CN114597858B - Chip over-temperature protection circuit and corresponding chip and chip circuit - Google Patents

Chip over-temperature protection circuit and corresponding chip and chip circuit Download PDF

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CN114597858B
CN114597858B CN202210497171.4A CN202210497171A CN114597858B CN 114597858 B CN114597858 B CN 114597858B CN 202210497171 A CN202210497171 A CN 202210497171A CN 114597858 B CN114597858 B CN 114597858B
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resistor
over
triode
temperature
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CN114597858A (en
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贾生龙
李瑞平
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Shanghai Xinlong Semiconductor Technology Co ltd Nanjing Branch
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Shanghai Xinlong Semiconductor Technology Co ltd Nanjing Branch
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H5/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection
    • H02H5/04—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature
    • H02H5/044—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature using a semiconductor device to sense the temperature
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/20—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for electronic equipment

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  • Power Engineering (AREA)
  • Protection Of Static Devices (AREA)

Abstract

The invention relates to the technical field of circuits, and discloses a chip over-temperature protection circuit, a corresponding chip and a chip circuit, which comprise: the device comprises an over-temperature detection unit, a threshold switching unit and an output power control unit; when the temperature of the chip reaches an over-temperature protection point, a first control signal VO output by the over-temperature detection unit triggers the threshold switching unit to enter a threshold switching mode, and the voltage value of a second control signal VP output by a second control signal output end of the threshold switching unit is reduced, so that the power signal output to the power signal output end SW by the output power control unit is reduced. The over-temperature protection circuit reduces the output power when triggering over-temperature instead of switching off the output, thereby ensuring the application under severe and special conditions and simultaneously embodying the advantages of simple over-temperature protection circuit and low power consumption.

Description

Chip over-temperature protection circuit and corresponding chip and chip circuit
Technical Field
The invention relates to the technical field of circuits, in particular to a chip over-temperature protection circuit and a corresponding chip and chip circuit.
Background
In daily production and life, a plurality of scenes in which the temperature of a chip needs to be controlled are met, and over-temperature detection and temperature protection are needed. Specifically, in the switching power supply chip: the switching power supply realizes the functions of managing and transferring electric energy, the load converts the input electric energy into heat energy, light energy, kinetic energy and the like in the working process of the switching power supply chip, 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 when the conditions such as chip work is unusual, heavily loaded, applied environment temperature is abominable, heat dissipation are poor, the heat can not in time conduct, radiate out and will arouse the chip to damage and arouse other accidents even, so avoid the chip to damage in order to detect the chip temperature in the switching power supply chip, can integrate overtemperature detection circuit usually and play the effect of temperature protection.
However, in the switching power supply chip, an over-temperature protection window is usually set through a thermal diode, an over-temperature detection circuit and the like, when the temperature of the chip is higher than an over-temperature protection point, the power tube of the chip is closed, the output power is zero, and when the temperature of the chip is reduced to the lowest temperature of the over-temperature protection window, the power tube of the chip is opened.
Disclosure of Invention
The invention aims to solve the problem that the conventional over-temperature protection circuit cannot be used in special conditions, and provides a chip over-temperature protection circuit, a corresponding chip and a chip circuit.
In order to achieve the above object, the present invention provides a chip over-temperature protection circuit, including: the device comprises an over-temperature detection unit, a threshold switching unit and an output power control unit;
the first end of the over-temperature detection unit is connected with an internal working voltage VDD, the second end of the over-temperature detection unit is connected with a ground end GND, and the third end of the over-temperature detection unit is used as a first control signal output end and used for sending an output first control signal VO to the first end of the threshold switching unit; the second end of the threshold switching unit is connected with an internal working voltage VDD, the third end of the threshold switching unit is connected with a reference voltage VREF, the fourth end of the threshold switching unit is connected with a ground end GND, the fifth end of the threshold switching unit serves as a second control signal output end to send an output second control signal VP to the first end of the output power control unit, and the sixth end B1 of the threshold switching unit is connected with the fourth end B0 of the over-temperature detection unit; the second end of the output power control unit is used for receiving a feedback signal input by a feedback signal input end FB, the third end of the output power control unit is connected with an internal working voltage VDD, the fourth end of the output power control unit is connected with a ground end GND, the fifth end of the output power control unit is connected with a power signal output end SW, and the sixth end of the output power control unit is connected with a VCC input end;
the over-temperature detection unit is used for detecting whether the temperature of the chip rises to an over-temperature protection point, when the temperature of the chip does not reach the over-temperature protection point, a first control signal VO output by a first control signal output end of the over-temperature detection unit cannot trigger the threshold switching unit to enter a threshold switching mode, and the voltage value of a second control signal VP output by a second control signal output end of the threshold switching unit to a first end of the output power control unit is kept unchanged, so that a power signal output by the output power control unit to the power signal output end SW is kept unchanged; when the temperature of the chip reaches an over-temperature protection point, a first control signal VO output by a first control signal output end of the over-temperature detection unit triggers the threshold switching unit to enter a threshold switching mode, so that the voltage value of a second control signal VP output by a second control signal output end of the threshold switching unit to a first end of the output power control unit is reduced, and a power signal output by the output power control unit to the power signal output end SW is reduced.
As an implementation manner, when the power signal output by the output power control unit to the power signal output terminal SW is reduced to lower the temperature of the chip until the temperature of the chip reaches a safe point, the first control signal VO output by the first control signal output terminal of the over-temperature detection unit cannot trigger the threshold switching unit to enter the threshold switching mode, and the voltage value of the second control signal VP output by the second control signal output terminal of the threshold switching unit to the first end of the output power control unit is increased, so that the power signal output by the output power control unit to the power signal output terminal SW is increased.
As an implementation, the over-temperature detecting unit includes a first resistor R0, a second resistor R1, a third resistor R2, a fourth resistor R3, a fifth resistor R4, a sixth resistor R5, a first transistor Q1, a second transistor Q2, a third transistor Q3, and a fourth transistor Q4;
one end of the first resistor R0 is connected to the first end of the over-temperature detection unit, the other end of the first resistor R0 is connected to the fourth end B0 of the over-temperature detection unit and one end of the second resistor R1, the other end of the second resistor R1 is connected to one end of the third resistor R2, the collector of the first triode Q1 and the base of the fourth triode Q4, the other end of the third resistor R2 is connected to the second end of the over-temperature detection unit, the emitter of the first triode Q1 is connected to the first end of the over-temperature detection unit, the base of the first triode Q1 is connected to the base of the second triode Q2, the collector of the second triode Q2 and one end of the fourth resistor R3, the emitter of the second triode Q2 is connected to the first end of the over-temperature detection unit, the base of the second diode Q2 is further connected to one end of the fifth resistor R4, A base of the third triode Q3 is connected, the other end of the fifth resistor R4 is connected to the first end of the over-temperature detection unit, an emitter of the third triode Q3 is connected to the first end of the over-temperature detection unit, a collector of the third triode Q3 is connected to the third end of the over-temperature detection unit and one end of the sixth resistor R5, and the other end of the sixth resistor R5 is connected to the second end of the over-temperature detection unit; a collector of the fourth transistor Q4 is connected to the other end of the fourth resistor R3, and an emitter of the fourth transistor Q4 is connected to the second end of the over-temperature detection unit;
as the temperature of the chip increases, the turn-on voltage of the fourth triode Q4 decreases; when the temperature of the chip does not reach an over-temperature protection point, the base voltage VT of the fourth triode Q4 is less than the turn-on voltage of the fourth triode Q4, a current mirror composed of the first triode Q1, the second triode Q2 and the third triode Q3 is not conducted, and a first control signal VO output by the first control signal output end is at a low level and cannot trigger the threshold switching unit to enter a threshold switching mode; when the temperature of the chip reaches an over-temperature protection point, the base voltage VT of the fourth triode Q4 is equal to the starting voltage of the fourth triode Q4, the first triode Q1, the second triode Q2 and a current mirror formed by the third triode Q3 are conducted, a first control signal VO output by the first control signal output end is at a high level, and the threshold switching unit is triggered to enter a threshold switching mode.
As an implementation manner, when the chip temperature does not reach the over-temperature protection point, the voltage value VT1= VR2= VVDD × RR2/(RR0+ RR1+ RR2) of the base voltage VT of the fourth transistor Q4, where VR2 represents the voltage value of the third resistor R2, VVDD represents the voltage value of the internal operating voltage VDD, and RR0, RR1, and RR2 represent resistance values of the first resistor R0, the second resistor R1, and the third resistor R2, respectively;
when the chip temperature reaches the over-temperature protection point, the voltage value VT2= (VVDD × RR2/(RR0+ RR1+ RR 2)) + I1 × RR2 of the base voltage VT of the fourth triode Q4, where VVDD represents the voltage value of the internal operating voltage VDD, RR0, RR1, and RR2 represent the resistance values of the first resistor R0, the second resistor R1, and the third resistor R2, respectively, and I1 represents the current value passing through the collector of the first triode Q1.
The threshold switching unit comprises a fifth triode Q5, a sixth triode Q6, a seventh triode Q7, an eighth triode Q8, a ninth triode Q9, a seventh resistor R6, an eighth resistor R7, a ninth resistor R8 and a tenth resistor R9;
a first end of the threshold switching unit is connected to the base of the fifth transistor Q5 as the first control signal input end, an emitter of the fifth transistor Q5 is connected to the fourth end of the threshold switching unit, a collector of the fifth transistor Q5 is connected to the base of the eighth transistor Q8 and the collector of the seventh transistor Q7, a base of the ninth transistor Q9 is connected to the sixth end B1 of the threshold switching unit, an emitter of the ninth transistor Q9 is connected to one end of the seventh resistor R6, the other end of the seventh resistor R6 is connected to the fourth end of the threshold switching unit, a collector of the ninth transistor Q9 is connected to the collector of the sixth transistor Q6, the base of the sixth transistor Q6 and the base of the seventh transistor Q7, an emitter of the sixth transistor Q6 is connected to the second end of the threshold switching unit, an emitter of the seventh triode Q7 is connected to the second end of the threshold switching unit; a collector of the eighth transistor Q8 is connected to the fourth terminal of the threshold switching unit, an emitter of the eighth transistor Q8 is connected to one end of the tenth resistor R9 and one end of the ninth resistor R8, respectively, the other end of the tenth resistor R9 is connected to the fourth terminal of the threshold switching unit, the other end of the ninth resistor R8 is connected to the fifth terminal of the threshold switching unit and one end of the eighth resistor R7, respectively, and the other end of the eighth resistor R7 is connected to the third terminal of the threshold switching unit;
when the temperature of the chip does not reach an over-temperature protection point, a first control signal VO received by the first control signal input end is at a low level, the voltage value of the first control signal VO is smaller than the starting voltage of the fifth triode Q5, the fifth triode Q5 and the eighth triode Q8 are not conducted, and the voltage value of a second control signal VP output by the second control signal output end is kept unchanged; when the temperature of the chip reaches an over-temperature protection point, a first control signal VO received by the first control signal input end is at a high level, the voltage value of the first control signal VO is greater than the starting voltage of the fifth triode Q5, the fifth triode Q5 is connected with the eighth triode Q8, and the voltage value of a second control signal VP output by the second control signal output end is reduced.
As an implementation manner, when the fifth transistor Q5 and the eighth transistor Q8 are not conductive, the voltage value VPH of the second control signal VP output by the second control signal output terminal = VVREF (RR8+ RR 9)/(RR 7+ RR8+ RR9), where VVREF represents the voltage value of the reference voltage VREF, and RR7, RR8, and RR9 represent the resistance values of the eighth resistor R7, the ninth resistor R8, and the tenth resistor R9, respectively;
when the fifth transistor Q5 and the eighth transistor Q8 are turned on, a voltage value VPL = VVREF × RR8/(RR7+ RR8) of the second control signal VP output by the second control signal output terminal, where VVREF represents a voltage value of the reference voltage VREF, and RR7 and RR8 represent resistance values of the eighth resistor R7 and the ninth resistor R8, respectively.
As one possible implementation, the output power control unit includes an error amplifier, an oscillator circuit, a comparator, an output control logic and other circuits, a power tube M1;
the positive input end of the error amplifier is used as the second end of the output power control unit to be connected with the feedback signal input end FB, the negative input end of the error amplifier is used as the first end of the output power control unit to be connected with the fifth end of the threshold switching unit, the output end of the error amplifier is connected with the positive input end of the comparator, the error amplifier is also respectively connected with the third end of the output power control unit and the fourth end of the output power control unit, the negative input end of the comparator is connected with the oscillator circuit, the output end of the comparator is connected with one end of the output control logic and other circuits, the comparator is also respectively connected with the third end of the output power control unit and the fourth end of the output power control unit, and the other ends of the output control logic and other circuits are respectively connected with the oscillator circuit, the feedback signal input end FB, A gate of the power transistor M1, a source of the power transistor M1 serving as a fifth terminal of the output power control unit is connected to the power signal output terminal SW, and a drain of the power transistor M1 serving as a sixth terminal of the output power control unit is connected to the VCC input terminal;
when the temperature of the chip does not reach the over-temperature protection point, the voltage value of the second control signal VP sent by the first end of the output power control unit to the positive input end of the error amplifier is kept unchanged, the error amplifier generates the voltage signal VE sent by the output end of the error amplifier to the positive input end of the comparator according to the voltage value of the second control signal VP sent by the first end of the output power control unit to the positive input end of the error amplifier and the voltage value of the feedback signal input by the feedback signal input end FB, the comparator generates the PWM signal sent by the output end of the comparator to the output control logic and other circuits according to the voltage value of the voltage signal VE and the voltage value of the sawtooth wave signal SAW sent by the oscillator circuit to the reverse input end of the comparator, and drives the output control logic and other circuits to control the power tube M1 to be opened or closed, the power signal output by the power signal output end SW keeps unchanged;
when the temperature of the chip reaches an over-temperature protection point, the voltage value of a second control signal VP sent by the first end of the output power control unit to the positive input end of the error amplifier is reduced, so that the time that the voltage value of the voltage signal VE sent by the output end of the error amplifier to the positive input end of the comparator is reduced and is greater than the voltage value of the sawtooth wave signal SAW sent by the oscillator circuit to the negative input end of the comparator is shortened, and the time that the voltage value of the sawtooth wave signal SAW sent by the oscillator circuit to the negative input end of the comparator is smaller is lengthened, the duty ratio of the PWM signal sent from the output terminal of the comparator to the output control logic and other circuits is reduced, and the time for driving the output control logic and other circuits to control the power transistor M1 to be turned on is reduced, so that the power signal output by the power signal output terminal SW is reduced.
Correspondingly, the invention also provides a chip comprising the over-temperature protection circuit.
Correspondingly, the invention also provides a chip circuit comprising the over-temperature protection circuit.
As an implementable mode, the method further comprises the following steps: the first capacitor C11, the second capacitor C12, the first feedback voltage-dividing resistor RF1, the second feedback voltage-dividing resistor RF2, the first inductor L1 and the first diode D1;
the positive electrode of the first capacitor C11 is connected to the VCC input terminal, the negative electrode of the first capacitor C12 is connected to the ground terminal GND, the negative electrode of the first diode D1 is connected to the power signal output terminal SW and one end of the first inductor L1, the positive electrode of the first diode D1 is connected to the ground terminal GND, the negative electrode of the second capacitor C12, one end of the second feedback voltage-dividing resistor RF2 and one end of the load RL1, the positive electrode of the second capacitor C12 is connected to the other end of the first inductor L1, one end of the first feedback voltage-dividing resistor RF1 and the other end of the load RL1, and the other end of the first feedback voltage-dividing resistor RF1 is connected to the feedback signal input terminal FB and the other end of the second feedback voltage-dividing resistor RF 2.
As an implementable mode, the method further comprises the following steps: the feedback voltage-dividing circuit comprises a first capacitor C11, a second capacitor C12, a first feedback voltage-dividing resistor RCS, a first inductor L1 and a first diode D1;
the positive electrode of the first capacitor C11 is connected to the VCC input terminal, the negative electrode of the first capacitor C12 is connected to the ground terminal GND, the negative electrode of the first diode D1 is connected to the power signal output terminal SW and one end of the first inductor L1, the positive electrode of the first diode D1 is connected to the ground terminal GND, the negative electrode of the second capacitor C12 and one end of the first feedback sampling resistor RCS, the positive electrode of the second capacitor C12 is connected to the other end of the first inductor L1 and one end of the load RL1, and the other end of the first feedback sampling resistor RCS is connected to the feedback signal input terminal FB and the other end of the load RL 1.
The invention has the beneficial effects that: the invention provides a chip over-temperature protection circuit and a corresponding chip and a chip circuit, when the temperature of the chip reaches an over-temperature protection point, a first control signal VO output by an over-temperature detection unit triggers a threshold switching unit to enter a threshold switching mode, and the voltage value of a second control signal VP output by a second control signal output end of the threshold switching unit is reduced, so that the duty ratio of a PWM signal is reduced, and the power signal output by a power signal output end SW is reduced. The over-temperature protection circuit reduces the output power when triggering the over-temperature protection point, but not turns off the output, thereby ensuring the application under severe and special conditions and simultaneously embodying the advantages of simple over-temperature protection circuit and low power consumption.
Drawings
Fig. 1 is a circuit diagram of an over-temperature protection circuit according to an embodiment of the present invention.
Fig. 2 is a chip circuit diagram of a constant voltage type switching power supply chip to which an over-temperature protection circuit is applied according to an embodiment of the present invention.
Fig. 3 is a chip circuit diagram of a constant current type switching power supply chip to which an over-temperature protection circuit is applied according to an embodiment of the present invention.
Fig. 4 is a schematic diagram illustrating a change of an over-temperature protection point T2 and a safety point T1 in the over-temperature protection circuit according to an embodiment of the present invention.
Fig. 5 is a schematic diagram illustrating changes of a voltage value of a voltage signal VE and a voltage value of a PWM signal of the over-temperature protection circuit when the chip temperature reaches the over-temperature protection point to trigger the over-temperature protection and when the chip temperature does not reach the over-temperature protection point to trigger the over-temperature protection.
Detailed Description
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 only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, the present embodiment provides a technical solution: an over-temperature protection circuit comprising: the device comprises an over-temperature detection unit, a threshold switching unit and an output power control unit;
the first end of the over-temperature detection unit is connected with an internal working voltage VDD, the second end of the over-temperature detection unit is connected with a ground end GND, and the third end of the over-temperature detection unit is used as a first control signal output end and used for sending an output first control signal VO to the first end of the threshold switching unit; the second end of the threshold switching unit is connected with an internal working voltage VDD, the third end of the threshold switching unit is connected with a reference voltage VREF, the fourth end of the threshold switching unit is connected with a ground end GND, the fifth end of the threshold switching unit serves as a second control signal output end to send an output second control signal VP to the first end of the output power control unit, and the sixth end B1 of the threshold switching unit is connected with the fourth end B0 of the over-temperature detection unit; the second end of the output power control unit is used for receiving a feedback signal input by a feedback signal input end FB, the third end of the output power control unit is connected with an internal working voltage VDD, the fourth end of the output power control unit is connected with a ground end GND, the fifth end of the output power control unit is connected with a power signal output end SW, and the sixth end of the output power control unit is connected with a VCC input end;
the over-temperature detection unit is used for detecting whether the temperature of the chip rises to an over-temperature protection point, when the temperature of the chip does not reach the over-temperature protection point, a first control signal VO output by a first control signal output end of the over-temperature detection unit cannot trigger the threshold switching unit to enter a threshold switching mode, and the voltage value of a second control signal VP output by a second control signal output end of the threshold switching unit to a first end of the output power control unit is kept unchanged, so that a power signal output by the output power control unit to the power signal output end SW is kept unchanged; when the temperature of the chip reaches an over-temperature protection point, a first control signal VO output by a first control signal output end of the over-temperature detection unit triggers the threshold switching unit to enter a threshold switching mode, so that the voltage value of a second control signal VP output by a second control signal output end of the threshold switching unit to a first end of the output power control unit is reduced, and a power signal output by the output power control unit to the power signal output end SW is reduced; thereby achieving the purpose of reducing the temperature of the chip.
It should be noted that, in the above description, when the chip temperature does not reach the over-temperature protection point, keeping the voltage value of the second control signal VP unchanged means that when the chip normally works, there is no normally output voltage value of the second control signal VP that is changed due to the chip temperature; the fact that the power signal of the power signal output end SW is kept unchanged means that when the chip works normally, no power signal which is changed due to the temperature of the chip and is normally output by the power signal output end SW exists.
And when the chip temperature reaches an over-temperature protection point, the power signal output to the power signal output end SW by the output power control unit is controlled to be reduced so as to lower the chip temperature until the chip temperature reaches a safety point, the first control signal VO output by the first control signal output end of the over-temperature detection unit cannot trigger the threshold switching unit to enter a threshold switching mode, the voltage value of the second control signal VP output by the second control signal output end of the threshold switching unit to the first end of the output power control unit is increased, and the power signal output to the power signal output end SW by the output power control unit is increased.
Specifically, as shown in fig. 1, the chip over-temperature protection circuit of this embodiment includes an over-temperature detection unit STAGE1, a threshold switching unit STAGE2, and an output power control unit STAGE3, where the over-temperature detection unit STAGE1 includes a first resistor R0, a second resistor R1, a third resistor R2, a fourth resistor R3, a fifth resistor R4, a sixth resistor R5, a first triode Q1, a second triode Q2, a third triode Q3, and a fourth triode Q4;
one end of the first resistor R0 is connected to the first end of the over-temperature detection unit, the other end of the first resistor R0 is connected to the fourth end B0 of the over-temperature detection unit and one end of the second resistor R1, the other end of the second resistor R1 is connected to one end of the third resistor R2, the collector of the first triode Q1 and the base of the fourth triode Q4, the other end of the third resistor R2 is connected to the second end of the over-temperature detection unit, the emitter of the first triode Q1 is connected to the first end of the over-temperature detection unit, the base of the first triode Q1 is connected to the base of the second triode Q2, the collector of the second triode Q2 and one end of the fourth resistor R3, the emitter of the second triode Q2 is connected to the first end of the over-temperature detection unit, the base of the second diode Q2 is further connected to one end of the fifth resistor R4, A base electrode of the third triode Q3 is connected, the other end of the fifth resistor R4 is connected to the first end of the over-temperature detection unit, an emitter electrode of the third triode Q3 is connected to the first end of the over-temperature detection unit, a collector electrode of the third triode Q3 is connected to the third end of the over-temperature detection unit and one end of the sixth resistor R5, and the other end of the sixth resistor R5 is connected to the second end of the over-temperature detection unit; a collector of the fourth transistor Q4 is connected to the other end of the fourth resistor R3, and an emitter of the fourth transistor Q4 is connected to the second end of the over-temperature detection unit;
as the temperature of the chip increases, the turn-on voltage of the fourth triode Q4 decreases; when the temperature of the chip does not reach an over-temperature protection point, that is, when the chip normally operates, the base voltage VT of the fourth triode Q4 is less than the turn-on voltage of the fourth triode Q4, a current mirror composed of the first triode Q1, the second triode Q2 and the third triode Q3 is not conducted, and the first control signal VO output by the first control signal output end is at a low level and cannot trigger the threshold switching unit to enter the threshold switching mode; when the chip temperature reaches the overtemperature protection point, the base voltage VT of the fourth triode Q4 is equal to the turn-on voltage of the fourth triode Q4, the first triode Q1, the second triode Q2, the current mirror that the third triode Q3 constitutes switches on, the first control signal VO of first control signal output end output is the high level, triggers the threshold value switch unit gets into the threshold value switch mode to along with the continuous rising of chip temperature, the base voltage VT of the fourth triode Q4 is greater than the turn-on voltage of the fourth triode Q4, the first triode Q1, the second triode Q2, the current mirror that the third triode Q3 constitutes is still for the conducting state.
When the chip temperature does not reach the over-temperature protection point, the voltage value VT1= VR2= VVDD × RR2/(RR0+ RR1+ RR2) of the base voltage VT of the fourth triode Q4, where VR2 represents the voltage value of the third resistor R2, VVDD represents the voltage value of the internal operating voltage VDD, and RR0, RR1, and RR2 represent resistance values of the first resistor R0, the second resistor R1, and the third resistor R2, respectively;
when the chip temperature reaches the over-temperature protection point, the voltage value VT2= (VVDD × RR2/(RR0+ RR1+ RR 2)) + I1 × RR2 of the base voltage VT of the fourth triode Q4, where VVDD represents the voltage value of the internal operating voltage VDD, RR0, RR1, and RR2 represent the resistance values of the first resistor R0, the second resistor R1, and the third resistor R2, respectively, and I1 represents the current value passing through the collector of the first triode Q1.
It should be noted that the base-emitter junction voltage drop Vbe of the transistor of this embodiment has a negative temperature coefficient, that is, the base-emitter junction voltage drop Vbe decreases with increasing temperature, that is, the turn-on voltage Vbe decreases, the second resistor R1 and the third resistor R2 are resistors of the same type made in proportion and have the same temperature coefficient, and the voltage VR2 of the third resistor R2 is equal to the base voltage of the fourth transistor Q4, so that the base voltage VT of the fourth transistor Q4 is not changed by the change of temperature.
At normal temperature, the chip temperature is lower than the over-temperature protection point T2, the voltage value of the base voltage VT of the fourth transistor Q4 is VT1= VR2= VVDD × RR2/(RR0+ RR1+ RR2), the base voltage VT of the fourth transistor Q4 is lower than the turn-on voltage Vbe of the fourth transistor Q4, when the chip temperature is higher than the over-temperature protection point T2, the turn-on voltage Vbe of the fourth transistor Q4 is decreased, the resistance values of the second resistor R1 and the third resistor R2 are set to make the voltage value of the base voltage VT of the fourth transistor Q4 = the voltage value of the turn-on voltage Vbe of the fourth transistor Q4, the fourth transistor Q4 is turned on, the current mirror formed by the first transistor Q1, the second transistor Q2 and the third transistor Q3 is turned on, the operation is started, the current signal passing through the collector of the third transistor Q3 flows through the sixth resistor R6 to make the sixth resistor R466 = the base voltage VO of the sixth transistor Q5, and the voltage VO is controlled by the upper end = the first resistor R5 A voltage VR5 outputting a first control signal VO at a high level, and simultaneously raising a voltage value of a base voltage VT of the fourth transistor Q4 by a current signal of a collector of the first transistor Q1 to VT2= (VVDD × RR2/(RR0+ RR1+ RR 2)) + I1 × RR2, wherein a fifth resistor R4 provides a base current for the first transistor Q1, the second transistor Q2 and the third transistor Q3, an absolute value of a base-emitter junction voltage drop of the second diode Q2 is Vbe, a current value I2= (VVDD-vvrr)/3 through the collector of the fourth transistor Q4, I2 provides mirror currents for I1 and I3, I1 and I3 are scaled by I2, specifically, I1= N × I2; i3= M × I2, wherein the emitter area ratio of the first transistor Q1, the second transistor Q2, and the third transistor Q3 is N: 1: m; wherein VVDD represents a voltage value of the internal operating voltage VDD, VVbe represents an absolute value of a base-emitter junction voltage drop of the second transistor Q2, I1 represents a current value through the collector of the first transistor Q1, I3 represents a current value of a current signal through the collector of the third transistor Q3, and I2 represents a current value of a current signal through the collector of the fourth transistor Q4.
Specifically, in this embodiment, the over-temperature detection module in this embodiment further has a hysteresis function, that is, when the power signal output by the control output power unit to the power signal output terminal SW decreases and reaches a safety point T1, the voltage value of the base voltage VT is VT2, and the over-temperature protection is cancelled, that is, when the power signal output by the control output power unit to the power signal output terminal SW decreases and the chip temperature decreases, the turn-on voltage of the fourth triode Q4 increases until the chip temperature reaches a safety point T1, the base voltage VT of the fourth triode Q4 is less than the turn-on voltage of the fourth triode Q4, and the current mirror composed of the first triode Q1, the second triode Q2, and the third triode Q3 is not turned on, and at this time, the current value I1, The current values I2 and I3 both become 0, the first control signal VO output by the first control signal output terminal is at low level and cannot trigger the threshold switching unit to enter the threshold switching mode, the voltage value of the second control signal VP output by the second control signal output terminal of the threshold switching unit to the first end of the output power control unit is increased, so that the power signal output by the output power control unit to the power signal output terminal SW is increased to the power signal output by the chip during normal operation; from the above analysis, it is found that when the chip temperature is T2, the temperature detection module outputs the first control signal VO at a high level, only when the chip temperature is less than T2 and reaches T1, the fourth transistor Q4 can be turned off, the output first control signal VO is at a low level, and the difference between T2 and T1 is a hysteresis window; fig. 4 is a schematic diagram showing changes of the over-temperature protection point T2 and the safety point T1 in the over-temperature protection circuit according to the embodiment of the present invention.
As shown in fig. 1, the threshold switching unit STAGE2 is specifically an error amplifier threshold switching unit, and is configured to adjust a voltage value of a second control signal VP input to a positive input terminal of the error amplifier 10 in the output power control unit STAGE3, and includes a fifth transistor Q5, a sixth transistor Q6, a seventh transistor Q7, an eighth transistor Q8, a ninth transistor Q9, a seventh resistor R6, an eighth resistor R7, a ninth resistor R8, and a tenth resistor R9;
a first end of the threshold switching unit is connected to the base of the fifth transistor Q5 as the first control signal input end, an emitter of the fifth transistor Q5 is connected to the fourth end of the threshold switching unit, a collector of the fifth transistor Q5 is connected to the base of the eighth transistor Q8 and the collector of the seventh transistor Q7, a base of the ninth transistor Q9 is connected to the sixth end B1 of the threshold switching unit, an emitter of the ninth transistor Q9 is connected to one end of the seventh resistor R6, the other end of the seventh resistor R6 is connected to the fourth end of the threshold switching unit, a collector of the ninth transistor Q9 is connected to the collector of the sixth transistor Q6, the base of the sixth transistor Q6 and the base of the seventh transistor Q7, an emitter of the sixth transistor Q6 is connected to the second end of the threshold switching unit, an emitter of the seventh triode Q7 is connected to the second end of the threshold switching unit; a collector of the eighth triode Q8 is connected to the fourth end of the threshold switching unit, an emitter of the eighth triode Q8 is connected to one end of the tenth resistor R9 and one end of the ninth resistor R8, respectively, the other end of the tenth resistor R9 is connected to the fourth end of the threshold switching unit, the other end of the ninth resistor R8 is connected to the fifth end of the threshold switching unit and one end of the eighth resistor R7, respectively, and the other end of the eighth resistor R7 is connected to the third end of the threshold switching unit;
when the temperature of the chip does not reach an over-temperature protection point, namely when the chip normally operates, a first control signal VO received by the first control signal input end is at a low level, the voltage value of the first control signal VO is smaller than the starting voltage of the fifth triode Q5, the fifth triode Q5 and the eighth triode Q8 are not conducted, and the voltage value of a second control signal VP output by the second control signal output end is kept unchanged; when the temperature of the chip reaches an over-temperature protection point, a first control signal VO received by the first control signal input end is at a high level, the voltage value of the first control signal VO is greater than the starting voltage of the fifth triode Q5, the fifth triode Q5 is connected with the eighth triode Q8, and the voltage value of a second control signal VP output by the second control signal output end is reduced.
When the fifth transistor Q5 and the eighth transistor Q8 are not conductive, the voltage value VPH = VVREF (RR8+ RR 9)/(RR 7+ RR8+ RR9) of the second control signal VP output by the second control signal output terminal, where VVREF represents the voltage value of the reference voltage VREF, and RR7, RR8, and RR9 represent resistance values of an eighth resistor R7, a ninth resistor R8, and a tenth resistor R9, respectively; when the fifth transistor Q5 and the eighth transistor Q8 are turned on, the voltage value VPL = VVREF × RR8/(RR7+ RR8) of the second control signal VP output by the second control signal output terminal, where VVREF represents the voltage value of the reference voltage VREF, and RR7 and RR8 represent resistance values of the eighth resistor R7 and the ninth resistor R8, respectively.
It should be noted that, in this embodiment, when the first control signal VO received by the first control signal input terminal is at a low level, the fifth transistor Q5 and the eighth transistor Q8 are not conductive, but the ninth transistor Q9 needs to be always in a conductive state, so that appropriate resistance values need to be set for the first resistor R0, the second resistor R1, and the third resistor R2, so as to obtain voltages of the fourth terminal B0 of the over-temperature detection unit and the sixth terminal B1 of the threshold switching unit, so that the ninth transistor Q9 is always in a conductive state; and because there is no temperature protection at normal temperature, the first control signal VO is at low level, so the fifth triode Q5 is turned off, the eighth triode Q8 is turned off, at this time, the voltage value of the second control signal VP input by the positive input end of the error amplifier is marked as VPH, when the temperature is higher than T2 and temperature protection occurs, the first control signal VO is at high level, Q5 is turned on, Q8 is turned on, and the voltage value of the second control signal VP is reduced to VPL.
As shown in fig. 1, the output power control unit STAGE3 includes an error amplifier 10, an oscillator circuit 20, a comparator 30, an output control logic and other circuits 40, a power transistor M1;
the positive input end of the error amplifier 10 is connected to the feedback signal input end FB as the second end of the output power control unit, the negative input end of the error amplifier 10 is connected to the fifth end of the threshold switching unit as the first end of the output power control unit, the output end of the error amplifier 10 is connected to the first input end of the comparator, the error amplifier 10 is further connected to the third end of the output power control unit and the fourth end of the output power control unit, the second input end of the comparator 30 is connected to the oscillator circuit 20, the output end of the comparator 30 is connected to one end of the output control logic and other circuit 40, the comparator 30 is further connected to the third end of the output power control unit and the fourth end of the output power control unit, and the other end of the output control logic and other circuit 40 is connected to the oscillator circuit 20 and the fourth end of the output control logic and other circuit 40 respectively, The grid electrode of the power tube M1, the source electrode of the power tube M1 as the fifth end of the output power control unit is connected to the power signal output end SW, and the drain electrode of the power tube M1 as the sixth end of the output power control unit is connected to the VCC input end;
when the chip temperature does not reach the over-temperature protection point, that is, when the chip normally operates, the voltage value of the second control signal VP sent by the first end of the output power control unit to the forward input end of the error amplifier 10 remains unchanged, the error amplifier 10 generates the voltage signal VE sent by the output end of the error amplifier 10 to the forward input end of the comparator according to the voltage value of the second control signal VP sent by the first end of the output power control unit to the forward input end of the error amplifier 10 and the voltage value of the feedback signal input by the feedback signal input end FB, the comparator generates the PWM signal sent by the output end of the comparator 30 to the output control logic and other circuits 40 according to the voltage value of the voltage signal VE and the voltage value of the sawtooth wave signal SAW sent by the oscillator circuit 20 to the reverse input end of the comparator, the output control logic and other circuits 40 are driven to control the power tube M1 to be turned on or off, and the power signal output by the power signal output end SW remains unchanged, that is, the power signal output when the chip operates normally;
that is to say, when the chip normally operates, the voltage value of the second control signal VP sent by the first end of the output power control unit to the positive input end of the error amplifier 10 is the voltage value of the second control signal VP output when the chip normally operates, where the voltage value of the second control signal VP is also greater than the voltage value of the second control signal VP sent by the first end of the output power control unit to the positive input end of the error amplifier 10 when the chip temperature reaches the over-temperature protection point; the voltage value of the second control signal VP keeps the voltage value of the voltage signal VE sent from the output terminal of the error amplifier 10 to the positive input terminal of the comparator 30 unchanged, wherein the voltage value of the voltage signal VE is also greater than the voltage value of the voltage signal VE sent from the output terminal of the error amplifier 10 to the positive input terminal of the comparator 30 when the chip temperature reaches the over-temperature protection point; the time that the voltage value of the voltage signal VE is greater than the time that the oscillator circuit 20 sends the voltage value of the sawtooth wave signal SAW to the inverting input terminal of the comparator 30 and the time that the voltage value of the sawtooth wave signal SAW is less than the time that the oscillator circuit 20 sends the voltage value of the sawtooth wave signal SAW to the inverting input terminal of the comparator 30 make the PWM signal sent from the output terminal of the comparator 30 to the output control logic and other circuits 40 be a certain duty ratio, the PWM signal controls the output control logic and other circuits 40 to control the time that the power tube M1 is turned on or turned off so that the power signal output from the power signal output terminal SW is the power signal output when the chip normally works;
when the chip temperature reaches the over-temperature protection point, the voltage value of the second control signal VP sent by the first end of the output power control unit to the positive input end of the error amplifier 10 is decreased, so that the time for the voltage value of the voltage signal VE sent by the output end of the error amplifier 10 to the positive input end of the comparator 30 to be smaller than the voltage value of the sawtooth wave signal SAW sent by the oscillator circuit 20 to the reverse input end of the comparator 30 is shortened, the time for the voltage value of the sawtooth wave signal SAW sent by the oscillator circuit 20 to the reverse input end of the comparator 30 to be longer, the duty ratio of the PWM signal sent by the output end of the comparator 30 to the output control logic and other circuits 40 is decreased, and the time for driving the output control logic and other circuits 40 to control the power tube M1 to be turned on is decreased, thereby reducing the power signal output from the power signal output terminal SW.
When the temperature of the chip decreases to reach a safety point T1, the over-temperature protection is cancelled, and the voltage value of the second control signal VP sent by the first end of the output power control unit to the positive input end of the error amplifier 10 increases, so that the time that the voltage value of the voltage signal VE sent by the output end of the error amplifier 10 to the positive input end of the comparator 30 increases and is greater than the voltage value of the sawtooth wave signal SAW sent by the oscillator circuit 20 to the negative input end of the comparator 30 becomes longer, the time that the voltage value of the sawtooth wave signal SAW sent by the oscillator circuit 20 to the negative input end of the comparator 30 becomes shorter, the duty ratio of the PWM signal sent by the output end of the comparator 30 to the output control logic and other circuits 40 increases, that is, the high level time of the PWM signal becomes longer, and the low level time of the PWM signal becomes shorter, the time for driving the output control logic and other circuits 40 to control the power transistor M1 to be turned on is made longer, so as to increase the power signal output from the power signal output terminal SW, i.e. the power signal output when the chip is in a normal operation state.
In the embodiment, the forward input end and the reverse input end of the error amplifier have the characteristics of 'virtual short and virtual break' and the voltages at the two ends are equal dynamically, the positive input end of the chip obtains a second control signal VP, the negative input end of the chip obtains a feedback signal, the voltage value of the feedback signal and the voltage value of the second control signal VP are in a dynamic balance state when the chip works normally, namely, when the temperature of the chip does not reach the over-temperature protection point or the temperature of the chip reaches the over-temperature protection point, the voltage value of the feedback signal may be larger or smaller than the voltage value of the second control signal VP, when the voltage value of the feedback signal is smaller than the voltage value of the second control signal VP, the voltage signal VE output by the error amplifier is at a high level, when the voltage value of the feedback signal is greater than the voltage value of the second control signal VP, the voltage signal VE output by the error amplifier is at a low level; therefore, the voltage value of the voltage signal VE is actually in a fluctuating state no matter when the chip temperature does not reach the over-temperature protection point or when the chip temperature reaches the over-temperature protection point, and the voltage value of the sawtooth wave signal SAW generated by the oscillator circuit, which is compared with the voltage value of the voltage signal VE, is also actually in a fluctuating state;
when the temperature of the chip reaches the over-temperature protection point, due to the reduction of the voltage value of the second control signal VP, the differential input of the feedback signal FB and the second control signal VP is reduced, so that the voltage value of the voltage signal VE is also reduced as a whole, and for more clear distinction, the voltage average values of the voltage signal VE when the over-temperature protection is not triggered and the voltage average value of the voltage signal VE when the over-temperature protection is triggered are respectively obtained and compared, as shown in fig. 5, the voltage average value of the voltage signal VE when the over-temperature protection is triggered, the voltage average value of the voltage signal VE when the over-temperature protection is not triggered and a voltage variation schematic diagram of the SAW sawtooth wave signal SAW are shown, it can be seen that when the temperature of the chip does not reach the over-temperature protection point, that is, that the voltage average value of the voltage signal VE when the over-temperature protection is not triggered is greater than the voltage average value of the voltage signal VE when the over-temperature protection point is triggered; when the over-temperature protection point is reached, namely the over-temperature protection is triggered, the time length that the voltage value of the voltage signal VE is greater than the voltage value of the sawtooth wave signal SAW is longer than the time length that the voltage value of the voltage signal VE is greater than the voltage value of the sawtooth wave signal SAW when the over-temperature protection point is reached, namely the over-temperature protection is triggered; referring to fig. 5 again, it can be seen from the relationship between the PWM signal and the voltage signal VE, the sawtooth wave signal SAW, when the voltage signal VE is compared with the sawtooth wave signal SAW generated by the oscillator circuit, when the voltage value of the voltage signal VE is lower than the SAW voltage, the PWM signal output from the output terminal of the comparator is at a high level, and the PWM signal at the high level can drive the output control logic circuit and other circuits 40 to turn on the power tube M1, and when the voltage value of the voltage signal VE is higher than the SAW voltage, the PWM signal output from the output terminal of the comparator is at a low level, and the PWM signal at the low level cannot drive the output control logic circuit and other circuits 40 to turn on the power tube M1, that is, the lower level PWM signal for a longer time can turn off the power tube M1 for a longer time, while the power signal for reducing the output is because the time for turning on the power tube M1 is shorter, the time for which the power signal output end SW can output the power signal is reduced, so that the overall power signal output by the power signal output end SW is reduced; finally, it can be concluded that, in this embodiment, the duty ratio of the PWM signal is controlled by the change of the second control signal VP, the feedback signal, and the voltage signal VE, so that the output of the chip reaches a balance.
In this embodiment, when the chip is at normal temperature and no over-temperature protection is triggered, the PWM signal controls the switch of the power tube M1 according to a certain duty ratio, and the chip operates normally; when the temperature becomes higher and is higher than the over-temperature protection point T2 to trigger the over-temperature protection, the turn-on voltage of the fourth triode Q4 becomes low, the output first control signal VO is at a high level, the output voltage value of the second control signal VP becomes low, the voltage signal VE becomes low, the duty ratio of the PWM signal is reduced, namely the high-level time of the PWM signal is shortened, and the conduction time of the power tube is shortened; the output voltage is reduced, the output power is reduced, the energy conversion is reduced, when the temperature is gradually reduced until the temperature is reduced to T1, the over-temperature protection is cancelled, the output power is reduced instead of the output is turned off when the over-temperature protection point is triggered, and therefore the application under severe and special conditions is guaranteed, and the over-temperature protection circuit has the advantages of being simple and low in power consumption.
Correspondingly, based on the same inventive concept, the embodiment of the invention also discloses a chip which comprises the over-temperature protection circuit, wherein the chip can be a constant voltage type switching power supply chip or a constant current type switching power supply chip.
Correspondingly, based on the same inventive concept, the embodiment of the invention also discloses a chip circuit which comprises the over-temperature protection circuit.
As an embodiment, the over-temperature protection circuit may be applied to a constant voltage type switching power supply chip, as shown in fig. 2, the chip circuit including: the over-temperature protection circuit S1, the other circuit S2, a first capacitor C11, a second capacitor C12, a first feedback voltage-dividing resistor RF1, a second feedback voltage-dividing resistor RF2, a first inductor L1 and a first diode D1;
the first capacitor C11 is used as a circuit voltage VCC, the positive electrode of the first capacitor C11 is connected to the VCC input terminal VCC1, the negative electrode of the first capacitor C12 is connected to the ground terminal GND, the negative electrode of the first diode D1 is connected to the power signal output terminal SW and one end of the first inductor L1, the positive electrode of the first diode D1 is connected to the ground terminal GND, the negative electrode of the second capacitor C12, one end of the second feedback voltage-dividing resistor RF2 and one end of the load RL1, the positive electrode of the second capacitor C12 is connected to the other end of the first inductor L1, one end of the first feedback voltage-dividing resistor RF1 and the other end of the load RL1, and the other end of the first feedback voltage-dividing resistor RF1 is connected to the feedback signal input terminal FB and the other end of the second feedback voltage-dividing resistor RF 2.
The voltage value VOUT = (RRF1+ RRF2) × VFB/RRF2, and the output power PCV = VOUT × VOUT/RRL1, where RRF1 represents the resistance value of the first feedback voltage dividing resistor RF1, RRF2 represents the resistance value of the second feedback voltage dividing resistor RF2, VFB represents the voltage value of the feedback signal input from the feedback signal input terminal FB, and RRL1 represents the resistance value of the load RL1, and when the over-temperature protection is not triggered, VFB is unchanged, VOUT is unchanged, and the output power PCV is unchanged; when over-temperature protection is triggered, VFB is reduced, VOUT is reduced, and PCV is reduced, so that the temperature is reduced; when the over-temperature protection is deactivated when the temperature drops to T1, VOUT returns to the state when the over-temperature protection was not triggered.
As another embodiment, the over-temperature protection circuit may be applied to a constant current type switching power supply chip, as shown in fig. 3, the chip circuit includes: the over-temperature protection circuit S1, the other circuits S2, the first capacitor C11, the second capacitor C12, the first feedback divider resistor RCS, the first inductor L1 and the first diode D1;
the first capacitor C11 is used as a circuit voltage VCC, the anode of the first capacitor C11 is connected to the VCC input terminal VCC1, the cathode of the first capacitor C12 is connected to the ground terminal GND, the cathode of the first diode D1 is connected to the power signal output terminal SW and one end of the first inductor L1, the anode of the first diode D1 is connected to the ground terminal GND, the cathode of the second capacitor C12 and one end of the first feedback sampling resistor RCS, the anode of the second capacitor C12 is connected to the other end of the first inductor L1 and one end of the load RL1, and the other end of the first feedback sampling resistor RCS is connected to the feedback signal input terminal FB and the other end of the load RL 1.
Wherein, the chip output current IOUT = VFB/RRCS, and the output power PCC = IOUT RRL2, where VFB represents a voltage value of the feedback signal input by the feedback signal input terminal FB, RRCS represents a resistance value of the first feedback sampling resistor, and RRL1 represents a resistance value of the load RL 1; when the over-temperature protection is not triggered, VFB and IOUT are unchanged, and PCC is unchanged; when over-temperature protection is triggered, VFB is reduced, IOUT is reduced, PCC is reduced, and therefore the temperature is reduced; when the over-temperature protection is deactivated when the temperature drops to T1, the IOUT reverts to the state when the over-temperature protection was not triggered.
The invention provides an over-temperature protection circuit, a chip and a chip circuit, which can reduce the output power when the temperature of a switching power supply chip is overhigh by controlling the output power, thereby reducing the temperature of the chip; the over-temperature protection circuit has the advantages of simplicity and low power consumption.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make variations and modifications of the present invention without departing from the spirit and scope of the present invention by using the methods and technical contents disclosed above.

Claims (11)

1. A chip over-temperature protection circuit, comprising: the device comprises an over-temperature detection unit, a threshold switching unit and an output power control unit;
the first end of the over-temperature detection unit is connected with an internal working voltage VDD, the second end of the over-temperature detection unit is connected with a ground end GND, and the third end of the over-temperature detection unit is used as a first control signal output end and used for sending an output first control signal VO to the first end of the threshold switching unit; the second end of the threshold switching unit is connected with an internal working voltage VDD, the third end of the threshold switching unit is connected with a reference voltage VREF, the fourth end of the threshold switching unit is connected with a ground end GND, the fifth end of the threshold switching unit serves as a second control signal output end to send an output second control signal VP to the first end of the output power control unit, and the sixth end B1 of the threshold switching unit is connected with the fourth end B0 of the over-temperature detection unit; the second end of the output power control unit is used for receiving a feedback signal input by a feedback signal input end FB, the third end of the output power control unit is connected with an internal working voltage VDD, the fourth end of the output power control unit is connected with a ground end GND, the fifth end of the output power control unit is connected with a power signal output end SW, and the sixth end of the output power control unit is connected with a VCC input end;
the over-temperature detection unit is used for detecting whether the temperature of the chip rises to an over-temperature protection point, when the temperature of the chip does not reach the over-temperature protection point, a first control signal VO output by a first control signal output end of the over-temperature detection unit cannot trigger the threshold switching unit to enter a threshold switching mode, and the voltage value of a second control signal VP output by a second control signal output end of the threshold switching unit to a first end of the output power control unit is kept unchanged, so that a power signal output by the output power control unit to the power signal output end SW is kept unchanged; when the temperature of the chip reaches an over-temperature protection point, a first control signal VO output by a first control signal output end of the over-temperature detection unit triggers the threshold switching unit to enter a threshold switching mode, and a voltage value of a second control signal VP output by a second control signal output end of the threshold switching unit to a first end of the output power control unit is reduced, so that a power signal output by the output power control unit to the power signal output end SW is reduced.
2. The chip over-temperature protection circuit according to claim 1, wherein when the power signal output by the output power control unit to the power signal output terminal SW is decreased to lower the temperature of the chip, so that the temperature of the chip is decreased until the temperature of the chip reaches a safe point, the first control signal VO output by the first control signal output terminal of the over-temperature detection unit cannot trigger the threshold switching unit to enter the threshold switching mode, and the voltage value of the second control signal VP output by the second control signal output terminal of the threshold switching unit to the first terminal of the output power control unit is increased, so that the power signal output by the output power control unit to the power signal output terminal SW is increased.
3. The chip over-temperature protection circuit of claim 1, wherein the over-temperature detection unit comprises a first resistor R0, a second resistor R1, a third resistor R2, a fourth resistor R3, a fifth resistor R4, a sixth resistor R5, a first triode Q1, a second triode Q2, a third triode Q3 and a fourth triode Q4;
one end of the first resistor R0 is connected to the first end of the over-temperature detection unit, the other end of the first resistor R0 is connected to the fourth end B0 of the over-temperature detection unit and one end of the second resistor R1, the other end of the second resistor R1 is connected to one end of the third resistor R2, the collector of the first triode Q1 and the base of the fourth triode Q4, the other end of the third resistor R2 is connected to the second end of the over-temperature detection unit, the emitter of the first triode Q1 is connected to the first end of the over-temperature detection unit, the base of the first triode Q1 is connected to the base of the second triode Q2, the collector of the second triode Q2 and one end of the fourth resistor R3, the emitter of the second triode Q2 is connected to the first end of the over-temperature detection unit, and the base of the second triode Q2 is further connected to one end of the fifth resistor R4, A base electrode of the third triode Q3 is connected, the other end of the fifth resistor R4 is connected to the first end of the over-temperature detection unit, an emitter electrode of the third triode Q3 is connected to the first end of the over-temperature detection unit, a collector electrode of the third triode Q3 is connected to the third end of the over-temperature detection unit and one end of the sixth resistor R5, and the other end of the sixth resistor R5 is connected to the second end of the over-temperature detection unit; a collector of the fourth transistor Q4 is connected to the other end of the fourth resistor R3, and an emitter of the fourth transistor Q4 is connected to the second end of the over-temperature detection unit;
as the temperature of the chip increases, the turn-on voltage of the fourth triode Q4 decreases; when the temperature of the chip does not reach an over-temperature protection point, the base voltage VT of the fourth triode Q4 is less than the turn-on voltage of the fourth triode Q4, a current mirror composed of the first triode Q1, the second triode Q2 and the third triode Q3 is not conducted, and a first control signal VO output by the first control signal output end is at a low level and cannot trigger the threshold switching unit to enter a threshold switching mode; when the temperature of the chip reaches an over-temperature protection point, the base voltage VT of the fourth triode Q4 is equal to the starting voltage of the fourth triode Q4, the first triode Q1, the second triode Q2 and a current mirror formed by the third triode Q3 are conducted, a first control signal VO output by the first control signal output end is at a high level, and the threshold switching unit is triggered to enter a threshold switching mode.
4. The over-temperature protection circuit of claim 3, wherein when the chip temperature does not reach the over-temperature protection point, the voltage value VT1= VR2= VVDD × RR2/(RR0+ RR1+ RR2) of the base voltage VT of the fourth transistor Q4, where VR2 represents the voltage value of the third resistor R2, VVDD represents the voltage value of the internal operating voltage VDD, and RR0, RR1, RR2 represent the resistance values of the first resistor R0, the second resistor R1, and the third resistor R2, respectively;
when the chip temperature reaches the over-temperature protection point, the voltage value VT2= (VVDD × RR2/(RR0+ RR1+ RR 2)) + I1 × RR2 of the base voltage VT of the fourth triode Q4, where VVDD represents the voltage value of the internal operating voltage VDD, RR0, RR1, and RR2 represent the resistance values of the first resistor R0, the second resistor R1, and the third resistor R2, respectively, and I1 represents the current value passing through the collector of the first triode Q1.
5. The chip over-temperature protection circuit of claim 1, wherein the threshold switching unit comprises a fifth transistor Q5, a sixth transistor Q6, a seventh transistor Q7, an eighth transistor Q8, a ninth transistor Q9, a seventh resistor R6, an eighth resistor R7, a ninth resistor R8 and a tenth resistor R9;
a first end of the threshold switching unit is used as a first control signal input end and is connected to a base of the fifth triode Q5, an emitter of the fifth triode Q5 is connected to a fourth end of the threshold switching unit, collectors of the fifth triode Q5 are respectively connected to a base of the eighth triode Q8 and a collector of the seventh triode Q7, a base of the ninth triode Q9 is connected to the sixth end B1 of the threshold switching unit, an emitter of the ninth triode Q9 is connected to one end of the seventh resistor R6, the other end of the seventh resistor R6 is connected to the fourth end of the threshold switching unit, a collector of the ninth triode Q9 is respectively connected to a collector of the sixth triode Q6, a base of the sixth triode Q6 and a base of the seventh triode Q7, an emitter of the sixth triode Q6 is connected to the second end of the threshold switching unit, an emitter of the seventh triode Q7 is connected to the second end of the threshold switching unit; a collector of the eighth transistor Q8 is connected to the fourth terminal of the threshold switching unit, an emitter of the eighth transistor Q8 is connected to one end of the tenth resistor R9 and one end of the ninth resistor R8, respectively, the other end of the tenth resistor R9 is connected to the fourth terminal of the threshold switching unit, the other end of the ninth resistor R8 is connected to the fifth terminal of the threshold switching unit and one end of the eighth resistor R7, respectively, and the other end of the eighth resistor R7 is connected to the third terminal of the threshold switching unit;
when the temperature of the chip does not reach an over-temperature protection point, a first control signal VO received by the first control signal input end is at a low level, the voltage value of the first control signal VO is smaller than the starting voltage of the fifth triode Q5, the fifth triode Q5 and the eighth triode Q8 are not conducted, and the voltage value of a second control signal VP output by the second control signal output end is kept unchanged; when the temperature of the chip reaches an over-temperature protection point, a first control signal VO received by the first control signal input end is at a high level, the voltage value of the first control signal VO is greater than the starting voltage of the fifth triode Q5, the fifth triode Q5 is connected with the eighth triode Q8, and the voltage value of a second control signal VP output by the second control signal output end is reduced.
6. The over-temperature protection circuit of claim 5, wherein when the fifth transistor Q5 and the eighth transistor Q8 are not conducting, the voltage value VPH = VVREF (RR8+ RR 9)/(RR 7+ RR8+ RR9) of the second control signal VP outputted from the second control signal output terminal, where VVREF represents the voltage value of the reference voltage VREF, and RR7, RR8, and RR9 represent the resistance values of an eighth resistor R7, a ninth resistor R8, and a tenth resistor R9, respectively;
when the fifth transistor Q5 and the eighth transistor Q8 are turned on, the voltage value VPL = VVREF × RR8/(RR7+ RR8) of the second control signal VP output by the second control signal output terminal, where VVREF represents the voltage value of the reference voltage VREF, and RR7 and RR8 represent resistance values of the eighth resistor R7 and the ninth resistor R8, respectively.
7. The over-temperature protection circuit of claim 1, wherein the output power control unit comprises an error amplifier, an oscillator circuit, a comparator, an output control logic and other circuits, a power tube M1;
the positive input end of the error amplifier is used as the second end of the output power control unit to be connected with the feedback signal input end FB, the negative input end of the error amplifier is used as the first end of the output power control unit to be connected with the fifth end of the threshold switching unit, the output end of the error amplifier is connected with the positive input end of the comparator, the error amplifier is also respectively connected with the third end of the output power control unit and the fourth end of the output power control unit, the negative input end of the comparator is connected with the oscillator circuit, the output end of the comparator is connected with one end of the output control logic and other circuits, the comparator is also respectively connected with the third end of the output power control unit and the fourth end of the output power control unit, and the other ends of the output control logic and other circuits are respectively connected with the oscillator circuit, the feedback signal input end FB, The grid electrode of the power tube M1, the source electrode of the power tube M1 as the fifth end of the output power control unit is connected to the power signal output end SW, and the drain electrode of the power tube M1 as the sixth end of the output power control unit is connected to the VCC input end;
when the temperature of the chip does not reach the over-temperature protection point, the voltage value of the second control signal VP sent by the first end of the output power control unit to the positive input end of the error amplifier is kept unchanged, the error amplifier generates the voltage signal VE sent by the output end of the error amplifier to the positive input end of the comparator according to the voltage value of the second control signal VP sent by the first end of the output power control unit to the positive input end of the error amplifier and the voltage value of the feedback signal input by the feedback signal input end FB, the comparator generates the PWM signal sent by the output end of the comparator to the output control logic and other circuits according to the voltage value of the voltage signal VE and the voltage value of the sawtooth wave signal SAW sent by the oscillator circuit to the reverse input end of the comparator, and drives the output control logic and other circuits to control the power tube M1 to be opened or closed, the power signal output by the power signal output end SW keeps unchanged;
when the temperature of the chip reaches an over-temperature protection point, the voltage value of a second control signal VP sent by the first end of the output power control unit to the positive input end of the error amplifier is reduced, so that the time that the voltage value of the voltage signal VE sent by the output end of the error amplifier to the positive input end of the comparator is reduced and is greater than the voltage value of the sawtooth wave signal SAW sent by the oscillator circuit to the negative input end of the comparator is shortened, and the time that the voltage value of the sawtooth wave signal SAW sent by the oscillator circuit to the negative input end of the comparator is smaller is lengthened, the duty ratio of the PWM signal sent from the output terminal of the comparator to the output control logic and other circuits is reduced, and the time for driving the output control logic and other circuits to control the power transistor M1 to be turned on is reduced, so that the power signal output by the power signal output terminal SW is reduced.
8. A chip comprising the over-temperature protection circuit according to any one of claims 1 to 7.
9. A chip circuit comprising the over-temperature protection circuit as claimed in any one of claims 1 to 7.
10. The chip circuit of claim 9, further comprising: the first capacitor C11, the second capacitor C12, the first feedback voltage-dividing resistor RF1, the second feedback voltage-dividing resistor RF2, the first inductor L1 and the first diode D1;
the positive electrode of the first capacitor C11 is connected to the VCC input terminal, the negative electrode of the first capacitor C11 is connected to the ground terminal GND, the negative electrode of the first diode D1 is connected to the power signal output terminal SW and one end of the first inductor L1, the positive electrode of the first diode D1 is connected to the ground terminal GND, the negative electrode of the second capacitor C12, one end of the second feedback voltage-dividing resistor RF2 and one end of the load RL1, the positive electrode of the second capacitor C12 is connected to the other end of the first inductor L1, one end of the first feedback voltage-dividing resistor RF1 and the other end of the load RL1, and the other end of the first feedback voltage-dividing resistor RF1 is connected to the feedback signal input terminal FB and the other end of the second feedback voltage-dividing resistor RF 2.
11. The chip circuit of claim 9, further comprising: the feedback voltage-dividing circuit comprises a first capacitor C11, a second capacitor C12, a first feedback voltage-dividing resistor RCS, a first inductor L1 and a first diode D1;
the positive electrode of the first capacitor C11 is connected to the VCC input terminal, the negative electrode of the first capacitor C11 is connected to the ground terminal GND, the negative electrode of the first diode D1 is connected to the power signal output terminal SW and one end of the first inductor L1, the positive electrode of the first diode D1 is connected to the ground terminal GND, the negative electrode of the second capacitor C12 and one end of the first feedback sampling resistor RCS, the positive electrode of the second capacitor C12 is connected to the other end of the first inductor L1 and one end of the load RL1, and the other end of the first feedback sampling resistor RCS is connected to the feedback signal input terminal FB and the other end of the load RL 1.
CN202210497171.4A 2022-05-09 2022-05-09 Chip over-temperature protection circuit and corresponding chip and chip circuit Active CN114597858B (en)

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