Circuit structure for humidity sensor
By introducing reverse connection protection circuit and ESD protection into the automotive humidity sensor circuit, the problems of device damage and electrostatic interference are solved, enabling rapid fault location and improving circuit reliability and fault diagnosis efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-06
- Publication Date
- 2026-04-14
AI Technical Summary
Existing automotive humidity sensor circuits lack reliable reverse connection protection, making them prone to damage due to incorrect reverse connection. The SENT signal output port is susceptible to electrostatic interference, leading to communication abnormalities. Furthermore, the power supply line lacks real-time voltage monitoring, making troubleshooting difficult.
A circuit structure including an interface module, a power supply module, a reverse connection protection circuit, an MCU microcontroller module, a humidity sensor chip, and an output module was designed. By adding a reverse connection protection circuit before the power supply module, ESD protection is set at the SENT signal output port, and real-time power supply voltage monitoring is provided through the ADC pin.
It effectively prevents device damage caused by incorrect or reverse connections, reduces electrostatic interference, ensures normal communication, and enables rapid fault location.
Smart Images
Figure CN224122576U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of humidity sensor technology, and in particular to a circuit structure for a humidity sensor. Background Technology
[0002] An automotive humidity sensor is a device used to detect humidity inside an engine. It converts changes in the humidity of gases or liquids into electrical signals that are then provided to the electronic control unit (ECU). It is widely used in modern automobiles, playing a crucial role, particularly in cold start control, idle speed control, fuel injection control, and emissions control. By monitoring and regulating the humidity inside the engine through automotive sensor circuitry, it ensures that the engine operates within its optimal range, improving vehicle performance and environmental friendliness.
[0003] Existing automotive sensor circuits have the following problems: the power input lacks reliable reverse connection protection, which can easily damage the device due to incorrect reverse connection; the SENT signal output port is easily affected by electrostatic interference, which can lead to communication abnormalities; in addition, the power supply line of the humidity sensor lacks real-time voltage monitoring, making fault diagnosis difficult. Utility Model Content
[0004] In response to the technical problems mentioned in the background section, this utility model provides a circuit structure for a humidity sensor.
[0005] The present invention solves the above-mentioned technical problems through the following technical solution:
[0006] This invention provides a circuit structure for a humidity sensor. The circuit structure includes an interface module, a power supply module, a reverse connection protection circuit, an MCU microcontroller module, a humidity sensor chip, and an output module.
[0007] One end of the reverse connection protection circuit is connected to the interface module, and the other end is connected to the power supply module; the power supply module is connected to the MCU microcontroller module.
[0008] The MCU microcontroller module is connected to the humidity sensor chip via the IIC bus, the MCU microcontroller module is connected to the output module, and the output module is connected to the interface module; wherein, the interface module includes a power supply port, a ground port, and a SENT signal output port.
[0009] Preferably, the reverse connection protection circuit includes a PMOS transistor, a Zener diode, a first resistor, and a first capacitor;
[0010] The source of the PMOS transistor is connected to the power supply port, the drain is connected to the power module, the gate is connected in parallel with the Zener diode, the first capacitor is connected in parallel with the PMOS transistor, one end of the first resistor is connected in series with the PMOS transistor, and the other end is grounded.
[0011] Preferably, the reverse connection protection circuit further includes a power supply filter sub-circuit, which includes a first filter capacitor, a second filter capacitor, and a ferrite bead.
[0012] The first filter capacitor and the second filter capacitor are connected in parallel to the input terminal of the power module; the ferrite bead is connected in series between the power supply port and the input terminal of the power module.
[0013] Preferably, the power module includes an LDO power chip, the input terminal of which is connected to the drain of the PMOS transistor, and the output terminal is connected to the MCU microcontroller module and the humidity sensor chip.
[0014] Preferably, the MCU microcontroller module includes an MCU, the input terminal of which is connected to the output terminal of the LDO power chip, and the output terminal is connected to the humidity sensor chip.
[0015] Preferably, the MCU microcontroller includes several peripheral pins, including but not limited to pins PTB1, PTB2, PTA2, PTA3, and PTD16.
[0016] The PTB2 pin is used to detect the power supply voltage of the humidity sensor chip.
[0017] The PTB1 pin is used to control the power supply to the humidity sensor chip;
[0018] Pin PTA2 is connected to the positive terminal of the humidity sensor chip via the SDA data signal line; pin PTA3 is connected to the negative terminal of the humidity sensor chip via the SCL clock signal line.
[0019] The PTD16 pin is connected to the output module, transmitting the humidity and temperature values read from the humidity sensor chip to the output module.
[0020] Preferably, the output module is used to convert the humidity value and temperature value read by the MCU from the humidity sensor chip into SENT protocol and send them to the electronic controller through the SENT signal output port.
[0021] Preferably, the output module includes a second resistor, a third filter capacitor, a SENT signal output port, and an ESD protection diode;
[0022] The second resistor is connected in series with the pin PTD16 and is connected to the SENT signal output port. The third filter capacitor and the ESD protection tube are connected in parallel on the SENT signal output port.
[0023] Preferably, the circuit structure further includes a diagnostic module, which is used to analyze various values in the MCU microcontroller module.
[0024] The positive and progressive effects of this utility model are as follows: This utility model provides a circuit structure for a humidity sensor. The circuit structure includes an interface module, a power supply module, a reverse connection protection circuit, an MCU microcontroller module, a humidity sensor chip, and an output module. One end of the reverse connection protection circuit is connected to the interface module, and the other end is connected to the power supply module. The power supply module is connected to the MCU microcontroller module. The MCU microcontroller module is connected to the humidity sensor chip via the IIC bus, and is also connected to the output module. The output module is connected to the interface module. This utility model's circuit structure for a humidity sensor reduces device damage caused by incorrect connection by adding a reverse connection protection circuit before the power supply module; it reduces electrostatic interference and ensures normal communication by setting an ESD (electrostatic impedance) at the SENT signal output port; and it provides real-time monitoring power supply voltage through the ADC pin (pin PTB2) to achieve rapid fault location. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of the circuit structure module for a humidity sensor according to the present invention.
[0026] Figure 2 This is a schematic diagram of the circuit structure for a humidity sensor according to the present invention.
[0027] Figure 3 This is a schematic diagram of the interface module of the humidity sensor circuit structure of this utility model.
[0028] Figure 4 This is a schematic diagram of the reverse connection protection circuit of this utility model.
[0029] Figure 5 These are the parameters of the SENT signal conversion method of this utility model;
[0030] Legend: 1. Interface module; 2. Reverse connection protection circuit; 3. Power supply module; 4. MCU microcontroller module; 5. Humidity sensor chip; 6. Output module; 7. Diagnostic module; 11. Power supply port; 12. Grounding port; 13. SENT signal output port; 21. PMOS transistor; 22. Zener diode; 23. First resistor; 24. First capacitor; 25. Power supply filter sub-circuit; 251. First filter capacitor; 252. Second filter capacitor; 253. Ferrite bead; 31. LDO power chip; 41. MCU; 51. SDA data signal line; 52. SCL clock signal line; 61. Second resistor; 62. Third filter capacitor; 63. ESD protection diode. Detailed Implementation
[0031] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.
[0032] Example 1
[0033] like Figure 1-2 As shown, this embodiment provides a circuit structure for a humidity sensor. The circuit structure includes an interface module 1, a power supply module 3, a reverse connection protection circuit 2, an MCU microcontroller module 4, a humidity sensor chip 5, and an output module 6. One end of the reverse connection protection circuit 2 is connected to the interface module 1, and the other end is connected to the power supply module 3. The power supply module 3 is connected to the MCU microcontroller module 4. The MCU microcontroller module 4 is connected to the humidity sensor chip 5 via an IIC bus, and is also connected to the output module 6. The output module 6 is connected to the interface module 1. The interface module 1 includes a power supply port 11, a ground port 12, and a SENT signal output port 13.
[0034] In this embodiment, as Figure 4As shown, the reverse connection protection circuit 2 includes a PMOS transistor 21, a Zener diode 22, a first resistor 23, and a first capacitor 24. The source of the PMOS transistor 21 is connected to the power supply port 11, the drain is connected to the power module 3, and the gate is connected in parallel with the Zener diode 22. The first capacitor 21 is connected in parallel with the PMOS transistor 21. One end of the first resistor 23 is connected in series with the PMOS transistor 21, and the other end is grounded. The reverse connection protection circuit 2 also includes a power supply filter sub-circuit 25, which includes a first filter capacitor 251, a second filter capacitor 252, and a ferrite bead 253. The first filter capacitor 251 and the second filter capacitor 252 are connected in parallel to the input terminal of the power module 3. The ferrite bead 253 is connected in series between the power supply port 11 and the input terminal of the power module 3. Specifically, when power module 3 is connected in the forward direction, the +5V supplied to power supply port 11 flows through PMOS transistor 21 to the source (S) terminal, Vs = 5V - 0.7V = 4.3V; the gate (G) terminal is connected to GND; therefore, Vgs = 0V - 4.3V = -4.3V, and PMOS transistor 21 conducts, preventing damage to the LDO power chip 31 due to reverse connection. When power module 3 is connected in the reverse direction, assuming PMOS transistor 21 conducts, Vgs = 0V - (-4.3V) = 4.3V, which contradicts the assumption that PMOS transistor 21 conducts. Therefore, in the reverse connection case, PMOS transistor 21 does not conduct, easily damaging the device. Since the maximum value of Vgs is ±20V, it needs protection using a 10V Zener diode 22 to ensure that the maximum value of Vgs does not exceed 10V.
[0035] In this embodiment, the power module 3 includes an LDO power chip 31. The input terminal of the LDO power chip 31 is connected to the drain of the PMOS transistor 21, and the output terminal is connected to the MCU microcontroller module 4 and the humidity sensor chip 5. Specifically, the LDO power chip 31 steps down the 5V input from the power supply port 11 to 3.3V to provide a stable power supply to the MCU 41 and the humidity sensor chip 5.
[0036] In this embodiment, the MCU microcontroller module 4 includes an MCU 41. The input terminal of the MCU 41 is connected to the output terminal of the LDO power chip 31, and the output terminal is connected to the humidity sensor chip 5. Specifically, the MCU 4 includes several peripheral pins, including but not limited to pins PTB1, PTB2, PTA2, PTA3, PTD16, etc. Among them, pin PTB2 is used to detect the power supply voltage of the humidity sensor chip 5; pin PTB1 is used to control the power supply of the humidity sensor chip 5; pin PTA2 is connected to the positive terminal of the humidity sensor chip 5 through the SDA data signal line 51; pin PTA3 is connected to the negative terminal of the humidity sensor chip 5 through the SCL clock signal line 52; pin PTD16 is connected to the output module 6, transmitting the humidity and temperature values read from the humidity sensor chip 5 to the output module 6.
[0037] In this embodiment, the output module 6 is used to convert the humidity and temperature values read by the humidity sensor chip 5 from the MCU 41 into SENT protocol values and send them to the electronic controller through the SENT signal output port 13. The output module 6 includes a second resistor 61, a third filter capacitor 62, and an ESD protection diode 63; the second resistor 61 is connected in series with pin PTD 16 and connected to the SENT signal output port 13, and the third filter capacitor 62 and the ESD protection diode 63 are connected in parallel to the SENT signal output port 13. Specifically, as shown... Figure 5 The parameters shown for SENT are converted from the temperature and humidity values read from the humidity sensor chip into SENT signals, which are then sent to the electronic controller via SENT signal output port 13. The conversion formula is as follows:
[0038] Humidity conversion formula:
[0039] Valid value range: 0% – 100%;
[0040] Temperature conversion formula:
[0041] Valid value range: -40℃ – 125℃.
[0042] In this embodiment, the circuit structure also includes a diagnostic module 7, which is used to monitor various values in the MCU microcontroller module 4. Specifically, the diagnostic module 7 monitors the power supply voltage of the humidity sensor through the ADC pin (PTB2) of the MCU41, detecting overvoltage (>5.5V) and undervoltage (<4.5V), triggering fault code (4092); the diagnostic module 7 detects IIC communication abnormalities through the PTA2 (SDA data signal line 51) and PTA3 (SCL clock signal line 52) pins of the MCU41, triggering fault code (4090) after 10 consecutive communication failures; the diagnostic module 7 verifies the humidity (0-100%RH) and temperature (-40~125℃) range collected by the humidity sensor chip 5 through the MCU41, triggering fault code (4088) when the data exceeds the range.
[0043] This embodiment provides a circuit structure for a humidity sensor. The circuit structure includes an interface module, a power supply module, a reverse connection protection circuit, an MCU microcontroller module, a humidity sensor chip, and an output module. One end of the reverse connection protection circuit is connected to the interface module, and the other end is connected to the power supply module. The power supply module is connected to the MCU microcontroller module. The MCU microcontroller module is connected to the humidity sensor chip via an IIC bus, and is also connected to the output module, which in turn is connected to the interface module. This circuit structure for a humidity sensor reduces device damage caused by incorrect connections by adding a reverse connection protection circuit before the power supply module; it reduces electrostatic interference and ensures normal communication by setting an ESD (electrostatic discharge resistor) at the SENT signal output port; and it provides real-time monitoring power supply voltage through the ADC pin (pin PTB2) to quickly locate abnormal faults.
[0044] The working principle of this utility model is as follows: The humidity sensor of this utility model is connected to the automotive electrical system. After the automotive engine controller (ECU) supplies power to the MCU (microcontroller unit, i.e., single-chip microcomputer) through the power module, the automotive electrical system performs MCU41 peripheral initialization. After the MCU41 initialization is complete, it sends a heating command to the humidity sensor chip 5 to start the heating function. After preheating, it enters normal operation. The MCU41 monitors the power supply voltage of the humidity sensor chip 5 through pin PTB2; controls the power supply of the humidity sensor chip 5 through pin PTB1; connects pin PTA2 to the positive terminal of the humidity sensor chip 5 through the SDA data signal line 51; and connects pin PTA3 to the negative terminal of the humidity sensor chip 5 through the SCL clock signal line 52, thereby acquiring the humidity and temperature values of the humidity sensor chip 5. Pin PTD16 is connected to the output module 6, transmitting the read humidity and temperature values of the humidity sensor chip 5 to the output module 6. After passing through the anti-static protection of the output module 6, the values are output to the ECU.
[0045] While specific embodiments of this utility model have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this utility model is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of this utility model, but all such changes and modifications fall within the scope of protection of this utility model.
Claims
1. A circuit structure for a humidity sensor, characterized in that, The circuit structure includes an interface module, a power supply module, a reverse connection protection circuit, an MCU microcontroller module, a humidity sensor chip, and an output module. One end of the reverse connection protection circuit is connected to the interface module, and the other end is connected to the power supply module; the power supply module is connected to the MCU microcontroller module. The MCU microcontroller module is connected to the humidity sensor chip via the IIC bus, the MCU microcontroller module is connected to the output module, and the output module is connected to the interface module; wherein, the interface module includes a power supply port, a ground port, and a SENT signal output port.
2. The circuit structure for a humidity sensor as described in claim 1, characterized in that, The reverse connection protection circuit includes a PMOS transistor, a Zener diode, a first resistor, and a first capacitor; The source of the PMOS transistor is connected to the power supply port, the drain is connected to the power module, the gate is connected in parallel with the Zener diode, the first capacitor is connected in parallel with the PMOS transistor, one end of the first resistor is connected in series with the PMOS transistor, and the other end is grounded.
3. The circuit structure for a humidity sensor as described in claim 2, characterized in that, The reverse connection protection circuit also includes a power supply filter sub-circuit, which includes a first filter capacitor, a second filter capacitor, and a ferrite bead. The first filter capacitor and the second filter capacitor are connected in parallel to the input terminal of the power module; the ferrite bead is connected in series between the power supply port and the input terminal of the power module.
4. The circuit structure for a humidity sensor as described in claim 3, characterized in that, The power module includes an LDO power chip, the input terminal of which is connected to the drain of the PMOS transistor, and the output terminal of which is connected to the MCU microcontroller module and the humidity sensor chip.
5. The circuit structure for a humidity sensor as described in claim 4, characterized in that, The MCU microcontroller module includes an MCU, the input terminal of which is connected to the output terminal of the LDO power chip, and the output terminal is connected to the humidity sensor chip.
6. The circuit structure for a humidity sensor as described in claim 5, characterized in that, The MCU microcontroller includes several peripheral pins, including but not limited to pins PTB1, PTB2, PTA2, PTA3, and PTD16. The PTB2 pin is used to detect the power supply voltage of the humidity sensor chip. The PTB1 pin is used to control the power supply to the humidity sensor chip; Pin PTA2 is connected to the positive terminal of the humidity sensor chip via the SDA data signal line; pin PTA3 is connected to the negative terminal of the humidity sensor chip via the SCL clock signal line. The PTD16 pin is connected to the output module, transmitting the humidity and temperature values read from the humidity sensor chip to the output module.
7. The circuit structure for a humidity sensor as described in claim 6, characterized in that, The output module is used to convert the humidity and temperature values read by the MCU from the humidity sensor chip into SENT protocol values and send them to the electronic controller through the SENT signal output port.
8. The circuit structure for a humidity sensor as described in claim 7, characterized in that, The output module includes a second resistor, a third filter capacitor, a SENT signal output port, and an ESD protection diode; The second resistor is connected in series with the pin PTD16 and is connected to the SENT signal output port. The third filter capacitor and the ESD protection tube are connected in parallel on the SENT signal output port.
9. The circuit structure for a humidity sensor as described in claim 8, characterized in that, The circuit structure also includes a diagnostic module, which is used to analyze various values in the MCU microcontroller module.