An over-temperature protection circuit

Abstract

The application relates to the field of over-temperature protection circuits, in particular to an over-temperature protection circuit which comprises a starting module, a PTAT current source module, a CTAT temperature sensing module and an output module; a first output end of the PTAT current source module is electrically connected with a first voltage input end of the CTAT temperature sensing module and a first voltage input end of the output module; a second output end of the PTAT current source module is electrically connected with a second voltage input end of the CTAT temperature sensing module; a third output end of the PTAT current source module is electrically connected with a current input end of the CTAT temperature sensing module; an output end of the CTAT temperature sensing module is electrically connected with an input end of the output module; the PTAT current source module provides a zero-temperature coefficient bias voltage and a bias current for the CTAT temperature sensing module, thereby improving protection precision; and the trend that the transconductance of a triode decreases with temperature rise is compensated, thereby improving overall performance stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of over-temperature protection circuit, in particular to an over-temperature protection circuit. BACKGROUND

[0002] The over-temperature protection circuit is an important functional module in electronic equipment for preventing core components or critical areas from being damaged due to excessive temperature. Its core principle is to automatically trigger a protection mechanism when the temperature exceeds a preset threshold by monitoring the temperature signal in real time, and to restore normal operation of the device after the temperature falls within a safe range. This type of circuit is usually composed of a temperature sensor, a signal processing unit, a comparator, control logic and an execution component. Temperature data is collected by a thermistor, a thermocouple or an integrated temperature sensor, and is compared with a reference voltage after amplification and filtering. If the temperature exceeds the limit, a control signal is output to cut off the power supply, reduce the power or start the cooling device.

[0003] For the temperature sensing part, the traditional over-temperature protection circuit usually uses a simple fixed current obtained by resistance division to bias the temperature sensing BJT, and measures its V BE . This fixed current itself varies with temperature and power supply voltage, which is an uncontrolled and harmful drift that introduces errors in the circuit, resulting in poor accuracy of the over-temperature protection circuit, and the transconductance of the transistor decreases with increasing temperature, making the overall circuit sensitive to temperature changes near the critical value and prone to oscillation. SUMMARY

[0004] The present application aims to provide an over-temperature protection circuit to improve the problem that the traditional over-temperature protection circuit uses a simple fixed current obtained by resistance division to bias the temperature sensing BJT, but the fixed current itself varies with temperature and power supply voltage, which introduces errors in the circuit, resulting in poor accuracy of the over-temperature protection circuit, and the transconductance of the transistor decreases with increasing temperature, making the overall circuit sensitive to temperature changes near the critical value and prone to oscillation.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] An over-temperature protection circuit, comprising a start-up module, a PTAT current source module, a CTAT temperature sensing module and an output module;

[0007] The output end of the start-up module is electrically connected to the input end of the PTAT current source module to provide a reference voltage for the PTAT current source module;

[0008] The first output end of the PTAT current source module is electrically connected with the first voltage input end of the CTAT temperature sensing module and the first voltage input end of the output module; the second output end of the PTAT current source module is electrically connected with the second voltage input end of the CTAT temperature sensing module; the third output end of the PTAT current source module is electrically connected with the current input end of the CTAT temperature sensing module, the first output end and the second output end of the PTAT current source module output zero temperature coefficient bias voltage to the CTAT temperature sensing module and the output module, and the third output end of the PTAT current source module outputs PTAT current to the CTAT temperature sensing module; the PTAT current source module compensates the tendency of the transconductance of the built-in triode to decrease with the increase of temperature;

[0009] The output end of the CTAT temperature sensing module is electrically connected with the input end of the output module, and the output module outputs voltage V OTP The CTAT temperature sensing module amplifies the temperature coefficient slope of the sensing voltage V Z and outputs the sensing voltage V Z and the bias voltage to the input end and the second voltage input end of the output module, and controls the output voltage V OTP to output high level or low level.

[0010] Further, the PTAT current source module comprises a triode Q0, a triode Q1, MOS tubes P5, P6, P7, P8, N5, and resistors R5, R6, R7, R8, R9, R10, R11 and R12.

[0011] The external power supply VCC is electrically connected with the source of the MOS tube P5; the starting module outputs a reference voltage to the gate of the MOS tube P5.

[0012] The drain of the MOS tube P5 is electrically connected with one end of the resistor R5, one end of the resistor R7, one end of the resistor R8, one end of the resistor R11 and one end of the resistor R12, and the other end of the resistor R12 is electrically connected with the first voltage input end of the CTAT temperature sensing module and the first voltage input end of the output module as the first output end; the other end of the resistor R5 is electrically connected with one end of the resistor R6, the base of the triode Q0 and the base of the triode Q1, and is electrically connected with the second voltage input end of the CTAT temperature sensing module as the second output end.

[0013] The other end of the resistor R7 is electrically connected with the source of the MOS tube P6, the gate and the drain of the MOS tube P6 are electrically connected with the gate of the MOS tube P7, the gate of the MOS tube P8 and the collector of the transistor Q0; the other end of the resistor R8 is electrically connected with the source of the MOS tube P7, the drain of the MOS tube P7 is electrically connected with the collector of the transistor Q1; the emitter of the transistor Q0 is electrically connected with one end of the resistor R9, the other end of the resistor R9 and the emitter of the transistor Q1 are electrically connected with one end of the resistor R10;

[0014] The other end of the resistor R11 is electrically connected with the source of the MOS tube P8, the drain of the MOS tube P8 is electrically connected with the drain and the source of the MOS tube N5, and is electrically connected with the current input end of the CTAT temperature sensing module as a third output end;

[0015] The source of the MOS tube N5, the other end of the resistor R6 and the other end of the resistor R10 are grounded.

[0016] Further, the PTAT current source module further comprises a MOS tube N3, a resistor R3, a resistor R4 and a capacitor C0;

[0017] An external power supply VCC is electrically connected with one end of the capacitor C0 and one end of the resistor R4, the other end of the capacitor C0 is electrically connected with one end of the resistor R3 and the gate of the MOS tube N3, the other end of the resistor R4 is electrically connected with the drain of the MOS tube N3, the other end of the resistor R3 and the source of the MOS tube N3 are electrically connected with the gate of the MOS tube P5.

[0018] Further, the following conditional expressions are met,

[0019] (W / L) P6 (W / L) P7 (W / L) P8 = 5:5:1;

[0020] Wherein, (W / L) P6 is the width-length ratio of the MOS tube P6, (W / L) P7 is the width-length ratio of the MOS tube P7, (W / L) P8 is the width-length ratio of the MOS tube P8.

[0021] Further, the CTAT temperature sensing module comprises a bias branch, a CTAT voltage sensing branch and a hysteresis adjustment branch;

[0022] The first output end, the second output end and the third output end of the PTAT current source module are electrically connected with the input end of the bias branch, and output bias voltage and PTAT current to the bias branch; the output end of the bias branch is electrically connected with the CTAT voltage sensing branch and the hysteresis adjustment branch, and outputs sensing voltage V Z to the output module; the output end of the hysteresis adjustment branch is electrically connected with the CTAT voltage sensing branch.

[0023] Further, the bias branch comprises MOS tube P9, MOS tube P10, MOS tube P11, MOS tube P12, MOS tube P13, MOS tube P14, MOS tube N6, MOS tube N7, MOS tube N8, MOS tube N9, MOS tube N10, MOS tube N13 and triode Q2;

[0024] The external power supply VCC is electrically connected with the source of the MOS tube P9, the source of the MOS tube P11, the source of the MOS tube P12 and the source of the MOS tube P14; the first output end of the PTAT current source module outputs bias voltage V X to the gate of the MOS tube N8, the gate of the MOS tube N9 and the gate of the MOS tube N10; the second output end of the PTAT current source module outputs bias voltage V Y to the base of the triode Q2; the third output end of the PTAT current source module outputs PTAT current to the gate of the MOS tube N6 and the gate of the MOS tube N7;

[0025] The gate and the drain of the MOS tube P9 are electrically connected with the drain of the MOS tube N8, the gate of the MOS tube P10, the gate of the MOS tube P13 and the hysteresis adjustment branch; the source of the MOS tube N8 is electrically connected with the drain of the MOS tube N6;

[0026] The gate of the MOS tube P11 is electrically connected with the drain of the MOS tube P10, the drain of the MOS tube N9, the gate of the MOS tube P12 and the gate of the MOS tube P14, the drain of the MOS tube P11 is electrically connected with the source of the MOS tube P10, the source of the MOS tube N9 is electrically connected with the drain of the MOS tube N7;

[0027] The drain of the MOS tube P12 is electrically connected with the source of the MOS tube P13, the drain of the MOS tube P13 is electrically connected with the gate, the drain of the MOS tube N13, the hysteresis adjustment branch and the output module;

[0028] The drain of the MOS tube P14 is electrically connected with the drain of the MOS tube N10, and outputs sensing voltage V ZThe source of the MOS tube N10 is electrically connected with the collector of the transistor Q2, and the emitter of the transistor Q2 is electrically connected with the CTAT voltage sensing branch;

[0029] The source of the MOS tube N5, the source of the MOS tube N6, the source of the MOS tube N7 and the source of the MOS tube N13 are grounded.

[0030] Further, the CTAT voltage sensing branch comprises the transistor Q3, the transistor Q4, the transistor Q5, the transistor Q6 and the resistor R13;

[0031] The output end of the biasing branch is electrically connected with the base and the collector of the transistor Q3, the emitter of the transistor Q3 is electrically connected with the base and the collector of the transistor Q4, the emitter of the transistor Q4 is electrically connected with the base and the collector of the transistor Q5, the emitter of the transistor Q5 is electrically connected with one end of the resistor R13, the other end of the resistor R13 and the output end of the hysteresis adjustment branch are electrically connected with the base and the collector of the transistor Q6;

[0032] The emitter of the transistor Q6 is grounded.

[0033] Further, the hysteresis adjustment branch comprises the MOS tube P15, the MOS tube P16, the MOS tube N14 and the MOS tube N15;

[0034] The external power supply VCC is electrically connected with the source of the MOS tube P15, the output sensing voltage V Z of the biasing branch is input to the gate of the MOS tube P15, and the biasing branch outputs the biasing voltage to the gate of the MOS tube N15 and the gate of the MOS tube P16;

[0035] The drain of the MOS tube P15 is electrically connected with the source of the MOS tube P16, the drain of the MOS tube P16 is electrically connected with the drain of the MOS tube N15 and the gate of the MOS tube N14, and the drain of the MOS tube N14 is electrically connected with the CTAT voltage sensing branch as an output end;

[0036] The source of the MOS tube N14 and the source of the MOS tube N15 are grounded.

[0037] Further, the starting module comprises the MOS tube P0, the MOS tube P1, the MOS tube P2, the MOS tube P3, the MOS tube N0, the MOS tube N1, the MOS tube N2, the MOS tube N4 and the resistor R0, the resistor R1 and the resistor R2;

[0038] The external power supply VCC is electrically connected with the source of the MOS tube P0, the source of the MOS tube P1, the source of the MOS tube P3 and one end of the resistor R0.

[0039] The other end of the resistor R0 is electrically connected with the gate of the MOS tube N1 and the drain of the MOS tube N0, the gate of the MOS tube N0 is electrically connected with the source of the MOS tube N1 and one end of the resistor R1; the gate and the drain of the MOS tube P0 are electrically connected with the gate of the MOS tube P1, the gate of the MOS tube P3 and one end of the resistor R2, the other end of the resistor R2 is electrically connected with the gate of the MOS tube P2 and the drain of the MOS tube N1;

[0040] The drain of the MOS tube P1 is electrically connected with the source of the MOS tube P2, the drain of the MOS tube P2 is electrically connected with the drain and the gate of the MOS tube N2 and the gate of the MOS tube N4; the drain of the MOS tube P3 is electrically connected with the drain of the MOS tube N4 and outputs the reference voltage to the PTAT current source module as an output end;

[0041] The source of the MOS tube N0, the source of the MOS tube N2, the source of the MOS tube N4 and the other end of the resistor R1 are grounded.

[0042] Further, the output module comprises the MOS tube P17, the MOS tube P18, the MOS tube N11, the MOS tube N12, the MOS tube N16 and the MOS tube N17;

[0043] The external power supply VCC is electrically connected with the source of the MOS tube P17 and the source of the MOS tube P18; the output end of the CTAT temperature sensing module outputs the sensing voltage V Z to the gate of the MOS tube P17; the PTAT current source module outputs the bias voltage to the gate of the MOS tube N11 and the gate of the MOS tube N12; the CTAT temperature sensing module outputs the bias voltage to the gate of the MOS tube N16 and the gate of the MOS tube N17;

[0044] The drain of the MOS tube P17 is electrically connected with the drain of the MOS tube N11 and the gate of the MOS tube P18, the source of the MOS tube N11 is electrically connected with the drain of the MOS tube N16; the drain of the MOS tube P18 is electrically connected with the drain of the MOS tube N12 and outputs the voltage V OTP as an output end; the source of the MOS tube N12 is electrically connected with the drain of the MOS tube N17;

[0045] The source of the MOS tube N16 and the source of the MOS tube N17 are grounded.

[0046] After the above technical solution is adopted, the present application has the following advantages compared with the background art:

[0047] 1. The startup module drives the PTAT current source module to operate, providing the CTAT temperature sensing module with a zero-temperature coefficient bias voltage and bias current, avoiding temperature drift that introduces errors into the circuit and improving protection accuracy. Furthermore, the PTAT current source module compensates for the decreasing transconductance of the transistor with increasing temperature, thus increasing the sensing voltage V of the CTAT temperature sensing module. Z The hysteresis range is reduced, the sensitivity of the circuit at the critical point is decreased, and the output module only changes the output level after the circuit has been completely cooled to the preset safe temperature. This avoids the output module repeatedly switching levels near the critical point due to insufficient circuit cooling, and improves the overall performance stability.

[0048] 2. The CTAT temperature sensing module outputs an enhanced CTAT voltage as the sensing voltage V. Z This amplifies the slope of the temperature coefficient of the sensed voltage, preventing large voltage changes caused by temperature and current variations near the critical point, and reducing the risk of oscillations near the critical point. Attached Figure Description

[0049] Figure 1 This is a circuit diagram of the over-temperature protection circuit described in this invention;

[0050] Figure 2 This is a simulation diagram of the hysteresis characteristics of the over-temperature protection circuit described in this invention. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0052] Additionally, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are all based on the orientation or positional relationship shown in the accompanying drawings. They are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element of the present invention must have a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0053] When an element is referred to as being "fixed to," "set on," or "contained on" another element, it can be directly on or indirectly on that other element. When an element is referred to as being "connected to," it can be directly connected to or indirectly connected to that other element.

[0054] Unless otherwise defined, the terms "mounting", "connected", "connecting" should be construed as broadly, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium, or can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the invention can be understood according to the specific circumstances. Embodiments

[0055] Please refer to Figure 1 The embodiment provides an over-temperature protection circuit, which comprises a starting module, a PTAT current source module, a CTAT temperature sensing module and an output module. The output end of the starting module is electrically connected with the input end of the PTAT current source module, so as to provide a reference voltage for the PTAT current source module.

[0056] The first output end of the PTAT current source module is electrically connected with the first voltage input end of the CTAT temperature sensing module and the first voltage input end of the output module; the second output end of the PTAT current source module is electrically connected with the second voltage input end of the CTAT temperature sensing module; and the third output end of the PTAT current source module is electrically connected with the current input end of the CTAT temperature sensing module. The first output end and the second output end of the PTAT current source module output a zero-temperature-coefficient bias voltage to the CTAT temperature sensing module and the output module; the third output end of the PTAT current source module outputs a PTAT current to the CTAT temperature sensing module; and the PTAT current source module compensates the tendency of the transconductance of the built-in triode to decrease with the increase of temperature.

[0057] The output end of the CTAT temperature sensing module is electrically connected with the input end of the output module, and the output module outputs a voltage V OTP . The CTAT temperature sensing module amplifies the temperature coefficient slope of the sensing voltage V Z , and outputs the sensing voltage V Z and the bias voltage to the input end and the second voltage input end of the output module, so as to control the output voltage V OTP to output a high level or a low level.

[0058] The starting module drives the PTAT current source module to work, provides the CTAT temperature sensing module with a zero-temperature-coefficient bias voltage and a bias current, avoids the introduction of errors in the circuit caused by temperature drift, and improves the protection accuracy; and the PTAT current source module compensates the tendency of the transconductance of the triode to decrease with the increase of temperature, and the CTAT temperature sensing module improves the sensing voltage V Zhysteresis range, reduce the sensitivity of the circuit at the critical point, ensure that the output module changes the output level only after the circuit is completely reduced to the preset safe temperature, avoid the output module repeatedly switching the level near the critical point due to insufficient cooling of the circuit, and improve the overall performance stability. At the same time, the CTAT temperature sensing module outputs an enhanced CTAT voltage as the sensing voltage V Z , amplifies the temperature coefficient slope of the sensing voltage, avoids large voltage changes caused by temperature current changes near the critical point of the circuit, and reduces the risk of oscillation near the critical point.

[0059] Specifically, the starting module includes MOS tubes P0, P1, P2, P3, N0, N1, N2, N4, and resistors R0, R1, and R2.

[0060] The external power supply VCC is electrically connected to the source of MOS tube P0, the source of MOS tube P1, the source of MOS tube P3, and one end of resistor R0.

[0061] The other end of resistor R0 is electrically connected to the gate of MOS tube N1 and the drain of MOS tube N0. The gate of MOS tube N0 is electrically connected to the source of MOS tube N1 and one end of resistor R1. The gate and drain of MOS tube P0 are electrically connected to the gate of MOS tube P1, the gate of MOS tube P3, and one end of resistor R2. The other end of resistor R2 is electrically connected to the gate of MOS tube P2 and the drain of MOS tube N1.

[0062] The drain of MOS tube P1 is electrically connected to the source of MOS tube P2. The drain of MOS tube P2 is electrically connected to the drain and gate of MOS tube N2 and the gate of MOS tube N4. The drain of MOS tube P3 is electrically connected to the drain of MOS tube N4 and serves as an output terminal to output a reference voltage to the PTAT current source module.

[0063] The source of MOS tube N0, the source of MOS tube N2, the source of MOS tube N4, and the other end of resistor R1 are all grounded.

[0064] When the external power supply VCC is powered on, the MOS tube N0 and the MOS tube N1 are turned on, and the starting module starts to work. The resistor R2, the MOS tube P0, the MOS tube P1, the MOS tube P2, the MOS tube P3, the MOS tube N2 and the MOS tube N4 form a current mirror, and the drain voltage of the MOS tube P3 is used as an output reference voltage to the PTAT current source module. The gate and the drain of the MOS tube P0 are short-circuited to provide a reference current, and the MOS tube P1 and the MOS tube N2 copy the reference current, wherein the MOS tube P2 stabilizes the internal operating point. The resistor R2 raises the drain voltage of the MOS tube P0 to prevent the MOS tube P0 from being broken down. The MOS tube P3 is a pull-up PMOS tube for outputting the reference voltage, and the MOS tube N4 is a pull-down NMOS tube for outputting the reference voltage.

[0065] Specifically, the PTAT current source module comprises a transistor Q0, a transistor Q1, a MOS tube P5, a MOS tube P6, a MOS tube P7, a MOS tube P8, a MOS tube N5, and resistors R5, R6, R7, R8, R9, R10, R11 and R12.

[0066] The external power supply VCC is electrically connected to the source of the MOS tube P5; the starting module outputs a reference voltage to the gate of the MOS tube P5, that is, the drain of the MOS tube P3 is electrically connected to the gate of the MOS tube P5.

[0067] The drain of the MOS tube P5 is electrically connected to one end of the resistor R5, one end of the resistor R7, one end of the resistor R8, one end of the resistor R11 and one end of the resistor R12, and the other end of the resistor R12 is electrically connected to the first voltage input end of the CTAT temperature sensing module and the first voltage input end of the output module as a first output end. The other end of the resistor R5 is electrically connected to one end of the resistor R6, the base of the transistor Q0 and the base of the transistor Q1, and is electrically connected to the second voltage input end of the CTAT temperature sensing module as a second output end.

[0068] The other end of the resistor R7 is electrically connected to the source of the MOS tube P6, and the gate and the drain of the MOS tube P6 are electrically connected to the gate of the MOS tube P7, the gate of the MOS tube P8 and the collector of the transistor Q0. The other end of the resistor R8 is electrically connected to the source of the MOS tube P7, and the drain of the MOS tube P7 is electrically connected to the collector of the transistor Q1. The emitter of the transistor Q0 is electrically connected to one end of the resistor R9, and the other end of the resistor R9 and the emitter of the transistor Q1 are both electrically connected to one end of the resistor R10.

[0069] The other end of the resistor R11 is electrically connected with the source of the MOS tube P8, the drain of the MOS tube P8 is electrically connected with the drain and the source of the MOS tube N5, and is electrically connected with the current input end of the CTAT temperature sensing module as the third output end, and outputs the PTAT current to the CTAT temperature sensing module.

[0070] The source of the MOS tube N5, the other end of the resistor R6 and the other end of the resistor R10 are grounded.

[0071] Further, the PTAT current source module further comprises the MOS tube N3, the resistor R3, the resistor R4 and the capacitor C0.

[0072] The external power supply VCC is electrically connected with one end of the capacitor C0 and one end of the resistor R4. The other end of the capacitor C0 is electrically connected with one end of the resistor R3 and the gate of the MOS tube N3, the other end of the resistor R4 is electrically connected with the drain of the MOS tube N3, and the other end of the resistor R3 and the source of the MOS tube N3 are electrically connected with the gate of the MOS tube P5.

[0073] And the following conditional expression is satisfied,

[0074] (W / L) P6 (W / L) P7 (W / L) P8 = 5:5:1;

[0075] Wherein, (W / L) P6 is the width-length ratio of the MOS tube P6, (W / L) P7 is the width-length ratio of the MOS tube P7, and (W / L) P8 is the width-length ratio of the MOS tube P8.

[0076] The PTAT current is a current proportional to the absolute temperature. Specifically, the drain voltage of the MOS tube P3 is provided as the output voltage to the gate of the MOS tube P5. The resistor R3, the resistor R4, the capacitor C0 and the MOS tube N3 form a surge suppression branch. When the output voltage suddenly changes, the voltage across the capacitor C0 cannot suddenly change, the gate-source voltage of the MOS tube N3 steps follow, the MOS tube N3 enters the saturation region, and the current flowing through the MOS tube N3 is automatically limited to the maximum current due to the current square law characteristic of the NMOS, thereby suppressing the surge.

[0077] The MOS tube P5 is turned on to pull up VCC to supply power to the PTAT current source module; the resistor R7, the resistor R8 and the resistor R11 are passive loads. The MOS tube P6, the MOS tube P7 and the MOS tube P8 form a current mirror branch. According to the width-length ratio relationship of the three and the circuit structure of the PTAT current source module, the current I R9 flowing through the resistor R9 is,

[0078] ;

[0079] wherein, V BE0 and V BE1 are the base-emitter voltages of the triode Q0 and the triode Q1 respectively, lnn is the logarithm with base e of n, wherein n is the parallel number ratio of the triode Q0 and the triode Q1; V T is the thermal voltage, and R9 is the resistance value of the resistor R9.

[0080] Since, V T =kT / q, wherein q is the charge of an electron, k is the Boltzmann constant, and T is the temperature, i.e. V T is proportional to the absolute temperature. Thus, the current I R9 flowing through the resistor R9 is also proportional to the absolute temperature, i.e. it is a PTAT current. Since the MOS transistor P6, the MOS transistor P7 and the MOS transistor P8 form a current mirror structure, the current flowing through the MOS transistor P8 is also a PTAT current, i.e. it is proportional to the absolute temperature.

[0081] Thus, it can be obtained that,

[0082] .

[0083] In combination with the attached Figure 1 , wherein the bias voltage V X and the bias voltage V Y are the voltages of the X node and the Y node respectively, i.e. V Y are the base voltages of the triode Q0 and the triode Q1 respectively, i.e.

[0084] ;

[0085] Since V Y is the voltage division of V X , it can be obtained that,

[0086] .

[0087] Since V BE is a negative temperature coefficient voltage and V T is a positive temperature coefficient voltage in terms of process parameters, i.e. the size of the positive temperature coefficient can be adjusted by adjusting the resistance value ratio of the resistor R10 and the resistor R9, so as to offset the negative temperature coefficient; so that V X and V Y are zero temperature coefficient voltages.

[0088] Further, the CTAT temperature sensing module comprises a bias branch, a CTAT voltage sensing branch and a hysteresis adjusting branch. The first output end, the second output end and the third output end of the PTAT current source module are electrically connected with the input end of the bias branch, and output bias voltage and PTAT current to the bias branch. The output end of the bias branch is electrically connected with the CTAT voltage sensing branch and the hysteresis adjusting branch, and outputs sensing voltage V Z to the output module. The output end of the hysteresis adjusting branch is electrically connected with the CTAT voltage sensing branch.

[0089] Specifically, the bias branch comprises MOS tube P9, MOS tube P10, MOS tube P11, MOS tube P12, MOS tube P13, MOS tube P14, MOS tube N6, MOS tube N7, MOS tube N8, MOS tube N9, MOS tube N10, MOS tube N13 and triode Q2.

[0090] The external power supply VCC is electrically connected with the source of the MOS tube P9, the source of the MOS tube P11, the source of the MOS tube P12 and the source of the MOS tube P14. The first output end of the PTAT current source module outputs bias voltage V X to the gate of the MOS tube N8, the gate of the MOS tube N9 and the gate of the MOS tube N10, that is, the other end of the resistor R12 is electrically connected with the gate of the MOS tube N8, the gate of the MOS tube N9 and the gate of the MOS tube N10. The second output end of the PTAT current source module outputs bias voltage V Y to the base of the triode Q2, that is, the other end of the resistor R5 is electrically connected with the base of the triode Q2. The third output end of the PTAT current source module outputs PTAT current to the gate of the MOS tube N6 and the gate of the MOS tube N7, that is, the drain of the MOS tube P8 is electrically connected with the gate of the MOS tube N6 and the gate of the MOS tube N7.

[0091] The gate and the drain of the MOS tube P9 are electrically connected with the drain of the MOS tube N8, the gate of the MOS tube P10, the gate of the MOS tube P13 and the hysteresis adjusting branch. The source of the MOS tube N8 is electrically connected with the drain of the MOS tube N6. The gate of the MOS tube P11 is electrically connected with the drain of the MOS tube P10, the drain of the MOS tube N9, the gate of the MOS tube P12 and the gate of the MOS tube P14, the drain of the MOS tube P11 is electrically connected with the source of the MOS tube P10, the source of the MOS tube N9 is electrically connected with the drain of the MOS tube N7. The drain of the MOS tube P12 is electrically connected with the source of the MOS tube P13, the drain of the MOS tube P13 is electrically connected with the gate, the drain of the MOS tube N13, the hysteresis adjusting branch and the output module.

[0092] The drain of the MOS tube P14 is electrically connected with the drain of the MOS tube N10, and outputs the sensing voltage V as an output terminal Z The output module and the hysteresis adjustment branch; refer to the attached Figure 1 It can be seen that the sensing voltage V Z is the voltage of the Z node. The source of the MOS tube N10 is electrically connected with the collector of the transistor Q2, and the emitter of the transistor Q2 is electrically connected with the CTAT voltage sensing branch.

[0093] The source of the MOS tube N5, the source of the MOS tube N6, the source of the MOS tube N7 and the source of the MOS tube N13 are all grounded.

[0094] Specifically, the CTAT voltage sensing branch includes the transistor Q3, the transistor Q4, the transistor Q5, the transistor Q6 and the resistor R13.

[0095] The output terminal of the biasing branch is electrically connected with the base and the collector of the transistor Q3, that is, the emitter of the transistor Q2 is electrically connected with the base and the collector of the transistor Q3. The emitter of the transistor Q3 is electrically connected with the base and the collector of the transistor Q4, the emitter of the transistor Q4 is electrically connected with the base and the collector of the transistor Q5, the emitter of the transistor Q5 is electrically connected with one end of the resistor R13, the other end of the resistor R13 and the output terminal of the hysteresis adjustment branch are electrically connected with the base and the collector of the transistor Q6. The emitter of the transistor Q6 is grounded.

[0096] Specifically, the hysteresis adjustment branch includes the MOS tube P15, the MOS tube P16, the MOS tube N14 and the MOS tube N15.

[0097] The external power supply VCC is electrically connected with the source of the MOS tube P15; the output sensing voltage V Z of the biasing branch is input to the gate of the MOS tube P15, that is, the drain of the MOS tube P14 is electrically connected with the gate of the MOS tube P15. The biasing branch outputs the biasing voltage to the gate of the MOS tube N15 and the gate of the MOS tube P16, that is, the gate and the drain of the MOS tube P9 are electrically connected with the gate of the MOS tube P16, and the drain of the MOS tube P13 is electrically connected with the gate of the MOS tube N5.

[0098] The drain of the MOS tube P15 is electrically connected with the source of the MOS tube P16, the drain of the MOS tube P16 is electrically connected with the drain of the MOS tube N15 and the gate of the MOS tube N14. The drain of the MOS tube N14 is electrically connected with the CTAT voltage sensing branch as an output terminal, that is, the drain of the MOS tube N14 is electrically connected with the base and the collector of the transistor Q6. The source of the MOS tube N14 and the source of the MOS tube N15 are both grounded.

[0099] Transistors Q2, N8, N9, and N10 are bias transistors, using a bias voltage V with a zero temperature coefficient. X and bias voltage V Y As a bias input, it avoids introducing errors. MOSFET N13 is a self-biased transistor, providing bias voltage to the hysteresis adjustment branch and the output branch. MOSFETs N5, N6, and N7 form a current mirror structure, replicating the PTAT current and introducing it into the CTAT temperature sensing module. MOSFETs P9, P10, P11, P12, P13, and P14 also form a current mirror structure, replicating the PTAT current to the CTAT voltage sensing branch. Resistor R13 raises the Z-node potential. The voltage drop generated by shorting and connecting the base-collector of transistors Q3, Q4, Q5, and Q6 in the CTAT voltage sensing branch is used as the sensing voltage. Since when T=300K, a single V BE The temperature coefficient is,

[0100] ;

[0101] The four transistors connected in series amplify the slope to approximately -6mV / K. This larger slope allows the circuit to generate a sufficiently large voltage change from a small temperature variation near the critical temperature point, thus maximizing the sensing voltage V. Z It has strong CTAT characteristics.

[0102] Transconductance gm is,

[0103] ;

[0104] Among them, I C It is the collector current, V T It is thermal voltage. When I C When it is a constant, the transconductance gm decreases with increasing temperature. In this embodiment, I C This is the PTAT current. Since the PTAT current is directly proportional to absolute temperature, it increases with increasing temperature.

[0105] ;

[0106] In this case, ∝ is a mathematical symbol representing a direct proportional relationship between two quantities. The transconductance gm is a constant, meaning it remains constant regardless of temperature changes. This constant transconductance gm stabilizes the transistor's gain and sensitivity, reducing the impact of temperature fluctuations on circuit performance. In other words, the PTAT current can compensate for the decreasing trend of the transistor's transconductance gm with increasing temperature.

[0107] When I C When V is constant, the transistor's V BEThe first and second derivatives of temperature T can be expressed as,

[0108] ;

[0109] ;

[0110] When I C is a PTAT current, i.e. I C = NT, where N is a constant, V BE T is a function of temperature T. The first and second derivatives of temperature T can be expressed as,

[0111] ;

[0112] ;

[0113] where m ~ -3 / 2, V T is the thermal voltage, E g is the bandgap energy of silicon, k is the Boltzmann constant, and q is the charge of an electron. That is, under the action of the PTAT current, the rate of change of the first-order temperature coefficient of V BE with temperature is smaller. That is, the degree of curvature of the first-order temperature coefficient curve of V BE is reduced. In the entire temperature range, the change of V BE is closer to linear, reducing the drift of the trigger point and improving the accuracy and consistency of temperature detection.

[0114] When the operating temperature of the circuit rises, the PTAT current increases with the rise in temperature, and the current flowing through MOS transistor N6 and MOS transistor N7 also increases, thereby raising the gate potential of MOS transistor P9, MOS transistor P11, and MOS transistor P14 through the current mirror structure. Ignoring the slight voltage drop generated when transistor Q2 and MOS transistor N10 are turned on, the Z node voltage is approximately equal to the sensing voltage, i.e. V Z is the sensing voltage.

[0115] Before the temperature rises to the critical point, V Z can be expressed as,

[0116] ;

[0117] where I Z is the PTAT current copied by MOS transistor P14 through the current mirror, and R13 is the resistance value of resistor R13. Due to the negative temperature characteristic of V BE , V Z will slowly decrease as the temperature rises, and when the temperature rises to the critical point, MOS transistor P15 will be turned on instantaneously, the drain potential of MOS transistor N15 will change from low to high, MOS transistor N14 will be turned on, transistor Q6 will be short-circuited, and V Z will be pulled down to a lower potential. At this time,

[0118] .

[0119] To restore V during cooling Z Potential, the circuit can only be raised by lowering the temperature to a lower level. BE Only then can V Z The original level is restored, that is, a wider hysteresis range is generated.

[0120] Please refer to Figure 2 As shown, attached Figure 2 This is a simulation diagram of the hysteresis characteristics of the over-temperature protection circuit disclosed in this embodiment. Figure 2 It can be seen that the hysteresis range of the over-temperature protection circuit disclosed in this embodiment can reach 30°C, which has a wide hysteresis range and effectively avoids the phenomenon of repeated opening and closing near the critical point due to insufficient circuit cooling.

[0121] Specifically, the output module includes MOSFETs P17, P18, N11, N12, N16, and N17.

[0122] The external power supply VCC is electrically connected to the source of MOSFET P17 and the source of MOSFET P18. The output terminal of the CTAT temperature sensing module outputs the sensing voltage V. Z The drain of MOSFET P14 is electrically connected to the gate of MOSFET P17. The PTAT current source module outputs a bias voltage to the gates of MOSFETs N11 and N12, meaning the other end of resistor R12 is electrically connected to the gates of MOSFETs N11 and N12. The CTAT temperature sensing module outputs a bias voltage to the gates of MOSFETs N16 and N17, meaning the drain of MOSFET P13 is electrically connected to the gates of MOSFETs N16 and N17.

[0123] The drain of MOSFET P17 is electrically connected to the drain of MOSFET N11 and the gate of MOSFET P18. The source of MOSFET N11 is electrically connected to the drain of MOSFET N16. The drain of MOSFET P18 is electrically connected to the drain of MOSFET N12, and serves as the output terminal for the output voltage V. OTP The source of MOSFET N12 is electrically connected to the drain of MOSFET N17. The sources of MOSFET N16 and MOSFET N17 are both grounded.

[0124] MOSFETs N11, N12, N16, and N17 are all bias transistors used to set the operating point; voltage V OTP This is the output voltage for over-temperature protection. When the sensed voltage V... ZWhen rising to the critical point potential, the MOS tube P17 turns on the pull-up VCC to close the MOS tube P18, and the voltage V OTP potential flips the output low-level over-temperature signal. After the circuit temperature drops to the safe point, the MOS tube P17 re-closes, the MOS tube P18 turns on the pull-up VCC, and the voltage V OTP potential recovers to the high level.

[0125] The above is only the preferred embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An over-temperature protection circuit, characterized in that, It includes a startup module, a PTAT current source module, a CTAT temperature sensing module, and an output module; The output terminal of the start-up module is electrically connected to the input terminal of the PTAT current source module to provide a reference voltage for the PTAT current source module. The first output terminal of the PTAT current source module is electrically connected to the first voltage input terminal of the CTAT temperature sensing module and the first voltage input terminal of the output module; the second output terminal of the PTAT current source module is electrically connected to the second voltage input terminal of the CTAT temperature sensing module; the third output terminal of the PTAT current source module is electrically connected to the current input terminal of the CTAT temperature sensing module; the first and second output terminals of the PTAT current source module output a zero temperature coefficient bias voltage to the CTAT temperature sensing module and the output module; and the third output terminal of the PTAT current source module outputs a PTAT current to the CTAT temperature sensing module. The PTAT current source module compensates for the decreasing transconductance of the built-in transistor as temperature increases. The output terminal of the CTAT temperature sensing module is electrically connected to the input terminal of the output module, and the output module outputs a voltage V. OTP The CTAT temperature sensing module senses the voltage V. Z The temperature coefficient slope is amplified and the sensing voltage V is output. Z The bias voltage is applied to the input terminal and the second voltage input terminal of the output module to control the output voltage V. OTP Output a high or low level; The CTAT temperature sensing module includes a bias branch, a CTAT voltage sensing branch, and a hysteresis adjustment branch. The first, second, and third output terminals of the PTAT current source module are electrically connected to the input terminal of the bias branch, and output bias voltage and PTAT current to the bias branch. The output terminal of the bias branch is electrically connected to the CTAT voltage sensing branch and the hysteresis adjustment branch, and outputs the sensed voltage V as the output terminal. Z The output terminal of the hysteresis adjustment branch is electrically connected to the CTAT voltage sensing branch.

2. The over-temperature protection circuit according to claim 1, characterized in that: The PTAT current source module includes transistors Q0, Q1, P5, P6, P7, P8, and N5, and resistors R5, R6, R7, R8, R9, R10, R11, and R12. The external power supply VCC is electrically connected to the source of MOSFET P5; the startup module outputs a reference voltage to the gate of MOSFET P5; The drain of the MOSFET P5 is electrically connected to one end of resistor R5, one end of resistor R7, one end of resistor R8, one end of resistor R11, and one end of resistor R12. The other end of resistor R12 serves as the first output terminal and is electrically connected to the first voltage input terminal of the CTAT temperature sensing module and the first voltage input terminal of the output module. The other end of resistor R5 is electrically connected to one end of resistor R6, the base of transistor Q0, and the base of transistor Q1, and serves as the second output terminal and is electrically connected to the second voltage input terminal of the CTAT temperature sensing module. The other end of resistor R7 is electrically connected to the source of MOSFET P6. The gate and drain of MOSFET P6 are electrically connected to the gate of MOSFET P7, the gate of MOSFET P8, and the collector of transistor Q0. The other end of resistor R8 is electrically connected to the source of MOSFET P7. The drain of MOSFET P7 is electrically connected to the collector of transistor Q1. The emitter of transistor Q0 is electrically connected to one end of resistor R9. The other end of resistor R9 and the emitter of transistor Q1 are both electrically connected to one end of resistor R10. The other end of the resistor R11 is electrically connected to the source of the MOSFET P8. The drain of the MOSFET P8 is electrically connected to the drain and source of the MOSFET N5, and is electrically connected to the current input terminal of the CTAT temperature sensing module as the third output terminal. The source of the MOS transistor N5, the other end of resistor R6, and the other end of resistor R10 are all grounded.

3. The over-temperature protection circuit according to claim 2, characterized in that: The PTAT current source module also includes MOSFET N3, resistor R3, resistor R4, and capacitor C0; The external power supply VCC is electrically connected to one end of capacitor C0 and one end of resistor R4. The other end of capacitor C0 is electrically connected to one end of resistor R3 and the gate of MOSFET N3. The other end of resistor R4 is electrically connected to the drain of MOSFET N3. The other end of resistor R3 is electrically connected to the source of MOSFET N3 and the gate of MOSFET P5.

4. The over-temperature protection circuit according to claim 2, characterized in that: The following conditions must be met. (W / L) P6 :(W / L) P7 :(W / L) P8 =5:5:1; Among them, (W / L) P6 The width-to-length ratio (W / L) of MOSFET P6 P7 The width-to-length ratio (W / L) of MOSFET P7. P8 This represents the width-to-length ratio of MOSFET P8.

5. The over-temperature protection circuit according to claim 1, characterized in that: The bias branch includes MOSFETs P9, P10, P11, P12, P13, P14, N6, N7, N8, N9, N10, N13 and transistor Q2; The external power supply VCC is electrically connected to the sources of MOSFETs P9, P11, P12, and P14; the first output terminal of the PTAT current source module outputs a bias voltage V. X The bias voltage V is output to the gates of MOSFET N8, MOSFET N9, and MOSFET N10; the second output terminal of the PTAT current source module outputs the bias voltage V. Y The PTAT current is output to the base of transistor Q2; the third output terminal of the PTAT current source module outputs PTAT current to the gate of MOSFET N6 and the gate of MOSFET N7. The gate and drain of MOS transistor P9 are electrically connected to the drain of MOS transistor N8, the gate of MOS transistor P10, the gate of MOS transistor P13, and the hysteresis adjustment branch; the source of MOS transistor N8 is electrically connected to the drain of MOS transistor N6. The gate of MOS transistor P11 is electrically connected to the drain of MOS transistor P10, the drain of MOS transistor N9, the gate of MOS transistor P12, and the gate of MOS transistor P14. The drain of MOS transistor P11 is electrically connected to the source of MOS transistor P10, and the source of MOS transistor N9 is electrically connected to the drain of MOS transistor N7. The drain of MOS transistor P12 is electrically connected to the source of MOS transistor P13, and the drain of MOS transistor P13 is electrically connected to the gate, drain, hysteresis adjustment branch, and output module of MOS transistor N13. The drain of MOSFET P14 is electrically connected to the drain of MOSFET N10, and serves as the output terminal to output the sensing voltage V. Z The hysteresis adjustment branch and output module; the source of the MOS transistor N10 is electrically connected to the collector of the transistor Q2, and the emitter of the transistor Q2 is electrically connected to the CTAT voltage sensing branch; The sources of MOSFETs N5, N6, N7, and N13 are all grounded.

6. The over-temperature protection circuit according to claim 1, characterized in that: The CTAT voltage sensing branch includes transistors Q3, Q4, Q5, and Q6, and resistor R13. The output terminal of the bias branch is electrically connected to the base and collector of transistor Q3, the emitter of transistor Q3 is electrically connected to the base and collector of transistor Q4, the emitter of transistor Q4 is electrically connected to the base and collector of transistor Q5, the emitter of transistor Q5 is electrically connected to one end of resistor R13, and the other end of resistor R13 and the output terminal of the hysteresis adjustment branch are electrically connected to the base and collector of transistor Q6. The emitter of the transistor Q6 is grounded.

7. The over-temperature protection circuit according to claim 1, characterized in that: The hysteresis adjustment branch includes MOSFET P15, MOSFET P16, MOSFET N14 and MOSFET N15; The external power supply VCC is electrically connected to the source of MOSFET P15, and the output sensing voltage V of the bias branch is... Z The bias branch provides bias voltage to the gate of MOSFET P15 and outputs bias voltage to the gate of MOSFET N15 and the gate of MOSFET P16. The drain of MOS transistor P15 is electrically connected to the source of MOS transistor P16, the drain of MOS transistor P16 is electrically connected to the drain of MOS transistor N15 and the gate of MOS transistor N14, and the drain of MOS transistor N14 is electrically connected to the CTAT voltage sensing branch as an output terminal. The sources of both MOS transistor N14 and MOS transistor N15 are grounded.

8. The over-temperature protection circuit according to claim 1, characterized in that: The startup module includes MOSFETs P0, P1, P2, P3, N0, N1, N2, and N4, and resistors R0, R1, and R2. The external power supply VCC is electrically connected to the source of MOSFET P0, the source of MOSFET P1, the source of MOSFET P3, and one end of resistor R0. The other end of resistor R0 is electrically connected to the gate and drain of MOSFET N1 and MOSFET N0, respectively. The gate of MOSFET N0 is electrically connected to the source of MOSFET N1 and one end of resistor R1. The gate and drain of MOSFET P0 are electrically connected to the gates of MOSFET P1 and MOSFET P3 and one end of resistor R2, respectively. The other end of resistor R2 is electrically connected to the gate of MOSFET P2 and the drain of MOSFET N1. The drain of MOSFET P1 is electrically connected to the source of MOSFET P2. The drain of MOSFET P2 is electrically connected to the drain and gate of MOSFET N2 and the gate of MOSFET N4. The drain of MOSFET P3 is electrically connected to the drain of MOSFET N4 and serves as the output terminal to output a reference voltage to the PTAT current source module. The source of MOS transistor N0, the source of MOS transistor N2, the source of MOS transistor N4, and the other end of resistor R1 are all grounded.

9. The over-temperature protection circuit according to claim 1, characterized in that: The output module includes MOSFETs P17, P18, N11, N12, N16, and N17. The external power supply VCC is electrically connected to the source of MOSFET P17 and the source of MOSFET P18; the output terminal of the CTAT temperature sensing module outputs the sensing voltage V. Z The bias voltage is output to the gate of MOSFET P17; the bias voltage is output to the gate of MOSFET N11 and the gate of MOSFET N12 by the PTAT current source module; the bias voltage is output to the gate of MOSFET N16 and the gate of MOSFET N17 by the CTAT temperature sensing module. The drain of MOSFET P17 is electrically connected to the drain of MOSFET N11 and the gate of MOSFET P18; the source of MOSFET N11 is electrically connected to the drain of MOSFET N16; the drain of MOSFET P18 is electrically connected to the drain of MOSFET N12, and serves as the output voltage V. OTP The source of the MOS transistor N12 is electrically connected to the drain of the MOS transistor N17. The sources of both MOS transistor N16 and MOS transistor N17 are grounded.

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