CN115588965B

CN115588965B - Over-temperature protection circuit and over-temperature protection chip

Info

Publication number: CN115588965B
Application number: CN202211408648.3A
Authority: CN
Inventors: 贾生龙; 李瑞平
Original assignee: Shanghai Xinlong Semiconductor Technology Co ltd Nanjing Branch
Current assignee: Shanghai Xinlong Semiconductor Technology Co ltd Nanjing Branch
Priority date: 2022-11-11
Filing date: 2022-11-11
Publication date: 2023-03-17
Anticipated expiration: 2042-11-11
Also published as: CN115588965A

Abstract

The invention provides an over-temperature protection circuit and an over-temperature protection chip. The over-temperature protection circuit comprises a threshold value adjusting module and an over-temperature detection module. The over-temperature detection module outputs or cancels an output over-temperature protection signal based on the first temperature and the second temperature. The threshold adjusting module is used for keeping or changing the output signal of the threshold adjusting module based on the triggering times of the over-temperature protection signal so as to influence the specific value of the first temperature. With the configuration, on one hand, the threshold value change rule which accords with the specific working condition is set through the built-in logic of the threshold value adjusting module, so that the false triggering or the false releasing of the over-temperature protection is avoided or reduced; on the other hand, through a modular design idea, logic of over-temperature detection and logic of threshold value change are decoupled, and optimization and iteration of a subsequent circuit are facilitated. Based on the over-temperature protection circuit and the over-temperature protection chip, various problems of the over-temperature protection circuit with invariable threshold are solved.

Description

Over-temperature protection circuit and over-temperature protection chip

Technical Field

The invention relates to the field of integrated circuits, in particular to an over-temperature protection circuit and an over-temperature protection chip.

Background

In daily production and life, many scenes in which the temperature needs to be controlled are met, and thus over-temperature detection and temperature protection are needed. Specific to integrated circuits/chips: the integrated circuit can realize the functions of managing and transferring electric energy, the load can convert the input electric energy into heat energy, light energy, kinetic energy and the like in the working process of the integrated circuit, and loss can be generated in the energy conversion process, and the heat energy, the light energy, the loss and the like can be consumed in the form of heat energy. If the conditions such as abnormal working, heavy load, severe application environment temperature, heat dissipation and the like of the chip are poor, the heat cannot be conducted and radiated out in time to cause chip damage or even other accidents, so that the chip damage is avoided in the chip for detecting the temperature, and an over-temperature detection circuit can be generally integrated to play a role in temperature protection.

We say in normal times the temperature of the chip is related to: junction (PN junction) temperature Tj of die (crystal grain, a term of art of semiconductor, a meaning of which can be clearly understood by a person skilled in the art) inside a chip, package surface temperature Tc, and temperature Ta of air around the chip, generally, silicon semiconductor Tj is controlled within 150 degrees celsius, and if the temperature is higher than 150 degrees celsius for a long time, reliability of the chip is reduced, and even the chip is damaged, so the temperature of the chip is generally controlled within 150 degrees celsius, that is, an over-temperature protection point of the chip is set at 150 degrees celsius. The chip is composed of a plurality of PN junctions, and heat Tj generated by the chip during operation (PN junctions) is firstly conducted and radiated to the whole chip die and then is a packaging body, and is conducted and radiated to a PCB board, air and the like by the packaging body.

In the application of high-power output chips such as power supplies, audio power amplifiers and the like, the input and output power of the chips is very high, the corresponding power consumption is correspondingly increased, the junction temperature Tj of the power part of the chips is rapidly increased, the chips are provided with good heat dissipation packaging bodies or heat dissipation measures, such as increasing the area of a heat dissipation welding disc of the chip, and even a plurality of chips are provided with special heat dissipation fins, so that the heat of the chips is conducted and radiated, and the die and the Tj in the chips are reduced.

The high-power output chip has high power and high power consumption, and can generate heat during working. Heat is transmitted to the whole die from a heating point of the chip (such as a power output part of the chip) through conduction and radiation, and then is transmitted to the air through the packaging body and the radiating fin, the temperature distribution is uneven, the temperature Tj (junction temperature) of the heating point is higher than Tc, and Tc is higher than Ta; in addition, the temperature (Tj) of the heating point of the die in the chip is the highest, and the temperature is lower as the distance from the heating point is farther; under the condition of good heat dissipation conditions of the chip (Ta is very low), the temperature difference of Tj, tc and Ta at a certain moment is very large, if the Tj at a certain moment (duration is short) exceeds 150 ℃, the chip stops working, at the moment, the Tj with good heat dissipation conditions can be quickly reduced, the chip cannot be damaged, if the equipment is not powered off, the fault can be eliminated without manual intervention, when the temperature is reduced to a certain value, the chip works again, the chip enters an over-temperature protection state again within a short time with high probability, the cycle is repeated, and the chip works under the condition of higher temperature for a long time, so that the service life and the reliability of the chip are seriously influenced.

If the threshold value of the over-temperature protection circuit is not variable, there are several problems of erroneous protection and erroneous release as follows.

1. When the chip or the equipment triggers the over-temperature protection due to some special reasons, if the equipment is not powered off, even if the chip or the equipment stops working after triggering the over-temperature protection, the temperature starts to be reduced, the chip or the equipment still continues to work, and under the condition that the abnormity is not eliminated, the over-temperature protection can still be triggered again at a large probability, but the over-temperature protection is not expected by a designer, and the temperature has a great influence on the service life and the reliability of the chip or the equipment. Therefore, it is desirable to reduce subsequent trigger temperatures after the first trigger to prevent repeated triggers.

2. When a chip or equipment is just started, the instantaneous temperature may be too high due to excessive instantaneous power, but the temperature is only temporary and can be immediately reduced to be below the safe temperature along with the smooth work of the chip and various heat dissipation structures and measures, and at the moment, if the over-temperature protection is triggered by mistake, the chip or the equipment cannot be started normally, or the starting process of the chip or the equipment is influenced; however, merely increasing the temperature of the over-temperature protection does not solve this problem, because such a design would result in that the protection cannot be activated due to the trigger threshold being too high when the over-temperature protection is actually needed in the subsequent period.

In a word, the over-temperature protection circuit with an invariable threshold under a specific working condition in the prior art easily causes error protection or error release, and then the performance and the service life of a chip are influenced.

Disclosure of Invention

The invention aims to provide an over-temperature protection circuit and an over-temperature protection chip, and aims to solve the problem that the over-temperature protection circuit with an invariable threshold value in the prior art is easy to cause error protection or error release, and then the performance and the service life of the chip are influenced.

In order to solve the above technical problem, the present invention provides an over-temperature protection circuit, which includes a threshold adjustment module and an over-temperature detection module.

The over-temperature detection module is configured to output and maintain an over-temperature protection signal when the temperature of the over-temperature detection module rises to exceed a first temperature, and to cancel and maintain the over-temperature protection signal when the temperature of the over-temperature detection module falls to be lower than a second temperature; the value of the first temperature is influenced by the output signal of the threshold adjustment module.

The threshold adjusting module is used for keeping or changing the output signal of the over-temperature protection signal based on the triggering times of the over-temperature protection signal.

Optionally, when the number of triggering times is 0, the threshold adjusting module outputs a first signal; when the triggering times are more than 0, the threshold adjusting module outputs a second signal; the first temperature corresponding to the first signal is greater than the first temperature corresponding to the second signal.

Optionally, the threshold adjustment module includes a self-locking sub-module, and the working state of the self-locking sub-module includes an initial state and a self-locking state; when the over-temperature protection circuit is started, the working state of the self-locking sub-module is the initial state; the self-locking sub-module is directly or indirectly switched to the self-locking state based on the over-temperature protection signal and keeps the self-locking state after the over-temperature protection signal disappears.

And the threshold adjusting module switches the output signal of the self-locking submodule based on the working state of the self-locking submodule.

Optionally, the over-temperature protection circuit further includes a current reference module, and the current reference module is configured to provide a bias current to the threshold adjustment module.

Optionally, the threshold adjustment module includes a self-locking sub-module, and the working state of the self-locking sub-module includes an initial state and a self-locking state; when the over-temperature protection circuit is started, the working state of the self-locking sub-module is the initial state; the self-locking sub-module is indirectly switched to the self-locking state based on the over-temperature protection signal and keeps the self-locking state after the over-temperature protection signal disappears.

When the working state of the self-locking sub-module is the initial state, the threshold adjusting module outputs a first signal; when the working state of the self-locking sub-module is the self-locking state, the threshold adjusting module outputs a second signal; the first temperature corresponding to the first signal is greater than the first temperature corresponding to the second signal.

Optionally, the current reference module includes a first triode, a second triode and a first resistor, where the first triode is a PNP-type triode, an emitter of the first triode is used for connecting a power supply, and a base of the first triode is connected to a collector of the first triode; the second triode is an NPN type triode, a collector of the second triode is connected with a collector of the first triode, and a base of the second triode is used for acquiring reference voltage; one end of the first resistor is connected with an emitting electrode of the second triode, and the other end of the first resistor is used for grounding.

Optionally, the threshold adjustment module includes a third triode, a fourth triode, a fifth triode, a sixth triode, a seventh triode, an eighth triode, a ninth triode, a thirteenth triode, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor.

The third triode, the sixth triode and the eighth triode are PNP type triodes, emitting electrodes of the third triode, the sixth triode and the eighth triode are all used for connecting a power supply, and bases of the third triode, the sixth triode and the eighth triode are all connected with a base electrode of the first triode.

And the first end of the second resistor is connected with the collector of the third triode.

The fourth triode is a PNP type triode, an emitting electrode of the fourth triode is connected with the first end of the second resistor, and a base electrode of the fourth triode is connected with the second end of the second resistor.

The fifth triode is an NPN triode, a collector of the fifth triode is connected with the second end of the second resistor, a base of the fifth triode is connected with a collector of the fourth triode, and an emitter of the fifth triode is used for being grounded.

The fourth triode and the fifth triode form the self-locking submodule, and the base electrode of the fifth triode is used for indirectly acquiring the over-temperature protection signal; the fourth triode and the fifth triode are both turned off and correspond to the initial state, and the fourth triode and the fifth triode are both turned on and correspond to the self-locking state.

One end of the third resistor is connected with a collector of the third triode, and the other end of the third resistor is used for grounding.

The seventh triode is an NPN type triode, a collector electrode of the seventh triode is connected with a collector electrode of the sixth triode, a base electrode of the seventh triode is connected with a collector electrode of the third triode, and an emitting electrode of the seventh triode is used for being grounded.

The ninth triode is an NPN type triode, a collector electrode of the ninth triode is connected with a collector electrode of the eighth triode, a base electrode of the ninth triode is connected with a collector electrode of the sixth triode, and an emitting electrode of the ninth triode is used for being grounded.

The thirteenth polar tube is an NPN type polar tube, the base electrode of the thirteenth polar tube is connected with the collector electrode of the eighth polar tube, and the emitter electrode of the thirteenth polar tube is used for grounding.

The first end of the fourth resistor is used for connecting a power supply, the second end of the fourth resistor is connected with the collector electrode of the thirteenth pole tube through the fifth resistor, and the second end of the fourth resistor is also used for being grounded through the sixth resistor.

The second end of the fourth resistor is used for outputting a signal influencing the first temperature.

Optionally, the over-temperature detection module includes an eleventh triode, a twelfth triode, a thirteenth triode, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, and a fifteenth resistor.

The eleventh triode is an NPN-type triode, a collector of the eleventh triode is used for being connected with a power supply, an emitter of the eleventh triode is connected with a first end of the seventh resistor, a second end of the seventh resistor is connected with a first end of the eighth resistor, a second end of the eighth resistor is connected with a first end of the ninth resistor, and a second end of the ninth resistor is used for being grounded.

The twelfth triode is an NPN type triode, a first end of the tenth resistor is used for connecting a power supply, a second end of the tenth resistor is connected with a first end of the eleventh resistor, a second end of the eleventh resistor is connected with a first end of the twelfth resistor, a second end of the twelfth resistor is connected with a collector of the twelfth triode, a base of the twelfth triode is connected with a first end of the eighth resistor, and an emitter of the twelfth triode is used for grounding.

The thirteenth triode is a PNP triode, an emitting electrode of the thirteenth triode is connected with the second end of the tenth resistor, a base electrode of the thirteenth triode is connected with the second end of the eleventh resistor, a collector electrode of the thirteenth triode is connected with the first end of the thirteenth resistor, and the second end of the thirteenth resistor is connected with the second end of the eighth resistor.

A first end of the fourteenth resistor is connected with a first end of the thirteenth resistor, and a second end of the fourteenth resistor is used for outputting the over-temperature protection signal; the first end of the thirteenth resistor is further connected with the first end of the fifteenth resistor, and the second end of the fifteenth resistor is connected with the base of the fifth triode.

Optionally, the base emitter voltages of the eleventh triode and the twelfth triode decrease with the increase of the temperature of the eleventh triode and the twelfth triode.

In order to solve the technical problem, the invention further provides an over-temperature protection chip which comprises the over-temperature protection circuit.

Compared with the prior art, in the over-temperature protection circuit and the over-temperature protection chip provided by the invention, the over-temperature protection circuit comprises a threshold value adjusting module and an over-temperature detecting module. The over-temperature detection module is configured to output and maintain an over-temperature protection signal when the temperature of the over-temperature detection module rises to exceed a first temperature, and to cancel and maintain the over-temperature protection signal when the temperature of the over-temperature detection module falls to be lower than a second temperature; the value of the first temperature is influenced by the output signal of the threshold adjustment module. The threshold adjusting module is used for keeping or changing the output signal of the over-temperature protection signal based on the triggering times of the over-temperature protection signal. With the configuration, on one hand, the threshold value change rule which accords with the specific working condition is set through the built-in logic of the threshold value adjusting module, so that the false triggering or the false releasing of the over-temperature protection is avoided or reduced; on the other hand, through a modular design idea, logic of over-temperature detection and logic of threshold value change are decoupled, and optimization and iteration of a subsequent circuit are facilitated. Based on the over-temperature protection circuit and the over-temperature protection chip, various problems of the over-temperature protection circuit with invariable threshold are solved.

Drawings

It will be appreciated by those skilled in the art that the drawings are provided for a better understanding of the invention and do not constitute any limitation to the scope of the invention. Wherein:

fig. 1 is a schematic structural diagram of an over-temperature protection circuit according to an embodiment of the present invention;

FIG. 2 is a circuit diagram of an over-temperature protection circuit according to an embodiment of the present invention;

fig. 3 is a voltage waveform diagram of an output terminal of the over-temperature protection circuit according to an embodiment of the invention.

In the drawings:

1-a current reference module; 2-a threshold adjustment module; 3-an over-temperature detection module; 4-self-locking submodule.

Detailed Description

To further clarify the objects, advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is to be noted that the drawings are in greatly simplified form and are not to scale, but are merely intended to facilitate and clarify the explanation of the embodiments of the present invention. Further, the structures illustrated in the drawings are often part of actual structures. In particular, the drawings may have different emphasis points and may sometimes be scaled differently.

As used in this disclosure, the singular forms "a," "an," and "the" include plural referents, the term "or" is generally employed in a sense including "and/or," the terms "a," "an," and "the" are generally employed in a sense including "at least one," the terms "at least two" are generally employed in a sense including "two or more," and further, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to imply that the number of indicated technical features is essential. Thus, features defined as "first", "second" and "third" may explicitly or implicitly include one or at least two of the features, "one end" and "the other end" and "proximal end" and "distal end" generally refer to the corresponding two parts, which include not only the end points, but also the terms "mounted", "connected" and "connected" should be understood broadly, e.g., as being fixedly connected, detachably connected, or integrated; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. Furthermore, as used in the present invention, the disposition of an element with another element generally only means that there is a connection, coupling, fit or driving relationship between the two elements, and the connection, coupling, fit or driving relationship between the two elements may be direct or indirect through intermediate elements, and cannot be understood as indicating or implying any spatial positional relationship between the two elements, i.e., an element may be in any orientation inside, outside, above, below or to one side of another element, unless the content clearly indicates otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The core idea of the invention is to provide an over-temperature protection circuit and an over-temperature protection chip, so as to solve the problem that the over-temperature protection circuit with an unchangeable threshold value in the prior art is easy to cause error protection or error release, and then affects the performance and the service life of the chip.

The following description refers to the accompanying drawings.

Referring to fig. 1, the present embodiment provides an over-temperature protection circuit, which includes a threshold adjustment module 2 and an over-temperature detection module 3.

Wherein the over-temperature detection module 3 is configured to output and maintain the over-temperature protection signal (e.g., continuously output a high level) when the temperature of the self rises above a first temperature, and to cancel and maintain the over-temperature protection signal (e.g., continuously output a low level) when the temperature of the self falls below a second temperature; the value of the first temperature is influenced by the output signal of the threshold adjustment module 2. That is, the protection trigger threshold of the over-temperature detection module 3 may be set to be changed.

The threshold adjusting module 2 is configured to maintain or change its own output signal based on the number of times of triggering the over-temperature protection signal.

With the configuration, on one hand, the threshold value change rule meeting the specific working condition is set through the built-in logic of the threshold value adjusting module 2, so that the false triggering or false releasing of the over-temperature protection is avoided or reduced; on the other hand, through a modular design idea, logic of over-temperature detection and logic of threshold value change are decoupled, and optimization and iteration of a subsequent circuit are facilitated. For example, when the external environment changes, and thus the temperature of the over-temperature protection changes, only the threshold adjusting module 2 needs to be replaced without modifying the internal structure of the over-temperature detecting module 3; when the over-temperature protection rule changes, for example, the logic for revoking the over-temperature protection is as follows: if the temperature is lower than a certain temperature and is kept for a certain period of time, the over-temperature protection is cancelled, and the design intention can be satisfied by only changing the internal structure of the over-temperature detection module 3.

The internal logic of the threshold adjustment module 2 may be various, and in this specification, the following logic is emphasized: when the triggering times are 0 times, the threshold value adjusting module outputs a first signal; when the triggering times are more than 0, the threshold adjusting module outputs a second signal; the first temperature (which may be referred to as Tmax) corresponding to the first signal is greater than the first temperature (which may be referred to as TH) corresponding to the second signal. An example of implementing the above logic is shown in FIG. 2, which is described in detail below.

The logic described above is set based on the following conditions: when the chip or the equipment triggers the over-temperature protection due to some special reasons, if the equipment is not powered off, the chip or the equipment can still restart to work even if the chip or the equipment stops working after triggering the over-temperature protection, the temperature starts to be reduced, and the over-temperature protection can still be triggered again at a high probability under the condition that the abnormity is not eliminated. Then, the present embodiment judges that the first overtemperature protection is triggered by Tmax (e.g., 160 ℃), and then lowers the trigger temperature of the overtemperature protection to TH (e.g., 150 ℃), thereby protecting the relevant circuits and elements further in advance until the failure is resolved.

In addition, the problem of too high instantaneous temperature at the starting time is also considered, as analyzed in the background art, if the threshold temperature is designed to be too high, the trigger cannot be triggered in the subsequent working state, and if the threshold temperature is designed to be too low, the starting process is affected. Therefore, it is also necessary to set a higher Tmax to prevent false triggering of the starting process, and to ensure normal triggering in the subsequent normal operating state through TH.

It will be appreciated that in other embodiments, other protection logic may be provided, depending on the actual requirements, such as: when the triggering times are odd times, outputting the first signal, and when the triggering times are even times, outputting the second signal; or when the triggering frequency is less than or equal to 2, outputting the first signal, and when the triggering frequency is greater than 2, outputting the second signal; or, when the condition 1 is satisfied, the 1 st signal is output, when the condition 2 is satisfied, the 2 nd signal is output, when the condition 3 is satisfied, the 3 rd signal … … is output, when the condition n is satisfied, the nth signal is output, and the first temperature corresponding to the ith signal is set according to actual needs.

Referring to fig. 1, the threshold adjustment module 2 includes a self-locking sub-module 4, and the working state of the self-locking sub-module 4 includes an initial state and a self-locking state; when the over-temperature protection circuit is started, the working state of the self-locking sub-module is the initial state; the self-locking sub-module 4 is directly or indirectly switched to the self-locking state based on the over-temperature protection signal, and keeps the self-locking state after the over-temperature protection signal disappears.

The threshold adjusting module 2 switches output signals of the self-locking submodule based on the working state of the self-locking submodule.

With the configuration, the circuit structure can be simplified, the control logic is realized by adopting hardware, the manufacturing cost is reduced, and the over-temperature protection circuit can be applied to various occasions.

It should be understood that "directly or indirectly" in this way, theoretically, the self-locking submodule 4 may directly acquire the over-temperature protection signal to trigger the switching of the working state of the self-locking submodule 4, but considering that the acquired signal itself may have various influences on the signal, another signal may also be indirectly acquired, and the other signal can change simultaneously with the over-temperature protection signal (the change timing is the same, but the waveform does not need to be the same), then the invention expectation can also be achieved through the other signal, and therefore, it is not limited here whether the self-locking submodule 4 directly acquires the signal or indirectly acquires the signal.

The over-temperature protection circuit further comprises a current reference module 1, wherein the current reference module 1 is used for providing bias current for the threshold adjusting module 2.

Referring to fig. 2, fig. 2 illustrates an exemplary embodiment. The embodiment can provide a secondary over-temperature protection function, so that the temperature point for triggering the over-temperature protection for the first time is higher than the trigger point for the subsequent over-temperature protection for the second time or the third time under the condition that the chip or the equipment is not powered off, namely, the reliability of the chip or the equipment is improved by reducing the trigger point for the subsequent over-temperature protection; meanwhile, as long as the equipment is electrified again, the over-temperature protection module is reset, and the first over-temperature protection point after electrification is still higher than the subsequent over-temperature protection point.

The invention of this embodiment is as follows: when the chip or the equipment triggers over-temperature protection due to some special reasons, if the equipment is not powered off, even if the chip or the equipment stops working after triggering the over-temperature protection, the temperature starts to be reduced, the chip or the equipment can still continue working, and under the condition that the abnormity is not eliminated, the over-temperature protection can still be triggered again at a high probability, and the influence of the temperature on the service life and the reliability of the chip or the equipment is known to be large; in order to prevent the chip or the device from influencing the service life at high temperature, the embodiment can trigger the over-temperature protection when the chip or the device works again after triggering the over-temperature protection and at a certain point lower than the first temperature, so that the highest working temperature under abnormal conditions is reduced, and the service life and the reliability are improved. And when the power is cut off and the power is powered on again, the over-temperature protection module is reset.

The current reference module 1 comprises a first triode Q1, a second triode Q2 and a first resistor R1, wherein the first triode Q1 is a PNP type triode, an emitting electrode of the first triode Q1 is used for being connected with a power supply vdd, and a base electrode of the first triode Q1 is connected with a collector electrode of the first triode Q1; the second triode Q2 is an NPN type triode, the collector electrode of the second triode Q2 is connected with the collector electrode of the first triode Q1, and the base electrode of the second triode Q2 is used for acquiring a reference voltage VREF; the reference voltage VREF is provided by other circuitry. One end of the first resistor R1 is connected with an emitting electrode of the second triode Q2, and the other end of the first resistor R1 is used for grounding. In fig. 2, I1 is a bias current, I1= (VREF-Vbe)/R1, wherein a base emitter voltage of the second transistor Q2 is denoted as Vbe.

Referring to fig. 2, the threshold adjustment module 2 includes a third transistor Q3, a fourth transistor Q4, a fifth transistor Q5, a sixth transistor Q6, a seventh transistor Q7, an eighth transistor Q8, a ninth transistor Q9, a thirteenth transistor Q10, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6.

The third triode Q3, the sixth triode Q6 and the eighth triode Q8 are PNP type triodes, the emitting electrodes of the third triode Q3, the sixth triode Q6 and the eighth triode Q8 are all used for connecting a power supply vdd, and the base electrodes of the third triode Q3, the sixth triode Q6 and the eighth triode Q8 are all connected with the base electrode of the first triode Q1.

A first end of the second resistor R2 is connected to a collector of the third transistor Q3.

The fourth triode Q4 is a PNP type triode, an emitting electrode of the fourth triode Q4 is connected with the first end of the second resistor R2, and a base electrode of the fourth triode Q4 is connected with the second end of the second resistor R2.

The fifth triode Q5 is an NPN-type triode, a collector of the fifth triode Q5 is connected to the second end of the second resistor R2, a base of the fifth triode Q5 is connected to a collector of the fourth triode Q4, and an emitter of the fifth triode Q5 is used for grounding.

The fourth triode Q4 and the fifth triode Q5 form the self-locking submodule 4, and the base of the fifth triode Q5 is used for indirectly acquiring the over-temperature protection signal; the fourth triode Q4 and the fifth triode Q5 are both turned off and correspond to the initial state, and the fourth triode Q4 and the fifth triode Q5 are both turned on and correspond to the self-locking state.

One end of the third resistor R3 is connected with the collector of the third triode Q3, and the other end of the third resistor R3 is used for grounding.

The seventh triode Q7 is an NPN type triode, a collector of the seventh triode Q7 is connected to a collector of the sixth triode Q6, a base of the seventh triode Q7 is connected to a collector of the third triode Q3, and an emitter of the seventh triode Q7 is used for grounding.

The ninth triode Q9 is an NPN type triode, a collector of the ninth triode Q9 is connected to a collector of the eighth triode Q8, a base of the ninth triode Q9 is connected to a collector of the sixth triode Q6, and an emitter of the ninth triode Q9 is used for grounding.

The thirteenth polar tube Q10 is an NPN type polar tube, a base electrode of the thirteenth polar tube Q10 is connected with a collector electrode of the eighth polar tube Q8, and an emitter electrode of the thirteenth polar tube Q10 is used for grounding.

A first end of the fourth resistor R4 is configured to be connected to a power supply vdd, a second end of the fourth resistor R4 is connected to the collector of the thirteenth diode Q10 through the fifth resistor R5, and a second end of the fourth resistor R4 is further configured to be grounded through the sixth resistor R6.

The second terminal of the fourth resistor R4 is used to output a signal, VA in fig. 2, which affects the first temperature.

As described above, the threshold adjustment module 2 changes the value of VA through Q4 and Q5, when the base voltage VB of the fifth transistor Q5 is low, VB is insufficient to turn on Q5, the base emitter voltage VbeQ7 of Q7 is I2 × R3 is greater than the turn-on voltage of Q7, Q7 is turned on, and Q10 is turned on, when the base voltage VA of Q11 = VAL = vdd (R5// R6)/(R4 + (R5// R6)), where "/" represents the resistance value after parallel connection. When the temperature rises to Tmax, VB is switched to a high voltage, Q4 and Q5 are always conducted until the chip is turned off, Q5 enters a saturation state, vbeQ7 is smaller than the turn-on voltage of Q7, Q7 is turned off, Q10 is turned off, VA is increased, and VA = VAH = vdd × R6/(R4 + R6).

That is, the first signal is a VAL voltage, and the second signal is a VAH voltage.

Further, the over-temperature detection module 3 includes an eleventh triode Q11, a twelfth triode Q12, a thirteenth triode Q13, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, and a fifteenth resistor R15.

The eleventh triode Q11 is an NPN-type triode, a collector of the eleventh triode Q11 is used for connecting a power supply, an emitter of the eleventh triode is connected with a first end of the seventh resistor, a second end of the seventh resistor is connected with a first end of the eighth resistor, a second end of the eighth resistor is connected with a first end of the ninth resistor, and a second end of the ninth resistor is used for grounding.

The twelfth triode is an NPN type triode, a first end of the tenth resistor R10 is used for connecting a power supply vdd, a second end of the tenth resistor R10 is connected with a first end of the eleventh resistor R11, a second end of the eleventh resistor R11 is connected with a first end of the twelfth resistor R12, a second end of the twelfth resistor R12 is connected with a collector of the twelfth triode Q12, a base of the twelfth triode Q12 is connected with a first end of the eighth resistor R8, and an emitter of the twelfth triode Q12 is used for grounding.

The thirteenth triode Q13 is a PNP-type triode, an emitter of the thirteenth triode Q13 is connected to the second end of the tenth resistor R10, a base of the thirteenth triode Q13 is connected to the second end of the eleventh resistor R11, a collector of the thirteenth triode Q13 is connected to the first end of the thirteenth resistor R13, and the second end of the thirteenth resistor R13 is connected to the second end of the eighth resistor R8.

A first end of the fourteenth resistor R14 is connected to a first end of the thirteenth resistor R13, and a second end of the fourteenth resistor R14 is configured to output the over-temperature protection signal; the first end of the thirteenth resistor R13 is further connected to the first end of the fifteenth resistor R15, and the second end of the fifteenth resistor R15 is connected to the base of the fifth triode Q5. The signal at the second end of the fourteenth resistor R14 is an OTP signal. The fifteenth resistor R15 is used to provide an indirect signal VB to eliminate the influence of the threshold adjustment module 2 on the over-temperature protection signal, but the voltage waveform of the indirect signal VB and the voltage waveform of the OTP are consistent.

The base emitter voltages of the eleventh and twelfth triodes Q11 and Q12 decrease as their temperatures increase. On the premise that the eleventh triode Q11 and the twelfth triode Q12 are the same in type selection, vbe (T) is used to describe the base emitter voltages of Q11 and Q12 for ease of understanding.

At normal temperature, the ambient temperature is not set to T0. When the circuit is just started, the voltage of VA is VAL, and the base emitter voltages of Q11 and Q12 can be satisfied by reasonably setting circuit parameters to be Vbe (T0), Q11 is switched on, Q12 is switched off, Q13 is switched off, and OTP and VB are both low levels; because the BE junction of the triode has the negative temperature coefficient characteristic, the base emitter voltages Vbe (T) of the Q11 and the Q12 gradually drop along with the rise of the temperature, and when the temperature reaches Tmax, the base emitter voltages of the Q11 and the Q12 are Vbe (Tmax); if VAL-I3R7 is satisfied to be slightly larger than 2Vbe (Tmax), Q11 and Q12 are both conducted, Q13 is conducted, so that the OTP voltage is increased, over-temperature protection is triggered, namely the over-temperature protection signal is output, and meanwhile VB is increased to be high, so that Q5 and Q4 are conducted.

When Q5 and Q4 are turned on, VA is changed to VAH. Meanwhile, the current flowing through R9 is increased from I3 to I3+ I4, so that the base voltage of Q12 is increased by R9 × I4, so that the base voltage of Q12 is changed to VAH-Vbe (Tmax) -I3R7+ R9 × I4= VAL-Vbe (Tmax) -I3R7+ (R9 × I4+ VAH-VAL). Since (R9 × I4+ VAH-VAL) is necessarily greater than 0, the base voltage of Q12 is necessarily greater than Vbe (Tmax), and Q12 remains on.

Since the over-temperature protection is triggered at this time, the protected object (i.e., the heat source) stops operating or the power is reduced, and the ambient temperature starts to decrease. When falling to TL, vbe (TL) is just slightly less than VAH-Vbe (TL) -I3R7+ R9I 4. At this time, VA cannot keep both Q11 and Q12 on, Q12 off, and the over-temperature protection is cancelled. That is, there is a hysteresis window from turning on the over-temperature protection to turning off the over-temperature protection.

Note that in the above formula, the specific value of I3 also varies with VA.

After the first over-temperature protection is triggered, the voltage VA is fixed to VAH, the temperature is not set to return to the ambient temperature T0, and at the moment, the voltage of VA still meets the conditions, so that Q11 is switched on, Q12 is switched off, and Q13 is switched off. When the temperature rises to TH, the voltage drop of the base-emitter junctions of the Q11 and the Q12 is reduced to Vbe (TH), if the VAH-I3R7 is slightly larger than 2Vbe (TH), the Q12 and the Q13 are conducted, and the over-temperature protection is triggered again. Obviously, vbe (TH) > Vbe (Tmax), and Tmax < TH, since VAL < VAH.

When the temperature drops to TL after the second and subsequent over-temperature protection is triggered, based on the analysis above, Q12 is turned off, thereby removing the over-temperature protection and forming a hysteresis window.

Through calculation, when the base-emitter voltage Vbe (T) = VA: (R8 + R9)/(R7 +2r8 +2r9) of Q12 is in an over-temperature protection critical state, namely, a value of the first temperature, the temperature is slightly increased again, vbe (T) is decreased, Q12 is turned on, and over-temperature protection is triggered. The base voltage of Q12 rises due to the action of I4; when the base voltage of Q12 is not enough to turn on Q12 during the temperature drop, the over-temperature protection is removed, and at this time, vbe (T) = (VA × (R8 + R9) + I4 × R7 × R9)/(R7 +2r8 +2r9) is the value of the second temperature. Wherein I4= VbeQ5/R13 (1-R9/(R8 + R9)), and VbeQ5 is the base emitter voltage of the fifth triode.

Specifically, VAH and VAL are respectively substituted into VA, and it can be known that, when VA increases, the temperatures of the corresponding over-temperature protection and the cancellation of the over-temperature protection decrease, that is, both the first temperature and the second temperature decrease, and the description of "the value of the first temperature is affected by the output signal of the threshold adjustment module" coincides with the actual situation. In particular, the amount of the solvent to be used,

Vbe(Tmax)=VAL*(R8+R9)/(R7+2R8+2R9)，

Vbe(TH)=VAH*(R8+R9)/(R7+2R8+2R9),

Vbe(TL)=(VAH *(R8+R9)+I4*R7*R9)/ (R7+2R8+2R9)。

the values of Tmax, TH and TL can be obtained by looking up a table through a process manual, or the values of Tmax, TH and TL are firstly determined according to requirements, then the values of Vbe (Tmax), vbe (TH) and Vbe (TL) are determined, and then the resistance values of the relevant resistance elements are confirmed.

In addition, there is also one Vbe (TK) = (VAL × (R8 + R9) + I4 × (R7 × (R9)/(R7 +2r8 +2r9), where the meaning of TK represents "critical temperature at which over-temperature protection is revoked when the number of times over-temperature protection is triggered is 0"). However, this temperature cannot occur in actual operation at all, since the current number of times of triggering is 0, which indicates that the over-temperature protection has not been triggered, and there is no possibility of "cancelling the over-temperature protection".

Referring to fig. 3, the variation of the voltage at the output terminal of the over-temperature protection circuit with temperature is shown in fig. 3. When the over-temperature protection is triggered for the first time, the trigger temperature Tmax is higher, and in the subsequent triggering process, the trigger temperature TH is lower relative to the Tmax.

The invention also provides an over-temperature protection chip which comprises the over-temperature protection circuit. The over-temperature protection chip can also adjust the triggering critical temperature of the over-temperature protection according to the triggering times of the over-temperature protection, so that the over-temperature protection chip is more in line with the actual situation.

In summary, the embodiment provides an over-temperature protection circuit and an over-temperature protection chip. The over-temperature protection circuit comprises a threshold value adjusting module and an over-temperature detection module. The over-temperature detection module is configured to output and maintain an over-temperature protection signal when the temperature of the over-temperature detection module rises above a first temperature, and cancel the output and maintain of the over-temperature protection signal when the temperature of the over-temperature detection module falls below a second temperature; the value of the first temperature is affected by the output signal of the threshold adjustment module. The threshold adjusting module is used for keeping or changing the output signal of the over-temperature protection signal based on the triggering times of the over-temperature protection signal. With the configuration, on one hand, the threshold value change rule which accords with the specific working condition is set through the built-in logic of the threshold value adjusting module, so that the false triggering or the false releasing of the over-temperature protection is avoided or reduced; on the other hand, through a modular design idea, logic of over-temperature detection and logic of threshold value change are decoupled, and optimization and iteration of a subsequent circuit are facilitated. Based on the over-temperature protection circuit and the over-temperature protection chip, various problems of the over-temperature protection circuit with invariable threshold are solved.

The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art according to the above disclosure are within the scope of the present invention.

Claims

1. An over-temperature protection circuit, which is characterized by comprising a threshold value adjusting module and an over-temperature detecting module, wherein,

the over-temperature detection module is configured to output and maintain an over-temperature protection signal when the temperature of the over-temperature detection module rises to exceed a first temperature, and to cancel and maintain the over-temperature protection signal when the temperature of the over-temperature detection module falls to be lower than a second temperature; the value of the first temperature is affected by the output signal of the threshold adjustment module;

the threshold adjusting module is used for keeping or changing the output signal of the threshold adjusting module based on the triggering times of the over-temperature protection signal;

the threshold adjusting module comprises a self-locking sub-module, and the working state of the self-locking sub-module comprises an initial state and a self-locking state; when the over-temperature protection circuit is started, the working state of the self-locking sub-module is the initial state; the self-locking sub-module is switched to the self-locking state directly or indirectly based on the over-temperature protection signal, and the self-locking state is maintained after the over-temperature protection signal disappears;

the threshold adjusting module switches output signals of the self-locking submodule based on the working state of the self-locking submodule;

the over-temperature protection circuit further comprises a current reference module, wherein the current reference module is used for providing bias current for the threshold value adjusting module;

the current reference module comprises a first triode, a second triode and a first resistor, wherein,

the first triode is a PNP triode, an emitting electrode of the first triode is used for being connected with a power supply, and a base electrode of the first triode is connected with a collector electrode of the first triode;

the second triode is an NPN type triode, a collector of the second triode is connected with a collector of the first triode, and a base of the second triode is used for acquiring reference voltage;

one end of the first resistor is connected with an emitting electrode of the second triode, and the other end of the first resistor is used for grounding;

the threshold value adjusting module comprises a third triode, a fourth triode, a fifth triode, a sixth triode, a seventh triode, an eighth triode, a ninth triode, a thirteenth triode, a second resistor, a third resistor, a fourth resistor, a fifth resistor and a sixth resistor, wherein,

the third triode, the sixth triode and the eighth triode are all PNP type triodes, emitting electrodes of the third triode, the sixth triode and the eighth triode are all used for being connected with a power supply, and base electrodes of the third triode, the sixth triode and the eighth triode are all connected with a base electrode of the first triode;

the first end of the second resistor is connected with the collector of the third triode;

the fourth triode is a PNP triode, an emitting electrode of the fourth triode is connected with the first end of the second resistor, and a base electrode of the fourth triode is connected with the second end of the second resistor;

the fifth triode is an NPN triode, a collector of the fifth triode is connected with the second end of the second resistor, a base of the fifth triode is connected with a collector of the fourth triode, and an emitter of the fifth triode is used for being grounded;

the base electrode of the fifth triode is used for indirectly acquiring the over-temperature protection signal; the fourth triode and the fifth triode form the self-locking submodule; the fourth triode and the fifth triode are both turned off and correspond to the initial state, and the fourth triode and the fifth triode are both turned on and correspond to the self-locking state;

one end of the third resistor is connected with a collector of the third triode, and the other end of the third resistor is grounded;

the seventh triode is an NPN type triode, a collector of the seventh triode is connected with a collector of the sixth triode, a base of the seventh triode is connected with a collector of the third triode, and an emitter of the seventh triode is used for grounding;

the ninth triode is an NPN type triode, a collector of the ninth triode is connected with a collector of the eighth triode, a base of the ninth triode is connected with a collector of the sixth triode, and an emitter of the ninth triode is used for being grounded;

the thirteenth polar tube is an NPN type polar tube, the base electrode of the thirteenth polar tube is connected with the collector electrode of the eighth polar tube, and the emitter electrode of the thirteenth polar tube is used for grounding;

the first end of the fourth resistor is used for connecting a power supply, the second end of the fourth resistor is connected with the collector electrode of the thirteenth pole tube through the fifth resistor, and the second end of the fourth resistor is also used for grounding through the sixth resistor;

2. The over-temperature protection circuit according to claim 1, wherein when the number of times of triggering is 0, the threshold adjustment module outputs a first signal; when the triggering times are more than 0, the threshold adjusting module outputs a second signal; the first temperature corresponding to the first signal is greater than the first temperature corresponding to the second signal.

3. The over-temperature protection circuit according to claim 1, wherein the over-temperature detection module comprises an eleventh transistor, a twelfth transistor, a thirteenth transistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, and a fifteenth resistor, wherein,

the eleventh triode is an NPN-type triode, a collector of the eleventh triode is used for being connected with a power supply, an emitter of the eleventh triode is connected with a first end of the seventh resistor, a second end of the seventh resistor is connected with a first end of the eighth resistor, a second end of the eighth resistor is connected with a first end of the ninth resistor, and a second end of the ninth resistor is used for being grounded;

the twelfth triode is an NPN type triode, a first end of the tenth resistor is used for connecting a power supply, a second end of the tenth resistor is connected with a first end of the eleventh resistor, a second end of the eleventh resistor is connected with a first end of the twelfth resistor, a second end of the twelfth resistor is connected with a collector of the twelfth triode, a base of the twelfth triode is connected with a first end of the eighth resistor, and an emitter of the twelfth triode is used for grounding;

the thirteenth triode is a PNP triode, an emitter of the thirteenth triode is connected to the second end of the tenth resistor, a base of the thirteenth triode is connected to the second end of the eleventh resistor, a collector of the thirteenth triode is connected to the first end of the thirteenth resistor, and the second end of the thirteenth resistor is connected to the second end of the eighth resistor;

4. The over-temperature protection circuit according to claim 3, wherein base emitter voltages of the eleventh and twelfth transistors decrease as their temperatures increase.

5. An over-temperature protection chip, comprising the over-temperature protection circuit of any one of claims 1~4.