourth switching tube Q3 and the fifth switching tube Q4 are connected, and are connected to the input terminal of one of the fourth switching tube Q3 and the fifth switching tube Q4, the controlled terminals of the fourth switching tube Q3 and the fifth switching tube Q4 may be connected to the input terminal of the fifth switching tube Q4, and the parameters of the fourth switching tube Q3 and the fifth switching tube Q4 are the same; the input end of the fifth switch tube Q4 is connected with the output end of the second switch tube Q5, the output end of the fifth switch tube Q4 is connected with the input end of the first component, the input end of the fourth switch tube Q3 is connected with the output end of the third switch tube Q6, and the output end of the fourth switch tube Q3 is connected with the input ends of the N first components through the fourth resistor r 1.
The fourth switching tube Q3 and the fifth switching tube Q4 may be transistors or field effect tubes. When the fourth switching tube Q3 and the fifth switching tube Q4 are triodes, they may be NPN triodes, with the base being the controlled terminal, the collector being the input terminal, and the emitter being the output terminal. When the fourth switch tube Q3 and the fifth switch tube Q4 are field effect tubes, they may be N-type field effect tubes, and the gate is a controlled end, the drain is an input end, and the source is an output end.
Of course, the isolation module is not limited to the above form composed of the fourth switching tube Q3 and the fifth switching tube Q4, and may also be another form of isolation module in the related art.
The working principle of the temperature measuring circuit and the subsequent related circuits will be described by taking the first components (i.e. Q1, Q3, Q4, Q5, Q6, and Q7 in the figure) as examples.
Since the base electrodes of Q5 and Q6 are connected with the base electrode of the first switch tube Q7, the base electrode voltages of Q5, Q6 and Q7 in the first circuit 102 are all V b Further, since Q5, Q6 and Q7 in the first circuit 102 constitute a current mirror circuit, i1= i2= i3. Since the parameters of Q3 and Q4 are identical and the currents flowing through Q3 and Q4 are also identical, i2 and i1, respectively, the voltage difference V between the base and emitter of Q3 is equal be3 Voltage difference V between base and emitter equal to Q4 be4 And since the base of Q3 is connected to the base of Q4, the base voltage V of Q3 b3 Base voltage V equal to Q4 b4 So that the emitter voltage V of Q3 e3 Emitter voltage V equal to Q4 e4 . Meanwhile, because the base electrode of the Q1 is connected with the collector electrode, the current i1 flowing from the Q4 to the collector electrode of a single triode Q1 and the current i2 flowing from the Q3 to the collector electrodes of N triodes Q1 connected in parallel are directly from the diode D between the base electrode and the emitter electrode be Flows into Ground (GND), so that at this time, the diode D be Pressure drop V of be Comprises the following steps:
V be = V t *ln（ic/is）（1.1）
wherein, V t The temperature is a thermal voltage, and the magnitude of the thermal voltage is in direct proportion to the absolute temperature; ic is a current-through diode D be Current of (i)c = i1= i2= i3; is a diode D be The reverse saturation current of (2) is proportional to the number of parallel diodes.
At this time, all emitters of Q1 are grounded, and therefore, emitter voltage V of Q1 connected to Q4 e1 And N parallel-connected Q1 emitter voltages V connected to Q3 e2 Are all 0, so that the voltage between the base and emitter of Q1 connected to Q4 is equal to its base voltage, i.e. V be1 =V b1 The voltage between the base and emitter of the N parallel Q1 s connected to Q3 is equal to its base voltage, i.e. V be2 =V b2 And as can also be seen from FIG. 3, V e4 =V b1 ，V e3 =V r1 +V b2 Wherein, V b2 Is the base voltage of N parallel Q1 connected with Q3, therefore, the following can be obtained:
V e4 =V be1 = V t *ln（i1/is）（1.2）
V e3 = V t *ln（i2/N*is）+i2*r1 （1.3）
from the above analysis, it can be seen that: v e3 =V e4 And i1= i2= i3= ic, then:
V t *ln（ic/N*is）+ic*r1= V t *ln（ic/is）（1.4）
by solving the above formula (1.4):
ic= V t *lnN/r1。
at a temperature of 0 Kelvin, V t =0V, so i1= i2= i3= ic =0. Therefore, Q5, Q6, Q7 in the first circuit 102, and M parallel Q7 in the comparison circuit 103 are all in the off state, so that the voltage difference between the base and the emitter of Q5, Q6 and all Q7 is 0V, and therefore the base voltage of the transistors Q5, Q6 and all Q7 is equal to the power supply voltage V dd 。
With increasing temperature, V t Slowly rising, ic also slowly increases from 0, at which time, the voltage difference between the base and the emitter of Q5, Q6 and Q7 in the first circuit 102 will slowly increase, since the emitter voltage of Q5, Q6 and Q7 in the first circuit 102 is always the preset voltage V dd Therefore, the base voltages of Q5, Q6 and Q7 in the first circuit 102 gradually decrease. Since Q5, Q6, Q7 in the first circuit 102, and M parallel Q7 in the comparison circuit 103 have the same base voltage, the base voltage of M parallel Q7 in the comparison circuit 103 also changes from V with an increase in temperature dd And decreases. Please refer to the above for the working principle of the subsequent comparison process, which is not described herein again.
In some specific embodiments, the circuit structure with temperature protection further includes a control module;
and the control module is used for outputting a corresponding control signal according to the comparison result signal, and the control signal is used for controlling the functional circuit to work or stop working.
In some optional embodiments, the functional circuit is a battery charging circuit.
In other embodiments, the functional circuit may be other circuits.
The embodiment of the invention also provides a power supply circuit with temperature protection, which comprises a battery charging circuit and any one of the circuit structures with temperature protection in the embodiments, wherein a comparison result signal output by the circuit structure with temperature protection is used for controlling the battery charging circuit to work or stop working.
The power supply circuit with the temperature protection function provided by the embodiment of the invention does not need to be provided with a reference voltage generating circuit, so that the battery power supply circuit has a simple structure and fewer components, the complexity of the battery power supply circuit is further reduced, and the volume of the circuit is reduced. In addition, the temperature protection and adjustment in the embodiment of the invention are convenient.
The power supply circuit with temperature protection provided by the embodiment of the invention further comprises a control module, wherein the control module is used for outputting a corresponding control signal according to a comparison result signal output by the circuit structure with temperature protection, and the control signal is used for controlling the battery charging circuit to work (close) or stop working (open). Specifically, when the comparison result signal indicates that the temperature is greater than the preset threshold, the control signal output by the control module controls the battery charging circuit to stop working (open), and when the comparison result signal indicates that the temperature is less than or equal to the preset threshold, the control signal output by the control module controls the battery charging circuit to work (close).
In some embodiments, the battery charging circuit includes a BOOST chopper circuit (BOOST circuit).
In some specific embodiments, referring to fig. 5, the BOOST circuit includes an inductor L1, a sixth switching tube M1, and a diode D1, one end of the inductor L1 is connected to a power supply, the other end of the inductor L1 is connected to an anode of the diode D1, a cathode of the diode D1 is an output end of the BOOST circuit, the other end of the inductor L1 is further grounded through the sixth switching tube M1, and on/off of the sixth switching tube M1 is controlled by a control module, where the control module and the control module (configured to output a corresponding control signal according to a comparison result signal) may be the same.
The temperature measuring circuit 101, the first circuit 102 and the comparison circuit 103 may be integrated with the control module in the control chip U1 shown in fig. 5. The internal circuit block diagram of the control chip U1 can be shown in fig. 6, wherein the temperature protection module is a circuit module composed of the temperature measurement circuit 101, the first circuit 102 and the comparison circuit 103. The control chip U1 may further include a bandgap reference (BG) module, an oscillator module, a current limiting control module, and the like. When the comparison result signal output by the comparison circuit 103 indicates that the temperature is greater than the preset threshold, the control module disconnects the output of the control chip U1 according to the comparison result signal, thereby turning off the battery charging circuit. It should be noted that, when the temperature measuring circuit 101, the first circuit 102 and the comparison circuit 103 are integrated in the control chip, the output terminal of the first circuit 102 and the second circuit in the comparison circuit are grounded through a preset circuit unit, so as to perform current sampling by using the preset circuit unit.
In some specific embodiments, referring to fig. 7, the power supply circuit with temperature protection further includes a power frequency transformer and a rectifying and filtering circuit, and the power frequency transformer, the rectifying and filtering circuit, and the battery charging circuit are sequentially connected in series. And the power supply is connected with the input end of the power frequency transformer.
The power supply circuit with temperature protection, which comprises the power frequency transformer, the rectifying and filtering circuit and the battery charging circuit, is also called a battery power supply circuit, and the power supply sequentially charges a battery load through the power frequency transformer, the rectifying and filtering circuit and the battery charging circuit.
The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims (9)

1. A circuit structure with temperature protection, comprising: the temperature measuring circuit comprises a temperature measuring circuit, a first circuit and a comparison circuit;
the current of the temperature measuring circuit is positively correlated with the temperature;
the current on the first circuit is equal to the current of the temperature measuring circuit, and the first circuit comprises a first switching tube Q7;
the comparison circuit comprises a first resistor r2, M first switching tubes Q7 and a comparison unit, wherein the M first switching tubes Q7 are connected in parallel and then connected in series with the first resistor r2 to form a second circuit, the input end of the first circuit and the input end of the second circuit are connected with a preset voltage, the output end of the first circuit and the output end of the second circuit are grounded or grounded through a preset circuit unit, the comparison circuit and the controlled end of each first switching tube Q7 in the first circuit are connected, the voltage of the controlled end of the first switching tube Q7 is reduced along with the increase of the current of the temperature measurement circuit, the comparison unit is used for comparing the current on the first circuit with the current on the second circuit and outputting a comparison result signal, and the comparison result signal is used for indicating whether the temperature is greater than a preset threshold value or not;
the temperature measuring circuit comprises a first component, the first component is a diode, a triode with a collector connected with a base electrode or a field effect transistor with a grid connected with a drain electrode, and under the condition that input voltage is constant, the voltage drop at two ends of the first component is positively correlated with temperature;
the temperature measuring circuit also comprises an isolation module, a fourth resistor r1, a second switching tube Q5 and a third switching tube Q6;
the input ends of the second switching tube Q5 and the third switching tube Q6 are connected with the preset voltage; the controlled ends of the second switching tube Q5 and the third switching tube Q6 are both connected with the controlled end of the first switching tube Q7, and are connected with the output end of one of the second switching tube Q5 and the third switching tube Q6, and the currents on the third switching tube Q6 and the second switching tube Q5 are the same;
the number of the first elements is N +1, and the parameters are the same; the input end of one of the first components is connected with the output end of the second switch tube Q5 through the isolation module, and the output end of the first component is grounded; the rest N first components are connected in parallel, the input ends of the N first components are connected with the output end of the third switching tube Q6 sequentially through the fourth resistor r1 and the isolation module, and the output ends of the N first components are grounded.
2. The circuit structure with temperature protection according to claim 1, wherein the first switch transistor Q7 is a triode or a field effect transistor.
3. The circuit structure with temperature protection according to claim 1, wherein the predetermined circuit unit includes a second resistor rs1 and a third resistor rs2, the second resistor rs1 is connected in series with the output terminal of the first circuit and then grounded, and the third resistor rs2 is connected in series with the output terminal of the second circuit and then grounded;
the resistance values of the second resistor rs1 and the third resistor rs2 are the same;
two input ends of the comparison unit are respectively connected with the first end of the second resistor rs1 and the first end of the third resistor rs2, and the first end of the second resistor rs1 and the first end of the third resistor rs2 are both the other ends except the grounding end.
4. The circuit structure with temperature protection according to claim 1, wherein the isolation module comprises a fourth switching tube Q3 and a fifth switching tube Q4, the controlled ends of the fourth switching tube Q3 and the fifth switching tube Q4 are connected, and are connected with the input end of one of the fourth switching tube Q3 and the fifth switching tube Q4, and the parameters of the fourth switching tube Q3 and the fifth switching tube Q4 are the same; the input end of the fifth switch tube Q4 is connected with the output end of the second switch tube Q5, the output end of the fifth switch tube Q4 is connected with the input end of the first component, the input end of the fourth switch tube Q3 is connected with the output end of the third switch tube Q6, and the output end of the fourth switch tube Q3 is connected with the input ends of the N first components through the fourth resistor r 1.
5. The circuit structure with temperature protection according to claim 1, further comprising a control module;
the control module is used for outputting a corresponding control signal according to the comparison result signal, and the control signal is used for controlling the functional circuit to work or stop working.
6. A power supply circuit with temperature protection, characterized by comprising a battery charging circuit and the circuit structure with temperature protection of any one of claims 1-4, wherein the comparison result signal output by the circuit structure with temperature protection is used for controlling the battery charging circuit to work or stop working.
7. The power supply circuit with temperature protection of claim 6, wherein the battery charging circuit comprises a boost chopper circuit.
8. The power supply circuit with temperature protection according to claim 7, wherein the boost chopper circuit includes an inductor L1, a sixth switching tube M1 and a diode D1, one end of the inductor L1 is connected to a power supply, the other end of the inductor L1 is connected to an anode of the diode D1, a cathode of the diode D1 is an output end of the boost chopper circuit, the other end of the inductor L1 is further grounded through the sixth switching tube M1, and on/off of the sixth switching tube M1 is controlled by a control module.
9. The power supply circuit with temperature protection as claimed in claim 6, further comprising a power frequency transformer and a rectifying filter circuit, wherein the power frequency transformer, the rectifying filter circuit and the battery charging circuit are connected in series in sequence.
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