A high-side switch control circuit based on a PTC heater
By using a high-side switch control circuit based on a PTC heater, combined with a comparator circuit and a high-side switch circuit, the problems of high cost and unsuitability for low-voltage, high-current environments in existing technologies are solved, enabling safe and reliable operation and extended lifespan of the heater in vehicle environments.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHENZHEN SHARING ELECTRONICS
- Filing Date
- 2025-05-27
- Publication Date
- 2026-06-19
AI Technical Summary
Existing auxiliary heating control circuits for automotive cockpits are costly, bulky, and unsuitable for low-voltage, high-current environments, thus failing to meet the needs of onboard heaters.
A high-side switch control circuit based on a PTC heater is adopted, including a comparator circuit and a high-side switch circuit. The comparator and high-side switch chip realize precise control of the heating process and multiple protection functions, reduce software dependence, and use capacitor filtering to reduce interference.
It achieves safe and reliable operation in low-voltage, high-current environments, reduces costs, improves stability and service life, and is suitable for complex vehicle environments.
Smart Images
Figure CN224385703U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of PTC heater technology, specifically to a high-side switch control circuit based on a PTC heater. Background Technology
[0002] The patent document with authorization announcement number CN211127114U discloses a high-current automotive high-side switch output circuit, specifically disclosing the following technical solution: including a main logic control circuit (1), a signal detection circuit (2), a voltage regulator circuit (3), and a high-side drive switch (4). The output terminal of the signal detection circuit (2) is connected to the input terminal of the main logic control circuit (1), and the output terminal of the main logic control circuit (1) is connected to the input terminal of the high-side drive switch (4). The voltage regulator circuit (3) provides regulated DC power to the main logic control circuit (1).
[0003] The main logic control circuit (1) includes a main logic control unit (101), an over-temperature detection module (102), an over-current detection module (103), an under-voltage detection module (104), and an over-voltage detection module (105). The output terminals OTP of the over-temperature detection module (102), OAP of the over-current detection module (103), LVP of the under-voltage detection module (104), and OVP of the over-voltage detection module (105) are all connected to the input terminal of the main logic control unit (101). The output terminal of the main logic control unit (101) is connected to the input terminal of the high-side drive switch (4).
[0004] The main logic control circuit (1) is composed of AND gate circuits. When the over-temperature detection module (102), over-current detection module (103), under-voltage detection module (104) and over-voltage detection module (105) output low level, the main logic control circuit (1) outputs low level to enable the high-side drive switch (4) and disconnect the high-side switch tube.
[0005] The circuit structures of the aforementioned prior art are too expensive and bulky, require software to operate, and are mostly used in high-voltage and high-power devices. The auxiliary heating in the local area of the car cabin is used in a low-voltage, high-current environment, which is not suitable for the above control circuits. Utility Model Content
[0006] To address the problems existing in the prior art, the purpose of this utility model is to provide a high-side switch control circuit based on a PTC heater, which requires no software control, has low circuit cost, simple structure, and high reliability.
[0007] To achieve the above objectives, the technical solution of this utility model is as follows:
[0008] A high-side switch control circuit based on a PTC heater includes:
[0009] Comparator circuit and high-side switch circuit;
[0010] The comparison circuit includes a first resistor, a second resistor, a third resistor, a third capacitor, and a comparator. One end of the first resistor is electrically connected to one end of the second resistor and the non-inverting input terminal of the comparator, and the other end of the second resistor is grounded. One end of the third resistor is electrically connected to one end of the third capacitor and the inverting input terminal of the comparator.
[0011] The output of the comparator is electrically connected to the input of the high-side switching circuit.
[0012] Furthermore, the comparison circuit also includes a first capacitor and a second capacitor, with one end of the first capacitor electrically connected to one end of the second capacitor and the eighth pin of the comparator.
[0013] Furthermore, the high-side switching circuit includes a fourth resistor, a fifth resistor, a sixth resistor, a fourth capacitor, a fifth capacitor, a sixth capacitor, and a high-side switching chip. The output terminal of the comparator is electrically connected to one end of the fourth resistor. The first, second, and third pins of the high-side switching chip are electrically connected to each other. The first pin of the high-side switching chip is electrically connected to the heating element and one end of the fifth capacitor, respectively. The fourth pin of the high-side switching chip is electrically connected to the other end of the fourth resistor and one end of the fourth capacitor, respectively. The fifth and sixth pins of the high-side switching chip are electrically connected to one end of the fifth resistor and one end of the sixth resistor, respectively. The other ends of the fourth capacitor, the fifth resistor, the sixth resistor, and the fifth capacitor, the seventh pin of the high-side switching chip, and one end of the sixth capacitor are grounded. The eighth pin of the high-side switching chip is electrically connected to the other end of the sixth capacitor.
[0014] The circuit in this embodiment achieves precise control of the heating process and multiple protection functions through the coordinated operation of a comparator circuit and a high-side switching circuit, eliminating the need for software control and thus reducing operating costs. The comparator circuit accurately judges the heating signal and outputs a control signal; the high-side switching circuit controls the on / off state of the heating element based on this signal, while also providing protection functions such as current limiting, thermal shutdown, undervoltage shutdown, and slow start, ensuring the safe and reliable operation of the PTC heater in low-voltage, high-current environments. Furthermore, the use of capacitors reduces interference, improves anti-interference capability and stability, and extends the heater's lifespan. It is suitable for heating applications in complex environments such as automotive applications, and boasts advantages such as simple structure, high reliability, good stability, and long service life. Attached Figure Description
[0015] Figure 1This is the circuit diagram of the comparator in this utility model;
[0016] Figure 2 This is the circuit diagram of the high-side switch circuit in this utility model. Detailed Implementation
[0017] In the description of this utility model, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. Therefore, the inclusion of "first" and "second" features may explicitly or implicitly include one or more of those features. In the description of this utility model, "a number" means two or more, unless otherwise explicitly specified.
[0018] In this utility model, unless otherwise explicitly specified and limited, the terms "assembly," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to a mechanical connection; they can refer to a direct connection or a connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0019] The utility model will be further described below with reference to the accompanying drawings and specific embodiments. The following description is merely exemplary and does not limit the scope of protection of the utility model.
[0020] Please refer to Figure 1 and Figure 2 , Figure 1 What is disclosed is a comparator circuit in a high-side switch control circuit based on a PTC heater. Figure 2 The disclosed circuit is a high-side switch control circuit based on a PTC heater. The high-side switch control circuit includes a comparator circuit and a high-side switch circuit.
[0021] In this embodiment, the comparator circuit includes a first resistor R17, a first resistor R18, a third resistor R19, a third capacitor C16, and a comparator U2A. One end of the first resistor R17 is electrically connected to one end of the first resistor R18 and the non-inverting input of the comparator U2A, and the other end of the first resistor R17 is connected to a +5V power supply. The other end of the first resistor R18 is grounded. One end of the third resistor R19 is electrically connected to one end of the third capacitor C16 and the inverting input of the comparator U2A, and the other end of the third resistor R19 is the circuit input port INT_2. The other end of the third capacitor C16 is grounded.
[0022] The comparator circuit also includes a first capacitor C11 and a second capacitor C12. One end of the first capacitor C11 is electrically connected to one end of the second capacitor C12 and the eighth pin of comparator U2A. One end of the first capacitor C11, one end of the second capacitor C12, and the eighth pin of comparator U2A are connected to a +5V power supply. The other end of the first capacitor C11, the other end of the second capacitor C12, and the fourth pin of comparator U2A are grounded. The output terminal INT_B of comparator U2A is electrically connected to the input terminal of the high-side switching circuit.
[0023] In this embodiment, the high-side switch circuit includes a fourth resistor R9, a fifth resistor R11, a sixth resistor R10, a fourth capacitor C20, a fifth capacitor C14, a sixth capacitor C15, and a high-side switch chip U3. The output terminal INT_B of comparator U2A is electrically connected to one end of the fourth resistor R9. The first, second, and third pins of the high-side switch chip U3 are electrically connected to each other. Furthermore, the first pin of the high-side switch chip U3 is electrically connected to the heating element PTC2 and one end of the fifth capacitor C14, respectively. The fourth pin of the high-side switch chip U3... The pins are electrically connected to the other end of the fourth resistor R9 and one end of the fourth capacitor C20, respectively. The fifth and sixth pins of the high-side switch chip U3 are electrically connected to one end of the fifth resistor R11 and one end of the sixth resistor R10, respectively. The other end of the fourth capacitor C20, the other end of the fifth resistor R11, the other end of the sixth resistor R10, the other end of the fifth capacitor C14, the seventh pin of the high-side switch chip U3, and one end of the sixth capacitor C15 are grounded. The eighth pin of the high-side switch chip U3 is electrically connected to the other end of the sixth capacitor C15.
[0024] In the comparison circuit of this embodiment, the circuit input port INT_2 is connected to the inverting input terminal of comparator U2A through the third resistor R19. The first resistors R17 and R18 are respectively connected between the +5V power supply and ground, and form a voltage divider at the node to provide a reference voltage for the non-inverting input terminal of comparator U2A, thus setting the comparison reference.
[0025] The output terminal INT_B of comparator U2A is the INT_B signal. When the voltage at the circuit input port INT_2 is lower than the reference voltage, the output terminal INT_B of comparator U2A is high; conversely, when the voltage at the circuit input port INT_2 is higher than the reference voltage, the output terminal INT_B of comparator U2A is low.
[0026] The first capacitor C11 and the second capacitor C12 act as filters, reducing the impact of high-frequency noise in the input signal on the comparison results and making the output of comparator U2A more stable. The third capacitor C16 serves as a bypass capacitor, providing a stable power supply voltage for comparator U2A.
[0027] In the comparator circuit of this embodiment, the main function of the comparator circuit is to determine whether the circuit input port INT_2 is a heating signal. By comparing it with the set reference voltage, the output terminal INT_B of the comparator U2A outputs the corresponding high-level or low-level signal to provide a control signal for the high-side switching circuit.
[0028] In the high-side switch circuit of this embodiment, the output signal INT_B of comparator U2A is input to the fourth pin (enable pin) of high-side switch chip U3 through the fourth resistor R9. This signal is determined by the comparator circuit. When the comparator circuit determines that heating is required, the output signal INT_B of comparator U2A is high; otherwise, it is low.
[0029] When the output terminal INT_B of comparator U2A is high, the high-side switch chip U3 is enabled, allowing current to flow through the heating element PTC2 and starting the heating process; when the output terminal INT_B of comparator U2A is low, the high-side switch chip U3 is disabled, cutting off the current to the heating element PTC2 and stopping the heating.
[0030] The high-side switch chip U3 has enable and control functions: it receives control signals through the enable pin to control the conduction and cutoff of the internal power switch, thereby controlling the power supply to and from the heating element PTC2.
[0031] The high-side switch chip U3 features current detection and limiting: It integrates a current detection function (via the CS port on pin 5) to monitor the current flowing through the heating element PTC2 in real time. When the current exceeds the set limit, the high-side switch chip U3 automatically limits the current to prevent overload.
[0032] The high-side switch chip U3 has thermal shutdown protection: The high-side switch chip U3 contains a temperature monitoring circuit. When the temperature of the high-side switch chip U3 is too high (such as due to overcurrent or increased ambient temperature), the thermal shutdown function will be triggered to cut off the output and protect the high-side switch chip U3 and related components.
[0033] The high-side switch chip U3 has undervoltage shutdown protection: the high-side switch chip U3 can monitor the supply voltage (through the VCC port of pin 8), and automatically shut down the output when the voltage is lower than the operating range of the high-side switch chip U3 to prevent abnormal operation or damage caused by low voltage.
[0034] The high-side switch chip U3 has a slow-start function: it may have a slow-start function, which is implemented through the sixth pin (such as the SEn port), which slowly increases the output current when powered on or enabled to avoid current surges.
[0035] The fifth capacitor C14 and the sixth capacitor C15 are used to filter out ripple and high-frequency noise in the power supply, ensuring that the high-side switching chip U3 receives a stable power supply voltage. The fourth capacitor C20 is used to filter out high-frequency interference in the input signal and prevent false triggering.
[0036] In the high-side switching circuit of this embodiment, the high-side switching circuit can precisely control the working state of the heating element PTC2 according to the INT_B signal at the output terminal of the comparator U2A, realize the switching between heating and stopping heating, and thus precisely control the heating process.
[0037] With protection functions such as current limiting, thermal shutdown, and undervoltage shutdown, the high-side switch chip U3 can automatically cut off high-current circuits under abnormal conditions, protecting itself and related electronic components, and improving the reliability and safety of the entire system.
[0038] The use of filter capacitors ensures stable power supply to the chip and clean input signals, reduces interference, and enables the heater to operate under stable voltage and current conditions, thus extending the heater's service life.
[0039] The circuit in this embodiment achieves precise control of the heating process and multiple protection functions through the coordinated operation of a comparator circuit and a high-side switching circuit, eliminating the need for software control and thus reducing operating costs. The comparator circuit accurately judges the heating signal and outputs a control signal; the high-side switching circuit controls the on / off state of the heating element based on this signal, while also providing protection functions such as current limiting, thermal shutdown, undervoltage shutdown, and slow start, ensuring the safe and reliable operation of the PTC heater in low-voltage, high-current environments. Furthermore, the use of capacitors reduces interference, improves anti-interference capability and stability, and extends the heater's lifespan. It is suitable for heating applications in complex environments such as automotive applications, and boasts advantages such as simple structure, high reliability, good stability, and long service life.
Claims
1. A high-side switch control circuit based on a PTC heater, characterized in that, include: Comparator circuit and high-side switch circuit; The comparison circuit includes a first resistor, a second resistor, a third resistor, a third capacitor, and a comparator. One end of the first resistor is electrically connected to one end of the second resistor and the non-inverting input terminal of the comparator, and the other end of the second resistor is grounded. One end of the third resistor is electrically connected to one end of the third capacitor and the inverting input terminal of the comparator. The output of the comparator is electrically connected to the input of the high-side switching circuit.
2. The high-side switch control circuit according to claim 1, characterized in that: The comparator circuit further includes a first capacitor and a second capacitor, with one end of the first capacitor electrically connected to one end of the second capacitor and the eighth pin of the comparator.
3. The high-side switch control circuit according to claim 1, characterized in that: The high-side switching circuit includes a fourth resistor, a fifth resistor, a sixth resistor, a fourth capacitor, a fifth capacitor, a sixth capacitor, and a high-side switching chip. The output terminal of the comparator is electrically connected to one end of the fourth resistor. The first, second, and third pins of the high-side switching chip are electrically connected to each other. The first pin of the high-side switching chip is electrically connected to the heating element and one end of the fifth capacitor, respectively. The fourth pin of the high-side switching chip is electrically connected to the other end of the fourth resistor and one end of the fourth capacitor, respectively. The fifth and sixth pins of the high-side switching chip are electrically connected to one end of the fifth resistor and one end of the sixth resistor, respectively. The other ends of the fourth, fifth, and sixth resistors, the other end of the fifth capacitor, the seventh pin of the high-side switching chip, and one end of the sixth capacitor are grounded. The eighth pin of the high-side switching chip is electrically connected to the other end of the sixth capacitor.