Silicon carbide constant temperature control circuit
By using silicon carbide bipolar junction transistors and related circuit components in constant temperature circuits, the problem of poor constant temperature effect in high-temperature and high-voltage environments is solved, and the stable constant temperature effect in harsh environments is achieved, and the reliability of the equipment is improved.
Patent Information
- Application Number
- CN202422384131.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-29
- Publication Date
- 2025-07-01
- Estimated Expiration
- 2034-09-29
AI Technical Summary
The existing constant temperature circuit cannot effectively maintain the constant temperature effect in high temperature and high voltage environments, affecting the performance and reliability of the satellite clock timing circuit.
Silicon carbide bipolar junction transistor is used, combined with temperature detection unit, operational amplifier, and hysteresis comparison circuit, to form a silicon carbide constant temperature control circuit, which can achieve better constant temperature effect in high temperature and high pressure environment.
In a high-temperature and high-pressure environment, the constant temperature circuit can maintain a stable temperature, ensure the performance and reliability of the crystal oscillator, and improve the constant temperature effect and the reliability of the equipment.
Smart Images
Figure CN223051665U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of constant temperature control circuits, and particularly relates to a silicon carbide constant temperature control circuit. Background Art
[0002] Constant temperature circuits are widely used in daily life. For satellite clock timing technology, the clock timing circuit in a constant temperature state can further improve the function of time synchronization. Traditional constant temperature systems usually use mechanical temperature switches, but the constant temperature effect of such systems is relatively poor, and the mechanical temperature switches have high costs and occupy a large space. Based on this, field effect transistors (FETs) are sometimes used to control temperature in the prior art. However, although field effect transistors (FETs) can reduce certain procurement costs and the volume is somewhat reduced compared with mechanical temperature switches, when the constant temperature circuit is applied to satellite clock timing technology, field effect transistors (FETs) cannot achieve a better constant temperature effect under high temperature and high pressure, so it is impossible to ensure that the crystal oscillator in the clock timing circuit always maintains stable performance and reliability. Summary of the Utility Model
[0003] In order to overcome the deficiencies of the prior art, the purpose of the utility model is to provide a silicon carbide constant temperature control circuit, which can use semiconductor transistors to achieve a better constant temperature effect in harsh environments of high temperature and high pressure.
[0004] The purpose of the utility model is realized through the following technical solutions:
[0005] A silicon carbide constant temperature control circuit includes a temperature detection unit, an operational amplifier, a hysteresis comparison circuit, and a silicon carbide bipolar junction transistor; the reference voltage and the temperature induction output terminal of the temperature detection unit are respectively connected to two input terminals of the operational amplifier, the output terminal of the operational amplifier is connected to the non-inverting input terminal of the hysteresis comparison circuit, the inverting input terminal of the hysteresis comparison circuit is connected to the working voltage, the output terminal of the hysteresis comparison circuit is connected to the base of the silicon carbide bipolar junction transistor, and the collector of the silicon carbide bipolar junction transistor is connected to the supply voltage.
[0006] Further, the temperature detection unit includes a thermistor RT1, a resistor R27, a resistor R31, a capacitor C24, a capacitor C25, and a potentiometer POT2; the thermistor RT1 is connected in series with the resistor R27, and the resistor R27 is connected to the operating voltage; the resistor R31, the capacitor C24, and the capacitor C25 are connected in series in sequence, the resistor R31 is connected to the operating voltage, the connection point between the capacitor C24 and the capacitor C25 is connected to the negative input terminal of the operational amplifier through a resistor R28, the potentiometer POT2 is connected between the resistor R31 and the capacitor C24, and the connection point between the potentiometer POT2 and the capacitor C24 is connected to the positive input terminal of the operational amplifier through a resistor R29.
[0007] Further, the hysteresis comparison circuit includes a hysteresis amplifier and a capacitor C29, a branch is led out from the output terminal of the hysteresis amplifier and connected to the capacitor C29, and the capacitor C29 is connected to the operating voltage.
[0008] Further, both the operational amplifier and the hysteresis amplifier use an amplifier of model LM7301.
[0009] Further, the silicon carbide bipolar junction transistor uses a transistor of model BC53-16.
[0010] Further, the silicon carbide bipolar junction transistor uses a DFN-3(2*2) packaging method, that is, the number of pads of the silicon carbide bipolar junction transistor is 3, and the packaging size is 2 mm * 2 mm.
[0011] The utility model has the following beneficial effects:
[0012] When the whole machine is powered on, the voltage of the reference voltage division of the temperature detection unit is greater than the voltage of the temperature induction output terminal division, and the current input to the negative input terminal (- terminal) of the operational amplifier is greater than the current of the positive input terminal (+ terminal). Therefore, a low level is obtained at the output terminal of the operational amplifier, and the low level is output to the in-phase input terminal of the hysteresis comparison circuit. When VE>VB>VC of the silicon carbide bipolar junction transistor, the circuit is in a state of amplified heating. During the heating process, the resistance value of the temperature detection unit becomes smaller due to the influence of temperature, which causes a high level to be output at the output terminal of the operational amplifier, and the high level is output to the silicon carbide bipolar junction transistor, that is, the top current amplifier. At this time, the transistor is in a cut-off state. Therefore, when the current input to the negative input terminal of the operational amplifier and the current of the positive input terminal work in a balanced state, a stable crystal oscillator output can be obtained. Therefore, in a harsh environment of high temperature and high pressure, the constant temperature circuit can still achieve a better constant temperature effect. Description of the Drawings
[0013] Figure 1This is the schematic diagram of the constant temperature control circuit of the present utility model. Specific embodiments
[0014] The present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. Terms such as "upper", "inner", "middle", "left", "right", and "one" cited in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present utility model. Changes or adjustments in their relative relationships shall also be regarded as the scope of implementation of the present utility model without substantial changes in the technical content.
[0015] The constant temperature control circuit of the present utility model can achieve good temperature control and constant temperature effects in harsh environments of high temperature and high pressure by using a silicon carbide bipolar junction transistor. When applied to satellite clock timing technology, it can provide a stable and accurate data transmission signal for the crystal oscillator to improve the performance and reliability of the crystal oscillator.
[0016] The following is a detailed introduction to the structure of the constant temperature control circuit:
[0017] As Figure 1 shown, a silicon carbide constant temperature control circuit includes a temperature detection unit, an operational amplifier (i.e., IC4A), a hysteresis comparison circuit, and a silicon carbide bipolar junction transistor (i.e., Q4); the reference voltage and the temperature sensing output terminal of the temperature detection unit are respectively connected to the two input terminals of the operational amplifier, the output terminal of the operational amplifier is connected to the non-inverting input terminal of the hysteresis comparison circuit, the inverting input terminal of the hysteresis comparison circuit is connected to the working voltage (i.e., VDD), the output terminal of the hysteresis comparison circuit is connected to the base of the silicon carbide bipolar junction transistor, and the collector of the silicon carbide bipolar junction transistor is connected to the supply voltage (i.e., VCC).
[0018] It can be seen that in the constant temperature control circuit of the present utility model, by setting a temperature detection unit, an operational amplifier, a hysteresis comparison circuit, and a silicon carbide bipolar junction transistor, the temperature detection unit is used to detect temperature, which can play a role in overheat protection and improve the performance and stability of the product. The two input terminals (non-inverting input terminal and inverting input terminal) and one output terminal of the operational amplifier amplify the signal by comparing the voltage difference between the input terminals. This method uses differential amplification and has the characteristic of common-mode rejection. The hysteresis comparison circuit is a comparator with a hysteresis characteristic. This hysteresis characteristic enables the hysteresis comparator to ensure the stability of the output when the input signal changes, preventing jitter or error, thereby improving the stability and reliability of the circuit. The silicon carbide bipolar junction transistor is reflected by establishing a model of the collector resistance changing with voltage and can undertake the conversion between the high-voltage blocking state and the quasi-saturation state with low conduction voltage drop, similar to a silicon carbide power switch device. Therefore, it can ensure the reliability and performance of the silicon carbide bipolar junction transistor in high-voltage and high-temperature environments.
[0019] Based on this, when the whole machine is powered on, the voltage of the reference voltage division of the temperature detection unit is greater than the voltage of the voltage division at the temperature sensing output terminal, and the current input to the negative input terminal (- terminal) of the operational amplifier is greater than the current input to the positive input terminal (+ terminal). Therefore, a low level is obtained at the output terminal of the operational amplifier, and the low level is output to the non-inverting input terminal of the hysteresis comparator circuit. When VE>VB>VC of the silicon carbide bipolar junction transistor, the circuit is in the state of amplified heating. During the heating process, the resistance value of the temperature detection unit becomes smaller due to the influence of temperature, which causes a high level to be output at the output terminal of the operational amplifier. The high level is output to the silicon carbide bipolar junction transistor, that is, the top current amplifier, and at this time the transistor is in the cut-off state. Therefore, when the current input to the negative input terminal of the operational amplifier and the current input to the positive input terminal work in a balanced state, a stable crystal oscillator output can be obtained. Therefore, in the harsh environment of high temperature and high pressure, the constant temperature circuit can still achieve a better constant temperature effect.
[0020] Among them, the silicon carbide bipolar junction transistor uses a transistor with the model BC53-16. At the same time, the silicon carbide bipolar junction transistor adopts the DFN-3(2*2) packaging method, that is, the number of pads of the silicon carbide bipolar junction transistor is 3, and the packaging size is 2 mm * 2 mm. It can be seen that the silicon carbide bipolar junction transistor adopted by the present invention has the advantages of small volume, small occupied space and cost saving compared with the mechanical temperature switch and field effect transistor (FET) in the prior art.
[0021] In this embodiment, as Figure 1 shown, the temperature detection unit includes a thermistor RT1, a resistor R27, a resistor R31, a capacitor C24, a capacitor C25, and a potentiometer POT2; the thermistor RT1 is connected in series with the resistor R27, and the resistor R27 is connected to the working voltage; the resistor R31, the capacitor C24, and the capacitor C25 are connected in series in turn, the resistor R31 is connected to the working voltage, and the connection point between the capacitor C24 and the capacitor C25 is connected to the negative input terminal of the operational amplifier through the resistor R28. The potentiometer POT2 is connected between the resistor R31 and the capacitor C24 through the resistor R32, and the connection point between the potentiometer POT2 and the capacitor C24 is connected to the positive input terminal of the operational amplifier through the resistor R29.
[0022] In this embodiment, as Figure 1 shown, the hysteresis comparator circuit includes a hysteresis amplifier and a capacitor C29. A branch is led out from the output terminal of the hysteresis amplifier and connected to the capacitor C29, and the capacitor C29 is connected to the working voltage. It should be noted that both the operational amplifier and the hysteresis amplifier use an amplifier with the model LM7301.
[0023] To sum up, the working principle of the silicon carbide constant temperature control circuit of the present invention:
[0024] When the whole machine is powered on, the current is the starting current. When the voltage division between resistor R31 and capacitors C24 and C25 obtains 1 / 2 of the working voltage VDD, and the voltage division between resistor R27 and thermistor RT1 obtains 1 / 4 of the working voltage VDD, and the current in the - terminal circuit of the operational amplifier is greater than that in the + terminal, at this time, a low level is obtained at the output terminal of the operational amplifier IC4A (LM7301). This low level is output to the non-inverting input terminal of the hysteresis amplifier IC5A (LM7301). The inverting input terminal of the hysteresis amplifier IC5A (LM7301) is connected to the working voltage VDD, thus forming a current amplification device. At this time, when VE>VB>VC of the silicon carbide bipolar junction transistor, it is in the amplified heating state.
[0025] During the heating process, the resistance value of the negative temperature coefficient thermistor RT1 decreases with the influence of temperature. When the resistance value of thermistor RT1 becomes smaller than K1, when the + terminal of the operational amplifier is greater than the - terminal of the operational amplifier, a high level is obtained at the output terminal of the operational amplifier. This high level is output to the silicon carbide bipolar junction transistor (Q4), that is, the current amplification device. At this time, the silicon carbide bipolar junction transistor is in the cut-off state; when the + terminal and - terminal of the operational amplifier work in a balanced state, a stable crystal oscillator output is finally obtained.
[0026] It can be seen from this that the present utility model has the following beneficial effects:
[0027] The constant temperature circuit of the present utility model uses a silicon carbide bipolar junction transistor, which has a relatively high breakdown electric field strength of high voltage characteristics, can withstand a relatively high voltage, helps to reduce the volume and weight of the device, and improves the power density of the equipment. Under the same withstand voltage value, a standardized on-resistance can be obtained, the rise rate is relatively low, and the on-resistance at high temperature is also very low, with the characteristics of high input resistance and low power consumption. At the same time, due to the low on-resistance of the silicon carbide bipolar junction transistor, the on-resistance and switching loss are greatly reduced, the temperature stability is improved, so it has higher thermal stability and is suitable for harsh environments of high temperature and high pressure.
[0028] In addition, due to the advantages of low cost, small volume, long life, strong anti-mechanical shock ability, high efficiency, etc. of the silicon carbide bipolar junction transistor, it can achieve a smaller volume and weight, and improve the integration degree of power devices.
[0029] The implementation manners of the present utility model are not limited to this. According to the above content of the present utility model, using the ordinary technical knowledge and customary means in the art, without departing from the above basic technical idea of the present utility model, the present utility model can also be modified, replaced or combined in many other forms, all of which fall within the scope of the protection of the rights of the present utility model.
Claims
1. A silicon carbide constant temperature control circuit, characterized in that: It includes a temperature detection unit, an operational amplifier, a hysteresis comparison circuit and a silicon carbide bipolar junction transistor; the reference voltage and the temperature sensing output end of the temperature detection unit are respectively connected to the two input ends of the operational amplifier, the output end of the operational amplifier is connected to the in-phase input end of the hysteresis comparison circuit, the inverting input end of the hysteresis comparison circuit is connected to the working voltage, the output end of the hysteresis comparison circuit is connected to the base of the silicon carbide bipolar junction transistor, and the collector of the silicon carbide bipolar junction transistor is connected to the supply voltage.
2. The silicon carbide constant temperature control circuit according to claim 1, characterized in that: The temperature detection unit includes a thermistor RT1, a resistor R27, a resistor R31, a capacitor C24, a capacitor C25, and a position changer POT2; the thermistor RT1 is connected in series with the resistor R27, and the resistor R27 is connected to the working voltage; the resistor R31, the capacitor C24 and the capacitor C25 are connected in series in sequence, the resistor R31 is connected to the working voltage, the connection point between the capacitor C24 and the capacitor C25 is connected to the negative input terminal of the operational amplifier through the resistor R28, the position changer POT2 is connected between the resistor R31 and the capacitor C24, and the connection point between the position changer POT2 and the capacitor C24 is connected to the positive input terminal of the operational amplifier through the resistor R29.
3. The silicon carbide constant temperature control circuit according to claim 1, characterized in that: The hysteresis comparison circuit includes a hysteresis amplifier and a capacitor C29. The output terminal of the hysteresis amplifier leads to a branch connected to the capacitor C29, and the capacitor C29 is connected to a working voltage.
4. The silicon carbide constant temperature control circuit according to claim 3, characterized in that: The operational amplifier and the hysteresis amplifier are both LM7301 amplifiers.
5. The silicon carbide constant temperature control circuit according to claim 1, characterized in that: The silicon carbide bipolar junction transistor is a transistor of model BC53-16.
6. The silicon carbide constant temperature control circuit according to any one of claims 1 to 5, characterized in that: The silicon carbide bipolar junction transistor adopts a DFN-3 (2*2) packaging method, that is, the number of pads of the silicon carbide bipolar junction transistor is 3 and the packaging size is 2 mm*2 mm.