Heating voltage output circuit

Abstract

The embodiment of the invention provides a heating voltage output circuit. The heating voltage output circuit comprises a first switch tube and a first control module, the control end of the first switch tube is connected to the first control module, the first end of the first switch tube is connected to a heating power supply end, and the first control module is further connected to the heating power supply end; the first control module is used for outputting a first control voltage to the first switching tube; and the first switching tube is used for outputting heating voltage through the heating output end when the first switching tube is switched on under the control of the first control voltage. According to the embodiment of the invention, the heating voltage output circuit is used for providing the heating voltage, and a high-side driving chip is not needed, so that the cost is reduced.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of automobile technology, and in particular to a heating voltage output circuit. Background Art

[0002] With the advancement of automobile manufacturing technology, users have higher and higher requirements for automobile comfort. As an important part of the car, the seat is the main contact point between the driver and the passenger and the car. Seats with heating function can improve the driving and riding experience.

[0003] The main consideration for seat heating performance is the temperature of the seat. Too high or too low a seat temperature will affect the user's experience. In a seat heating system, the seat is usually heated by a seat heating circuit to control the seat temperature within the temperature range required by the user. In the seat heating circuit, a high-side driver chip can be used to provide heating voltage to the seat.

[0004] In the prior art, a high-side driver chip is usually used to provide a heating voltage, but the cost of the high-side driver chip is high. Summary of the invention

[0005] In view of this, an embodiment of the present application provides a heating voltage output circuit for reducing costs.

[0006] A first aspect provides a heating voltage output circuit, comprising: a first switch tube and a first control module, wherein a control end of the first switch tube is connected to the first control module, a first end of the first switch tube is connected to a heating power supply end, and the first control module is also connected to the heating power supply end;

[0007] The first control module is used to output a first control voltage to the first switch tube;

[0008] The first switch tube is used to output a heating voltage through the heating output terminal when it is turned on under the control of the first control voltage.

[0009] In a possible implementation, the heating voltage output circuit further includes: a sampling module and a second control module, the second control module is connected to the first control module, the second end of the first switch tube is connected to the first end of the sampling module, and the second end of the sampling module is connected to the heating output end;

[0010] The second control module is used to receive a second control voltage output by the integrated circuit chip according to the heating current after the integrated circuit chip obtains the heating current according to the sampling module, and control the first control module to output the first control voltage according to the second control voltage.

[0011] In a possible implementation, the heating voltage output circuit further includes: a sampling module and a circuit protection module, the circuit protection module is connected to the first control module and the hardware protection circuit, the second end of the first switch tube is connected to the first end of the sampling module, and the second end of the sampling module is connected to the heating output end;

[0012] The circuit protection module is used to receive a third control voltage output by the hardware protection circuit according to the voltage drop voltage after the hardware protection circuit obtains the voltage drop voltage according to the sampling module, and enable the first control module to control the first switch tube to be turned off under the control of the third control voltage.

[0013] In a possible implementation, the first control module includes: a first resistor, a second resistor, and a second switch tube;

[0014] A first end of the first resistor is connected to a first node, and a second end of the first resistor is connected to a second node;

[0015] A first end of the second resistor is connected to the second node, and a second end of the second resistor is connected to a first end of the second switch tube;

[0016] The control end of the second switch tube is connected to the third node, and the second end of the second switch tube is connected to the first voltage end.

[0017] In a possible implementation, the second control module includes: a third resistor and a fourth resistor;

[0018] A first end of the third resistor is connected to the integrated circuit chip, and a second end of the third resistor is connected to a third node;

[0019] A first end of the fourth resistor is connected to the third node, and a second end of the fourth resistor is connected to the second voltage terminal.

[0020] In a possible implementation, the sampling module includes: a fifth resistor and a sixth resistor;

[0021] A first end of the fifth resistor is connected to the fourth node, and a second end of the fifth resistor is connected to the heating output end;

[0022] A first end of the sixth resistor is connected to the fourth node, and a second end of the sixth resistor is connected to the heating output end.

[0023] In a possible implementation, the circuit protection module includes: a transistor, a seventh resistor and an eighth resistor;

[0024] The base of the transistor is connected to the fifth node, the collector of the transistor is connected to the third node, and the emitter of the third switch is connected to the second voltage terminal;

[0025] A first end of the seventh resistor is connected to the hardware protection circuit, and a second end of the seventh resistor is connected to the fifth node;

[0026] A first end of the eighth resistor is connected to the fifth node, and a second end of the eighth resistor is connected to the second voltage end.

[0027] In a possible implementation, the heating voltage output circuit further includes: a first capacitor and a second capacitor;

[0028] The first end of the first capacitor is connected to the first node, and the second end of the first capacitor is connected to the fourth node;

[0029] A first terminal of the second capacitor is connected to the first node, and a second terminal of the second capacitor is connected to the second node.

[0030] In a possible implementation, the heating voltage output circuit further includes: a third capacitor, a first end of the third capacitor is connected to the heating output end, and a second end of the third capacitor is connected to the first voltage end.

[0031] In the technical solution provided in the embodiment of the present application, the heating voltage output circuit includes a first switch tube and a first control module. The control end of the first switch tube is connected to the first control module, the first end of the first switch tube is connected to the heating power supply end, and the first control module is also connected to the heating power supply end. The first control module is used to output a first control voltage to the first switch tube. The first switch tube is used to output a heating voltage through the heating output end when it is turned on under the control of the first control voltage. The embodiment of the present application uses a heating voltage output circuit to provide a heating voltage, and there is no need to use a high-side driver chip, thereby reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0033] Figure 1 A schematic diagram of the structure of a heating voltage output circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0034] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0035] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0036] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0037] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0038] Figure 1 A schematic diagram of a heating voltage output circuit provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the heating voltage output circuit includes: a first switch tube Q1 and a first control module, the control end of the first switch tube Q1 is connected to the first control module, the first end of the first switch tube Q1 is connected to the heating power supply end, and the first control module is also connected to the heating power supply end.

[0039] The first control module is used to output a first control voltage to the first switch tube Q1; when the first switch tube Q1 is turned on under the control of the first control voltage, it outputs a heating voltage through the heating output terminal.

[0040] In an embodiment of the present application, the heating voltage output circuit also includes: a sampling module and a second control module, the second control module is connected to the first control module, the second end of the first switch tube Q1 is connected to the first end of the sampling module, and the second end of the sampling module is connected to the heating output end.

[0041] The second control module is used to receive a second control voltage output by the integrated circuit chip according to the heating current after the integrated circuit chip obtains the heating current according to the sampling module, and control the first control module to output the first control voltage according to the second control voltage.

[0042] In the embodiment of the present application, the heating voltage output circuit further includes a circuit protection module, which is connected to the first control module and the hardware protection circuit. The circuit protection module is used to receive a third control voltage output by the hardware protection circuit according to the voltage drop voltage after the hardware protection circuit obtains the voltage drop voltage according to the sampling module, and enables the first control module to control the first switch tube Q1 to be turned off under the control of the third control voltage.

[0043] like Figure 1 As shown, the first control module includes a first resistor R1, a second resistor R2 and a second switch tube Q2. The first end of the first resistor R1 is connected to the first node TP1, and the second end of the first resistor R1 is connected to the second node TP2; the first end of the second resistor R2 is connected to the second node TP2, and the second end of the second resistor R2 is connected to the first end of the second switch tube Q2; the control end of the second switch tube Q2 is connected to the third node TP3, and the second end of the second switch tube Q2 is connected to the first voltage end.

[0044] like Figure 1 As shown, the second control module includes a third resistor R3 and a fourth resistor R4. A first end of the third resistor R3 is connected to the integrated circuit chip, and a second end of the third resistor R3 is connected to a third node TP3; a first end of the fourth resistor R4 is connected to the third node TP3, and a second end of the fourth resistor R4 is connected to the second voltage terminal.

[0045] like Figure 1 As shown, the sampling module includes a fifth resistor R5 and a sixth resistor R6. The first end of the fifth resistor R5 is connected to the fourth node TP4, and the second end of the fifth resistor R5 is connected to the heating output terminal; the first end of the sixth resistor R6 is connected to the fourth node TP4, and the second end of the sixth resistor is connected to the heating output terminal. The fifth resistor R5 and the sixth resistor R6 are added as sampling resistors in the output path of the heating voltage. The resistance values ​​of the fifth resistor R5 and the sixth resistor R6 are the same. For example, the resistance values ​​of the fifth resistor R5 and the sixth resistor R6 are both 0.01Ω. The fifth resistor R5 and the sixth resistor R6 are arranged in parallel. The parallel connection can increase the overcurrent capacity of the sampling resistor. If the fifth resistor R5 and the sixth resistor R6 use 2512 resistors, theoretically, under the 2512 package, the fifth resistor R5 and the sixth resistor R6 can pass a maximum current of 14A. When the heating output circuit is heating, current will pass through the fifth resistor R5 and the sixth resistor R6, that is, a voltage drop voltage will be generated on the sampling module, and the heating current can be calculated by the collected voltage drop voltage. Therefore, the fifth resistor R5 and the sixth resistor R6 must be high-precision, high-power resistors, for example, 2512 resistors. The voltage drop voltage at both ends of the sampling module reflects the heating current. As the heating current increases, the voltage drop voltage increases, and the heating current and the voltage drop voltage change in direct proportion.

[0046] like Figure 1 As shown, the circuit protection module includes a transistor Q3, a seventh resistor R7 and an eighth resistor R8. The base of the transistor Q3 is connected to the fifth node TP5, the collector of the transistor Q3 is connected to the third node TP3, and the emitter of the third switch is connected to the second voltage terminal; the first end of the seventh resistor R7 is connected to the hardware protection circuit, and the second end of the seventh resistor R7 is connected to the fifth node TP5; the first end of the eighth resistor R8 is connected to the fifth node TP5, and the second end of the eighth resistor R8 is connected to the second voltage terminal.

[0047] like Figure 1 As shown, the heating voltage output circuit further includes a first capacitor C1 and a second capacitor C2. The first end of the first capacitor C1 is connected to the first node TP1, and the second end of the first capacitor C1 is connected to the fourth node TP4; the first end of the second capacitor C2 is connected to the first node TP1, and the second end of the second capacitor C2 is connected to the second node TP2.

[0048] like Figure 1 As shown, the heating voltage output circuit further includes a third capacitor C3, a first end of the third capacitor C3 is connected to the heating output end, and a second end of the third capacitor C3 is connected to the first voltage end.

[0049] In the present application embodiment, for example, Figure 1 As shown, the first voltage terminal is the heating ground terminal HEAT-GND, and the second terminal of the second switch tube Q2 and the second terminal of the third capacitor C3 are connected to the heating ground terminal HEAT-GND.

[0050] In the present application embodiment, for example, Figure 1 As shown, the second voltage terminal may be the ground terminal GND, and the second terminal of the fourth resistor R4, the second terminal of the eighth resistor R8 and the emitter of the transistor Q3 are connected to the ground terminal GND.

[0051] In the embodiment of the present application, the heating ground terminal HEAT-GND and the ground terminal GND can be isolated by a 0Ω resistor.

[0052] As an optional solution, the integrated circuit chip may include a microcontroller unit (MCU). In the embodiment of the present application, the integrated circuit chip is described as an MCU.

[0053] Combine the following Figure 1 , the working principle of the heating voltage output circuit provided in the embodiment of the present application is described in detail.

[0054] The MCU outputs a second control voltage to the second control module, wherein the second control voltage may be a PWM signal MCU_HEAT1_PWM, and the second control voltage may be a high level or a low level, for example, the high level may be 3.3V. The low level may be a ground voltage. When the second control voltage is at a high level, the third resistor R3 and the fourth resistor R4 may divide the second control voltage so that the voltage at the third node TP3 is the fourth control voltage, the fourth control voltage is lower than the second control voltage, and the fourth control voltage is at a high level, and the second switch tube Q2 is turned on under the control of the high level; when the second control voltage is at a low level, the fourth control voltage at the third node TP3 is at a low level, and the second switch tube Q2 is turned off under the control of the low level.

[0055] When the second switch tube Q2 is turned on, the first resistor R1 and the second resistor R2 can divide the power supply voltage HEAT_POWER so that the voltage of the second node TP2 is the first control voltage. Specifically, the first control voltage can be HEAT_POWER*R2 / (R1+R2), the voltage of the first node TP1 is the power supply voltage HEAT_POWER, and the difference between the voltage of the first node TP1 and the voltage of the second node TP2 meets the turn-on condition of the first switch tube Q1, so the first switch tube Q1 is turned on. When the second switch tube Q2 is turned off, the voltage of the first node TP1 is the power supply voltage HEAT_POWER, the first control voltage of the second node TP2 is also the power supply voltage HEAT_POWER, the voltage of the first node TP1 is the same as the voltage of the second node TP2, there is no voltage drop between the first node TP1 and the second node TP2, and the difference between the voltage of the first node TP1 and the voltage of the second node TP2 does not meet the turn-on condition of the first switch tube Q1, so the first switch tube Q1 is turned off.

[0056] In summary, when the second control voltage MCU_HEAT1_PWM is at a high level, the second switch tube Q2 is turned on, and the first switch tube Q1 is turned on; when the second control voltage MCU_HEAT1_PWM is at a low level, the second switch tube Q2 is turned off, and the first switch tube Q1 is turned off.

[0057] The heating output terminal is suspended by default. In the suspended state, there is no voltage on the heating output terminal and the heating output terminal is not grounded. When the first switch tube Q1 is turned on, the first switch tube Q1 turned on under the action of the power supply voltage HEAT_POWER of the heating power supply terminal can output the heating voltage HEAT1+ at the heating output terminal, that is, the power supply voltage HEAT_POWER of the heating power supply terminal passes through the turned-on first switch tube Q1 to output the heating voltage HEAT1+ at the heating output terminal, and the heating output terminal will output the heating voltage HEAT1+ to the positive electrode of the heating wire of the seat to heat the heating wire. When the first switch tube Q1 is turned off, the heating voltage output by the heating output terminal is 0V, that is, no heating voltage is output, and the heating of the heating wire is stopped at this time.

[0058] The heating voltage output circuit can reserve software overcurrent protection. Figure 1 As shown, the MCU can detect the voltage drop across the sampling module, wherein the voltage drop is the difference between the sampling voltage HEAT1_SAMPLY at the first end of the sampling module and the sampling module's second end HEAT1+. The MCU amplifies the voltage drop, or the peripheral circuit amplifies the voltage drop, and the MCU collects the amplified voltage drop from the peripheral voltage; the MCU calculates the heating current based on the amplified voltage drop and the resistance value of the sampling module. Specifically, the MCU can divide the amplified voltage drop by the amplification factor, and then divide it by the resistance value of the sampling module to obtain the heating current, wherein the resistance value of the sampling module = (R5*R6) / (R5+R6). The MCU determines whether the heating current is greater than or equal to the current threshold. If it is determined that the heating current is greater than or equal to the current threshold, it indicates that the heating current is too large and heating abnormality occurs. The MCU outputs a second control voltage to the second control module, and the second control voltage is low level to control the second switch tube Q2 to turn off, thereby turning off the first switch tube Q1, and then causing the heating output end to not output the heating voltage to stop heating the heating wire. If the MCU determines that the heating current is less than the current threshold, indicating that the heating is normal, the MCU outputs a second control voltage to the second control module, and the second control voltage is a high level to control the second switch tube Q2 to turn on, thereby turning on the first switch tube Q1, and then the heating output terminal outputs the heating voltage HEAT1+ to continue heating the heating wire. This method of controlling whether to turn off the heating voltage output by detecting the heating current of the heating wire through software is software overcurrent protection.

[0059] The heating voltage output circuit can reserve hardware overcurrent protection. Figure 1As shown, the hardware protection circuit can detect the voltage drop across the sampling module, wherein the voltage drop is the difference between the sampling voltage HEAT1_SAMPLY at the first end of the sampling module and the sampling voltage HEAT1+ at the second end of the sampling module. The hardware protection circuit can amplify the voltage drop and determine whether the voltage drop after amplification is greater than or equal to the voltage threshold. If it is determined that the voltage drop is greater than or equal to the voltage threshold, the third control voltage is output to the circuit protection module. At this time, the third control voltage is greater than or equal to the conduction voltage, for example, the conduction voltage is 0.8V; the seventh resistor R7 and the eighth resistor R8 can divide the third control voltage so that the voltage of the fifth node TP5 is the fourth control voltage, and the transistor Q3 is turned on under the control of the fourth control voltage; when the transistor Q3 is turned on, the third node TP3 is grounded, and the second switch tube Q2 is turned off. If the hardware protection circuit determines that the voltage drop after the amplification process is less than the voltage threshold, it outputs the third control voltage to the circuit protection module. At this time, the third control voltage is 0V or suspended, and the voltage of the fifth node TP5 is 0V or suspended, and the transistor Q3 is turned off. At this time, the second switch tube Q2 is not affected by the transistor Q3, but only by the second control voltage (i.e., MCU_HEAT1_PWM). In summary, whether the second switch tube Q2 is in the on or off state, the conduction of the transistor Q3 will definitely turn off the second switch tube Q2, thereby shutting off the output of the heating voltage HEAT1+; the closing of the transistor Q3 will definitely not affect the original state of the second switch tube Q2 itself. This method of forcibly cutting off the software output by setting a voltage threshold can be called hardware overcurrent protection.

[0060] like Figure 1 As shown, the filter capacitor C3 can filter the heating voltage HEAT1+.

[0061] like Figure 1 As shown, the first capacitor C1 and the second capacitor C2 use appropriate capacitance values, which can alleviate the rising speed of the rising edge and the falling speed of the falling edge of the PWM signal, so that the first switch tube Q1 is turned on and off more slowly, and no oscillation occurs, thereby improving the electromagnetic compatibility (EMC) performance. The larger the capacitance value of the first capacitor C1 and the second capacitor C2, the longer the charging time required for the first capacitor C1 and the second capacitor C2, so that the voltage of the control end and the first end of the first switch tube Q1 reaches the turn-on voltage more slowly, thereby reducing the speed of turning on and off the first switch tube Q1, and then making the first switch tube Q1 turn on and off more slowly, and no oscillation occurs, thereby improving the EMC performance. Therefore, in the embodiment of the present application, the first capacitor C1 and the second capacitor C2 can use a larger capacitance value.

[0062] In the technical solution provided in the embodiment of the present application, the heating voltage output circuit includes a first switch tube and a first control module. The control end of the first switch tube is connected to the first control module, the first end of the first switch tube is connected to the heating power supply end, and the first control module is also connected to the heating power supply end. The first control module is used to output a first control voltage to the first switch tube. The first switch tube is used to output a heating voltage through the heating output end when it is turned on under the control of the first control voltage. The embodiment of the present application uses a heating voltage output circuit to provide a heating voltage, and there is no need to use a high-side driver chip, thereby reducing costs.

[0063] In the embodiment of the present application, the first capacitor C1 and the second capacitor C2 can adopt appropriate capacitance values, which can control the rising speed of the rising edge and the falling speed of the falling edge of the PWM signal, thereby reducing the speed of turning on and off the first switch tube Q1, thereby making the conduction and closing of the first switch tube Q1 smoother and will not generate oscillation, thereby improving the EMC performance.

[0064] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A heating voltage output circuit, characterized in that: include: A first switch tube and a first control module, wherein the control end of the first switch tube is connected to the first control module, the first end of the first switch tube is connected to the heating power supply end, and the first control module is also connected to the heating power supply end; The first control module is used to output a first control voltage to the first switch tube; The first switch tube is used to output a heating voltage through the heating output terminal when it is turned on under the control of the first control voltage.

2. The circuit according to claim 1, characterized in that The heating voltage output circuit further includes: a sampling module and a second control module, the second control module is connected to the first control module, the second end of the first switch tube is connected to the first end of the sampling module, and the second end of the sampling module is connected to the heating output end; The second control module is used to receive a second control voltage output by the integrated circuit chip according to the heating current after the integrated circuit chip obtains the heating current according to the sampling module, and control the first control module to output the first control voltage according to the second control voltage.

3. The circuit according to claim 1, characterized in that The heating voltage output circuit further includes: a sampling module and a circuit protection module, wherein the circuit protection module is connected to the first control module and the hardware protection circuit, the second end of the first switch tube is connected to the first end of the sampling module, and the second end of the sampling module is connected to the heating output end; The circuit protection module is used to receive a third control voltage output by the hardware protection circuit according to the voltage drop voltage after the hardware protection circuit obtains the voltage drop voltage according to the sampling module, and enable the first control module to control the first switch tube to be turned off under the control of the third control voltage.

4. The circuit according to claim 1, characterized in that The first control module includes: a first resistor, a second resistor and a second switch tube; A first end of the first resistor is connected to a first node, and a second end of the first resistor is connected to a second node; A first end of the second resistor is connected to the second node, and a second end of the second resistor is connected to a first end of the second switch tube; The control end of the second switch tube is connected to the third node, and the second end of the second switch tube is connected to the first voltage end.

5. The circuit according to claim 2, characterized in that The second control module includes: a third resistor and a fourth resistor; A first end of the third resistor is connected to the integrated circuit chip, and a second end of the third resistor is connected to a third node; A first end of the fourth resistor is connected to the third node, and a second end of the fourth resistor is connected to the second voltage terminal.

6. The circuit according to claim 2 or 3, characterized in that: The sampling module includes: a fifth resistor and a sixth resistor; A first end of the fifth resistor is connected to the fourth node, and a second end of the fifth resistor is connected to the heating output end; A first end of the sixth resistor is connected to the fourth node, and a second end of the sixth resistor is connected to the heating output end.

7. The circuit according to claim 3, characterized in that The circuit protection module includes: a transistor, a seventh resistor and an eighth resistor; The base of the transistor is connected to the fifth node, the collector of the transistor is connected to the third node, and the emitter of the third switch is connected to the second voltage terminal; A first end of the seventh resistor is connected to the hardware protection circuit, and a second end of the seventh resistor is connected to the fifth node; A first end of the eighth resistor is connected to the fifth node, and a second end of the eighth resistor is connected to the second voltage end.

8. The circuit according to claim 1, characterized in that The heating voltage output circuit further includes: a first capacitor and a second capacitor; The first end of the first capacitor is connected to the first node, and the second end of the first capacitor is connected to the fourth node; A first terminal of the second capacitor is connected to the first node, and a second terminal of the second capacitor is connected to the second node.

9. The circuit according to claim 1, characterized in that The heating voltage output circuit further includes: a third capacitor, a first end of the third capacitor is connected to the heating output end, and a second end of the third capacitor is connected to the first voltage end.

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