Driving circuit and vehicle-mounted device

Abstract

The utility model provides a drive circuit and a vehicle-mounted device, the vehicle-mounted device comprises a power supply, a load circuit and a drive circuit, the drive circuit comprises a comparator circuit, the comparator circuit is used for generating PWM waveform; the input end of the bootstrap circuit is connected with the output end of the comparator circuit, and the bootstrap circuit is used for charging according to the PWM waveform output by the comparator circuit and outputting a high-voltage signal; the control end of the transistor is connected with the output end of the bootstrap circuit, the first connecting end of the transistor is used for being connected with a power supply, the second connecting end of the transistor is used for being connected with a load circuit, and the transistor is used for conducting the first connecting end and the second connecting end according to a high-voltage signal output by the bootstrap circuit. According to the driving circuit, on the basis of ensuring power supply to the load circuit, more compact design layout can be realized, dependence on an integrated circuit (IC) can be eliminated, and the cost is reduced.

Description

Technical Field

[0001] This utility model relates to the field of vehicle-mounted device technology, specifically to a drive circuit and a vehicle-mounted device. Background Technology

[0002] Nowadays, the functional requirements of in-vehicle infotainment systems (IVI), telematics boxes (T-BOX), and advanced driver assistance systems (ADAS) are becoming increasingly complex. The electrical load on vehicles is increasing, and the parameters and number of in-vehicle navigation and entertainment screens are also constantly growing. This places increasingly higher demands on the current-carrying capacity of control assemblies such as the vehicle's infotainment system.

[0003] Because EMC certification requires power supply-related interference immunity tests on the vehicle's infotainment system, such as reverse connection tests, the vehicle's battery cannot be directly connected to the infotainment system. The reverse connection protection test for the power input is typically implemented using a series diode or a dedicated integrated circuit (IC). In designs using N-type metal-oxide-semiconductor (N-MOS) transistors as switching circuits, the switching drive signal is often generated by the integrated IC. However, integrated ICs suffer from high design complexity, high cost, and poor reliability. Utility Model Content

[0004] The problem solved by this invention is that the integrated ICs in existing driver circuits are difficult to design and costly.

[0005] To address the aforementioned problems, this utility model provides a drive circuit for use in a vehicle-mounted device. The vehicle-mounted device includes a power supply, a load circuit, and a drive circuit. The drive circuit includes:

[0006] A comparator circuit is used to generate a pulse width modulation (PWM) waveform;

[0007] A bootstrap circuit, wherein the input terminal of the bootstrap circuit is connected to the output terminal of the comparator circuit, and the bootstrap circuit is used to charge according to the PWM waveform output by the comparator circuit and output a high voltage signal;

[0008] A transistor, wherein the control terminal of the transistor is connected to the output terminal of the bootstrap circuit, the first connection terminal of the transistor is connected to the power supply, and the second connection terminal of the transistor is connected to the load circuit, and the transistor is used to turn on the first connection terminal and the second connection terminal according to the high voltage signal output by the bootstrap circuit.

[0009] Optionally, the comparator circuit includes a comparator, a first capacitor, and a first resistor. The first end of the first resistor is connected to the output terminal of the comparator, the second end of the first resistor is connected to the first end of the first capacitor, the first end of the first capacitor is also connected to the inverting input terminal of the comparator, and the second end of the first capacitor is grounded.

[0010] When the voltage at the non-inverting input of the comparator is greater than the voltage across the first capacitor, the comparator outputs a high level and the first capacitor charges; when the voltage at the non-inverting input of the comparator is less than the voltage across the first capacitor, the comparator outputs a low level and the first capacitor discharges.

[0011] Optionally, the non-inverting input terminal of the comparator is used to input a reference voltage, the positive terminal of the comparator is used to input a power supply voltage, and the negative terminal of the comparator is grounded, wherein the power supply voltage is greater than the reference voltage.

[0012] Optionally, the comparator circuit further includes a second resistor, the first end of which is connected to the non-inverting input of the comparator, and the second end of which is connected to the output of the comparator.

[0013] Optionally, the comparator circuit further includes a Zener diode, with its first terminal connected to the negative terminal of the comparator and its second terminal grounded.

[0014] Optionally, the comparator circuit further includes a third resistor, the first end of which is connected to the output of the comparator, and the second end of which is connected to a power supply.

[0015] Optionally, the bootstrap circuit includes a bootstrap capacitor, a second capacitor, a first diode, and a second diode. The anode of the first diode is used to input the power supply voltage. The cathode of the first diode is connected to the first terminal of the bootstrap capacitor. The second terminal of the bootstrap capacitor is connected to the output terminal of the comparator. The anode of the second diode is connected to the cathode of the first diode. The cathode of the second diode is connected to the control terminal of the transistor. The first terminal of the second capacitor is connected to the control terminal of the transistor. The second terminal of the second capacitor is grounded.

[0016] When the comparator outputs a high level, the bootstrap capacitor and the second capacitor are charged, and the voltage of the high-voltage signal is the sum of the power supply voltage and the voltage of the bootstrap capacitor; when the comparator outputs a low level, the second capacitor is discharged, and the voltage of the high-voltage signal is the sum of the power supply voltage and the voltage of the second capacitor.

[0017] Optionally, the driving circuit further includes a fourth resistor and a fifth resistor. The first end of the fourth resistor is connected to a power supply, the second end of the fourth resistor is connected to the first end of the fifth resistor, the second end of the fifth resistor is grounded, and the first end of the fifth resistor is connected to the non-inverting input of the comparator.

[0018] Optionally, the driving circuit further includes a rheostat, the first end of which is connected to the first connection terminal of the transistor, and the second end of which is grounded.

[0019] This utility model embodiment also provides a vehicle-mounted device, including:

[0020] power supply;

[0021] Load circuit;

[0022] The driving circuit described in any of the above is used to drive the power supply to provide power voltage to the load circuit.

[0023] The driving circuit provided in this embodiment includes a comparator circuit, a bootstrap circuit, and a transistor. The comparator circuit generates a PWM waveform, which is used as a trigger source to charge the bootstrap circuit, so that the bootstrap circuit outputs a high-voltage signal to the transistor. This causes the first and second connection terminals of the transistor to conduct to supply power to the load circuit. This driving circuit can achieve a more compact design layout while ensuring power supply to the load circuit, and it can also get rid of the dependence on integrated ICs and reduce costs. Attached Figure Description

[0024] Figure 1 A schematic diagram of the drive circuit provided in an embodiment of this utility model;

[0025] Figure 2 for Figure 1 The diagram shows the structure of the comparator circuit in the driving circuit shown.

[0026] Figure 3 for Figure 1 The diagram shows the structure of the bootstrap circuit in the driving circuit.

[0027] Explanation of reference numerals in the attached figures:

[0028] 100. Driver circuit; 10. Comparator circuit; 20. Bootstrap circuit; 30. Transistor;

[0029] 200. Load circuit;

[0030] R1, the first resistor; R2, the second resistor; R3, the third resistor; R4, the fourth resistor; R5, the fifth resistor;

[0031] C1, first capacitor; C2, bootstrap capacitor; C3, second capacitor;

[0032] U1, comparator; D1, Zener diode; D2, first diode; D3, second diode; D4, rheostat. Detailed Implementation

[0033] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below.

[0034] In electronic system design, reverse polarity protection at the power input is crucial, effectively preventing equipment damage or safety accidents caused by incorrect power polarity connection. Currently, there are two main approaches to achieving this function: using series diodes and utilizing dedicated integrated ICs. However, both approaches face the following shortcomings in practice:

[0035] 1. During power supply-related interference immunity testing of the vehicle's infotainment system, the current draw of the entire unit is extremely high under full load operation. Traditional series diode designs can meet reverse polarity protection requirements under low current conditions, but the voltage drop across the diodes increases significantly under high current. This excessive voltage drop, especially with the vehicle's low voltage, can prevent downstream ICs from reaching their normal operating voltage range, leading to system malfunctions. Furthermore, the conduction current of diodes is generally not very high, typically between 1A and 3A, which is insufficient for the high current requirements of vehicle infotainment systems. Using high-current diodes would also be very expensive. Therefore, using series diodes for reverse polarity protection is no longer suitable for current applications.

[0036] 2. Using integrated ICs may result in significant dark current, failing to meet the automotive manufacturer's standards, and are also more expensive, creating cost pressure. Furthermore, in the pursuit of extreme miniaturization, integrated ICs do not offer outstanding space-saving performance.

[0037] Therefore, embodiments of this application provide a drive circuit and an on-board device to solve the above-mentioned technical problems.

[0038] Please see Figure 1 , Figure 1This is a schematic diagram of the drive circuit provided in an embodiment of the present invention. The present invention provides a drive circuit 100 applied to an in-vehicle device. The in-vehicle device includes a power supply, a load circuit 200, and the drive circuit 100. The drive circuit 100 includes a comparator circuit 100, a bootstrap circuit 20, and a transistor 30. The comparator circuit 100 generates a PWM waveform. The input terminal of the bootstrap circuit 20 is connected to the output terminal of the comparator circuit 100. The bootstrap circuit 20 charges and outputs a high-voltage signal according to the PWM waveform output by the comparator circuit 100. The control terminal of the transistor 30 is connected to the output terminal of the bootstrap circuit 20. The first connection terminal of the transistor 30 is connected to the power supply, and the second connection terminal of the transistor 30 is connected to the load circuit 200. The transistor 30 conducts the first and second connection terminals according to the high-voltage signal output by the bootstrap circuit 20. In this embodiment, a PWM waveform is generated by a comparator circuit 100. The waveform is used as a trigger source to charge the bootstrap circuit 20, so that the bootstrap circuit 20 outputs a high-voltage signal to the transistor 30, causing the first and second connection terminals of the transistor 30 to conduct to supply power to the load circuit 200. The drive circuit 100 generates a high-voltage signal through the comparator U1 and the bootstrap circuit 20 to drive the transistor 30 to turn on and off. This can achieve a more compact design layout while maintaining functional integrity, and can also get rid of the dependence on integrated ICs, thus reducing costs.

[0039] Transistor 30 can be a commonly used transistor, MOSFET, or other types of switching devices; this application embodiment does not specifically limit it. In this embodiment, MOSFET is used as an example, where the control terminal of transistor 30 is the gate, the first connection terminal is the source, and the second connection terminal is the drain.

[0040] It should be noted that the power supply can be the battery power supply voltage, such as 14V. The comparator circuit 100 generates a PWM waveform from the battery power supply voltage, and the bootstrap circuit 20 boosts the voltage to turn on the transistor 30 for power supply. With the trend of vehicle cabin integration, the drive circuit 100 provided in this application can maintain a low on-state voltage drop even under high load and high current, ensuring the normal operation of the subsequent ICs.

[0041] The drive circuit 100 provided in this application can be applied not only to T-BOX or IVI vehicle infotainment products, but also to any switching circuit in automotive architecture that requires low conduction loss.

[0042] Please continue reading. Figure 2 , Figure 2 for Figure 1The schematic diagram of the comparator circuit in the driving circuit shown illustrates that the comparator circuit 100 also includes a comparator U1, a first capacitor C1, and a first resistor R1. The first end of the first resistor R1 is connected to the output terminal of the comparator U1, and the second end of the first resistor R1 is connected to the first end of the first capacitor C1. The first end of the first capacitor C1 is also connected to the inverting input terminal of the comparator U1, and the second end of the first capacitor C1 is grounded. When the voltage at the non-inverting input terminal of the comparator U1 is greater than the voltage across the first capacitor C1, the comparator U1 outputs a high level, and the first capacitor C1 charges. When the voltage at the non-inverting input terminal of the comparator U1 is less than the voltage across the first capacitor C1, the comparator U1 outputs a low level, and the first capacitor C1 discharges. The first capacitor C1 is charged by the high-level output of the comparator U1, and the first capacitor C1 is discharged using the first resistor R1 as a discharging element. This process can be adjusted by changing the capacitance value of the first capacitor C1 to regulate the charging and discharging time of the first capacitor C1, thereby adjusting the frequency of the PWM waveform generated by the comparator U1.

[0043] In some embodiments, the comparator U1 may be an LT1001A, the first capacitor C1 has a capacitance of 470nF, and the first resistor R1 has a resistance of 100KΩ.

[0044] In some embodiments, the non-inverting input of comparator U1 is used to input a reference voltage, the positive terminal of comparator U1 is used to input a power supply voltage, and the negative terminal of comparator U1 is grounded, wherein the power supply voltage is greater than the reference voltage. By setting the power supply voltage to be greater than the reference voltage, that is, setting the voltage at the positive terminal of comparator U1 to be greater than the voltage at the non-inverting input, it is ensured that the first capacitor C1 is charged by the high-level output of comparator U1, so that the voltage of the first capacitor C1 is greater than the reference voltage. This, in turn, ensures that the voltage at the non-inverting input of comparator U1 is greater than the voltage at the inverting input, thereby enabling the first capacitor C1 to discharge.

[0045] The power supply voltage is the voltage provided by the aforementioned power source, which can be 14V.

[0046] The reference voltage can be provided by a bypass circuit. For example, in some embodiments, the drive circuit 100 further includes a fourth resistor R4 and a fifth resistor R5. The first terminal of the fourth resistor R4 is connected to the power supply, the second terminal of the fourth resistor R4 is connected to the first terminal of the fifth resistor R5, the second terminal of the fifth resistor R5 is grounded, and the first terminal of the fifth resistor R5 is connected to the non-inverting input terminal of the comparator U1. By setting the fourth resistor R4 and the fifth resistor R5, the power supply voltage is divided, thereby ensuring that the power supply voltage is greater than the reference voltage.

[0047] Among them, the resistance of the fourth resistor R4 can be 10 KΩ, and the resistance of the fifth resistor R5 can be 10 KΩ.

[0048] In some embodiments, the comparator circuit 100 further includes a second resistor R2, one end of which is connected to the non-inverting input terminal of the comparator U1, and the other end of which is connected to the output terminal of the comparator U1. By connecting the second resistor R2 to the comparator U1, a hysteresis effect can be achieved in the comparator U1, reducing the impact of noise and interference.

[0049] The resistance of the second resistor R2 can be 10 KΩ.

[0050] In some embodiments, the comparator circuit 100 further includes a Zener diode D1, one end of which is connected to the negative terminal of the comparator U1, and the other end of which is grounded. By using the Zener diode D1, reverse power connection can be prevented from damaging the comparator U1.

[0051] Among them, the Zener diode D1 can be a 1N5817.

[0052] In some embodiments, the comparator circuit 100 further includes a third resistor R3. One end of the third resistor R3 is connected to the output terminal of the comparator U1, and the second end of the third resistor R3 is used to connect to the power supply. The third resistor R3 is a pull-up resistor, which can clamp the signal output by the comparator U1 to a high level and also limit the current.

[0053] Please continue reading. Figure 3 , Figure 3 for Figure 1 The schematic diagram of the bootstrap circuit in the driving circuit shown illustrates the structure of the bootstrap circuit 20. The bootstrap circuit 20 includes a bootstrap capacitor C2, a second capacitor C3, a first diode D2, and a second diode D3. The anode of the first diode D2 is connected to the power supply, and the cathode of the first diode D2 is connected to the first terminal of the bootstrap capacitor C2. The second terminal of the bootstrap capacitor C2 is connected to the output terminal of comparator U1. The anode of the second diode D3 is connected to the cathode of the first diode D2, and the cathode of the second diode D3 is connected to the control terminal of transistor 30. The first terminal of the second capacitor C3 is connected to the control terminal of transistor 30, and the second terminal of the second capacitor C3 is grounded. When comparator U1 outputs a high level, the second capacitor C3 charges, and the high-voltage signal is the sum of the power supply voltage and the discharge voltage of the bootstrap capacitor C2. When comparator U1 outputs a low level, the second capacitor C3 discharges, and the high-voltage signal is the sum of the power supply voltage and the discharge voltage of the second capacitor C3. This application utilizes the polarity of the bootstrap capacitor C2 to boost the voltage and form a high-voltage signal, thereby turning on transistor 30 and supplying power to the vehicle's load. In addition, the voltage drop of transistor 30 is particularly small even when the circuit consumes a large current.

[0054] In some embodiments, the drive circuit 100 further includes a variable resistor D4, one end of which is connected to the first connection terminal of the transistor 30, and the second end of which is grounded. By using the variable resistor D4, protection can be provided when the power supply voltage is negative or when subjected to surges, preventing damage to subsequent circuits. In some embodiments, protection can also be further achieved by incorporating a body diode in the transistor 30.

[0055] This utility model embodiment also provides a vehicle-mounted device, which includes a power supply, a load circuit 200, and a drive circuit 100 as described in any of the above embodiments. The drive circuit 100 provides a power supply voltage to the load circuit 200 through the drive power supply. The specific contents of the drive circuit 100 are described above and will not be repeated here.

[0056] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A drive circuit for use in a vehicle-mounted device, characterized in that, The vehicle-mounted device includes a power supply, a load circuit, and a drive circuit, wherein the drive circuit includes: A comparator circuit is used to generate a pulse width modulation (PWM) waveform; A bootstrap circuit, wherein the input terminal of the bootstrap circuit is connected to the output terminal of the comparator circuit, and the bootstrap circuit is used to charge according to the PWM waveform output by the comparator circuit and output a high voltage signal; A transistor, wherein the control terminal of the transistor is connected to the output terminal of the bootstrap circuit, the first connection terminal of the transistor is connected to the power supply, and the second connection terminal of the transistor is connected to the load circuit, and the transistor is used to turn on the first connection terminal and the second connection terminal according to the high voltage signal output by the bootstrap circuit.

2. The driving circuit according to claim 1, characterized in that, The comparator circuit includes a comparator, a first capacitor, and a first resistor. The first end of the first resistor is connected to the output terminal of the comparator, the second end of the first resistor is connected to the first end of the first capacitor, the first end of the first capacitor is also connected to the inverting input terminal of the comparator, and the second end of the first capacitor is grounded. When the voltage at the non-inverting input of the comparator is greater than the voltage across the first capacitor, the comparator outputs a high level and the first capacitor charges; when the voltage at the non-inverting input of the comparator is less than the voltage across the first capacitor, the comparator outputs a low level and the first capacitor discharges.

3. The driving circuit according to claim 2, characterized in that, The non-inverting input terminal of the comparator is used to input a reference voltage, the positive terminal of the comparator is used to input a power supply voltage, and the negative terminal of the comparator is grounded, wherein the power supply voltage is greater than the reference voltage.

4. The driving circuit according to claim 2, characterized in that, The comparator circuit further includes a second resistor, the first end of which is connected to the non-inverting input of the comparator, and the second end of which is connected to the output of the comparator.

5. The driving circuit according to claim 2, characterized in that, The comparator circuit also includes a Zener diode, with its first terminal connected to the negative terminal of the comparator and its second terminal grounded.

6. The driving circuit according to claim 2, characterized in that, The comparator circuit further includes a third resistor, the first end of which is connected to the output terminal of the comparator, and the second end of which is connected to the power supply.

7. The driving circuit according to any one of claims 1 to 6, characterized in that, The bootstrap circuit includes a bootstrap capacitor, a second capacitor, a first diode, and a second diode. The anode of the first diode is used to input the power supply voltage. The cathode of the first diode is connected to the first terminal of the bootstrap capacitor. The second terminal of the bootstrap capacitor is connected to the output terminal of the comparator. The anode of the second diode is connected to the cathode of the first diode. The cathode of the second diode is connected to the control terminal of the transistor. The first terminal of the second capacitor is connected to the control terminal of the transistor. The second terminal of the second capacitor is grounded. When the comparator outputs a high level, the bootstrap capacitor and the second capacitor are charged, and the voltage of the high-voltage signal is the sum of the power supply voltage and the voltage of the bootstrap capacitor; when the comparator outputs a low level, the second capacitor is discharged, and the voltage of the high-voltage signal is the sum of the power supply voltage and the voltage of the second capacitor.

8. The driving circuit according to any one of claims 1 to 6, characterized in that, The driving circuit further includes a fourth resistor and a fifth resistor. The first end of the fourth resistor is connected to the power supply, the second end of the fourth resistor is connected to the first end of the fifth resistor, the second end of the fifth resistor is grounded, and the first end of the fifth resistor is connected to the non-inverting input of the comparator.

9. The driving circuit according to any one of claims 1 to 6, characterized in that, The driving circuit also includes a variable resistor, the first end of which is connected to the first connection terminal of the transistor, and the second end of which is grounded.

10. A vehicle-mounted device, characterized in that, include: power supply; Load circuit; The driving circuit according to any one of claims 1 to 9 is used to drive the power supply to provide a power supply voltage to the load circuit.

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