System and method for automatically compensating temperature of electronic product in extremely cold environment

Abstract

The invention relates to the technical field of electronic product temperature compensation in an extremely cold environment, and aims to solve the limitation that active heating or low-temperature adaptive design or internal space temperature acquisition design used in a traditional solution has high power consumption and is not suitable for long-term unattended operation. According to the automatic temperature compensation system and method for the electronic product in the extremely cold environment, the monitored working voltage of the electronic product is compared with the reference voltage threshold range through the temperature compensation control circuit, starting and stopping of the working state of the heating piece are completed through the output control signal, and the problem that in the ultra-low temperature environment, the temperature of the electronic product cannot be automatically compensated is solved. The problem that the electronic product cannot work stably for a long time is solved, the working stability and reliability of the electronic product in the extremely cold environment are improved, and the electronic product can stably run in the low-temperature environment for a long time.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature compensation for electronic products in extremely cold environments, and more particularly to a system and method for automatic temperature compensation of electronic products in extremely cold environments. Background Art

[0002] Extremely cold environments, such as those found in polar regions, significantly impact the operating conditions of electronic components. Low temperatures can easily degrade semiconductor device performance, alter passive component characteristics, and cause mechanical stress failures. For example, carrier mobility decreases (for example, silicon mobility drops significantly below -55°C), leading to slower transistor switching speeds, reduced amplification, and increased PN junction conduction voltage. Silicon diodes can experience a 20% increase in forward voltage drop at -40°C, impacting circuit logic levels. Electrolytic capacitors can freeze (typically failing below -40°C), causing a sharp drop in capacitance or an increase in ESR. Ceramic capacitors experience changes in dielectric constant, leading to capacitance drift. Differences in material thermal expansion coefficients can cause solder joint cracking, and BGA packages are prone to fracture during low-temperature cycling. Low temperatures can also lead to real-time power supply instability and crystal oscillator frequency drift. TCXOs can experience frequency deviations of up to ±50ppm at -30°C, impacting communication synchronization.

[0003] Traditional solutions using active heating, cryogenically adaptable designs, or internal temperature sensing all have limitations. 1) Active heating uses resistive heating films or PTC elements to maintain local temperatures, such as in the Mars rover electronics compartment, which is kept constant above -20°C. However, this increases overall power consumption and is not suitable for long-term unmanned operation. Thermal expansion coefficient mismatch: Local heating can cause differential expansion between materials (such as metal and ceramic), leading to cracks or delamination. High heat loss: In ultra-low temperature environments (such as -196°C liquid nitrogen), heat rapidly diffuses into surrounding cold areas, requiring continuous high power input to maintain local temperature. 2) Cryogenically adaptable designs use wide-temperature components (such as military-grade components with a -55°C to 125°C rating), which can be costly and limited in available models. Demand for military-grade chips is far lower than for consumer-grade chips, and manufacturers typically produce them in small batches, giving them a low production priority. Military project cycles can last 10-30 years, requiring long-term supply from chip manufacturers. However, some older process technologies (such as 180nm) face capacity constraints. Processes such as high-temperature resistance (-55°C to 125°C) require dedicated production lines, resulting in lower yields. Procurement requires long-term supply agreements (LTAs) with chip manufacturers to lock in production capacity. 3) Internal temperature acquisition requires the use of temperature sensors and microcontroller circuits, which undoubtedly increases the number of critical components that require heating. These components are significantly affected by temperature fluctuations, compromising data accuracy and significantly increasing the risk of low-temperature intolerance. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a temperature automatic compensation system and method for electronic products in extremely cold environments. This invention is mainly used for electronic products in extremely cold regions. By comparing the working voltage of the electronic product with the reference voltage in real time and using a temperature compensation control system for automatic temperature compensation, long-term stable operation is achieved.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A temperature automatic compensation system for electronic products in extremely cold environments includes a temperature compensation control circuit, a temperature compensation drive circuit, and a 2.9V_REF reference circuit that provides a reference voltage. The temperature compensation control circuit realizes the start and stop of the working state of the heating element through the output control signal according to the change process of the monitored working voltage of the electronic product. The signal input terminal of the temperature compensation control circuit uses the working voltage of the electronic product as the measured signal, and the output terminal of the temperature compensation control circuit is connected to the temperature compensation drive circuit;

[0007] The temperature compensation drive circuit controls the heating element through the received output signal of the temperature compensation control circuit. The output terminal VOUT of the temperature compensation drive circuit is connected to the heating element; the temperature compensation drive circuit includes a voltage follower circuit and a MOS tube drive circuit;

[0008] The 2.9V_REF reference circuit provides a reference voltage for the temperature compensation control circuit. The input terminal of the 2.9V_REF reference circuit is connected to the power supply VIN. When the working voltage is lower than the threshold voltage of the cooling process, temperature compensation is started through the temperature compensation control circuit and the temperature compensation drive circuit, and the temperature compensation stops until the working voltage exceeds the threshold voltage of the heating process.

[0009] Further, the 2.9V_REF reference circuit includes three parallel branches. The first branch is a series connection of resistor R5 and resistor R4 grounded; the second branch is Schottky diode U2. The REF terminal of Schottky diode U2 is connected to the connection terminal of resistor R5 and resistor R4. The CATHODE terminal of Schottky diode U2 outputs the reference voltage V 2.9V_REF , and the ANODE terminal of Schottky diode U2 is grounded; the third branch is capacitor C3. One end of capacitor C3 is grounded, and the other end is connected to the CATHODE terminal of Schottky diode U2; a current-limiting resistor R6 is provided between the working voltage and the parallel branches.

[0010] Further, the threshold voltage of the heating process of the 2.9V_REF reference circuit is 3.2V, and the threshold voltage of the cooling process is 2.6V.

[0011] Further, the non-inverting input terminal of the operational comparator in the temperature compensation control circuit is connected to the 2.9V_REF reference circuit through the resistor R2, the inverting input terminal is connected to the working voltage DC_JC of the electronic product through the resistor R1, the output terminal of the operational comparator is connected to the non-inverting input terminal through the resistor R3, and the output terminal of the operational comparator is the signal output terminal of the temperature compensation control circuit.

[0012] Further, in the temperature compensation driving circuit, the voltage follower circuit is used to improve the driving ability of the output signal of the temperature compensation control circuit, and the MOS transistor driving circuit is used to convert the level state of the output signal of the temperature compensation control circuit into the level state of the output terminal VOUT.

[0013] A method for automatically compensating the temperature of electronic products in extremely cold environments, based on the above-mentioned temperature automatic compensation system for electronic products in extremely cold environments, compares the monitored working voltage of the electronic product with the reference voltage, and realizes the start and stop of the working state of the heating sheet through the output control signal;

[0014] When the temperature automatic compensation system is started for the first time in an extremely cold environment, the input terminal of the 2.9V_REF reference circuit is short-circuited with the output terminal of the temperature compensation driving circuit for 1 to 2 minutes to ensure the normal start of the temperature automatic compensation system. In the initial state, the temperature automatic compensation system is powered by 12VDC, and the heating sheet heats until the supply voltages of the measured object, 5V and 3.3V, work normally, and then the heating sheet stops heating;

[0015] As the ambient temperature and time change, the temperature of the measured object also decreases. During this change process, when the working voltage of the measured object is lower than the threshold voltage of the cooling process of the reference voltage, the output 12V_CTL signal of the temperature compensation control circuit becomes a high-level signal, the temperature compensation control circuit outputs a start signal, and the MOS transistor Q2 in the temperature compensation driving circuit conducts, so that the temperature compensation driving circuit drives the heating sheet to start heating until the working voltage is higher than the threshold voltage of the heating process of the reference voltage and then stops heating; ensure that the working voltage of the measured object is always within the normal working range during the working state, and the measured object can work normally.

[0016] Further, the reference voltage is calculated according to the following formula:

[0017] V 2.9V_REF = ((R5 + R4) / R4) * 2.5

[0018] Wherein, R4 and R5 are the resistance values of the resistor R4 and the resistor R5 respectively.

[0019] In summary, the invention has the following beneficial effects:

[0020] Through the comparison of the working voltage and the reference voltage by the temperature compensation control circuit, the temperature compensation control circuit uses the output signal to control the start and stop of the temperature compensation drive circuit and the heating sheet, realizing automatic temperature compensation, and solving the problem that electronic products cannot maintain stable operation for a long time in ultra-low temperature environments. The present invention adopts global space heating, enabling the electronic products to be evenly heated; and greatly reducing the maintenance and replacement during the use of the electronic products, reducing the maintenance cost of the equipment and shortening the production cycle of the products; the present invention improves the stability and reliability of the electronic products operating in extremely cold environments, enabling the electronic products to operate stably in low-temperature environments for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the frame diagram of the temperature compensation system of the present invention;

[0022] Figure 2 is the circuit diagram of the temperature compensation control circuit of the present invention;

[0023] Figure 3 is the circuit diagram of the temperature compensation drive circuit of the present invention;

[0024] Figure 4 is the circuit diagram of the 2.9V_REF reference circuit of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will be further described in detail below with reference to the accompanying drawings.

[0026] It should be noted that for the sake of convenient description, the descriptions of directions in the following text are consistent with the directions of the accompanying drawings themselves, but do not limit the structure of the present invention.

[0027] As Figures 1 to 4 shown, the present invention discloses a temperature automatic compensation system for electronic products in extremely cold environments, including a temperature compensation control circuit, a temperature compensation drive circuit, and a 2.9V_REF reference circuit for providing a reference voltage. The temperature compensation control circuit realizes the start and stop of the working state of the heating sheet through the output control signal according to the change process of the monitored working voltage of the electronic product. The input end of the temperature compensation control circuit takes the working voltage of the electronic product as the measured signal, and the output end of the temperature compensation control circuit is connected to the temperature compensation drive circuit; the positive input end of the operational comparator of the temperature compensation control circuit is connected to the 2.9V_REF reference circuit through a resistor R2, the negative input end is connected to the working voltage DC_JC of the electronic product through a resistor R1, the output end of the operational comparator is connected to the positive input end through a resistor R3, and the output end of the operational comparator is the signal output end of the temperature compensation control circuit.

[0028] The temperature compensation driving circuit controls the heating element by receiving the output signal of the temperature compensation control circuit. The output terminal of the temperature compensation driving circuit is connected to the heating element. The temperature compensation driving circuit includes a voltage follower circuit and a MOS transistor driving circuit. The voltage follower circuit is used to improve the driving ability of the output signal of the temperature compensation control circuit (i.e., U1.2 and its peripheral circuit). The MOS transistor driving circuit (i.e., MOS transistor Q2 and its peripheral circuit) is used to convert the level state of the output signal of the temperature compensation control circuit into the level state of the output terminal VOUT. When the temperature compensation control circuit outputs a high level, MOS transistor Q2 conducts, and the output terminal VOUT outputs a high level. When the temperature compensation control circuit outputs a low level, MOS transistor Q2 is cut off, and the output terminal VOUT outputs a low level. The output signal current driving ability of U1.2 in the temperature compensation control circuit is further amplified by the voltage division of resistor R8 and resistor R7 to effectively control the on / off of MOS transistor Q2. The parallel connection of capacitor C5 and capacitor C6 further improves the stability of the control signal of the 1st pin of the MOS transistor and prevents the MOS transistor from being affected by spike pulses.

[0029] The 2.9V_REF reference circuit provides a reference voltage for the temperature compensation control circuit. The input terminal of the 2.9V_REF reference circuit is connected to the 12VDC DC power supply VIN. When the working voltage exceeds the reference voltage threshold range, temperature compensation is enabled through the temperature compensation control circuit and the temperature compensation driving circuit. When the working voltage is within the reference voltage threshold range, temperature compensation stops. The 2.9V_REF reference circuit includes three parallel branches. The first branch is a series connection of resistor R5 and resistor R4 grounded. The second branch is Schottky diode U2. The REF terminal (i.e., pin 2 in the figure) of Schottky diode U2 is connected to the connection terminal of resistor R5 and resistor R4. The CATHODE of Schottky diode U2 (i.e., pin 1 in the figure) outputs the reference voltage V as the output terminal of the 2.9V_REF reference circuit. 2.9V_REF, the ANODE terminal of Schottky diode U2 (i.e., pin 3 in the figure) is grounded. The third branch is capacitor C3. One end of capacitor C3 is grounded, and the other end is connected to the CATHODE terminal of Schottky diode U2. A current-limiting resistor R6 is set between power supply VIN and the parallel branch. The heating threshold voltage of the 2.9V_REF reference circuit is 3.2V, and the cooling threshold voltage is 2.6V. Whether the heating element works depends on the working voltage. In the temperature compensation control circuit, the working voltage DC_JC is compared with the reference voltage. During the cooling process, when the working voltage is lower than 2.7V, the heating element works; during the heating process, when the working voltage is not higher than 3.2V, the heating element remains in the working state. When the external environmental temperature drops, the temperature of the measured object will also drop accordingly. When the temperature changes from -40°C to -60°C, due to the characteristics of the silicon material of the device, the output voltage of the 3.3V voltage regulator chip will gradually decrease. When the temperature rises from -60°C to -40°C, the output value of the 3.3V voltage regulator chip will gradually increase until it reaches 3.3V. The working voltage range of the heating element is: during the cooling process, the working voltage is lower than 2.7V; during the heating process, the working voltage is lower than 3.2V.

[0030] The present invention also discloses a method for automatically compensating the temperature of electronic products in extremely cold environments. Based on the above-mentioned temperature automatic compensation system for electronic products in extremely cold environments, the working voltage of the monitored electronic product is compared with the reference voltage threshold range, and the start and stop of the working state of the heating element are realized through the output control signal.

[0031] When the temperature automatic compensation system is initially started in an extremely cold environment, the input terminal of the 2.9V_REF reference circuit is short-circuited with the output terminal of the temperature compensation drive circuit for 1 - 2 minutes to ensure the normal start of the temperature automatic compensation system. In the initial state, the temperature automatic compensation system is powered by 12V, and the heating element heats until the power supply voltages of 5V and 3.3V of the measured object work normally, and then the heating element stops heating.

[0032] As the environmental temperature and time change, the temperature of the measured object also decreases. During this change process, when the working voltage of the measured object is lower than the cooling process threshold of the reference voltage, the output 12V_CTL signal of the temperature compensation control circuit becomes a high-level signal, the MOS tube Q2 in the temperature compensation drive circuit conducts, and the temperature compensation control circuit outputs a start signal to drive the temperature compensation drive circuit to drive the heating element to start heating until the working voltage is higher than the heating process threshold voltage of the reference voltage and then stops heating; ensuring that the working voltage of the measured object in the working state is always within the normal working range, and the measured object can work normally.

[0033] The reference voltage is calculated according to the following formula:

[0034] V 2.9V_REF = ((R5 + R4) / R4) * 2.5

[0035] Wherein, R4 and R5 are the resistance values of resistor R4 and resistor R5 respectively.

[0036] Example:

[0037] In this embodiment, heat conduction and sealing adopt a combined solution that can achieve both efficient heat dissipation and strong sealing protection, which is particularly suitable for industrial electronic equipment with high power and high protection requirements:

[0038] Thermal grease: solves the heat dissipation problem in local high heat flux density areas (chips / MOSFETs) (thermal conductivity coefficient 3~10W / m·K).

[0039] Epoxy sealant: provides overall rigid protection (compressive strength > 50MPa) and achieves IP68 protection.

[0040] Composite effect: It avoids the insufficient heat conduction of pure potting glue and solves the problem of no sealing of pure silicone grease.

[0041] The key parameters for material selection are as follows:

[0042] Material Type Recommended Parameter Requirements Typical Model Examples

[0043] Thermal grease with a thermal conductivity of ≥5W / m·K and a temperature resistance of 200°C. Shin-Etsu X-23-7783D (6.0W / m·K)

[0044] Epoxy potting adhesive thermal conductivity ≥1.2W / m·K, TG point ≥120℃ Henkel Loctite EE-1188 (1.5W / m·K

[0045] Step-by-step process

[0046] 1) Accurate application of thermal grease

[0047] Surface treatment: Use a plasma cleaning machine to treat the chip and radiator surface (improve adhesion by more than 10%), and control the contact surface roughness to Ra≤0.8μm.

[0048] Coating process: screen printing process (accuracy ±0.1mm), thickness controlled at 80-120μm (optimal thermal resistance range)

[0049] Curing pre-pressing: Preheat at 80℃ for 1 minute to soften the silicone grease, and press the radiator with a pressure of 0.3-0.5MPa.

[0050] 2) Precision control of epoxy potting

[0051] Mold design: Use CNC machined aluminum alloy mold (gap 0.2mm) and set exhaust channels (spacing ≤50mm).

[0052] Vacuum potting: First, evacuate to 5 Pa and maintain for 10 minutes, and control the glue injection speed at 5 - 10 ml / s.

[0053] Gradient curing:

[0054]

[0055] Thermal stress buffering:

[0056] Add 20% silicon microspheres to the epoxy glue (reduce CTE to 25 ppm / °C), and reserve a 0.5 mm buffer gap at the four corners of the chip.

[0057] Interface enhancement: Make a 45° ramp transition at the junction of the silicone grease and the epoxy glue, and add 3M TM Scotch - Weld TM PR100 primer.

[0058] Failure prevention: Set X - ray detection points (monitor the potting bubble rate < 1%), and conduct 100% thermal cycle tests (-40°C to 125°C, 500 times). The application comparison is shown in Table 1:

[0059] Table 1

[0060]

[0061] The PCB of the electronic product is used as the object to be measured, and the normal operating temperature is -40°C + 85°C. When the temperature in the severe cold environment is as low as -60°C, the working voltage on the PCB tends to 0V, and all components of the object to be measured basically stop working. Supply 12V to the temperature control compensation system, and the ceramic high - temperature heating sheet starts to work. The generated heat is transferred along the thermal conductive silicone grease. After 3 - 5 minutes, the temperature of the object to be measured rises to -40°C + 85°C. The supply voltages of 5V and 3.3V of the object to be measured return to normal. At the same time, the temperature control compensation system can also start to work normally. When the temperature control compensation system monitors 3.3V of the object to be measured, the ceramic heating sheet stops working. As the ambient temperature decreases, the temperature of the object to be measured also decreases. During this change process, the power supply voltage of 3.3V of the object to be measured will also gradually decrease at a certain moment. When it drops to 2.7V, the temperature automatic compensation system immediately starts the heating sheet, and the temperature of the object to be measured gradually recovers. When the working voltage of 3.3V of the object to be measured returns to 3.2V, the temperature automatic compensation system stops heating. The process is executed in a loop to ensure that the working voltage of the object to be measured is stable in the reasonable range of 2.6V - 3.3V. When starting for the first time at ultra - low temperature, it is necessary to short - circuit the two electrodes of VIN and VOUT with a cable for 1 - 2 minutes to ensure the normal start of the temperature compensation automatic system.

[0062] In the ambient temperature range of -40°C to +85°C, the normal operating voltage of the core MCUSTM32F103 chip of the object under test in this embodiment is 2.0V - 3.6V, and the normal operating voltage of other devices is 2.5V - 3.6V. The comprehensive operating voltage of 2.5V - 3.3V is selected as the normal operating voltage of the object under test. As long as the PCB operating voltage of the electronic product satisfies 2.5V - 3.3V, it indicates that the electronic product can operate normally.

[0063] In this embodiment, R5 = 4KΩ; R4 = 25KΩ, R6 = 910KΩ; applying the above formula gives V 2.9V_REF＝ 2.9V, 1mA ≤ (VIN - V 2.9V_REF) / R6 = 10mA ≤ 500mA, meeting the inter-electrode current index of the TL431AIDBZR chip.

[0064] The temperature control compensation circuit control part is used to monitor the change process of the operating voltage of 3.3V of the PCB (object under test) of the electronic product, and output the start and stop signals of the ceramic heating sheet according to the voltage change value. The temperature center value of the temperature control compensation system is selected as 2.9V, the heating threshold is 3.2V, and the cooling threshold is 2.6V, as shown in Table 2:

[0065] Table 2 Relationship between the ceramic heating sheet and the temperature rise and fall process

[0066] Temperature Operating voltage Ceramic high-temperature heating element (cooling) Ceramic high-temperature heating element (heating) -40℃+85℃ 3.3V Not working Not working -41℃ 3.2V Not working Not working -41.6℃ 3.1V Not working Working -41.8℃ 3.0V Not working Working -42.1℃ 2.9V Not working Working -42.1℃ 2.8V Not working Working -42.6℃ 2.7V Not working Working -42.9℃ 2.6V Working Working -43℃ 2.5V Working Working

[0067] VP = V 2.9V_REF *R3 / (R2 + R3) + V 12V_CTL *R2 / (R2 + R3)

[0068] VP represents the in-phase voltage of pin 3 of U1.1;

[0069] VPH = V 2.9V_REF *R3 / (R2 + R3) + V 12V_CTL H * R2 / (R2 + R3)

[0070] VPH represents the heating threshold, V 24V_CTL H represents the output high level of 5V;

[0071] VPL = V 2.9V_REF *R3 / (R2 + R3) + V 12V_CTL L * R2 / (R2 + R3)

[0072] VPL represents the cooling threshold, V 12V_CTL L represents the output ground level of 0V;

[0073] Substituting the values, VPH = 3.2V, VPL = 2.6V.

[0074] In this embodiment, a ceramic high-temperature heating sheet is selected. The ceramic high-temperature heating sheet realizes the conversion of electrical energy into heat energy through resistance heating: Resistance material: Resistance wires (such as nickel-chromium alloy, tungsten-molybdenum alloy) or printed resistance circuits (thick film / thin film process) are embedded inside the heating sheet, and heat is generated due to the resistance effect after being powered on. Ceramic matrix: High thermal conductivity ceramics (such as alumina, aluminum nitride, silicon carbide) are used as insulating substrates to quickly and evenly conduct heat, while being resistant to high temperatures (usually up to above 800 °C, and some materials even exceed 1600 °C). The core of the ceramic high-temperature heating sheet is to efficiently convert electrical energy into heat energy through the combination of the ceramic matrix and the resistance element, and at the same time utilize the high-temperature resistance, high thermal conductivity and insulation characteristics of the ceramic to achieve stable and reliable heating. The performance advantages make the ceramic high-temperature heating sheet an ideal choice for high-temperature and precision heating scenarios.

[0075] Table 3 Relationship between power and temperature of ceramic high-temperature heating sheet

[0076] Voltage Static power Dry-burning surface temperature 3.7V 3W 130℃ 5V 1.2W 70℃ 5V 5W 170℃ 12V 1.5W 100℃ 12V 7W 220℃ 12V 28W 440℃ 24V 6W 200℃ 36V 13W 320℃ 48V 25W 400℃

[0077] The above are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the concept of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, several improvements and refinements made without departing from the principle of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. An automatic temperature compensation system for electronic products in extremely cold environments, characterized in that: It includes a temperature compensation control circuit, a temperature compensation drive circuit, and a 2.9V_REF reference circuit that provides a reference voltage. The temperature compensation control circuit realizes the start and stop of the working state of the heating sheet through the output control signal according to the change process of the working voltage of the monitored electronic product. The signal input end of the temperature compensation control circuit takes the working voltage of the electronic product as the measured signal, and the output end of the temperature compensation control circuit is connected to the temperature compensation drive circuit; The temperature compensation drive circuit controls the heating sheet through the received output signal of the temperature compensation control circuit. The output end VOUT of the temperature compensation drive circuit is connected to the heating sheet. The temperature compensation drive circuit includes a voltage follower circuit and a MOS transistor drive circuit; The 2.9V_REF reference circuit provides a reference voltage for the temperature compensation control circuit. The input end of the 2.9V_REF reference circuit is connected to the power supply VIN. When the working voltage is lower than the temperature drop process threshold voltage, temperature compensation is started through the temperature compensation control circuit and the temperature compensation drive circuit until the temperature compensation stops when the working voltage exceeds the temperature rise process threshold voltage.

2. The temperature automatic compensation system for electronic products in extremely cold environments according to claim 1, wherein: The 2.9V_REF reference circuit includes three parallel branches. The first branch is composed of resistor R5 and resistor R4 connected in series to ground. The second branch is Schottky diode U2. The REF terminal of Schottky diode U2 is connected to the connection terminal of resistor R5 and resistor R4. The CATHODE terminal of Schottky diode U2 serves as the output terminal of the 2.9V_REF reference circuit to output the reference voltage V 2.9V_REF . The ANODE terminal of Schottky diode U2 is grounded. The third branch is capacitor C3. One end of capacitor C3 is grounded, and the other end is connected to the CATHODE terminal of Schottky diode U2. A current-limiting resistor R6 is provided between the working voltage and the parallel branches.

3. The temperature automatic compensation system for electronic products in extremely cold environments according to claim 2, wherein: The temperature rise process threshold voltage of the 2.9V_REF reference circuit is 3.2V, and the temperature drop process threshold voltage is 2.6V.

4. The temperature automatic compensation system for electronic products in extremely cold environments according to claim 1, characterized in that: The positive input end of the operational comparator of the temperature compensation control circuit is connected to the 2.9V_REF reference circuit through a resistor R2, the negative input end is connected to the working voltage DC_JC of the electronic product through a resistor R1, and the output end of the operational comparator is connected to the positive input end through a resistor R3. The output end of the operational comparator is the signal output end of the temperature compensation control circuit.

5. The temperature automatic compensation system for electronic products in extremely cold environments according to claim 1, characterized in that: In the temperature compensation drive circuit, the voltage follower circuit is used to improve the driving ability of the output signal of the temperature compensation control circuit, and the MOS transistor drive circuit is used to convert the level state of the output signal of the temperature compensation control circuit into the level state of the output end VOUT.

6. A method for automatic temperature compensation of electronic products in extremely cold environments, based on the system for automatic temperature compensation of electronic products in extremely cold environments according to any one of claims 1 to 5, characterized in that: Compare the monitored working voltage of the electronic product with the reference voltage, and realize the start and stop of the working state of the heating sheet through the output control signal; When the temperature automatic compensation system is initially started in an extremely cold environment, the input end of the 2.9V_REF reference circuit is short-circuited with the output end of the temperature compensation drive circuit for 1 - 2 minutes to ensure the normal start of the temperature automatic compensation system. In the initial state, the temperature automatic compensation system is powered by 12VDC, and the heating sheet heats until the supply voltages of the measured object, 5V and 3.3V, work normally, and then the heating sheet stops heating; As the ambient temperature and time change, the temperature of the measured object also decreases. During this change process, when the working voltage of the measured object is lower than the temperature drop process threshold voltage of the reference voltage, the output 12V_CTL signal of the temperature compensation control circuit becomes a high-level signal, the temperature compensation control circuit outputs a start signal, and the MOS transistor Q2 in the temperature compensation drive circuit conducts, so that the temperature compensation drive circuit drives the heating sheet to start heating until the heating stops when the working voltage is higher than the temperature rise process threshold voltage of the reference voltage; Ensure that the working voltage of the measured object in the working state is always within the normal working range, so that the measured object can work normally.

7. The method for automatically compensating the temperature of electronic products in an extremely cold environment according to claim 6, wherein: The reference voltage is calculated according to the following formula: V 2.9V_REF = ((R5 + R4) / R4) * 2.5 wherein, R4 and R5 are the resistance values of resistor R4 and resistor R5 respectively.

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