Over-temperature protection circuit with temperature hysteresis for high-side switch chip

Abstract

The utility model discloses an over-temperature protection circuit with temperature hysteresis for a high-side switch chip. The over-temperature protection circuit comprises a reference voltage circuit, a temperature detection circuit, a voltage comparison circuit and a hysteresis output circuit, the reference voltage circuit is used for dividing power supply voltage by adopting a series resistor to generate reference voltage; the temperature detection circuit is used for receiving bias current of the bias current module from the high-side switch chip and enabling a temperature sensing element to work according to the bias current to generate temperature sensing voltage; the in-phase input end of the voltage comparison circuit receives the temperature sensing voltage, the negative-phase input end of the voltage comparison circuit receives the reference voltage, and the voltage comparison circuit is used for comparing the temperature sensing voltage with the reference voltage and generating a first logic signal and a second logic signal according to a comparison result; and the hysteresis output circuit is used for receiving the first logic signal and the second logic signal, and generating an over-temperature protection signal with hysteresis after signal shaping and RS latching.

Description

Technical Field

[0001] The utility model belongs to the technical field of integrated circuits, and in particular relates to an over-temperature protection circuit with temperature hysteresis for a high-side switch chip. Background Art

[0002] High Side Driver refers to an intelligent power component that integrates a driver control module, a status detection and protection circuit, and a power device. It is widely used in new energy vehicles, automation control, aerospace, and other fields. High Side Switches must cope with harsh conditions such as cold and high temperatures, and have high reliability, high stability, and active protection. The stability of various detection and protection circuits plays an important role. Among them, the temperature detection and over-temperature protection module for the power tube area with high heat generation of the chip can effectively prevent the chip from continuing to work beyond the safe working area of ​​the power tube, causing thermal damage to the entire chip.

[0003] Most traditional over-temperature protection circuits use diodes as temperature sensing elements, using their negative temperature characteristics to detect the forward voltage drop of the diode in real time and compare it with the over-temperature protection point. However, the forward voltage drop of the diode is greatly affected by the process and the inflow current. The fluctuation of the process and current will cause the protection temperature and recovery temperature of the over-temperature protection circuit to fluctuate as well, which will affect the stability of the circuit operation. Utility Model Content

[0004] In view of the above problems, the utility model provides an over-temperature protection circuit with temperature hysteresis for a high-side switch chip.

[0005] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0006] An over-temperature protection circuit with temperature hysteresis for a high-side switch chip, comprising a reference voltage circuit, a temperature detection circuit, a voltage comparison circuit and a hysteresis output circuit;

[0007] The reference voltage circuit is used to divide the power supply voltage by using series resistors to generate a reference voltage;

[0008] The temperature detection circuit is used to receive the bias current of the bias current module from the high-side switch chip, and to operate the temperature sensing element to generate a temperature sensing voltage according to the bias current;

[0009] The non-inverting input terminal of the voltage comparison circuit receives the temperature sensing voltage, the negative-inverting input terminal of the voltage comparison circuit receives the reference voltage, the voltage comparison circuit is used to compare the temperature sensing voltage with the reference voltage, and generate a first logic signal and a second logic signal according to the comparison result;

[0010] The hysteresis output circuit is used to receive the first logic signal and the second logic signal, and generate an over-temperature protection signal with hysteresis after signal shaping and RS latching.

[0011] In a possible implementation manner, the reference voltage circuit is configured in a manner of at least two resistors connected in series.

[0012] In a possible implementation, the temperature detection circuit includes a first PMOS transistor M1, a second PMOS transistor M2, a resistor R3, a first transistor Q1, and a bias current IBIAS provided by an internal bias circuit of the chip.

[0013] In a possible implementation, the first transistor Q1 is a PNP transistor, the base and collector of the first transistor are grounded and connected, the first PMOS transistor M1 and the second PMOS transistor M2 form a current mirror structure to provide a constant bias current for the first transistor Q1, one end of the third resistor R3 is connected to the drain of the second PMOS transistor, and the other end of the third resistor R3 is connected to the emitter of the first transistor Q1.

[0014] In a possible implementation manner, the voltage comparison circuit includes a third PMOS tube M3, a fourth PMOS tube M4, a fifth PMOS tube M5, a sixth PMOS tube M11, a seventh PMOS tube M12, an eighth PMOS tube M13, a first NMOS tube M6, a second NMOS tube M7, a third NMOS tube M8, a fourth NMOS tube M9, a fifth NMOS tube M10 and a sixth NMOS tube M14, the gate of the fourth PMOS tube serves as a non-inverting input terminal of the voltage comparator circuit and is connected to the output terminal of the temperature detection circuit; the gate of the fifth PMOS tube serves as an inverting input terminal of the voltage comparison circuit and is connected to the reference voltage VREF.

[0015] In a possible implementation manner, the fourth NMOS tube M9 and the fifth NMOS tube M10 have the same width-to-length ratio; the width-to-length ratio of the eighth PMOS tube M13 is slightly larger than that of the seventh PMOS tube M12, so as to realize the temperature hysteresis function; the drain of the seventh PMOS tube M12 and the drain of the fourth NMOS tube M9 are connected as the first logic signal output terminal; the drain of the eighth PMOS tube M13 and the drain of the fifth NMOS tube M10 are connected as the second logic signal output terminal, when the chip temperature is lower than the over-temperature protection point, the voltage of the in-phase input terminal of the comparator circuit is greater than the inverting input terminal, and both the first logic signal and the second logic signal output a high level; when the chip temperature is high, so that the voltage of the in-phase input terminal of the comparator circuit is less than the inverting input terminal, the first logic signal will become a low level, and the second logic signal will remain a high level; if the chip temperature continues to rise by several degrees Celsius, both the first logic signal and the second logic signal output a low level.

[0016] In a possible implementation manner, the hysteresis output circuit includes a first inverter INV1, a second inverter INV2, a third inverter INV3 and an RS latch RSFF.

[0017] In one possible implementation, the input end of the first inverter INV1 is connected to the second logic signal, and the output end of the first inverter INV1 is connected to the set end of the RS latch RSFF; the second inverter INV2 and the third inverter INV3 are connected in series, the input end of the second inverter INV2 is connected to the second logic signal, and the output end of the third inverter INV3 is connected to the reset end of the RS latch RSFF; the state output end of the RS latch RSFF outputs the OTP signal.

[0018] The utility model has the following beneficial effects:

[0019] (1) The voltage at the inverting input of the voltage comparator circuit is obtained by dividing the VDD voltage generated by the LDO circuit of the high-side switch through a series resistor. Its value is not affected by temperature and process, so that the over-temperature protection point has a high stability.

[0020] (2) The bias current of the temperature detection circuit comes from the bias current generated by the bias circuit of the high-side switch, which effectively avoids the fluctuation of the over-temperature threshold point caused by the fluctuation of the bias current.

[0021] (3) The over-temperature protection point can be set by adjusting the bias current and the voltage divider resistor ratio, and the temperature hysteresis value can be set by adjusting the size of M12 and M13 of the voltage comparison circuit. The adjustment is convenient and increases the flexibility of the application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the main circuit modules of the high-side switch chip in the prior art;

[0023] Figure 2 A schematic diagram of an over-temperature protection circuit with temperature hysteresis for a high-side switch chip according to an embodiment of the utility model;

[0024] Figure 3 The figure is a working waveform diagram of an over-temperature protection circuit with temperature hysteresis for a high-side switch chip in a specific application example. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0026] Reference Figure 1 , showing an over-temperature protection circuit with temperature hysteresis for a high-side switch chip and a high-side switch according to an embodiment of the utility model chip The key signal connection relationships of other circuits are as follows: Figure 1 As shown, the over-temperature protection circuit with temperature hysteresis for the high-side switch chip receives the voltage source VDD from the low dropout regulator (LDO) circuit, and receives the bias current IBIAS from the bias circuit, and generates an over-temperature protection signal (OTP) which is output to the drive control circuit.

[0027] According to the above-described embodiment of the utility model, the over-temperature protection circuit with temperature hysteresis for the high-side switch chip is as follows: Figure 2 As shown, it includes a reference voltage circuit 1, a temperature detection circuit 2, a voltage comparison circuit 3 and a hysteresis output circuit 4; wherein the reference voltage circuit 1 is used to divide the power supply voltage by a series resistor to generate a reference voltage VREF; the temperature detection circuit 2 is used to receive a bias current IBIAS from a bias current module of a high-side switch chip, and to operate a temperature sensing element to generate a temperature sensing voltage according to the bias current IBIAS; the non-inverting input terminal of the voltage comparison circuit receives the temperature sensing voltage, and the negative phase input terminal of the voltage comparison circuit receives the reference voltage; the voltage comparison circuit is used to compare the temperature sensing voltage and the reference voltage, and to generate a first logic signal and a second logic signal according to the comparison result; the hysteresis output circuit 4 is used to receive the first logic signal and the second logic signal, and to generate an over-temperature protection signal OTP with hysteresis after signal shaping and RS latching.

[0028] Further references Figure 2 In the embodiment of the utility model, the reference voltage circuit 1 of the over-temperature protection circuit with temperature hysteresis for the high-side switch chip is set in a manner of at least two resistors connected in series. In the figure, two resistors R1 and R2 are taken in series as an example. VREF is obtained by dividing the voltage source VDD by the resistors R1 and R2, which serves as the temperature comparison threshold point of the over-temperature protection.

[0029] Further references Figure 2The temperature detection circuit 2 of the over-temperature protection circuit with temperature hysteresis for the high-side switch chip of the embodiment of the utility model comprises a first PMOS tube M1, a second PMOS tube M2, a resistor R3, a first transistor Q1 and a bias current IBIAS provided by the bias circuit inside the chip. The first transistor Q1 is a PNP transistor; the base and the collector of the first transistor are grounded and connected, the first PMOS tube M1 and the second PMOS tube M2 form a current mirror structure to provide a constant bias current for the first transistor Q1, one end of the third resistor R3 is connected to the drain of the second PMOS tube, and the other end of the third resistor R3 is connected to the emitter of the first transistor Q1.

[0030] Further references Figure 2 The voltage comparison circuit 3 of the over-temperature protection circuit with temperature hysteresis for the high-side switch chip of the embodiment of the utility model includes a third PMOS tube M3, a fourth PMOS tube M4, a fifth PMOS tube M5, a sixth PMOS tube M11, a seventh PMOS tube M12, an eighth PMOS tube M13, a first NMOS tube M6, a second NMOS tube M7, a third NMOS tube M8, a fourth NMOS tube M9, a fifth NMOS tube M10 and a sixth NMOS tube M14. The gate of the fourth PMOS tube serves as the non-inverting input terminal of the voltage comparator circuit and is connected to the output terminal of the temperature detection circuit; the gate of the fifth PMOS tube serves as the inverting input terminal of the voltage comparison circuit and is connected to the reference voltage VREF. Furthermore, the fourth NMOS tube M9 and the fifth NMOS tube M10 have the same width-to-length ratio; the width-to-length ratio of the eighth PMOS tube M13 is slightly larger than that of the seventh PMOS tube M12, so as to realize the temperature hysteresis function; the drain of the seventh PMOS tube M12 and the drain of the fourth NMOS tube M9 are connected as the first logic signal A output terminal; the drain of the eighth PMOS tube M13 and the drain of the fifth NMOS tube M10 are connected as the second logic signal B output terminal. When the chip temperature is lower than the over-temperature protection point, the voltage of the in-phase input terminal of the comparator circuit is greater than the inverting input terminal, and both the first logic signal and the second logic signal output a high level; when the chip temperature is high, so that the voltage of the in-phase input terminal of the comparator circuit is less than the inverting input terminal, the first logic signal will become a low level, and the second logic signal will remain a high level; if the chip temperature continues to rise by several degrees Celsius, both the first logic signal and the second logic signal output a low level.

[0031] Further references Figure 2The hysteresis output circuit 4 of the over-temperature protection circuit with temperature hysteresis for the high-side switch chip of the embodiment of the utility model includes a first inverter INV1, a second inverter INV2, a third inverter INV3 and an RS latch RSFF. Further, the input end of the first inverter INV1 is connected to the second logic signal, and the output end of the first inverter INV1 is connected to the set end of the RS latch RSFF; the second inverter INV2 and the third inverter INV3 are connected in series, the input end of the second inverter INV2 is connected to the second logic signal, and the output end of the third inverter INV3 is connected to the reset end of the RS latch RSFF; the state output end of the RS latch RSFF outputs the OTP signal. The inverter realizes the signal shaping of the first logic signal A and the second logic signal B, and increases the driving capability of the inverter. The latch RSFF realizes the hysteresis output of the over-temperature protection signal. The output OTP signal is connected to the chip's drive control circuit. The drive control circuit performs current limiting, output shutdown and other operations according to the OTP level to prevent the chip from further heating up and achieve over-temperature protection for the chip.

[0032] In the over-temperature protection circuit with temperature hysteresis for the high-side switch chip set above, the first transistor Q1 is placed near the power tube of the high-side switch chip, and serves as a temperature sensing element when the high-side switch chip is working. Because its base and collector are grounded, the voltage drop from the emitter to the collector decreases with the increase of temperature. Therefore, the influence of the temperature of the high-side switch chip is reflected in the emitter voltage of Q1 acting on the gate voltage of M4 in the voltage comparison circuit 3. A constant bias current is provided to the transistor Q1 through the current mirror structure of M1 and M2, avoiding the fluctuation of the over-temperature threshold point caused by the fluctuation of the bias current.

[0033] Further, Figure 3 The figure shows a typical working waveform of the over-temperature protection circuit with temperature hysteresis for high-side switch chip of the embodiment of the present invention, where the temperature is scanned from 20°C to 200°C, and then from 200°C to 20°C. The working principle of the circuit is as follows:

[0034] (1) Temperature rise stage: When the high-side switch chip is powered on, the chip operating temperature is at room temperature, the emitter voltage of Q1 in the temperature detection circuit 2 is higher than the VREF voltage, the first logic signal A and the second logic signal B in the voltage comparison circuit 3 both output high level, the OTP signal output after shaping by the hysteresis output circuit 4 is low level, and the drive control circuit performs normal conduction work on the load. In a specific application example, the load can be a car light, a door lock, a motor, etc. As the power tube of the high-side switch chip continues to work, the temperature of Q1 is also higher than when it is started, and the voltage reflected on the emitter also decreases, but is still higher than VREF. When the load is too large or the load is short-circuited, the temperature continues to rise, and the voltage on the emitter of Q1 continues to decrease until it is lower than VREF. The first logic signal A in the voltage comparison circuit 3 begins to change from high level to low level, the second logic signal B level is still high level, and OTP still outputs low level. At this time, the temperature is 168℃. The chip temperature continues to rise, and when it reaches 175°C, the level of the second logic signal B also begins to change from high level to low level, causing OTP to also change from low level to high level, triggering the subsequent drive control circuit to perform protection operations to prevent the temperature from continuing to rise.

[0035] (2) Temperature drop stage: After executing current limiting, output shutdown and other operations, the chip temperature begins to drop, and the emitter voltage of Q1 in the temperature detection circuit 2 gradually rises. When the temperature is lower than 175°C, the second logic control signal B in the voltage comparison circuit 3 changes from low level to high level, the first logic control signal A is still low level, and the OTP signal of the temperature hysteresis output circuit 4 maintains the previous state and is still high level. The chip temperature continues to drop. When it drops to 168°C, the emitter voltage of Q1 rises to a voltage higher than VREF voltage, and point A in the voltage comparison circuit 3 changes from low level to high level, so that OTP also changes from high level to low level, and the subsequent drive control circuit resumes normal operation. By setting the temperature when the first landing control signal A and the second logic control signal B are flipped, a hysteresis range of 175°C-168°C=7°C is achieved. The chip temperature protection interval can be adjusted by the parameter values ​​of the bias current IBIAS, the voltage divider resistors R1, R2 and M12, M13 in the circuit design.

[0036] From the above description, it can be known that in the over-temperature protection circuit with temperature hysteresis for the high-side switch chip of the embodiment of the utility model, the voltage at the inverting input end of the voltage comparison circuit is obtained by dividing the VDD voltage generated by the LDO circuit of the high-side switch through a series resistor, and its value is not affected by temperature and process, so that the over-temperature protection point has a high stability. The bias current of the temperature detection circuit comes from the bias current generated by the bias circuit of the high-side switch, which effectively avoids the fluctuation of the over-temperature threshold point caused by the fluctuation of the bias current. The over-temperature protection point can be set by adjusting the bias current and the voltage divider resistor ratio, and the temperature hysteresis value can be set by adjusting the size of M12 and M13 of the voltage comparison circuit, which is convenient to adjust and increases the flexibility of application.

[0037] It should be understood that the exemplary embodiments described herein are illustrative rather than restrictive. Although one or more embodiments of the present invention are described in conjunction with the accompanying drawings, it should be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

1. An over-temperature protection circuit with temperature hysteresis for a high-side switch chip, characterized in that: It includes a reference voltage circuit, a temperature detection circuit, a voltage comparison circuit and a hysteresis output circuit; The reference voltage circuit is used to divide the power supply voltage by using series resistors to generate a reference voltage; The temperature detection circuit is used to receive the bias current of the bias current module from the high-side switch chip, and to operate the temperature sensing element to generate a temperature sensing voltage according to the bias current; The non-inverting input terminal of the voltage comparison circuit receives the temperature sensing voltage, the negative-inverting input terminal of the voltage comparison circuit receives the reference voltage, the voltage comparison circuit is used to compare the temperature sensing voltage with the reference voltage, and generate a first logic signal and a second logic signal according to the comparison result; The hysteresis output circuit is used to receive the first logic signal and the second logic signal, and generate an over-temperature protection signal with hysteresis after signal shaping and RS latching.

2. The over-temperature protection circuit with temperature hysteresis for a high-side switch chip according to claim 1, characterized in that: The reference voltage circuit is arranged in a manner of at least two resistors connected in series.

3. The over-temperature protection circuit with temperature hysteresis for a high-side switch chip according to claim 1, characterized in that: The temperature detection circuit includes a first PMOS tube M1, a second PMOS tube M2, a resistor R3, a first transistor Q1 and a bias current IBIAS provided by a bias circuit inside the chip.

4. The over-temperature protection circuit with temperature hysteresis for a high-side switch chip according to claim 3, characterized in that: The first transistor Q1 is a PNP transistor, the base and collector of the first transistor are grounded and connected, the first PMOS tube M1 and the second PMOS tube M2 form a current mirror structure to provide a constant bias current for the first transistor Q1, one end of the third resistor R3 is connected to the drain of the second PMOS tube, and the other end of the third resistor R3 is connected to the emitter of the first transistor Q1.

5. The over-temperature protection circuit with temperature hysteresis for a high-side switch chip according to claim 1, characterized in that: The voltage comparison circuit includes a third PMOS tube M3, a fourth PMOS tube M4, a fifth PMOS tube M5, a sixth PMOS tube M11, a seventh PMOS tube M12, an eighth PMOS tube M13, a first NMOS tube M6, a second NMOS tube M7, a third NMOS tube M8, a fourth NMOS tube M9, a fifth NMOS tube M10 and a sixth NMOS tube M14. The gate of the fourth PMOS tube serves as a non-inverting input terminal of the voltage comparator circuit and is connected to the output terminal of the temperature detection circuit; the gate of the fifth PMOS tube serves as an inverting input terminal of the voltage comparison circuit and is connected to a reference voltage VREF.

6. The over-temperature protection circuit with temperature hysteresis for a high-side switch chip according to claim 5, characterized in that: The fourth NMOS tube M9 and the fifth NMOS tube M10 have the same width-to-length ratio; the width-to-length ratio of the eighth PMOS tube M13 is slightly larger than that of the seventh PMOS tube M12, and is used to realize the temperature hysteresis function; the drain of the seventh PMOS tube M12 and the drain of the fourth NMOS tube M9 are connected as the first logic signal terminal output; the drain of the eighth PMOS tube M13 and the drain of the fifth NMOS tube M10 are connected as the second logic signal output terminal. When the chip temperature is lower than the over-temperature protection point, the voltage of the in-phase input terminal of the comparator circuit is greater than the inverting input terminal, and the first logic signal and the second logic signal both output a high level; when the chip temperature is high, so that the voltage of the in-phase input terminal of the comparator circuit is less than the inverting input terminal, the first logic signal will become a low level, and the second logic signal will remain a high level; if the chip temperature continues to rise by several degrees Celsius, the first logic signal and the second logic signal will both output a low level.

7. The over-temperature protection circuit with temperature hysteresis for a high-side switch chip according to claim 6, characterized in that: The hysteresis output circuit includes a first inverter INV1, a second inverter INV2, a third inverter INV3 and an RS latch RSFF.

8. The over-temperature protection circuit with temperature hysteresis for a high-side switch chip according to claim 7, characterized in that: An input end of the first inverter INV1 is connected to a second logic signal, and an output end of the first inverter INV1 is connected to a set end of the RS latch RSFF; The second inverter INV2 and the third inverter INV3 are connected in series, the input end of the second inverter INV2 is connected to the second logic signal, the output end of the third inverter INV3 is connected to the reset end of the RS latch RSFF; the state output end of the RS latch RSFF outputs the OTP signal.

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