Driving circuit unit for mos transistor and electric heating device

Abstract

The application provides a driving circuit unit of a MOS tube and an electric heating device. The driving circuit unit comprises a microprocessor, a transistor, a first MOS tube and a second MOS tube; wherein a PWM pin of the microprocessor is electrically connected with a base of the transistor, an emitter of the transistor is grounded, a collector of the transistor is electrically connected with a gate of the second MOS tube, a source of the second MOS tube is connected with a power supply voltage, a drain of the second MOS tube is electrically connected with a gate of the first MOS tube, and the power supply voltage is greater than an output voltage of the microprocessor; the transistor comprises an NPN transistor, the first MOS tube comprises an NMOS tube, and the second MOS tube comprises a PMOS tube. Through the application, the problem that the transistor is insufficiently turned on caused by directly driving the transistor by the PWM of the MCU in the prior art is solved.

Description

Technical Field

[0001] This application relates to the field of temperature control technology, and more specifically, to a MOSFET driving circuit unit and an electric heating device. Background Technology

[0002] In temperature control systems where the power management system (PMU) and microcontroller (MCU) work together, especially in the field of temperature control for electric heating products such as home heating equipment, medical equipment, or automotive heating products, the commonly used solution is to directly control the gate of the NMOS transistor with the PWM signal of the MCU, thereby determining the on / off state of the heating element.

[0003] However, NMOS transistors have a gate threshold voltage (V th Only when the gate-source voltage (V) gs (Exceeding this V) th An NMOS transistor only begins to conduct when the gate voltage reaches its threshold voltage. That is, a sufficient gate voltage is required for an NMOS transistor to fully conduct. A lower drive voltage will cause the NMOS to be in a suboptimal conduction state, thus limiting the performance of the entire system. In traditional designs, the PWM output of the MCU is typically 3.3V, which is relatively low. When driving the NMOS transistor, this leads to insufficient conduction, affecting switching speed and efficiency. Furthermore, due to the incomplete conduction of the NMOS, the current passing through the transistor generates additional heat, which can cause the device temperature to become too high over long-term, reducing system stability and lifespan. In addition, the efficiency of the heat sink will also be affected by the non-ideal conduction of the NMOS transistor.

[0004] Therefore, there is an urgent need for a MOSFET driving circuit unit to at least solve the problem of insufficient transistor conduction caused by using MCU PWM to directly drive transistors in the existing technology. Utility Model Content

[0005] The main objective of this application is to provide a driving circuit unit for a MOSFET and an electric heating device, so as to at least solve the problem that insufficient transistor conduction is caused by using PWM to directly drive transistors with an MCU in the prior art.

[0006] To achieve the above objectives, according to one aspect of this application, a driving circuit unit for a MOSFET is provided, comprising a microprocessor, a transistor, a first MOSFET, and a second MOSFET; wherein, the PWM pin of the microprocessor is electrically connected to the base of the transistor, the emitter of the transistor is grounded, the collector of the transistor is electrically connected to the gate of the second MOSFET, the source of the second MOSFET is connected to a power supply voltage, and the drain of the second MOSFET is electrically connected to the gate of the first MOSFET; the power supply voltage is greater than the output voltage of the microprocessor; the transistor includes an NPN transistor, the first MOSFET includes an NMOS transistor, and the second MOSFET includes a PMOS transistor.

[0007] In some embodiments, the driving circuit unit of the MOS transistor further includes: an electric heating element having a first pin and a second pin, the first pin of the electric heating element being electrically connected to a power supply voltage, the second pin of the electric heating element being electrically connected to the drain of the first MOS transistor, and the source of the first MOS transistor being grounded.

[0008] In some embodiments, the driving circuit unit of the MOS transistor further includes a first resistor, one end of which is grounded and the other end is electrically connected to the gate of the first MOS transistor.

[0009] In some embodiments, the driving circuit unit of the MOS transistor further includes: a first diode, the anode of the first diode being electrically connected to the second pin of the electric heating element, and the cathode of the first diode being electrically connected to the first pin of the electric heating element.

[0010] In some embodiments, the driving circuit unit of the MOSFET further includes a second resistor, one end of which is electrically connected to the PWM pin and the other end of which is electrically connected to the base.

[0011] In some embodiments, the driving circuit unit of the MOS transistor further includes a third resistor, one end of which is electrically connected to the base and the other end of which is electrically connected to the emitter.

[0012] In some embodiments, the driving circuit unit of the MOSFET further includes a fourth resistor, one end of which is electrically connected to the power supply voltage and the other end of which is electrically connected to the collector.

[0013] In some embodiments, the driving circuit unit of the MOSFET further includes a second diode, wherein the anode of the second diode is electrically connected to the drain of the second MOSFET, and the cathode of the second diode is electrically connected to the source of the second MOSFET.

[0014] According to another aspect of this application, an electric heating device is provided, comprising: a button unit, a power management unit, and a driving circuit unit for a MOS transistor as described above. The button unit is electrically connected to the microprocessor of the driving circuit unit and the power management unit, respectively, and the power management unit is also electrically connected to the microprocessor. The driving circuit unit comprises: an electric heating element having a first pin and a second pin. The first pin of the electric heating element is electrically connected to a power supply voltage, and the second pin of the electric heating element is electrically connected to the drain of a first MOS transistor of the driving circuit unit. The source of the first MOS transistor is grounded.

[0015] In some embodiments, the electric heating device further includes a temperature detection unit, which is electrically connected to the electric heating element of the drive circuit unit and the microprocessor of the drive circuit unit, respectively.

[0016] The application of the technical solution of this application has the following beneficial effects:

[0017] This solution connects a transistor and a second MOSFET between the microprocessor's PWM pin and the gate of the first MOSFET. The microprocessor's PWM pin is electrically connected to the base of the transistor, the emitter of the transistor is grounded, and the collector of the transistor is electrically connected to the gate of the second MOSFET. Thus, when the microprocessor outputs a positive PWM voltage, the transistor is turned on, pulling the gate potential of the second MOSFET low, thereby turning on the second MOSFET. When the second MOSFET is on, since its source is connected to the power supply voltage and its drain is electrically connected to the gate of the first MOSFET, the power supply voltage passes through the second MOSFET to reach the gate of the first MOSFET, turning on the first MOSFET. Because the power supply voltage is greater than the output voltage of the microprocessor's PWM pin, this application increases the drive voltage of the first MOSFET's gate, allowing the first MOSFET to conduct sufficiently. Therefore, this application solves the problem in existing technologies where directly driving transistors with the MCU's PWM leads to insufficient transistor conduction.

[0018] Furthermore, when the first MOSFET is fully turned on, its on-resistance (Rds(on)) between its source and drain is very low, approaching that of an ideal conductor. This means that it allows for a larger current to flow, thereby increasing output power. At the same current, the smaller the voltage drop across the first MOSFET, the less power loss is generated, thus reducing device heat generation. Additionally, when the transistor and the second MOSFET are turned on, and the power supply voltage is directly applied to the gate of the first MOSFET, it provides a more powerful voltage source during the charging process of the gate capacitance (Cg) of the first MOSFET. This reduces the total time required for the gate capacitance to charge. Since the switching speed of a transistor is mainly limited by the charging and discharging speed of the gate capacitance, this accelerates the switching speed of the first MOSFET. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0020] Figure 1 A schematic diagram of the circuit structure of a driving circuit unit of a MOS device according to an embodiment of this application is shown;

[0021] Figure 2 A connection diagram of an electric heating device according to an embodiment of this application is shown;

[0022] Figure 3 A schematic diagram of the circuit structure of a microcontroller in a driving circuit unit of a MOS device according to an embodiment of this application is shown.

[0023] Figure 4 A schematic diagram of the circuit structure of the button unit in an electric heating device according to an embodiment of this application is shown;

[0024] Figure 5 This paper shows a partial circuit structure diagram of a power management unit in an electric heating device according to an embodiment of the present application.

[0025] Figure 6 This paper shows a partial circuit structure diagram of a power management unit in an electric heating device according to an embodiment of the present application.

[0026] Figure 7 A partial circuit diagram of a temperature detection unit in an electric heating device according to an embodiment of this application is shown.

[0027] The above figures include the following reference numerals:

[0028] 10. Button unit; 20. Power management unit; 30. Drive circuit unit; 40. Temperature detection unit; J2. Electric heating element; 1. First pin; 2. Second pin; Q1. First MOSFET; Q8. Transistor; Q9. Second MOSFET; D11. First diode; R61. First resistor; R1. Second resistor; R2. Third resistor; R60. Fourth resistor. Detailed Implementation

[0029] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0030] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0031] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of the utility model described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0032] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be an intermediate element present. Furthermore, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element via a third element.

[0033] For ease of description, the following explains some of the nouns or terms used in the embodiments of this application:

[0034] PMU (Power Management Unit): A highly integrated power management module used in consumer electronics, embedded systems, and other scenarios.

[0035] MCU (Micro Controller Unit): A microcontroller is a chip-level computer that integrates functions such as CPU, memory, and peripheral interfaces. It is widely used in the control of electronic devices.

[0036] PWM (Pulse-Width Modulation): Pulse width modulation technology is a very effective technique that uses the digital output of a microprocessor to control analog circuits. It achieves the purpose of adjusting voltage and frequency by changing the duty cycle of the conduction time.

[0037] NTC (Negative Temperature Coefficient Thermistor): Its core characteristic is that the resistance decreases as the temperature increases, and its nominal value is 10KΩ.

[0038] NPN: An NPN transistor consists of two N-type semiconductors sandwiching a P-type semiconductor, with the P-type semiconductor in the middle and the N-type semiconductors on both sides. Its name reflects the arrangement of the materials (NPN).

[0039] PMOS (Positive channel Metal Oxide Semiconductor): A type of P-channel MOSFET with an N-type silicon substrate. Two P+ regions are formed through doping to serve as the source (S) and drain (D). When a negative voltage is applied to the gate (G), a P-type inversion layer channel is formed on the surface of the N-type substrate, enabling current conduction.

[0040] NMOS (N-Metal-Oxide-Semiconductor): It is an electronic device based on N-channel MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). Its core structure consists of two highly doped N+ regions (source and drain) diffused on a P-type silicon substrate, and the formation of the conductive channel is controlled by the gate voltage.

[0041] As described in the background section, in the prior art, the PWM output of an MCU is typically 3.3V, which is relatively low. When driving an NMOS transistor, this leads to insufficient conduction of the NMOS transistor, affecting switching speed and efficiency. Furthermore, due to the incomplete conduction of the NMOS transistor, additional heat is generated as current passes through it, leading to excessively high device temperatures over long-term operation, reducing system stability and lifespan. In addition, the efficiency of the heating element is also affected by the non-ideal conduction of the NMOS transistor. To at least solve the problem of insufficient transistor conduction caused by directly driving the transistor with the MCU's PWM in the prior art, embodiments of this application provide a MOS transistor driving circuit unit and an electric heating device.

[0042] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0043] Figure 1 This is a circuit diagram of a MOS transistor driving circuit unit according to an embodiment of this application. Figure 1 As shown, the driving circuit unit of the MOSFET includes: a microprocessor (not shown in the figure), a transistor Q8, a first MOSFET Q1, and a second MOSFET Q9.

[0044] In some embodiments, the microprocessor described above has a PWM pin for outputting a pulse width modulation (PWM) signal. For example, Figure 3 The microcontroller and its external clock circuit are shown, wherein:

[0045] The aforementioned microprocessor U1 is a 32-bit microprocessor, model AC6321A, such as... Figure 3 As shown, the pins are as follows:

[0046] PIN1 (PB0) is an I / O pin, which is unused and left floating.

[0047] PIN2(SW) is the internal DC-DC switching power supply pin of the chip, used for the internal DC-DC switch of the chip;

[0048] PIN3 (VBAT) is the chip power supply pin, used for the chip to input 3.3V power.

[0049] PIN4 (LDOIN / PP0) is the battery charging pin, used for charging function 5V - unused, floating;

[0050] PIN5 (VDDIO) is the I / O level power supply pin, used for I / O level pull-up input of 3.3V;

[0051] PIN6 (DCVDD / BTAVDD) is the Bluetooth power supply pin, which is connected to the SW pin;

[0052] PIN7 (PA9 / P00 / ADC8) is a GPIO pin, which is unused and left floating.

[0053] PIN8 (BT / RF) is the RF pin, used to connect the Bluetooth antenna;

[0054] PIN9 (BTOSCI) is a GPIO input pin used for chip crystal oscillator output;

[0055] PIN10 (BTOSCO) is a GPIO output pin used for chip crystal oscillator input;

[0056] PIN11 (PA8 / ADC4) is a GPIO pin used to control the indicator light;

[0057] PIN12 (PA7 / ADC3) is a GPIO pin used for vibration function button control;

[0058] PIN13 (PA6 / RX) is a GPIO pin used for power-on button control;

[0059] PIN14 (USB0DM) is the USB DM pin, used for programming.

[0060] PIN15 (USB0DP) is the USB DP pin, used for programming.

[0061] PIN16 (PA5 / TX) is a GPIO pin used for battery power detection;

[0062] PIN17 (PA4 / PWMI) is the PWM pulse output pin, used to output PWM signals to the base of the NPN transistor in the drive circuit unit to control the operation of the heating element;

[0063] PIN18 (PA3 / ADCI) is a GPIO pin used for motor 1 control;

[0064] PIN19 (PA2) is a GPIO pin used for motor 2 control;

[0065] PIN20 (PA1 / ADC0) is a GPIO pin used for rechargeable battery temperature detection;

[0066] PIN21 (PA0 / PWMCH0H) is a GPIO pin, which is unused and left floating.

[0067] PIN22 (PB9 / 32K_OSCI) is a GPIO pin used to detect the charging status indicator light;

[0068] PIN23 (PB8 / 32K_OSCO) is a GPIO pin used to detect the charging indicator light;

[0069] PIN24 (PB7) is a GPIO pin used for buzzer control;

[0070] PIN25 (PB6) is a GPIO pin used for controlling the heating function button;

[0071] PIN26 (PB5) is a GPIO pin, used when unused and left floating.

[0072] PIN27 (PB4) is a GPIO pin used to control the power switch transistor on the motherboard to keep the system powered continuously.

[0073] PIN28 (USB1DM) is a GPIO pin used for LED driver chip status detection;

[0074] PIN29 (USB1DP) is the I2C CLK pin, used for clock signal communication with the LED driver chip;

[0075] PIN30 (PB3) is a GPIO pin used for charging insertion detection;

[0076] PIN31 (PB2) is the I2C DAT pin, used for data signal communication of the LED driver chip.

[0077] PIN32 (PB1) is a GPIO pin used for heating element temperature detection.

[0078] The aforementioned clock circuit includes a 24MHz crystal oscillator (Y1) and matching capacitors (MC7, MC8) to provide clock signals for the microcontroller.

[0079] Bluetooth RF related components: antenna, matching resistor (ML2), matching capacitor (MC5, MC6), used for Bluetooth signal transmission and reception;

[0080] Power conditioning components: inductor (ML1), capacitor (MC1, MC2, MC3, MC4), to achieve power supply regulation and noise filtering, and to power the microcontroller.

[0081] Specifically, the transistor Q8 has three terminals: a base (B), a collector (C), and an emitter (E). In some embodiments, the transistor Q8 may be an NPN transistor Q8.

[0082] Specifically, the first MOSFET Q1 and the second MOSFET Q9 each have three terminals: gate (G), source (S), and drain (D).

[0083] In some embodiments, the first MOSFET Q1 may include an NMOS transistor, and the second MOSFET Q9 may include a PMOS transistor.

[0084] In this application, the PWM pin of the microprocessor is electrically connected to the base of the transistor Q8, the emitter of the transistor Q8 is grounded, the collector of the transistor Q8 is electrically connected to the gate of the second MOSFET Q9, the source of the second MOSFET Q9 is connected to the power supply voltage, and the drain of the second MOSFET Q9 is electrically connected to the gate of the first MOSFET Q1. The power supply voltage is greater than the output voltage of the microprocessor.

[0085] This design incorporates a transistor Q8 and a second MOSFET Q9 between the microprocessor's PWM pin and the gate of the first MOSFET Q1. The microprocessor's PWM pin is electrically connected to the base of transistor Q8, the emitter of transistor Q8 is grounded, and the collector of transistor Q8 is electrically connected to the gate of the second MOSFET Q9. Thus, when the microprocessor outputs a positive PWM voltage, transistor Q8 is turned on, pulling the gate potential of the second MOSFET Q9 low, thereby turning on Q9. With the second MOSFET Q9 on, since its source is connected to the power supply voltage and its drain is electrically connected to the gate of the first MOSFET Q1, the power supply voltage passes through Q9 to the gate of the first MOSFET Q1, turning on Q1. Since the power supply voltage is greater than the output voltage of the microprocessor's PWM pin, this application increases the gate drive voltage of the first MOSFET Q1, enabling the first MOSFET Q1 to be fully turned on. Thus, this application solves the problem in the prior art where using the MCU's PWM to directly drive the transistor leads to insufficient transistor conduction.

[0086] Furthermore, when the first MOSFET Q1 is fully turned on, its on-resistance (Rds(on)) between its source and drain is very low, approaching that of an ideal conductor. This means that it allows for a larger current to flow, thereby increasing the output power. At the same current, the smaller the voltage drop of the first MOSFET Q1 itself, the less power loss it generates, thus reducing device heat generation. Additionally, when transistors Q8 and Q9 are turned on, and the power supply voltage is directly applied to the gate of the first MOSFET Q1, it provides a more powerful voltage source during the charging process of the gate capacitance (Cg) of the first MOSFET Q1. This reduces the total time required for the gate capacitance to charge. Since the switching speed of a transistor is mainly limited by the charging and discharging speed of the gate capacitance, this accelerates the switching speed of the first MOSFET Q1.

[0087] For example, when the PWM signal is high, the voltage difference between the base and emitter of the NPN transistor Q8 is sufficient to turn it on. When the NPN transistor Q8 is on, the current at its collector begins to flow through the path connected to the gate of the PMOS transistor. Since the NPN transistor Q8 pulls the gate of the PMOS transistor low, it triggers the PMOS transistor's turn-on condition, causing the PMOS transistor to turn on. When the PMOS transistor is on, the high supply voltage reaches the gate of the NMOS transistor through the PMOS transistor, providing a drive voltage much higher than the threshold voltage (Vth). This high drive voltage ensures that the potential difference between the gate and source of the NMOS transistor is sufficient to bring it into the on state, forming a low-impedance current path from the source to the drain.

[0088] For example, when the PWM signal goes low, the NPN transistor Q8 enters the off state. When the NPN transistor Q8 is off, it stops providing current to the PMOS transistor to pull the voltage low. At this time, the gate voltage of the PMOS transistor returns to a higher level, and the PMOS transistor enters the off state. When the PMOS transistor is off, it cuts off the path from the power supply voltage to the gate of the NMOS transistor, the gate capacitance of the NMOS transistor begins to discharge, the gate voltage drops below the threshold voltage (Vth), and the NMOS transistor enters the off state.

[0089] Optionally, the microprocessor's output voltage (the voltage output by the PWM pin) is 3.3V, and the power supply voltage is 7.4V.

[0090] In some alternative implementations, such as Figure 1 As shown, the driving circuit unit of the MOS transistor further includes an electric heating element J2, which has a first pin 1 and a second pin 2. The first pin 1 of the electric heating element J2 is electrically connected to the power supply voltage, and the second pin 2 of the electric heating element J2 is electrically connected to the drain of the first MOS transistor Q1. The source of the first MOS transistor Q1 is grounded.

[0091] In the above embodiment, the electric heating element J2 is connected to the drain of the first MOSFET Q1. The conduction state of the first MOSFET Q1 directly controls the current of the electric heating element J2, thereby controlling the heating state of the electric heating element J2. Specifically, when the first MOSFET Q1 is turned on, the current forms a circuit through the electric heating element J2, achieving heating. In this way, the transistor Q8 can quickly respond to the PWM signal, control the conduction and cutoff of the second MOSFET Q9, and thus affect the switching state of the first MOSFET Q1, ultimately controlling the operation of the electric heating element J2. This ensures that the electric heating element J2 can heat up quickly when needed, improving the accuracy and response speed of temperature control.

[0092] For example, when the PWM signal is high, the NPN transistor Q8 will turn on, which in turn causes the PMOS transistor to turn on. When the PMOS transistor is on, the high voltage of the power supply reaches the gate of the NMOS transistor through the PMOS transistor, causing the NMOS transistor to enter the conducting state. At this time, the first pin 1 of the electric heating element J2 is connected to the power supply voltage, and the second pin 2 forms a closed loop through the drain and source (ground) of the NMOS transistor, and the electric heating element J2 starts to work and generates heat.

[0093] For example, when the PWM signal goes low, the positive voltage at the base of the NPN transistor Q8 disappears, and the NPN transistor Q8 is turned off, so no current flows from the collector to ground. As the collector current of the NPN transistor Q8 disappears, the gate voltage of the PMOS transistor returns to a higher level, and the PMOS transistor enters the off state, preventing the power supply voltage from flowing to the gate of the NMOS transistor. The gate capacitance of the NMOS transistor begins to discharge, and the gate voltage drops below the threshold voltage (Vth). The NMOS transistor enters the off state, disconnecting the electric heating element J2 from the power supply voltage, and the electric heating element J2 stops heating.

[0094] Optionally, the aforementioned electric heating element J2 includes a heating element.

[0095] In some alternative implementations, such as Figure 1 As shown, the driving circuit unit of the MOS transistor also includes a first resistor R61, one end of which is grounded and the other end is electrically connected to the gate of the first MOS transistor Q1.

[0096] In the above embodiment, when the PWM signal is low, the first resistor R61 pulls the gate voltage of the first MOSFET Q1 down to a low potential, causing the first MOSFET Q1 to turn off and the electric heating element J2 to stop working. Specifically, the first resistor R61 is used to pull down the gate of the first MOSFET Q1 to ensure that the first MOSFET Q1 is reliably turned off when the PWM signal is low. Thus, since the gate of the first MOSFET Q1 is connected to the first resistor R61, the residual voltage on the gate capacitor will discharge to ground through the first resistor R61, quickly reducing the gate voltage of the first MOSFET Q1 to ground level. This ensures that the first MOSFET Q1 can be reliably turned off during the low-level period of the PWM signal, avoiding a conducting or semi-conducting state caused by residual gate voltage, thereby improving the stability and reliability of the circuit and preventing the electric heating element J2 from malfunctioning when heating is not required.

[0097] Optionally, the first resistor R61 mentioned above includes a thin-film resistor.

[0098] In some alternative implementations, such as Figure 1As shown, the driving circuit unit of the MOS transistor further includes a first diode D11. The anode of the first diode D11 is electrically connected to the second pin 2 of the electric heating element J2, and the cathode of the first diode D11 is electrically connected to the first pin 1 of the electric heating element J2. That is, the first diode D11 is connected in parallel across the two ends of the electric heating element J2.

[0099] In the above embodiment, when the PWM signal is low, transistor Q8 is cut off, and the second MOSFET Q9 is turned off due to the rise in gate voltage, cutting off the direct path from the power supply voltage to the electric heating element J2, thus interrupting the current of the electric heating element J2. At the instant the current is interrupted, the residual current in the electric heating element J2 attempts to flow from the first pin 1 of the electric heating element J2 to the drain of the first MOSFET Q1. At this time, the first diode D11 acts as a forward conducting path. The first diode D11 acts as a freewheeling protection component in the circuit, allowing current to flow, ensuring that when the PWM signal switches from high to low, i.e., when the control signal stops working, the residual current of the electric heating element J2 can be released through an appropriate path, thereby avoiding the impact of reverse voltage on the circuit and protecting the first MOSFET Q1 and the electric heating element J2 from damage.

[0100] Optionally, the first diode D11 mentioned above includes a Schottky diode.

[0101] In some alternative implementations, such as Figure 1 As shown, the driving circuit unit of the MOS transistor also includes a second resistor R1, one end of which is electrically connected to the PWM pin and the other end is electrically connected to the base.

[0102] In the above embodiment, the second resistor R1 is used to limit the current from the PWM signal to the base of transistor Q8, preventing excessive current from damaging the transistor Q8. Specifically, the PWM signal is current-limited by the second resistor R1 before being input to the base of transistor Q8, ensuring that transistor Q8 operates within a safe current range. This improves circuit safety and the lifespan of transistor Q8.

[0103] Optionally, the second resistor R1 mentioned above may include a thin-film resistor.

[0104] In some alternative implementations, such as Figure 1 As shown, the driving circuit unit of the MOS transistor also includes a third resistor R2, one end of which is electrically connected to the base and the other end of which is electrically connected to the emitter.

[0105] In the above embodiment, the third resistor R2 is used to bias the emitter of transistor Q8, ensuring that transistor Q8 is reliably turned off when the PWM signal is low. Specifically, when the PWM signal becomes low, the base current of transistor Q8 is rapidly reduced until it disappears through the third resistor R2, thereby pulling the emitter voltage of transistor Q8 down to ground potential (low potential) and turning off transistor Q8. This improves the turn-off speed of transistor Q8, allowing it to turn off quickly, thus ensuring that the second MOSFET Q9 can be turned off in time, cutting off the current path from the power supply voltage to the gate of the first MOSFET Q1, achieving circuit stability and control accuracy. Furthermore, this also further ensures that the first MOSFET Q1 can be reliably turned off during the low-level period of the PWM signal, further avoiding the conduction or semi-conducting state caused by residual gate voltage, thereby further improving the stability and reliability of the circuit, and further preventing the electric heating element J2 from malfunctioning when heating is not required.

[0106] Optionally, the third resistor R2 mentioned above may include a thin-film resistor.

[0107] In some alternative implementations, such as Figure 1 As shown, the driving circuit unit of the MOS transistor also includes a fourth resistor R60, one end of which is electrically connected to the power supply voltage and the other end is electrically connected to the collector.

[0108] In the above embodiment, the fourth resistor R60 is used to pull up the gate of the second MOSFET Q9, so that the gate of the second MOSFET Q9 can quickly return to a high level, ensuring that the second MOSFET Q9 can be turned off in time, cutting off the path of the power supply voltage to the gate of the first MOSFET Q1. Specifically, when the PWM signal switches from a high level to a low level, the base voltage of the transistor Q8 drops, the transistor Q8 is turned off, and no current flows through the collector. At this time, since the gate of the second MOSFET Q9 is connected to the power supply voltage through the fourth resistor R60, and since the power supply voltage is higher than the threshold voltage of the gate of the second MOSFET Q9, the fourth resistor R60 can quickly pull the gate voltage of the second MOSFET Q9 up to the power supply voltage level. In this way, it is ensured that the second MOSFET Q9 can quickly return to the off state, thereby ensuring that even when the PWM signal is low, the gate of the first MOSFET Q1 will not receive any signal, thus preventing the first MOSFET Q1 from being accidentally turned on, improving the stability and control accuracy of the circuit. Furthermore, this also ensures that the first MOSFET Q1 can be reliably cut off during the low level of the PWM signal, further avoiding the conduction or semi-conducting state caused by residual gate voltage, thereby further improving the stability and reliability of the circuit, and further preventing the electric heating element J2 from malfunctioning when heating is not required.

[0109] Optionally, the fourth resistor R60 mentioned above includes a thin-film resistor.

[0110] In some alternative implementations, such as Figure 1 As shown, the driving circuit unit of the aforementioned MOSFET also includes a second diode (not labeled in the figure). The anode of the second diode is electrically connected to the drain of the second MOSFET Q9, and the cathode of the second diode is electrically connected to the source of the second MOSFET Q9. That is, the second diode is connected in parallel between the source and drain of the second MOSFET Q9.

[0111] In the above embodiment, the second diode provides a freewheeling path for the gate of the first MOSFET Q1 when the second MOSFET Q9 is off, preventing sudden gate voltage changes from impacting the circuit. Specifically, when the second MOSFET Q9 switches from the on state to the off state, the current in the gate of the first MOSFET Q1 freewheels through the second diode until the charge in the gate is completely released. This improves the stability of the circuit and the lifespan of the first MOSFET Q1.

[0112] Understandably, the second diode will not conduct when the PWM signal is high.

[0113] Optionally, the second diode mentioned above includes a Schottky diode.

[0114] To enable those skilled in the art to better understand the technical solution of this application, the driving circuit unit of the MOS device of this application will be described in detail below with reference to specific embodiments.

[0115] This embodiment relates to a specific driving circuit unit for a MOS device, such as... Figure 1 As shown, it includes:

[0116] The first pin 1 of the connector socket of the electric heating element J2 is connected to the power supply voltage, and the second pin 2 is connected to the drain pin D of the first MOSFET Q1. A first diode D11 is connected in parallel between the first pin 1 and the second pin 2, which acts as a freewheeling diode. The source of the first MOSFET Q1 is grounded. When the first MOSFET Q1 is turned on, the power supply voltage passes through the electric heating element J2, and then through the source of the first NMOS transistor Q1 to ground to form a loop, and the electric heating element J2 is working. The gate of the first MOSFET Q1 is connected to the drain of the second MOSFET Q9. The first resistor R61 pulls down the gate. When the second MOSFET Q9 is turned off, the first resistor R61 (parallel resistor to ground) pulls the gate of the first MOSFET Q1 to ground, and the first MOSFET Q1 is turned off.

[0117] The source of the second MOSFET Q9 is connected to the power supply voltage, the gate of the second MOSFET Q9 is connected to the collector of the transistor Q8, and the fourth resistor R60 is pulled up to the source of the second MOSFET Q9. The second resistor R1 (the series resistor of the MCU's PWM signal) is connected to the base of the NPN transistor Q8, and the third resistor R2 is connected in parallel to ground. The emitter of the transistor Q8 is grounded.

[0118] When the PWM is positive, transistor Q8 is turned on, the gate of the second MOSFET Q9 is pulled low, and the second MOSFET Q9 is turned on. The power supply voltage reaches the gate of the first MOSFET Q1 through the second MOSFET Q9, and the first MOSFET Q1 is turned on, so the electric heating element J2 works. When the PWM is negative, transistor Q8 is not turned on, the gate of the second MOSFET Q9 is pulled up to the source and connected to the power supply voltage, so the second MOSFET Q9 is turned off. The gate of the first MOSFET Q1 is pulled down to ground by the first resistor R61, the NMOS transistor Q1 is turned off, and the electric heating element J2 does not work.

[0119] like Figure 2 As shown, in some optional embodiments, according to another aspect of this application, an electric heating device is provided, comprising: a button unit 10, a power management unit 20, and a drive circuit unit 30 as described above. The button unit 10 is electrically connected to the microprocessor (IO port) of the drive circuit unit 30 and the power management unit 20, respectively. The power management unit 20 is also electrically connected to the microprocessor. The drive circuit unit 30 includes an electric heating element having a first pin and a second pin. The first pin of the electric heating element is electrically connected to the power supply voltage, and the second pin of the electric heating element is electrically connected to the drain of a first MOSFET of the drive circuit unit 30. The source of the first MOSFET is grounded.

[0120] In the above embodiments, the electric heating device integrates the button unit 10, the power management unit 20, and the drive circuit unit 30 to achieve automated control and power management. Specifically, the button unit 10 is used to receive user input, the power management unit 20 is used to manage power, and the microprocessor of the drive circuit unit 30 controls the transistor, the second MOSFET, and the first MOSFET of the drive circuit unit 30 through PWM signals, thereby realizing the heating control of the electric heating element of the drive circuit unit 30.

[0121] In this application, because the power supply voltage is greater than the output voltage of the microprocessor's PWM pin, the drive voltage of the gate of the first MOSFET is increased, allowing the first MOSFET to conduct fully. This solves the problem of insufficient transistor conduction caused by directly driving the transistor with the MCU's PWM in the prior art. Furthermore, when the first MOSFET is fully conducting, its on-resistance (Rds(on)) between its source and drain is very low, approaching that of an ideal conductor. This means that it allows for a larger current flow, thereby increasing the output power and improving the efficiency of the electric heating element. At the same current, the smaller the voltage drop of the first MOSFET itself, the less power loss is generated, thus reducing device heat generation. Additionally, when the transistor and the second MOSFET are conducting, and the power supply voltage is directly applied to the gate of the first MOSFET, it provides a more powerful voltage source during the charging process of the gate capacitance (Cg) of the first MOSFET. This reduces the total time required for the gate capacitance to charge. Since the switching speed of the transistor is mainly limited by the charging and discharging speed of the gate capacitance, this accelerates the switching speed of the first MOSFET.

[0122] Specifically, the drive circuit unit 30 in the electric heating device can be any of the drive circuit units 30 mentioned in the above embodiments, and will not be described again here.

[0123] Specifically, the circuit structure diagram of the aforementioned button unit 10 is as follows: Figure 4 As shown in the diagram. POWER_KEY is used for power or signal input / output association. Components in this circuit include diodes (e.g., D10), resistors (e.g., R22, R12, R40), capacitors (e.g., C5, C6, C32), and push-button switches (e.g., S1, S2, S3), etc. The connections between these components are shown in the diagram. Figure 4 As shown, it will not be elaborated further here.

[0124] The circuit structure diagram of the power management unit is shown below. Figure 5 and Figure 6 As shown. Among them, Figure 5 The circuit shown includes components such as resistors (e.g., R37, R38, R39), diodes (e.g., D9), MOSFETs (e.g., Q6), and transistors (e.g., Q7). The connections between these components are as follows: Figure 5 As shown, it will not be elaborated further here. Figure 6 The circuit shown includes components such as resistors (e.g., R18, R13, R14, R17), capacitors (e.g., C4, C7, C19, C20, C21, C22, C1, C3, C2), inductors (e.g., L3), and chips (e.g., U4, U3). The connections between these components are shown below. Figure 6 As shown, it will not be elaborated further here.

[0125] Specifically, when the KEY1 button is pressed, the POWER_KEY signal is connected to... Figure 5 When the gate of MOSFET Q6 is pulled down to ground, MOSFET Q6 is turned on, and the battery power supply VBAT_7.4V is connected to MOSFET Q6 with the signal name changed to VBUS_POWER. Figure 6 The U4 DC-DC step-down chip outputs a 5V power supply to power the motor and buzzer. The 5V power supply VCC_5.1V is then further processed... Figure 6 The LDO chip U3 is converted to VCC_3.3V to power the main control chip MCU and LED driver, and also to provide a pull-up power supply for the NTC circuit used in the product.

[0126] In some alternative implementations, such as Figure 2 As shown, the electric heating device further includes a temperature detection unit 40, which is electrically connected to the electric heating element of the drive circuit unit 30 and the microprocessor (ADC port) of the drive circuit unit 30.

[0127] In the above embodiment, the temperature detection unit 40 is used to monitor the temperature of the electric heating element in real time to ensure the accuracy and safety of temperature control. Specifically, the temperature detection unit 40 detects temperature changes through an NTC thermistor, converts the temperature signal into a voltage signal, and inputs it into a microprocessor for processing. This achieves intelligent temperature control of the electric heating device, improving the accuracy and response speed of temperature control.

[0128] Specifically, the circuit structure diagram of the temperature detection unit is as follows: Figure 7 As shown. Among them, Figure 7 The components in the circuit shown include resistors (such as R15 and R16), capacitors (such as C11), and NTC thermistors (such as J9). The connections between these components are as follows: Figure 7 As shown, it will not be elaborated further here.

[0129] Specifically, using the above Figure 6 The LDO chip mentioned above converts VCC_3.3V as a pull-up power supply. This voltage is divided by a 10K 1% thin-film resistor (R15) and an NTC thermistor (J9), and then connected to the MCU's PIN32 (PB1) heating element temperature detection pin via a second resistor (R16). Due to the characteristics of the NTC, the higher the detected heating element temperature, the lower the NTC resistance (standard 10K 25℃). When the MCU detects that the voltage feedback from the PIN32 (PB1) heating element temperature detection pin reaches the desired temperature, it begins temperature control. Figure 1 The HOT_PWM signal.

[0130] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0131] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A driving circuit unit for a MOS transistor, characterized in that, It includes a microprocessor, a transistor, a first MOSFET, and a second MOSFET; among which, The PWM pin of the microprocessor is electrically connected to the base of the transistor, the emitter of the transistor is grounded, the collector of the transistor is electrically connected to the gate of the second MOSFET, the source of the second MOSFET is connected to the power supply voltage, and the drain of the second MOSFET is electrically connected to the gate of the first MOSFET. The power supply voltage is greater than the output voltage of the microprocessor. The transistor includes an NPN transistor, the first MOS transistor includes an NMOS transistor, and the second MOS transistor includes a PMOS transistor.

2. The MOS transistor driving circuit unit according to claim 1, wherein The driving circuit unit of the MOS transistor further includes an electric heating element, which has a first pin and a second pin. The first pin of the electric heating element is electrically connected to the power supply voltage, and the second pin of the electric heating element is electrically connected to the drain of the first MOS transistor. The source of the first MOS transistor is grounded.

3. The MOS transistor driving circuit unit according to claim 2, wherein The driving circuit unit of the MOS transistor also includes: The first resistor has one end grounded and the other end electrically connected to the gate of the first MOS transistor.

4. The MOS transistor driving circuit unit according to claim 2, wherein The driving circuit unit of the MOS transistor also includes: A first diode, the positive terminal of which is electrically connected to the second pin of the electric heating element, and the negative terminal of which is electrically connected to the first pin of the electric heating element.

5. The MOS transistor driving circuit unit according to any one of claims 2 to 4, wherein The driving circuit unit of the MOS transistor also includes: The second resistor has one end electrically connected to the PWM pin and the other end electrically connected to the base.

6. The MOS transistor driving circuit unit according to any one of claims 2 to 4, wherein The driving circuit unit of the MOS transistor also includes: A third resistor, one end of which is electrically connected to the base and the other end of which is electrically connected to the emitter.

7. The MOS transistor driving circuit unit according to any one of claims 2 to 4, wherein The driving circuit unit of the MOS transistor also includes: A fourth resistor, one end of which is electrically connected to the power supply voltage and the other end of which is electrically connected to the collector.

8. The MOS transistor driving circuit unit according to any one of claims 2 to 4, wherein The driving circuit unit of the MOS transistor also includes: The second diode has its anode electrically connected to the drain of the second MOSFET, and its cathode electrically connected to the source of the second MOSFET.

9. An electric heating device, characterized in that include: The device includes a button unit, a power management unit, and a MOSFET driving circuit unit as described in any one of claims 2 to 8, wherein the button unit is electrically connected to the microprocessor of the driving circuit unit and the power management unit, and the power management unit is also electrically connected to the microprocessor.

10. The electric heating device according to claim 9, characterized in that The electric heating device further includes a temperature detection unit, which is electrically connected to the electric heating element of the drive circuit unit and the microprocessor of the drive circuit unit, respectively.

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