Over-temperature protection circuit and power operational amplifier with over-temperature protection function

Abstract

The application discloses a kind of over-temperature protection circuit and the power operational amplifier with over-temperature protection function, over-temperature protection circuit includes temperature detection unit, control module and signal output unit, temperature detection unit is used to export corresponding temperature response voltage according to ambient temperature;Control module is used to export the over-temperature opening voltage greater than third voltage threshold when the temperature response voltage is higher than first voltage threshold to signal output unit, and until the temperature response voltage is lower than second voltage threshold, stop outputting over-temperature opening voltage or make over-temperature opening voltage lower than third voltage threshold;Signal output unit is used to export over-temperature protection current signal when over-temperature opening voltage is greater than third voltage threshold.The application can export over-temperature protection current signal to protected device when ambient temperature is too high, and has hysteresis reaction function when ambient temperature decreases, avoid frequently switching working state.

Description

Technical Field

[0001] This invention belongs to the field of device over-temperature protection, and in particular relates to an over-temperature protection circuit and a power operational amplifier with over-temperature protection function. Background Technology

[0002] Power integrated circuits dissipate significant power, resulting in high chip temperatures. To ensure their long-term operation at high temperatures without damage, over-temperature protection circuits are essential. For bipolar integrated circuits, the junction temperature on the chip must not exceed +200°C, and in most bipolar integrated circuit designs, the maximum operating temperature is chosen to be between +100°C and +170°C. To guarantee this, an over-temperature protection circuit is designed in this circuit. When the silicon wafer temperature reaches the protection temperature (e.g., 160°C), the over-temperature protection circuit automatically cuts off the power path until the temperature drops to the safe operating temperature (e.g., 140°C), at which point the power operational amplifier resumes normal operation. Traditional over-temperature protection circuits also suffer from problems such as the temperature protection point being susceptible to operating voltage fluctuations and the difficulty of chip integration, necessitating improvements. Summary of the Invention

[0003] To address the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide an over-temperature protection circuit and a power operational amplifier with over-temperature protection function.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0005] An over-temperature protection circuit, including

[0006] The temperature detection unit is used to output a corresponding temperature sensing voltage based on the ambient temperature.

[0007] The control module is configured to output an over-temperature trigger voltage greater than a third voltage threshold to the signal output unit when the temperature sensing voltage is higher than a first voltage threshold, and to stop outputting the over-temperature trigger voltage or lower the over-temperature trigger voltage below the third voltage threshold when the temperature sensing voltage is lower than a second voltage threshold; wherein the first voltage threshold is greater than the second voltage threshold; and

[0008] The signal output unit is used to output an over-temperature protection current signal when the over-temperature start-up voltage is greater than the third voltage threshold.

[0009] Furthermore, the temperature detection unit includes a JFET J1 and a Zener diode D1. The JFET J1 is a PJFET field-effect transistor, and the Zener diode D1 has a positive temperature coefficient. The source and gate of the JFET J1 are shorted and connected to the positive supply voltage VCC. The drain of the JFET J1 is electrically connected to the negative terminal of the Zener diode D1. The negative terminal of the Zener diode D1 outputs a temperature sensing voltage, and the positive terminal of the Zener diode D1 is connected to the negative supply voltage VEE.

[0010] Furthermore, the signal output unit includes at least one output sub-unit, which includes a transistor Q16 and a resistor R10. The base of the transistor Q16 is connected to the over-temperature turn-on voltage through the resistor R10, the emitter of the transistor Q16 is connected to the negative supply voltage VEE, and the collector of the transistor Q16 is used to output an over-temperature protection current signal.

[0011] Furthermore, the control module includes

[0012] The bias unit is used to output a corresponding bias voltage to the over-temperature control unit based on the temperature sensing voltage.

[0013] The over-temperature control unit is used to generate a corresponding over-temperature control current for the execution unit based on the bias voltage; the value of the over-temperature control current when the temperature sensing voltage is equal to the first voltage threshold is used as the turn-on current threshold.

[0014] An execution unit is configured to output an over-temperature turn-on voltage when the sum of the over-temperature control current and the over-temperature hysteresis current reaches or exceeds the turn-on current threshold, and to stop outputting the over-temperature turn-on voltage when the sum of the over-temperature control current and the over-temperature hysteresis current is less than the turn-on current threshold; and

[0015] The over-temperature hysteresis unit is used to respond to the over-temperature turn-on voltage and output the over-temperature hysteresis current. When the temperature sensing voltage is equal to the second voltage threshold, the sum of the corresponding over-temperature control current and over-temperature hysteresis current is equal to the turn-on current threshold.

[0016] Furthermore, the bias unit includes transistors Q1, Q2, Q3, Q4, Q6 and resistor R1;

[0017] The collector of transistor Q1 is connected to the forward power supply voltage VCC, the base of transistor Q1 is connected to the temperature sensing voltage, and the emitter of transistor Q1 is electrically connected to the over-temperature control unit, the execution unit, and the over-temperature hysteresis unit, respectively.

[0018] The emitter of transistor Q1 is also electrically connected to the collector and base of transistor Q2, and the emitter of transistor Q2 is electrically connected to the collector and base of transistor Q3; the emitter of transistor Q3 is electrically connected to the collector and base of transistor Q4 through resistor R1.

[0019] The collector of transistor Q4 is electrically connected to the over-temperature control unit, and the emitter of transistor Q4 is electrically connected to both the over-temperature control unit and the over-temperature hysteresis unit; the emitter of transistor Q4 is also electrically connected to the collector of transistor Q6.

[0020] The base of transistor Q6 is electrically connected to the over-temperature control unit, and the emitter of transistor Q6 is connected to the negative power supply voltage VEE.

[0021] Furthermore, the over-temperature control unit includes transistor Q5, transistor Q7, and resistor R2;

[0022] The collector of transistor Q5 is used to output over-temperature control current. The base of transistor Q5 is electrically connected to the collector of transistor Q4. The emitter of transistor Q5 is electrically connected to the base of transistor Q6 and the collector of transistor Q7, respectively.

[0023] The base of transistor Q7 is electrically connected to the collector of transistor Q6, and the emitter of transistor Q7 is connected to the negative supply voltage VEE through resistor R2.

[0024] Furthermore, the execution unit includes a transistor Q15, a resistor R6, and a resistor R8; the emitter of transistor Q15 is electrically connected to the emitter of transistor Q1, the base of transistor Q15 is electrically connected to the emitter of transistor Q1 through resistor R8, and the base of transistor Q15 is also electrically connected to the collector of transistor Q5; the collector of transistor Q15 is connected to the negative supply voltage VEE through resistor R6, and the collector of transistor Q15 is used to output an over-temperature turn-on voltage.

[0025] Furthermore, the over-temperature hysteresis unit includes transistors Q10, Q11, Q12, and Q13, resistors R3, R4, and R5.

[0026] The base of transistor Q10 is electrically connected to the collector of transistor Q6, the emitter of transistor Q10 is connected to the negative supply voltage VEE through resistor R3, and the collector of transistor Q10 is electrically connected to the emitters of transistors Q11 and Q12 respectively.

[0027] The base of transistor Q11 is electrically connected to the emitter of transistor Q3, and the collector of transistor Q11 is electrically connected to the collector of transistor Q5. When transistor Q11 is turned on, its collector outputs an over-temperature hysteresis current, which is superimposed on the over-temperature control current output by the collector of transistor Q5.

[0028] The collector of transistor Q12 is electrically connected to the emitter of transistor Q1; the base of transistor Q12 is electrically connected to the emitter of transistor Q1 through resistor R4; the base of transistor Q12 is also electrically connected to the collector of transistor Q13.

[0029] The base of transistor Q13 is electrically connected to the collector of transistor Q15 through resistor R5, and the emitter of transistor Q13 is connected to the negative power supply voltage VEE.

[0030] Furthermore, the over-temperature control unit, the execution unit, and the over-temperature hysteresis unit all adopt a differential circuit structure. The over-temperature control unit also includes a transistor Q8, the over-temperature hysteresis unit also includes a transistor Q9, and the execution unit also includes a transistor Q14 and a resistor R7.

[0031] The collector of transistor Q8 is used to output over-temperature control current. The base of transistor Q8 is electrically connected to the base of transistor Q5, and the emitter of transistor Q8 is electrically connected to the emitter of transistor Q5.

[0032] The base of transistor Q9 is electrically connected to the base of transistor Q11, the emitter of transistor Q9 is electrically connected to the emitter of transistor Q11, and the collector of transistor Q9 is electrically connected to the collector of transistor Q8. When transistor Q9 is turned on, its collector outputs an over-temperature hysteresis current, which is superimposed on the over-temperature control current output by the collector of transistor Q8.

[0033] The emitter of transistor Q14 is electrically connected to the emitter of transistor Q15. The base of transistor Q14 is electrically connected to the emitter of transistor Q1 through resistor R7. The base of transistor Q14 is also electrically connected to the collector of transistor Q8. The collector of transistor Q14 is electrically connected to the collector of transistor Q15.

[0034] A power operational amplifier with over-temperature protection function includes the over-temperature protection circuit as described in any of the above claims.

[0035] In this invention, an over-temperature protection current signal can be output when the ambient temperature is too high, and a hysteresis response function is provided when the ambient temperature decreases. The protected device frequently switches between the over-temperature protection state and the normal operating state. A PJFET is used to form a constant current source to provide constant current bias for the Zener diode, which can ensure the working stability of the Zener diode. The change of the over-temperature protection point of the circuit is very small. The temperature protection point can be easily changed by adjusting the resistance value of resistor R2 or R3 to avoid the protected device from burning out due to over-temperature. In addition, the over-temperature protection circuit of this invention does not affect other performance of the protected device, which is conducive to chip integration. It is also highly versatile and suitable for bipolar processes. Attached Figure Description

[0036] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0037] Figure 1 This is a circuit diagram of an embodiment of the over-temperature protection circuit of the present invention.

[0038] Figure 2 This is a circuit diagram of an embodiment of the power operational amplifier with over-temperature protection function of the present invention.

[0039] Figure 3 Temperature simulation diagram of an embodiment of a power operational amplifier with over-temperature protection;

[0040] Figure 4 The above diagram shows the over-temperature protection waveform of an embodiment of a power operational amplifier with over-temperature protection function.

[0041] The diagrams in the instruction manual are labeled as follows:

[0042] Temperature detection unit-1; bias unit-2; over-temperature control unit-3; execution unit-4; over-temperature hysteresis unit-5; signal output unit-6. Detailed Implementation

[0043] The following specific examples illustrate the implementation of the present invention. The illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0044] Please see Figure 1 , Figure 1 This is a circuit diagram of an embodiment of the over-temperature protection circuit of the present invention. The over-temperature protection circuit of this embodiment includes a temperature detection unit 1, a control module, and a signal output unit 6. The temperature detection unit 1 is used to output a corresponding temperature sensing voltage based on the ambient temperature.

[0045] The temperature detection unit 1 includes a JFET J1 and a Zener diode D1. The JFET J1 can be a PJFET (P-channel Junction Field-Effect Transistor), and the Zener diode D1 can be a Zener diode with a positive temperature coefficient. When this embodiment is used for over-temperature protection of a power operational amplifier chip, the temperature detection unit 1 is used to detect the operating temperature of the power operational amplifier chip; in this case, the JFET J1 and the Zener diode D1 can be disposed on the surface of the power operational amplifier chip.

[0046] The source and gate of the JFET J1 are shorted and connected to the positive supply voltage VCC. The drain of the JFET J1 is electrically connected to the negative terminal of the Zener diode D1. The negative terminal of the Zener diode D1 outputs a temperature-sensing voltage, and the positive terminal of the Zener diode D1 is connected to the negative supply voltage VEE. In this embodiment, a PJFET is used, and its source and gate are shorted to form a constant current source to provide constant current bias for the Zener diode D1. This provides a relatively constant current to the Zener diode D1 when the supply voltage and temperature change, ensuring the operating stability of the Zener diode D1.

[0047] The control module is used to output an over-temperature activation voltage greater than a third voltage threshold to the signal output unit 6 when the temperature sensing voltage is higher than a first voltage threshold, and to stop outputting the over-temperature activation voltage or lower the over-temperature activation voltage to the third voltage threshold when the temperature sensing voltage is lower than a second voltage threshold. The first voltage threshold is greater than the second voltage threshold. The ambient temperature corresponding to the first voltage threshold is the over-temperature protection temperature, i.e., the temperature at which the power operational amplifier chip needs to enter the over-temperature protection state. The ambient temperature corresponding to the second voltage threshold is the safe operating temperature, i.e., the temperature at which the power operational amplifier chip exits the over-temperature protection state and enters the normal operating state.

[0048] In this embodiment, the control module includes a bias unit 2, an over-temperature control unit 3, an execution unit 4, and an over-temperature hysteresis unit 5. The bias unit 2 is used to output a corresponding bias voltage to the over-temperature control unit 3 according to the temperature sensing voltage. The bias unit 2 may include transistors Q1, Q2, Q3, Q4, and Q6, and a resistor R1; in this embodiment, transistors Q1, Q2, Q3, Q4, and Q6 are all NPN transistors.

[0049] The collector of transistor Q1 is connected to the positive supply voltage VCC, and the base of transistor Q1 is connected to the temperature sensing voltage. The emitter of transistor Q1 is electrically connected to the over-temperature control unit 3, the execution unit 4, and the over-temperature hysteresis unit 5, respectively. The emitter of transistor Q1 is also electrically connected to the collector and base of transistor Q2, and the emitter of transistor Q2 is electrically connected to the collector and base of transistor Q3. The emitter of transistor Q3 is electrically connected to the collector and base of transistor Q4 through resistor R1. The collector of transistor Q4 is electrically connected to the over-temperature control unit 3, and the emitter of transistor Q4 is electrically connected to both the over-temperature control unit 3 and the over-temperature hysteresis unit 5, respectively. The emitter of transistor Q4 is also electrically connected to the collector of transistor Q6. The base of transistor Q6 is electrically connected to the over-temperature control unit 3, and the emitter of transistor Q6 is connected to the negative supply voltage VEE.

[0050] The over-temperature control unit 3 generates a corresponding over-temperature control current for the execution unit 4 based on the bias voltage. When the temperature sensing voltage equals the first voltage threshold, the value of the over-temperature control current output by the over-temperature control unit 3 is the turn-on current threshold. The over-temperature control unit 3 may include transistors Q5 and Q7 and resistor R2; in this embodiment, transistors Q5 and Q7 are both NPN transistors.

[0051] The collector of transistor Q5 is used to output over-temperature control current. The base of transistor Q5 is electrically connected to the collector of transistor Q4. The emitter of transistor Q5 is electrically connected to the base of transistor Q6 and the collector of transistor Q7, respectively. The base of transistor Q7 is electrically connected to the collector of transistor Q6. The emitter of transistor Q7 is connected to the negative supply voltage VEE through resistor R2.

[0052] The execution unit 4 is used to output an over-temperature turn-on voltage when the sum of the over-temperature control current and the over-temperature hysteresis current reaches or exceeds the turn-on current threshold, and to stop outputting the over-temperature turn-on voltage when the sum of the over-temperature control current and the over-temperature hysteresis current is less than the turn-on current threshold. The execution unit 4 may include a transistor Q15, a resistor R6, and a resistor R8; in this embodiment, the transistor Q15 is a PNP transistor.

[0053] The emitter of transistor Q15 is electrically connected to the emitter of transistor Q1, and the base of transistor Q15 is electrically connected to the emitter of transistor Q1 through resistor R8. The base of transistor Q15 is also electrically connected to the collector of transistor Q5. The collector of transistor Q15 is connected to the negative supply voltage VEE through resistor R6, and the collector of transistor Q15 is used to output the over-temperature turn-on voltage.

[0054] The over-temperature hysteresis unit 5 is used to respond to the over-temperature turn-on voltage and output the over-temperature hysteresis current; when the temperature sensing voltage is equal to the second voltage threshold, the sum of the corresponding over-temperature control current and the over-temperature hysteresis current is equal to the turn-on current threshold. The over-temperature hysteresis unit 5 includes transistors Q10, Q11, Q12, and Q13, resistors R3, R4, and R5; in this embodiment, transistors Q10, Q11, Q12, and Q13 are all NPN transistors.

[0055] The base of transistor Q10 is electrically connected to the collector of transistor Q6. The emitter of transistor Q10 is connected to the negative supply voltage VEE through resistor R3. The collector of transistor Q10 is electrically connected to the emitters of transistors Q11 and Q12. The base of transistor Q11 is electrically connected to the emitter of transistor Q3, and the collector of transistor Q11 is electrically connected to the collector of transistor Q5. When transistor Q11 is turned on, its collector outputs an over-temperature hysteresis current, which is superimposed on the over-temperature control current output by the collector of transistor Q5. The collector of transistor Q12 is electrically connected to the emitter of transistor Q1; the base of transistor Q12 is electrically connected to the emitter of transistor Q1 through resistor R4, and the base of transistor Q12 is also electrically connected to the collector of transistor Q13. The base of transistor Q13 is electrically connected to the collector of transistor Q15 through resistor R5, and the emitter of transistor Q13 is connected to the negative power supply voltage VEE.

[0056] To improve the circuit's anti-interference capability, the over-temperature control unit 3, the execution unit 4, and the over-temperature hysteresis unit 5 can all adopt a differential circuit structure. In this case, the over-temperature control unit 3 further includes a transistor Q8, the over-temperature hysteresis unit 5 further includes a transistor Q9, and the execution unit 4 further includes a transistor Q14 and a resistor R7. Transistors Q8 and Q9 are both NPN transistors, and transistor Q15 is a PNP transistor.

[0057] Transistors Q8 and Q5 form a differential circuit. The base of transistor Q8 is electrically connected to the base of transistor Q5, and the emitter of transistor Q8 is electrically connected to the emitter of transistor Q5. The collector of transistor Q5 is used to output a first over-temperature control current, and the collector of transistor Q8 is used to output a second over-temperature control current. The two over-temperature control currents are of the same magnitude.

[0058] Transistors Q9 and Q11 form a differential circuit. The base of transistor Q9 is electrically connected to the base of transistor Q11, the emitter of transistor Q9 is electrically connected to the emitter of transistor Q11, and the collector of transistor Q9 is electrically connected to the collector of transistor Q8. The collector of transistor Q11 is used to output a first over-temperature hysteresis current, and the collector of transistor Q9 is used to output a second over-temperature hysteresis current. The two over-temperature hysteresis currents are of the same magnitude. The second over-temperature hysteresis current is superimposed on the over-temperature control current output from the collector of transistor Q8.

[0059] The emitter of transistor Q14 is electrically connected to the emitter of transistor Q15. The base of transistor Q14 is electrically connected to the emitter of transistor Q1 through resistor R7. The base of transistor Q14 is also electrically connected to the collector of transistor Q8. The collector of transistor Q14 is electrically connected to the collector of transistor Q15.

[0060] The signal output unit 6 is used to output an over-temperature protection current signal when the over-temperature threshold voltage exceeds the third voltage threshold. When this embodiment is used for over-temperature protection of a power operational amplifier, the over-temperature protection current signal is connected to the constant current source of the power operational amplifier's bias circuit. When the signal output unit 6 is not working, there is no over-temperature protection current signal output, and the power operational amplifier operates normally. When the signal output unit 6 is working and outputs the over-temperature protection current signal, it shunts the constant current source of the power operational amplifier's bias circuit, preventing it from providing current to subsequent circuits, thereby cutting off the power path of the power operational amplifier and achieving the purpose of over-temperature protection.

[0061] The signal output unit 6 may include at least one output sub-unit. The number of output sub-units is determined by the number of bias circuits of the power operational amplifier. That is, the output sub-units correspond one-to-one with the bias circuits of the power operational amplifier.

[0062] For example, when the power operational amplifier has two bias circuits, the signal output unit 6 includes two output sub-units with identical structures. One of the output sub-units includes a transistor Q16 and a resistor R10. The transistor Q16 is an NPN transistor. The base of the transistor Q16 is connected to the over-temperature turn-on voltage (i.e., the collectors of transistors Q14 and Q15) through the resistor R10. The emitter of the transistor Q16 is connected to the negative supply voltage VEE. The collector of the transistor Q16 is used to output the over-temperature protection current signal I1.

[0063] Another output sub-unit includes a transistor Q17 and a resistor R9. The transistor Q17 is an NPN transistor. The base of the transistor Q17 is connected to the over-temperature turn-on voltage through the resistor R9. The emitter of the transistor Q17 is connected to the negative supply voltage VEE. The collector of the transistor Q17 is used to output the over-temperature protection current signal I2.

[0064] The third voltage threshold is the voltage required for transistors Q16 and Q17 to conduct. Two over-temperature protection current signals (i.e., over-temperature protection current signal I1 and over-temperature protection current signal I2) are respectively connected to the two bias circuits of the power operational amplifier to control the operating state of these two bias circuits.

[0065] Of course, when the power operational amplifier has only one bias circuit, the signal output unit 6 can include only one structural output subunit, so that only one over-temperature protection current signal is output to the bias circuit of the power operational amplifier.

[0066] The working principle of this embodiment is as follows:

[0067] Please see Figure 1 The node formed by connecting the drain of JFET J1, the negative terminal of Zener diode D1, and the base of transistor Q1 is designated as node A, which outputs a temperature-sensing voltage. The node formed by connecting the collectors of transistors Q14 and Q15 with resistors R5, R6, R9, and R10 is designated as node B, which outputs an over-temperature turn-on voltage.

[0068] When each electronic component adopts Figure 1 When configuring the parameters, the first voltage threshold corresponds to an ambient temperature of 160℃, and the second voltage threshold corresponds to an ambient temperature of 140℃. That is, when the ambient temperature is 160℃, the temperature sensing voltage value output by temperature detection unit 1 is equal to the first voltage threshold; when the ambient temperature is 140℃, the temperature sensing voltage value output by temperature detection unit 1 is equal to the second voltage threshold. The temperature protection point (i.e., over-temperature protection temperature and safe operating temperature) can be changed by adjusting the resistance values ​​of resistor R2 or resistor R3.

[0069] When the ambient temperature is below 160℃, the temperature sensing voltage value output by the temperature detection unit 1 is less than the first voltage threshold. Transistors Q14 and Q15 are both in the cutoff state, which in turn causes transistors Q16 and Q17 to also be in the cutoff state. As a result, there is no output of the over-temperature protection current signal I1 and over-temperature protection current signal I2 (i.e., the current value is 0).

[0070] When the ambient temperature rises, the potential at node A increases (i.e., the temperature-sensing voltage increases) because Zener diode D1 has a positive temperature coefficient. This causes the voltage between the base and emitter of transistors Q1 / Q2 / Q3 / Q4 / Q7 / Q10 to decrease, resulting in an increase in the current IC1 flowing through transistor Q1. This, in turn, increases the current IC5 flowing through the collector of transistor Q5 and the current IC8 flowing through the collector of transistor Q8 (i.e., the over-temperature control current increases). Consequently, the current flowing through resistors R7 and R8 increases, and the voltage drop across resistors R7 and R8 increases.

[0071] As the ambient temperature gradually increases, the voltage drop across resistors R7 and R8 also gradually increases. When this voltage drop reaches the voltage required for transistors Q14 and Q15 to conduct, transistors Q14 and Q15 conduct, thereby increasing the current IR6 flowing through resistor R6. This increases the voltage drop across resistor R6, causing the potential at node B (i.e., the over-temperature threshold voltage) to rise. When the ambient temperature reaches 160℃, the temperature sensing voltage output by temperature detection unit 1 reaches the first voltage threshold, and the potential at point B reaches the third voltage threshold, causing transistors Q16 and Q17 to conduct. This outputs over-temperature protection current signals I1 and I2, which shunt the constant current sources of the two bias circuits of the power operational amplifier, preventing them from providing current to the subsequent circuits. This effectively cuts off the power path of the power operational amplifier, achieving the purpose of protecting the power operational amplifier from over-temperature.

[0072] Simultaneously, when the potential at point B turns on transistors Q16 and Q17, transistor Q13 also turns on, causing transistor Q12 to turn off. Transistors Q11 and Q9 turn on, providing current to transistor Q10. A first over-temperature hysteresis current is output from the collector of transistor Q11, and a second over-temperature hysteresis current is output from the collector of transistor Q9. These two over-temperature hysteresis currents are superimposed on the two over-temperature control currents output from the collectors of transistors Q5 and Q8, respectively. This provides an additional hysteresis current for circuit R7 and resistor R8, ensuring that when the ambient temperature is slightly below 160°C, the potential at point B remains above the third voltage threshold, maintaining the output of over-temperature protection current signals I1 and I2. Only when the ambient temperature drops below 140°C does the potential at point B fall below the third voltage threshold, stopping the output of over-temperature protection current signals I1 and I2. The power operational amplifier is now in normal working condition.

[0073] In this embodiment, the temperature protection point can be easily changed by adjusting the resistance values ​​of resistors R2 or R3, preventing the power operational amplifier from burning out due to overheating. A PJFET J1 is used to form a constant current source to provide constant current bias to the Zener diode D1, ensuring the stability of Zener diode D1 and minimizing the change in the over-temperature protection point within the ±10V to ±35V operating voltage range. Furthermore, the over-temperature protection circuit of this embodiment does not affect other performance characteristics of the power operational amplifier, facilitating chip-level integration; and the over-temperature protection circuit of this embodiment is highly versatile and suitable for bipolar processes.

[0074] Please see Figure 2 , Figure 2 This is a circuit diagram of an embodiment of the power operational amplifier with over-temperature protection function according to the present invention. The power operational amplifier with over-temperature protection function in this embodiment includes the over-temperature protection circuit of any of the above embodiments.

[0075] Please see Figure 3 and Figure 4 With the above circuit structure, when the ambient temperature reaches 160℃, the power operational amplifier will enter an over-temperature protection state, cutting off the power path; it will only exit the over-temperature protection state and enter normal operation when the ambient temperature drops below 140℃. This protects the power operational amplifier when the ambient temperature reaches 160℃ and avoids frequent switching between over-temperature protection and normal operation states.

[0076] The power operational amplifier in this embodiment can be easily modified to change the temperature protection point, thus preventing the power operational amplifier from burning out due to overheating. The circuit operates stably, and the change in the over-temperature protection point is very small within the operating voltage range of ±10V to ±35V, which is conducive to chip integration and is suitable for bipolar processes.

[0077] The above embodiments merely illustrate preferred implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention should be determined by the appended claims.

Claims

1. An over-temperature protection circuit, characterized in that: include The temperature detection unit is used to output a corresponding temperature sensing voltage based on the ambient temperature. The control module is configured to output an over-temperature trigger voltage greater than a third voltage threshold to the signal output unit when the temperature sensing voltage is higher than a first voltage threshold, and to stop outputting the over-temperature trigger voltage or lower the over-temperature trigger voltage below the third voltage threshold when the temperature sensing voltage is lower than a second voltage threshold; wherein the first voltage threshold is greater than the second voltage threshold; and The signal output unit is used to output an over-temperature protection current signal when the over-temperature start-up voltage is greater than the third voltage threshold. The temperature detection unit includes a JFET J1 and a Zener diode D1. The JFET J1 is a PJFET field-effect transistor, and the Zener diode D1 has a positive temperature coefficient. The source and gate of the JFET J1 are shorted and connected to a positive supply voltage VCC. The drain of the JFET J1 is electrically connected to the negative terminal of the Zener diode D1. The negative terminal of the Zener diode D1 outputs a temperature sensing voltage, and the positive terminal of the Zener diode D1 is connected to a negative supply voltage VEE. The control module includes The bias unit is used to output a corresponding bias voltage to the over-temperature control unit based on the temperature sensing voltage. The over-temperature control unit is used to generate a corresponding over-temperature control current for the execution unit based on the bias voltage; the value of the over-temperature control current when the temperature sensing voltage is equal to the first voltage threshold is used as the turn-on current threshold. The execution unit is used to output an over-temperature start-up voltage when the sum of the over-temperature control current and the over-temperature hysteresis current reaches or exceeds the start-up current threshold, and to stop outputting the over-temperature start-up voltage when the sum of the over-temperature control current and the over-temperature hysteresis current is less than the start-up current threshold. as well as The over-temperature hysteresis unit is used to respond to the over-temperature turn-on voltage and output the over-temperature hysteresis current. When the temperature sensing voltage is equal to the second voltage threshold, the sum of the corresponding over-temperature control current and over-temperature hysteresis current is equal to the turn-on current threshold.

2. The over-temperature protection circuit as described in claim 1, characterized in that: The signal output unit includes at least one output subunit, which includes a transistor Q16 and a resistor R10. The base of the transistor Q16 is connected to the over-temperature turn-on voltage through the resistor R10, the emitter of the transistor Q16 is connected to the negative supply voltage VEE, and the collector of the transistor Q16 is used to output an over-temperature protection current signal.

3. The over-temperature protection circuit as described in any one of claims 1 to 2, characterized in that: The bias unit includes transistors Q1, Q2, Q3, Q4, Q6 and resistor R1; The collector of transistor Q1 is connected to the forward power supply voltage VCC, the base of transistor Q1 is connected to the temperature sensing voltage, and the emitter of transistor Q1 is electrically connected to the over-temperature control unit, the execution unit, and the over-temperature hysteresis unit, respectively. The emitter of transistor Q1 is also electrically connected to the collector and base of transistor Q2, and the emitter of transistor Q2 is electrically connected to the collector and base of transistor Q3; the emitter of transistor Q3 is electrically connected to the collector and base of transistor Q4 through resistor R1. The collector of transistor Q4 is electrically connected to the over-temperature control unit, and the emitter of transistor Q4 is electrically connected to both the over-temperature control unit and the over-temperature hysteresis unit; the emitter of transistor Q4 is also electrically connected to the collector of transistor Q6. The base of transistor Q6 is electrically connected to the over-temperature control unit, and the emitter of transistor Q6 is connected to the negative power supply voltage VEE.

4. The over-temperature protection circuit as described in claim 3, characterized in that: The over-temperature control unit includes transistor Q5, transistor Q7, and resistor R2; The collector of transistor Q5 is used to output over-temperature control current. The base of transistor Q5 is electrically connected to the collector of transistor Q4. The emitter of transistor Q5 is electrically connected to the base of transistor Q6 and the collector of transistor Q7, respectively. The base of transistor Q7 is electrically connected to the collector of transistor Q6, and the emitter of transistor Q7 is connected to the negative supply voltage VEE through resistor R2.

5. The over-temperature protection circuit as described in claim 4, characterized in that: The execution unit includes a transistor Q15, resistors R6 and R8; the emitter of transistor Q15 is electrically connected to the emitter of transistor Q1, the base of transistor Q15 is electrically connected to the emitter of transistor Q1 through resistor R8, and the base of transistor Q15 is also electrically connected to the collector of transistor Q5; the collector of transistor Q15 is connected to the negative supply voltage VEE through resistor R6, and the collector of transistor Q15 is used to output an over-temperature turn-on voltage.

6. The over-temperature protection circuit as described in claim 5, characterized in that: The over-temperature hysteresis unit includes transistors Q10, Q11, Q12, and Q13, resistors R3, R4, and R5; The base of transistor Q10 is electrically connected to the collector of transistor Q6, the emitter of transistor Q10 is connected to the negative supply voltage VEE through resistor R3, and the collector of transistor Q10 is electrically connected to the emitters of transistors Q11 and Q12 respectively. The base of transistor Q11 is electrically connected to the emitter of transistor Q3, and the collector of transistor Q11 is electrically connected to the collector of transistor Q5. When transistor Q11 is turned on, its collector outputs an over-temperature hysteresis current, which is superimposed on the over-temperature control current output by the collector of transistor Q5. The collector of transistor Q12 is electrically connected to the emitter of transistor Q1; the base of transistor Q12 is electrically connected to the emitter of transistor Q1 through resistor R4; the base of transistor Q12 is also electrically connected to the collector of transistor Q13. The base of transistor Q13 is electrically connected to the collector of transistor Q15 through resistor R5, and the emitter of transistor Q13 is connected to the negative power supply voltage VEE.

7. The over-temperature protection circuit as described in claim 6, characterized in that: The over-temperature control unit, the execution unit, and the over-temperature hysteresis unit all adopt a differential circuit structure. The over-temperature control unit also includes a transistor Q8, the over-temperature hysteresis unit also includes a transistor Q9, and the execution unit also includes a transistor Q14 and a resistor R7. The collector of transistor Q8 is used to output over-temperature control current. The base of transistor Q8 is electrically connected to the base of transistor Q5, and the emitter of transistor Q8 is electrically connected to the emitter of transistor Q5. The base of transistor Q9 is electrically connected to the base of transistor Q11, the emitter of transistor Q9 is electrically connected to the emitter of transistor Q11, and the collector of transistor Q9 is electrically connected to the collector of transistor Q8. When transistor Q9 is turned on, its collector outputs an over-temperature hysteresis current, which is superimposed on the over-temperature control current output by the collector of transistor Q8. The emitter of transistor Q14 is electrically connected to the emitter of transistor Q15. The base of transistor Q14 is electrically connected to the emitter of transistor Q1 through resistor R7. The base of transistor Q14 is also electrically connected to the collector of transistor Q8. The collector of transistor Q14 is electrically connected to the collector of transistor Q15.

8. A power operational amplifier with over-temperature protection, characterized in that: Includes the over-temperature protection circuit as described in any one of claims 1 to 7.

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