An over-temperature detection circuit and a high-side switch

Abstract

The present invention relates to the technical field of high-side switches, and discloses an over-temperature detection circuit and a high-side switch. The over-temperature detection circuit comprises a resistor R1, a current source IREF1, a current source IREF2, a comparator Comp1, a comparator Comp2, a diode D1 for detecting the temperature of a power tube of the high-side switch, and a diode D2 placed on the periphery of a chip. In actual use, the over-temperature detection circuit realizes temperature detection of the power tube through the diode D1, the current source IREF1 and the comparator Comp1, and realizes temperature difference detection inside and outside the chip through the resistor R1, the diode D2, the comparator Comp2 and the current source IREF2, so that temperature detection of two requirements can be realized through only one over-temperature detection circuit.

Description

Technical Field

[0001] The invention relates to the technical field of high side switches, and in particular to an over-temperature detection circuit and a high side switch. Background Art

[0002] Intelligent high-side power switch is one of the typical applications of intelligent power integrated circuits. It adds more functions based on the simple switch structure and is used to replace traditional contact circuit breakers, thermal relays, electromechanical circuit breakers and other components, avoiding arcing, contact wear and welding caused by traditional components. The specific application diagram is as follows Figure 1 As shown, Figure 1 The dotted box area in the figure is the structure of the high-side switch, which integrates the drive circuit, control circuit, detection and protection circuit and power device;

[0003] for Figure 1 In actual use, the input signal IN is converted into an internal level signal of the chip through the interface circuit, and the logic control circuit controls the driving circuit to turn on the power tube M100, so that the voltage at the OUT terminal rises to a value close to the power supply voltage VBB, and the power supply voltage VBB supplies power to the load. During this period, the detection and protection circuit detects over-temperature, over-voltage, etc. of the power tube M100, and protects the power tube M100 in time when abnormal working conditions occur.

[0004] For high-side switches, over-temperature detection and protection is one of the necessary key functions. It can detect the operating temperature of the power tube M100 in time, and convert the temperature signal into an electrical signal and transmit it to the logic control circuit before the operating temperature rises to affect the normal operation and reliability of the power tube M100. The logic control circuit then adjusts the drive circuit to quickly shut down the power tube M100 to reduce the temperature.

[0005] Most of the existing over-temperature detection and protection circuits use the temperature characteristics of the forward-biased PN junction's on-voltage to compare with a reference voltage to achieve detection. During the detection process, the current flowing through the PN junction is controlled to remain unchanged. When the temperature rises, the on-voltage drop across the forward-biased PN junction decreases; when the on-voltage drop decreases, the comparator input voltage increases, and the detection point voltage is higher than the reference voltage, the comparator output result is triggered to flip, and then the over-temperature signal is transmitted to the logic control circuit. The principle is as follows: Figure 2 shown.

[0006] exist Figure 2 In the figure, the current flowing through the diode D1 is determined by the current source IREF, which does not change with temperature. According to the current formula of the forward biased PN junction: , the forward conduction voltage drop formula can be reversed: ; Where I is the current source IREF, k is the Boltzmann constant, q is the elementary charge, IS is the reverse saturation current, and the forward conduction voltage drop at normal temperature shows a negative temperature characteristic. The temperature rise reduces the voltage drop across the diode D1, and the voltage VA at point A increases. When the VA voltage is greater than the reference voltage VREF, the over-temperature protection is triggered, the comparator output changes from high to low, and the voltage signal is transmitted to the logic control circuit.

[0007] for Figure 2 The detection method of the circuit shown is also called over-temperature protection under absolute temperature conditions, that is, when the temperature of the detection diode D1 reaches an absolute temperature threshold, the over-temperature protection is triggered. This requires that the detection diode D1 must be close to the power device to accurately reflect the operating temperature of the power device, and at the same time avoid the over-temperature shutdown delay caused by heat transfer.

[0008] In addition, in the actual use of high-side switches, it is not only the absolute temperature of the power device that affects the reliability of the high-side power switch, but also the temperature difference between the inside and outside of the chip can also cause the overall failure of the circuit system. With the development of integrated circuit process technology, the power density of high-side power switches is very high. Instantaneous surges or load short circuits will cause the temperature of the power device to rise rapidly. Since the thermal conductivity of silicon materials decreases with increasing temperature, positive feedback of heat transfer is generated. The rapid heating of power devices will cause a large temperature gradient inside and outside the chip, thereby forming a large thermomechanical stress. Due to the mismatch of thermal expansion coefficients of different materials, thermomechanical stress is more likely to act on the interface of different materials. When the thermomechanical stress exceeds a certain level, it will cause peeling and delamination at the interface. At the same time, it may also cause changes in the internal metal structure and degradation of the power metal (Bonding material), which will jointly lead to the reliability and life of the high-side power switch. Therefore, only detecting the absolute temperature cannot completely solve the temperature protection problem of the high-side power switch. Summary of the invention

[0009] In view of the shortcomings of the background technology, the present invention provides an over-temperature detection circuit and a high-side switch. The technical problem to be solved is that the existing over-temperature detection circuit for high-side switches can only perform absolute temperature detection of the power tube, but cannot perform temperature detection protection of the temperature difference between the inside and outside of the chip.

[0010] To solve the above technical problems, in a first aspect, the present invention provides the following technical solutions: an over-temperature detection circuit, comprising a resistor R1, a current source IREF1, a current source IREF2, a comparator Comp1, a comparator Comp2, a diode D1 for detecting the temperature of a power tube of a high-side switch, and a diode D2 placed on the periphery of a chip;

[0011] The anode of the diode D1 and the anode of the diode D2 are used to connect to the power supply VCC;

[0012] The cathode of the diode D1 is electrically connected to one end of the resistor R1 and the negative input terminal of the comparator Comp1 respectively, and the positive input terminal of the comparator Comp1 is used to input a reference voltage VREF;

[0013] The cathode of the diode D2 is electrically connected to the positive input terminal of the comparator Comp2 and the current source IREF2 respectively;

[0014] The other end of the resistor R1 is electrically connected to the current source IREF1 and the negative input terminal of the comparator Comp2 respectively.

[0015] In a certain embodiment of the first aspect, the present invention also includes a threshold current generating circuit, which is electrically connected to both ends of the resistor R1 and is used to generate a current I1 flowing out of one end of the resistor R1 and a current I2 input to the other end of the resistor R1.

[0016] In a certain implementation manner of the first aspect, the current I1 is equal to the current I2, and both the current I1 and the current I2 are proportional to the source-drain voltage difference of the power tube of the high-side switch.

[0017] In a certain implementation manner of the first aspect, the threshold current generating circuit includes MOS transistors M12-M18 and a resistor R2;

[0018] The source of the MOS tube M12, the source of the MOS tube M13, the source of the MOS tube M17 and the source of the MOS tube M18 are all electrically connected to the power supply VCC, the gate of the MOS tube M12 is electrically connected to the gate of the MOS tube M13, the drain of the MOS tube M12 and the source of the MOS tube M11 respectively, the gate of the MOS tube M11 is used to input the control signal IN_N, and the drain of the MOS tube M11 is electrically connected to the output end of the power tube of the high-side switch through the resistor R2;

[0019] The drain of the MOS tube M13 is electrically connected to the drain of the MOS tube M14, the gate of the MOS tube M14, the gate of the MOS tube M15 and the gate of the MOS tube M16 respectively, and the source of the MOS tube M14, the source of the MOS tube M15 and the source of the MOS tube M16 are all grounded;

[0020] The drain of the MOS tube M15 is electrically connected to the drain of the MOS tube M17, the gate of the MOS tube M17 and the gate of the MOS tube M18 respectively; the drain of the MOS tube M16 is electrically connected to one end of the resistor R1, and the drain of the MOS tube M18 is electrically connected to the other end of the resistor R1.

[0021] In a certain implementation of the first aspect, the present invention further includes a current adjustment circuit, which is electrically connected to both ends of the resistor R1 and is used to adjust the magnitude of the current flowing through the resistor R1.

[0022] In a certain implementation manner of the first aspect, the current adjustment circuit includes MOS transistors M1-M10 and a current source IREF3;

[0023] The source of the MOS tube M9 and the source of the MOS tube M10 are both electrically connected to the power supply VCC, the gate of the MOS tube M9 is electrically connected to the gate of the MOS tube M10, the drain of the MOS tube M9 and the drain of the MOS tube M8 respectively, the drain of the MOS tube M10 is electrically connected to the other end of the resistor R1, and the drain of the MOS tube M6 is electrically connected to one end of the resistor R1;

[0024] The gate of the MOS tube M6 is electrically connected to the gate of the MOS tube M8, and is used to input a control signal ABC_OTP_N. The control signal ABC_OTP_N and the output signal of the comparator Comp1 are two opposite signals.

[0025] The source of the MOS tube M6 is electrically connected to the drain of the MOS tube M5, the source of the MOS tube M8 is electrically connected to the drain of the MOS tube M7, the gate of the MOS tube M5 is electrically connected to the gate of the MOS tube M7, and is used to input the output signal DYN_OTP of the comparator Comp2, the source of the MOS tube M5 is electrically connected to the drain of the MOS tube M2, the source of the MOS tube M7 is electrically connected to the drain of the MOS tube M3, the source of the MOS tube M1, the source of the MOS tube M2, the source of the MOS tube M3 and the source of the MOS tube M4 are all grounded, the gate of the MOS tube M1 is electrically connected to the gate of the MOS tube M2, the gate of the MOS tube M3, the gate of the MOS tube M4, the drain of the MOS tube M1 and the current source IREF3 respectively; the MOS tube M4 is the current source IREF1, and the drain of the MOS tube M4 is electrically connected to the other end of the resistor R1.

[0026] In a certain implementation manner of the first aspect, the comparator Coomp1 includes MOS tubes M19-M29, an inverter INV1 and an inverter INV2;

[0027] The source of the MOS tube M22, the source of the MOS tube M23 and the source of the MOS tube M29 are all electrically connected to the power supply VCC; the gate of the MOS tube M22 is electrically connected to the gate of the MOS tube M23, the drain of the MOS tube M22 and the drain of the MOS tube M24 respectively, and the gate of the MOS tube M24 is the negative input terminal of the comparator Comp1; the drain of the MOS tube M23 is electrically connected to the gate of the MOS tube M29, the drain of the MOS tube M27, the source of the MOS tube M28 and the drain of the MOS tube M25 respectively, and the gate of the MOS tube M25 is electrically connected to the gate of the MOS tube M26, which is the positive input terminal of the comparator Comp1; the source of the MOS tube M27 and the drain of the MOS tube M28 are all electrically connected to the drain of the MOS tube M26, the gate of the MOS tube M27 is electrically connected to the input terminal of the inverter INV2, and the gate of the MOS tube M28 is electrically connected to the input terminal of the inverter INV2;

[0028] The source of the MOS tube M24 is electrically connected to the source of the MOS tube M25, the source of the MOS tube M26 and the drain of the MOS tube M20 respectively, and the source of the MOS tube M19, the source of the MOS tube M20 and the source of the MOS tube M21 are all grounded; the gate of the MOS tube M19 is electrically connected to the drain of the MOS tube M19, the current source IREF4, the gate of the MOS tube M20 and the gate of the MOS tube M21 respectively; the drain of the MOS tube M29 is electrically connected to the drain of the MOS tube M21 and the input end of the inverter INV1 respectively, and the output end of the inverter INV1 is electrically connected to the input end of the inverter INV2.

[0029] In a certain implementation of the first aspect, the MOS tube M24, the MOS tube M25 and the MOS tube M26 have the same length, and the sum of the widths of the MOS tube M25 and the MOS tube M26 is the same as the width of the MOS tube M24.

[0030] In a certain implementation manner of the first aspect, the comparator Coomp2 includes MOS tubes M30-M37, inverters INV3 and INV4;

[0031] The source of the MOS tube M33, the source of the MOS tube M34 and the source of the MOS tube M37 are all used to be electrically connected to the power supply VCC, the gate of the MOS tube M33 is electrically connected to the gate of the MOS tube M34, the drain of the MOS tube M33 and the drain of the MOS tube M35 respectively, the drain of the MOS tube M34 is electrically connected to the gate of the MOS tube M37 and the drain of the MOS tube M36 respectively; the gate of the MOS tube M35 is the negative input terminal of the comparator Comp2, the gate of the MOS tube M36 is the positive input terminal of the comparator Comp2; the source of the MOS tube M35 and the MOS The source of the MOS tube M36 is electrically connected to the drain of the MOS tube M31; the gate of the MOS tube M31 is electrically connected to the gate of the MOS tube M32, the gate of the MOS tube M30, the drain of the MOS tube M30 and the current source IREF5 respectively; the source of the MOS tube M30, the source of the MOS tube M31 and the source of the MOS tube M32 are all grounded; the drain of the MOS tube M32 is electrically connected to the drain of the MOS tube M37 and the input end of the inverter INV3 respectively; the output end of the inverter INV3 is electrically connected to the input end of the inverter INV4, for outputting the signal DYN_OTP.

[0032] In a second aspect, the present invention provides a high-side switch, including the above-mentioned over-temperature detection circuit, and also including an interface circuit, a logic control circuit, a drive circuit and a power tube, the logic control circuit is electrically connected to the interface circuit, and the control signal transmitted by the interface circuit controls the drive circuit to drive the power tube to turn on, the logic control circuit is electrically connected to the output end of the comparator Comp1 and the output end of the comparator Comp2 of the over-temperature detection circuit, and the power tube is turned off through the drive circuit based on the output signal of the comparator Comp1 and the output signal of the comparator Comp2.

[0033] Compared with the prior art, the present invention has the following beneficial effects: in actual use, the over-temperature detection circuit of the present invention realizes the temperature detection of the power tube through the diode D1, the current source IREF1 and the comparator Comp1, and the over-temperature detection circuit of the present invention realizes the temperature difference detection inside and outside the chip through the resistor R1, the diode D2, the comparator Comp2 and the current source IREF2, so that the temperature detection of two requirements can be realized by only one over-temperature detection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of existing high-side switch applications;

[0035] Figure 2 is a schematic diagram of an existing over-temperature detection circuit;

[0036] Figure 3 is a circuit diagram of an over-temperature detection circuit in an embodiment;

[0037] Figure 4 is a circuit diagram of a threshold current generating circuit in an embodiment;

[0038] Figure 5 is a circuit diagram of a current regulating circuit in an embodiment;

[0039] Figure 6 is a circuit diagram of a comparator Comp1 in the embodiment;

[0040] Figure 7 is a circuit diagram of a comparator Comp2 in the embodiment;

[0041] Figure 8 Schematic diagram of the structure of the high side switch in the second embodiment. DETAILED DESCRIPTION

[0042] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0043] Embodiment 1

[0044] like Figure 3 As shown, an over-temperature detection circuit includes a resistor R1, a current source IREF1, a current source IREF2, a comparator Comp1, a comparator Comp2, a diode D1 for detecting the temperature of a power tube of a high-side switch, and a diode D2 placed on the periphery of a chip;

[0045] The anode of the diode D1 and the anode of the diode D2 are used to connect to the power supply VCC;

[0046] The cathode of the diode D1 is electrically connected to one end of the resistor R1 and the negative input terminal of the comparator Comp1 respectively, and the positive input terminal of the comparator Comp1 is used to input a reference voltage VREF;

[0047] The cathode of the diode D2 is electrically connected to the positive input terminal of the comparator Comp2 and the current source IREF2 respectively;

[0048] The other end of the resistor R1 is electrically connected to the current source IREF1 and the negative input terminal of the comparator Comp2 respectively.

[0049] for Figure 3 In the circuit shown, the diode D1, the current source IREF1 and the comparator Comp1 realize the absolute temperature detection of the power tube, and the resistor R1, the diode D2, the comparator Comp2 and the current source IREF2 realize the temperature difference detection between the inside and outside of the chip, so that two temperature detection requirements can be realized by only one over-temperature detection circuit. Specifically, two temperature detections can be performed according to the output signals of the comparator Comp1 and the comparator Comp2.

[0050] In actual use, the comparator Comp2 converts the voltage V B Compared with the electrical signal reflecting the chip's peripheral temperature, that is, the cathode voltage of diode D1, V B The voltage at node A is V A The voltage drop on resistor R1 is reduced by the reference current IREF1 multiplied by the resistance value of resistor R1. When the internal temperature of the chip rises, the voltage drop on R1 remains unchanged. V B With V A The temperature rises synchronously with the rise of the chip. When the temperature difference between the inside and outside of the chip is too large, the output signal of the comparator Comp2 flips. According to the principle, the voltage drop on the resistor R1 reflects the threshold of the over-temperature protection triggered by the internal and external temperature difference, that is, the threshold of the dynamic over-temperature protection can be adjusted by adjusting the voltage drop on R.

[0051] for Figure 3 The circuit shown, in actual use, can adjust the setting of the temperature difference detection threshold between the inside and outside of the chip by providing a current flowing from node A and providing a current flowing to node B. In order to achieve this function, in this embodiment, the present invention also includes a threshold current generating circuit, which is electrically connected to both ends of the resistor R1 and is used to generate a current I1 flowing from one end of the resistor R1 and a current I2 input to the other end of the resistor R1.

[0052] Furthermore, the current I1 is equal to the current I2, and both the current I1 and the current I2 are proportional to the source-drain voltage difference of the power tube of the high-side switch.

[0053] Through the current I1 and current I2 Figure 3 The circuit shown is analyzed as follows:

[0054] When current I1 is set, current IREF1 flowing through resistor R1 becomes IREF1-I1, thereby reducing the voltage drop on resistor R1 and lowering the internal and external temperature difference threshold of dynamic over-temperature protection. However, current flowing through diode D1 is still IREF1 and does not affect the threshold point of absolute temperature triggering over-temperature protection.

[0055] During the use of the chip, when a surge occurs or the load is suddenly short-circuited, the power tube is prone to rapid heating due to a large current in a short period of time, resulting in a rapid increase in the internal and external temperature difference. At this time, the source-drain voltage difference of the power tube will also increase, and the current values ​​of current I1 and current I2 are designed to be proportional to the source-drain voltage difference of the power tube, that is, when a surge occurs or the load is short-circuited, the values ​​of current I1 and current I2 will also increase, and the dynamic over-temperature protection threshold will be reduced, making it easier to trigger the dynamic over-temperature protection, thereby avoiding a surge in the internal and external temperature difference caused by surges and load short-circuits. In addition, during this process, the absolute over-temperature protection is always working, that is, the over-temperature protection will be directly triggered when the operating temperature of the power tube exceeds the threshold.

[0056] Specifically, in this embodiment, Figure 4 As shown, the threshold current generating circuit includes MOS tubes M12-M18 and a resistor R2;

[0057] The source of the MOS tube M12, the source of the MOS tube M13, the source of the MOS tube M17 and the source of the MOS tube M18 are all electrically connected to the power supply VCC, the gate of the MOS tube M12 is electrically connected to the gate of the MOS tube M13, the drain of the MOS tube M12 and the source of the MOS tube M11 respectively, the gate of the MOS tube M11 is used to input the control signal IN_N, and the drain of the MOS tube M11 is electrically connected to the output end of the power tube of the high-side switch through the resistor R2;

[0058] The drain of the MOS tube M13 is electrically connected to the drain of the MOS tube M14, the gate of the MOS tube M14, the gate of the MOS tube M15 and the gate of the MOS tube M16 respectively, and the source of the MOS tube M14, the source of the MOS tube M15 and the source of the MOS tube M16 are all grounded;

[0059] The drain of the MOS tube M15 is electrically connected to the drain of the MOS tube M17, the gate of the MOS tube M17 and the gate of the MOS tube M18 respectively; the drain of the MOS tube M16 is electrically connected to one end of the resistor R1 to provide a current I1 flowing out of one end of the resistor R1, and the drain of the MOS tube M18 is electrically connected to the other end of the resistor R1 to provide a current I2.

[0060] for Figure 4 As shown in the circuit, MOS tube M11 is a switch tube, resistor R2 is a current limiting current, MOS tube M12 and MOS tube M13 form a current mirror, MOS tube M14, MOS tube M15 and MOS tube M16 form a current mirror, and MOS tube M17 and MOS tube M18 form a current mirror. In actual use, by controlling the current copy ratio of the current mirror, the current I1 and the current I2 can be made the same. In addition, when the control signal IN_N is at a low level, the MOS tube M11 is turned on, and the power tube is turned on to make the OUT terminal voltage rise to a value close to VCC. The source-drain voltage difference of the power tube is the voltage difference between VCC and OUT. When the source-drain voltage difference increases, the voltage difference from VCC to OUT increases, and the current I1 and the current I2 will also increase, which meets the function setting of adjusting the dynamic over-temperature protection threshold when a surge or load short circuit occurs.

[0061] When the threshold current generating circuit is applied to the high-side switch, when the high-side switch receives a start signal, the control signal IN_N can be set to a low level, thereby turning on the MOS tube M11.

[0062] In addition, in this embodiment, in order to adjust the dynamic over-temperature protection threshold according to demand, the present invention further includes a current adjustment circuit, which is electrically connected to both ends of the resistor R1 and is used to adjust the current flowing through the resistor R1.

[0063] Specifically, in this embodiment, the circuit of the current adjustment circuit is as follows: Figure 5 As shown, it includes MOS tubes M1-MOS tubes M10 and a current source IREF3;

[0064] The source of the MOS tube M9 and the source of the MOS tube M10 are both electrically connected to the power supply VCC, the gate of the MOS tube M9 is electrically connected to the gate of the MOS tube M10, the drain of the MOS tube M9 and the drain of the MOS tube M8 respectively, the drain of the MOS tube M10 is electrically connected to the other end of the resistor R1, and the drain of the MOS tube M6 is electrically connected to one end of the resistor R1;

[0065] The gate of the MOS tube M6 is electrically connected to the gate of the MOS tube M8, and is used to input a control signal ABC_OTP_N. The control signal ABC_OTP_N and the output signal of the comparator Comp1 are two opposite signals.

[0066] The source of the MOS tube M6 is electrically connected to the drain of the MOS tube M5, the source of the MOS tube M8 is electrically connected to the drain of the MOS tube M7, the gate of the MOS tube M5 is electrically connected to the gate of the MOS tube M7, and is used to input the output signal DYN_OTP of the comparator Comp2, the source of the MOS tube M5 is electrically connected to the drain of the MOS tube M2, the source of the MOS tube M7 is electrically connected to the drain of the MOS tube M3, the source of the MOS tube M1, the source of the MOS tube M2, the source of the MOS tube M3 and the source of the MOS tube M4 are all grounded, the gate of the MOS tube M1 is electrically connected to the gate of the MOS tube M2, the gate of the MOS tube M3, the gate of the MOS tube M4, the drain of the MOS tube M1 and the current source IREF3 respectively; the MOS tube M4 is the current source IREF1, and the drain of the MOS tube M4 is electrically connected to the other end of the resistor R1.

[0067] for Figure 5 In the circuit shown, MOS tubes M1 to M4 form a current mirror, MOS tubes M9 and M10 form a current mirror, and MOS tubes M5 to M8 are switch tubes.

[0068] In actual use, when the over-temperature protection is not triggered, the control signal ABS_OTP_N is high level, that is, the output signal of the comparator Comp1 is low level, and the signal DYN_OTP is low level; the MOS tube M5 and the MOS tube M7 are turned off;

[0069] When the dynamic over-temperature protection is triggered, the signal DYN_OTP flips to a high level. At this time, the current flowing through the resistor R1 decreases, and the dynamic over-temperature protection threshold changes. Hysteresis is established for the dynamic over-temperature protection to avoid thermal oscillation. The current I1 and the current I2 are provided by the threshold current generation circuit and are used to adjust the dynamic over-temperature protection threshold according to the source-drain voltage difference of the power tube.

[0070] Specifically, in this embodiment, the circuit of the comparator Coomp1 is as follows: Figure 6 As shown, it includes MOS tubes M19-MOS tubes M29, inverters INV1 and INV2;

[0071] The source of the MOS tube M22, the source of the MOS tube M23 and the source of the MOS tube M29 are all electrically connected to the power supply VCC; the gate of the MOS tube M22 is electrically connected to the gate of the MOS tube M23, the drain of the MOS tube M22 and the drain of the MOS tube M24 respectively, and the gate of the MOS tube M24 is the negative input terminal of the comparator Comp1; the drain of the MOS tube M23 is electrically connected to the gate of the MOS tube M29, the drain of the MOS tube M27, the source of the MOS tube M28 and the drain of the MOS tube M25 respectively, and the gate of the MOS tube M25 is electrically connected to the gate of the MOS tube M26, which is the positive input terminal of the comparator Comp1; the source of the MOS tube M27 and the drain of the MOS tube M28 are all electrically connected to the drain of the MOS tube M26, the gate of the MOS tube M27 is electrically connected to the input terminal of the inverter INV2, and the gate of the MOS tube M28 is electrically connected to the input terminal of the inverter INV2;

[0072] The source of the MOS tube M24 is electrically connected to the source of the MOS tube M25, the source of the MOS tube M26 and the drain of the MOS tube M20 respectively, and the source of the MOS tube M19, the source of the MOS tube M20 and the source of the MOS tube M21 are all grounded; the gate of the MOS tube M19 is electrically connected to the drain of the MOS tube M19, the current source IREF4, the gate of the MOS tube M20 and the gate of the MOS tube M21 respectively; the drain of the MOS tube M29 is electrically connected to the drain of the MOS tube M21 and the input end of the inverter INV1 respectively, and the output end of the inverter INV1 is electrically connected to the input end of the inverter INV2.

[0073] In addition, the lengths of the MOS transistor M24 , the MOS transistor M25 , and the MOS transistor M26 are the same, and the sum of the widths of the MOS transistor M25 and the MOS transistor M26 is the same as the width of the MOS transistor M24 .

[0074] exist Figure 6In the figure, MOS tubes M19 to M21 form a current mirror, MOS tubes M23 and M23 form a current mirror, MOS tubes M27 and M28 form a transmission gate, MOS tube M29 is the input tube of the secondary amplifier, and MOS tubes M24, M25 and M26 form an input pair tube.

[0075] In actual use, when the high-side switch works normally, the signal ABS_OTP_N outputs a high level, and the transmission gate is turned on, so that the size of the differential input pair tubes is consistent; when the absolute temperature rises to trigger the over-temperature protection, the signal ABS_OTP_N flips to a low potential, the control signal ABS_OTP is a high potential, the transmission gate is closed, and the size of the MOS tube M24 in the differential input pair tube size is larger than the size of the MOS tube M25, the absolute temperature over-temperature protection threshold changes, and hysteresis is established to prevent thermal oscillation.

[0076] Specifically, in this embodiment, the circuit of the comparator Coomp2 is as follows: Figure 7 As shown, it includes MOS tubes M30-MOS tubes M37, inverters INV3 and INV4;

[0077] The source of the MOS tube M33, the source of the MOS tube M34 and the source of the MOS tube M37 are all used to be electrically connected to the power supply VCC, the gate of the MOS tube M33 is electrically connected to the gate of the MOS tube M34, the drain of the MOS tube M33 and the drain of the MOS tube M35 respectively, the drain of the MOS tube M34 is electrically connected to the gate of the MOS tube M37 and the drain of the MOS tube M36 respectively; the gate of the MOS tube M35 is the negative input terminal of the comparator Comp2, the gate of the MOS tube M36 is the positive input terminal of the comparator Comp2; the source of the MOS tube M35 and the MOS The source of the MOS tube M36 is electrically connected to the drain of the MOS tube M31; the gate of the MOS tube M31 is electrically connected to the gate of the MOS tube M32, the gate of the MOS tube M30, the drain of the MOS tube M30 and the current source IREF5 respectively; the source of the MOS tube M30, the source of the MOS tube M31 and the source of the MOS tube M32 are all grounded; the drain of the MOS tube M32 is electrically connected to the drain of the MOS tube M37 and the input end of the inverter INV3 respectively; the output end of the inverter INV3 is electrically connected to the input end of the inverter INV4, for outputting the signal DYN_OTP.

[0078] for Figure 7 In the circuit shown, MOS tube M33 and MOS tube M34 form a current mirror, MOS tube M30-MOS tube M32 form a current mirror, MOS tube M35 and MOS tube M36 form a differential input pair tube, and MOS tube M37 is a secondary amplifier input tube.

[0079] In actual use, when the high-side switch is working normally, the signal DYN_OTP_N is high and the signal DYN_OTP is low; when the temperature difference between the inside and outside is too large to trigger the dynamic over-temperature protection, the signal DYN_OTP_N flips to a low level and the signal DYN_OTP flips to a high level, and the signal DYN_OTP is transmitted to Figure 5 The circuit in is used to establish dynamic over-temperature protection hysteresis.

[0080] In summary, combined with the above content, the over-temperature detection circuit in this embodiment adopts a dual over-temperature protection mechanism of absolute temperature and dynamic temperature, which can prevent the failure of the intelligent high-side power switch system caused by thermal mechanical stress caused by the excessive operating temperature of the power tube and the excessive temperature difference between the inside and outside of the chip; in addition, the dynamic over-temperature protection threshold can be adjusted according to the source-drain voltage drop of the power tube in the high-side switch, which can solve the problem of excessive internal and external temperature difference caused by the sudden increase of the power tube current during surge or load short circuit; finally, the over-temperature detection circuit in this embodiment can effectively increase the reliability of the intelligent high-side power switch system and extend the service life of the chip system through a more comprehensive over-temperature protection mechanism.

[0081] Embodiment 2

[0082] like Figure 8 As shown, this embodiment provides a high-side switch, including the above-mentioned over-temperature detection circuit 4, and also including an interface circuit 1, a logic control circuit 2, a drive circuit 3 and a power tube M100, the logic control circuit 2 is electrically connected to the interface circuit 1, and the control signal IN transmitted by the interface circuit 1 controls the drive circuit 3 to drive the power tube M100 to be turned on, the logic control circuit 2 is electrically connected to the output end of the comparator Comp1 and the output end of the comparator Comp2 of the over-temperature detection circuit 4, wherein the output end of the comparator Comp1 is the output end of the inverter INV1, and the output end of the comparator Comp2 is the output end of the inverter INV3, and the power tube M100 is controlled to be turned off through the drive circuit 3 based on the output signal of the comparator Comp1 and the output signal of the comparator Comp2, wherein when the output end of the comparator Comp1 is high level or the output end of the comparator Comp2 outputs a high level, the logic control circuit 2 controls the power tube M100 to be turned off.

[0083] In this embodiment, when the high-side switch receives an input start signal IN, the logic control circuit 2 outputs a low-level control signal IN_N.

[0084] The above is based on the present invention as an inspiration. Through the above description, relevant staff can make various changes and modifications without departing from the technical idea of ​​this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. An over-temperature detection circuit, characterized in that: It includes a resistor R1, a current source IREF1, a current source IREF2, a comparator Comp1, a comparator Comp2, a diode D1 for detecting the temperature of a power tube of a high-side switch, and a diode D2 placed on the periphery of the chip; The anode of the diode D1 and the anode of the diode D2 are used to connect to the power supply VCC; The cathode of the diode D1 is electrically connected to one end of the resistor R1 and the negative input terminal of the comparator Comp1 respectively, and the positive input terminal of the comparator Comp1 is used to input a reference voltage VREF; The cathode of the diode D2 is electrically connected to the positive input terminal of the comparator Comp2 and the current source IREF2 respectively; The other end of the resistor R1 is electrically connected to the current source IREF1 and the negative input end of the comparator Comp2 respectively; Also included is a threshold current generating circuit, the threshold current generating circuit is electrically connected to both ends of the resistor R1, and is used to generate a current I1 flowing out of one end of the resistor R1 and a current I2 input to the other end of the resistor R1; The threshold current generating circuit includes MOS tubes M12-M18 and a resistor R2; The source of the MOS tube M12, the source of the MOS tube M13, the source of the MOS tube M17 and the source of the MOS tube M18 are all electrically connected to the power supply VCC, the gate of the MOS tube M12 is electrically connected to the gate of the MOS tube M13, the drain of the MOS tube M12 and the source of the MOS tube M11 respectively, the gate of the MOS tube M11 is used to input the control signal IN_N, and the drain of the MOS tube M11 is electrically connected to the output end of the power tube of the high-side switch through the resistor R2; The drain of the MOS tube M13 is electrically connected to the drain of the MOS tube M14, the gate of the MOS tube M14, the gate of the MOS tube M15 and the gate of the MOS tube M16 respectively, and the source of the MOS tube M14, the source of the MOS tube M15 and the source of the MOS tube M16 are all grounded; The drain of the MOS tube M15 is electrically connected to the drain of the MOS tube M17, the gate of the MOS tube M17 and the gate of the MOS tube M18 respectively; the drain of the MOS tube M16 is electrically connected to one end of the resistor R1, and the drain of the MOS tube M18 is electrically connected to the other end of the resistor R1.

2. An over-temperature detection circuit according to claim 1, characterized in that: The current I1 is equal to the current I2, and both the current I1 and the current I2 are proportional to the source-drain voltage difference of the power tube of the high-side switch.

3. The over-temperature detection circuit according to claim 1, characterized in that: It also includes a current regulating circuit, which is electrically connected to both ends of the resistor R1 and is used to adjust the magnitude of the current flowing through the resistor R1.

4. An over-temperature detection circuit according to claim 3, characterized in that: The current adjustment circuit includes MOS tubes M1-M10 and a current source IREF3; The source of the MOS tube M9 and the source of the MOS tube M10 are both electrically connected to the power supply VCC, the gate of the MOS tube M9 is electrically connected to the gate of the MOS tube M10, the drain of the MOS tube M9 and the drain of the MOS tube M8 respectively, the drain of the MOS tube M10 is electrically connected to the other end of the resistor R1, and the drain of the MOS tube M6 is electrically connected to one end of the resistor R1; The gate of the MOS tube M6 is electrically connected to the gate of the MOS tube M8, and is used to input a control signal ABC_OTP_N. The control signal ABC_OTP_N and the output signal of the comparator Comp1 are two opposite signals. The source of the MOS tube M6 is electrically connected to the drain of the MOS tube M5, the source of the MOS tube M8 is electrically connected to the drain of the MOS tube M7, the gate of the MOS tube M5 is electrically connected to the gate of the MOS tube M7, and is used to input the output signal DYN_OTP of the comparator Comp2, the source of the MOS tube M5 is electrically connected to the drain of the MOS tube M2, the source of the MOS tube M7 is electrically connected to the drain of the MOS tube M3, the source of the MOS tube M1, the source of the MOS tube M2, the source of the MOS tube M3 and the source of the MOS tube M4 are all grounded, the gate of the MOS tube M1 is electrically connected to the gate of the MOS tube M2, the gate of the MOS tube M3, the gate of the MOS tube M4, the drain of the MOS tube M1 and the current source IREF3 respectively; the MOS tube M4 is the current source IREF1, and the drain of the MOS tube M4 is electrically connected to the other end of the resistor R1.

5. An over-temperature detection circuit according to claim 4, characterized in that: The comparator Coomp1 includes MOS tubes M19-M29, inverters INV1 and INV2; The source of the MOS tube M22, the source of the MOS tube M23 and the source of the MOS tube M29 are all electrically connected to the power supply VCC; the gate of the MOS tube M22 is electrically connected to the gate of the MOS tube M23, the drain of the MOS tube M22 and the drain of the MOS tube M24 respectively, and the gate of the MOS tube M24 is the negative input terminal of the comparator Comp1; the drain of the MOS tube M23 is electrically connected to the gate of the MOS tube M29, the drain of the MOS tube M27, the source of the MOS tube M28 and the drain of the MOS tube M25 respectively, and the gate of the MOS tube M25 is electrically connected to the gate of the MOS tube M26, which is the positive input terminal of the comparator Comp1; the source of the MOS tube M27 and the drain of the MOS tube M28 are all electrically connected to the drain of the MOS tube M26, the gate of the MOS tube M27 is electrically connected to the input terminal of the inverter INV2, and the gate of the MOS tube M28 is electrically connected to the input terminal of the inverter INV2; The source of the MOS tube M24 is electrically connected to the source of the MOS tube M25, the source of the MOS tube M26 and the drain of the MOS tube M20 respectively, and the source of the MOS tube M19, the source of the MOS tube M20 and the source of the MOS tube M21 are all grounded; the gate of the MOS tube M19 is electrically connected to the drain of the MOS tube M19, the current source IREF4, the gate of the MOS tube M20 and the gate of the MOS tube M21 respectively; the drain of the MOS tube M29 is electrically connected to the drain of the MOS tube M21 and the input end of the inverter INV1 respectively, and the output end of the inverter INV1 is electrically connected to the input end of the inverter INV2.

6. An over-temperature detection circuit according to claim 5, characterized in that: The MOS tube M24 , the MOS tube M25 and the MOS tube M26 have the same length, and the sum of the widths of the MOS tube M25 and the MOS tube M26 is the same as the width of the MOS tube M24 .

7. An over-temperature detection circuit according to any one of claims 4 to 6, characterized in that: The comparator Commp2 includes MOS tubes M30-M37, inverters INV3 and INV4; The source of the MOS tube M33, the source of the MOS tube M34 and the source of the MOS tube M37 are all used to be electrically connected to the power supply VCC, the gate of the MOS tube M33 is electrically connected to the gate of the MOS tube M34, the drain of the MOS tube M33 and the drain of the MOS tube M35 respectively, the drain of the MOS tube M34 is electrically connected to the gate of the MOS tube M37 and the drain of the MOS tube M36 respectively; the gate of the MOS tube M35 is the negative input terminal of the comparator Comp2, the gate of the MOS tube M36 is the positive input terminal of the comparator Comp2; the source of the MOS tube M35 and the MOS The source of the MOS tube M36 is electrically connected to the drain of the MOS tube M31; the gate of the MOS tube M31 is electrically connected to the gate of the MOS tube M32, the gate of the MOS tube M30, the drain of the MOS tube M30 and the current source IREF5 respectively; the source of the MOS tube M30, the source of the MOS tube M31 and the source of the MOS tube M32 are all grounded; the drain of the MOS tube M32 is electrically connected to the drain of the MOS tube M37 and the input end of the inverter INV3 respectively; the output end of the inverter INV3 is electrically connected to the input end of the inverter INV4, for outputting the signal DYN_OTP.

8. A high side switch, characterized in that: The invention comprises the over-temperature detection circuit as described in any one of claims 1 to 7, and further comprises an interface circuit, a logic control circuit, a drive circuit and a power tube, wherein the logic control circuit is electrically connected to the interface circuit, and controls the drive circuit to drive the power tube to be turned on through a control signal transmitted through the interface circuit, and the logic control circuit is electrically connected to the output end of the comparator Comp1 and the output end of the comparator Comp2 of the over-temperature detection circuit, and controls the power tube to be turned off through the drive circuit based on the output signal of the comparator Comp1 and the output signal of the comparator Comp2.

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