ACC detection circuit for vehicle machine

Abstract

The utility model relates to the technical field of automobile infotainment, and provides an ACC detection circuit for an automobile infotainment in order to solve the technical problem that the existing ACC detection circuit is insufficient in high-voltage protection, the ACC detection circuit for the automobile infotainment comprises an NPN-type triode Q3 and an NPN-type triode Q8, a collector electrode of the triode Q3 is connected with a power supply VCC through a pull-up resistor R47, and the collector electrode of the triode Q3 is connected with an ACC detection port MCUACC of an MCU in the automobile infotainment; the ACC power supply input end is connected with a base electrode of a triode Q3 through an inductor L2, a resistor R46 and a voltage stabilizing diode Z2 in sequence, and the base electrode of the triode Q3 is grounded through a resistor R72; the ACC power supply input end is connected with a base electrode of a triode Q8 through an inductor L2, a resistor R45 and a voltage stabilizing diode Z1 in sequence, and the base electrode of the triode Q8 is grounded through a resistor R44; the withstand voltage value of the Zener diode Z1 is larger than that of the Zener diode Z2. When the ACC voltage is overvoltage, the triode Q8 is conducted, the base electrode of the triode Q3 is lowered, the triode Q3 is cut off, and the MCUACC port is kept at a high level, so that the vehicle machine is prevented from being started, and the overvoltage protection effect is achieved.

Description

Technical Field

[0001] This utility model relates to the field of automotive infotainment technology, and in particular to an ACC detection circuit for automotive infotainment systems. Background Technology

[0002] In automobiles, ACC (Accessory Power) refers to the power supply provided by the vehicle when the ignition switch is in the "ACC" (Accessory) position. Accessory means accessories, which include devices such as the car's infotainment system, air conditioning, and dashcam. When the key is inserted and placed in the ACC position, the car provides power to these accessories.

[0003] The car infotainment system is equipped with an ACC detection circuit. The car infotainment system also has another power source called B+, which is the positive terminal of the car battery and provides constant power to the car infotainment system. The car infotainment system will not start when only the B+ power source is available. It will only start when the ACC power source is detected.

[0004] When a vehicle is started, the voltage changes drastically due to the instantaneous consumption of battery voltage and the instantaneous low and high voltage generated by inductive devices such as the alternator. Therefore, a series of protection circuits must be installed.

[0005] Patent document CN217360091 U discloses an ACC detection circuit. Referring to paragraphs

[0005] to

[0021] and Figure 5 of its specification, it is equipped with diode D1, ferrite bead FB1 and diode ED1 for protection, but it is not comprehensive enough. In particular, it cannot play a good protective role under high voltage. Diode ED1 is mainly used for anti-static, and it cannot play a good protective role for voltages far below the static electricity level. Utility Model Content

[0006] The purpose of this invention is to provide an ACC detection circuit for vehicle infotainment systems to solve the technical problem of insufficient high-voltage protection in existing ACC detection circuits.

[0007] To achieve the above objectives, this utility model provides an ACC detection circuit for an in-vehicle infotainment system, including a first voltage detection circuit, a second voltage detection circuit, NPN transistors Q3 and Q8, with the emitters of transistors Q3 and Q8 grounded, the collector of transistor Q3 connected to the base of transistor Q8, the collector of transistor Q3 connected to the power supply VCC through a pull-up resistor R47, and the collector of transistor Q3 connected to the ACC detection port MCU_ACC of the MCU in the in-vehicle infotainment system.

[0008] The ACC power input terminal is connected in sequence through inductor L2, resistor R46, Zener diode Z2 and the base of transistor Q3. The base of transistor Q3 is grounded through resistor R72.

[0009] The ACC power input terminal is connected in sequence through inductor L2, resistor R45, Zener diode Z1 and the base of transistor Q8. The base of transistor Q8 is grounded through resistor R44.

[0010] Resistor R46, Zener diode Z2 and resistor R72 constitute the first voltage detection circuit, and resistor R45, Zener diode Z1 and resistor R44 constitute the second voltage detection circuit. The voltage rating of Zener diode Z1 is greater than that of Zener diode Z2.

[0011] Furthermore, the two ends of inductor L2 are grounded through capacitors C32 and C33, respectively.

[0012] Furthermore, the ACC power input terminal is grounded through a bidirectional TVS diode D2.

[0013] Furthermore, the collector of transistor Q3 is grounded through capacitor C30.

[0014] Furthermore, the base of transistor Q3 is grounded through capacitor C31.

[0015] The beneficial effects of this utility model are:

[0016] Resistors R46 and R72 form a series voltage divider circuit to divide the ACC voltage to a suitable range and provide base bias for transistor Q3. The Zener diode Z2 in resistors R46 and R72 clamps the voltage to a predetermined voltage to prevent excessive voltage from damaging transistor Q3.

[0017] When the ACC voltage is within the normal range, such as 9V to 14.4V, transistor Q3 is turned on, and its collector voltage decreases; when the voltage is low, transistor Q3 cannot be triggered.

[0018] Resistors R45 and R44 form a series voltage divider circuit to divide the ACC voltage to a suitable range and provide base bias for transistor Q8. The Zener diode Z1 in resistors R45 and R44 clamps the voltage to a predetermined voltage to prevent excessive voltage from damaging transistor Q8.

[0019] The voltage rating of Zener diode Z2 is lower than that of Zener diode Z1.

[0020] When the ACC voltage is too high, such as exceeding 14.4V, transistor Q8 turns on, and transistor Q8 pulls down the base voltage of transistor Q3, causing transistor Q3 to turn off, preventing the vehicle's infotainment system from starting, thus providing protection. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Among them:

[0022] Figure 1 This utility model presents an ACC detection circuit diagram for an in-vehicle infotainment system. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0024] Reference Figure 1 This utility model provides an ACC detection circuit for vehicle infotainment systems, including an MCU, an NPN transistor Q3, and a transistor Q8. The CAR_ACC port serves as the positive input port of the vehicle's ACC power supply. The ACC power supply is connected to the base of transistor Q3 via inductor L2, resistor R46, and Zener diode Z2. The ACC power supply is also connected to the base of transistor Q8 via inductor L2, resistor R45, and Zener diode Z1. The collector of transistor Q8 is connected to the base of transistor Q3. The emitters of transistors Q3 and Q8 are grounded. Transistor Q3 is connected to the VCC power supply via a pull-up power supply. The collector of transistor Q3 is connected to the ACC detection port MCU_ACC of the MCU via resistor R50.

[0025] Zener diodes Z1 and Z2 are both Zener diodes. The anode of Zener diode Z2 is connected to the base of transistor Q3, and the cathode of Zener diode Z2 is connected to resistor R46. The anode of Zener diode Z1 is connected to the base of transistor Q8, and the cathode of Zener diode Z1 is connected to resistor R45.

[0026] Among them, resistors R46 and R45 are connected to Zener diodes Z2 and Z1 respectively for voltage stabilization and current limiting.

[0027] A bidirectional TVS diode D2 is provided, with one end connected to the CAR_ACC port and the other end grounded. The two ends of inductor L2 are grounded through capacitors C32 and C33 respectively, with the negative terminal connected to terminal 1 of L2.

[0028] Inductor L2, capacitors C33 and C32, and bidirectional TVS diode D2 form a filter circuit for noise filtering and circuit protection. Specifically, inductor L2, capacitors C33 and C32 form an LC filter, and bidirectional TVS diode D2 is used to prevent reverse voltage.

[0029] The base of transistor Q3 is grounded through resistor R72 and capacitor C31; the collector of transistor Q3 is grounded through capacitor C30; and the base of transistor Q8 is grounded through resistor R44.

[0030] Working principle

[0031] Input voltage processing:

[0032] The input voltage, i.e., the ACC power supply, is filtered by an LC filter to remove high-frequency noise and prevented by a bidirectional TVS diode D2.

[0033] Voltage stabilization, current limiting, and protection:

[0034] The MCU_ACC port on the MCU side is active low, meaning the vehicle system will only start when the voltage on this port is low. When the ACC power is not connected, this port is high by default.

[0035] Resistors R46 and R72 form a series voltage divider circuit to divide the ACC voltage to a suitable range and provide base bias for transistor Q3. The Zener diode Z2 in resistors R46 and R72 clamps the voltage to a predetermined voltage to prevent excessive voltage from damaging transistor Q3.

[0036] When the ACC voltage is within the normal range, such as 9V to 14.4V, transistor Q3 is turned on, and its collector voltage decreases; when the voltage is low, transistor Q3 cannot be triggered.

[0037] Resistors R45 and R44 form a series voltage divider circuit to divide the ACC voltage to a suitable range and provide base bias for transistor Q8. The Zener diode Z1 in resistors R45 and R44 clamps the voltage to a predetermined voltage to prevent excessive voltage from damaging transistor Q8.

[0038] The voltage rating of Zener diode Z2 is lower than that of Zener diode Z1.

[0039] When the ACC voltage is too high, such as exceeding 14.4V, transistor Q8 turns on, and transistor Q8 pulls down the base voltage of transistor Q3, causing transistor Q3 to turn off, preventing the vehicle's infotainment system from starting, thus providing protection.

[0040] The ACC detection circuit for vehicle infotainment systems provided by this utility model has the following advantages:

[0041] This invention provides an ACC detection circuit for in-vehicle infotainment systems, aiming to improve the circuit's anti-interference and overvoltage protection capabilities. A dual protection mechanism is constructed using two NPN transistors, Q3 and Q8, combined with an LC filter and a TVS diode for noise suppression and reverse voltage protection. The ACC power supply first passes through an LC filter to remove high-frequency noise and is protected against reverse voltage by a bidirectional TVS diode, D2. Then, the voltage signal enters two branches: the first branch uses resistor R46 and Zener diode Z2 to regulate and clamp the voltage and limit current, supplying power to the base of transistor Q3. When the ACC voltage is within the normal range (9V-14.4V), Q3 conducts, its collector voltage decreases, and the ACC detection port MCU_ACC of the MCU reaches a low level, thus starting the in-vehicle infotainment system; when the voltage is too low, transistor Q3 cannot conduct, MCU_ACC remains high, and the in-vehicle infotainment system does not start. The second path uses resistor R45 and Zener diode Z1 to regulate and clamp the voltage and limit the current, providing power to the base of transistor Q8. When the ACC voltage exceeds 14.4V, transistor Q8 conducts, pulling the base of transistor Q3 low, thus cutting off Q3 and keeping the MCU_ACC port high, preventing the vehicle's infotainment system from starting and providing overvoltage protection. The advantages of this circuit are its dual protection mechanism, strong anti-interference capability, voltage stability and current limiting, simple structure, and low cost. It effectively prevents false starts or damage caused by voltage fluctuations, thereby extending the lifespan of the vehicle's infotainment system.

[0042] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An ACC detection circuit for vehicle infotainment systems, characterized in that, It includes a first voltage detection circuit, a second voltage detection circuit, NPN transistors Q3 and Q8, the emitters of transistors Q3 and Q8 are grounded, the collector of transistor Q3 is connected to the base of transistor Q8, the collector of transistor Q3 is connected to the power supply VCC through a pull-up resistor R47, and the collector of transistor Q3 is connected to the ACC detection port MCU_ACC of the MCU in the vehicle's infotainment system. The ACC power input terminal is connected in sequence through inductor L2, resistor R46, Zener diode Z2 and the base of transistor Q3. The base of transistor Q3 is grounded through resistor R72. The ACC power input terminal is connected in sequence through inductor L2, resistor R45, Zener diode Z1 and the base of transistor Q8. The base of transistor Q8 is grounded through resistor R44. Resistor R46, Zener diode Z2 and resistor R72 constitute the first voltage detection circuit, and resistor R45, Zener diode Z1 and resistor R44 constitute the second voltage detection circuit. The voltage rating of Zener diode Z1 is greater than that of Zener diode Z2.

2. The ACC detection circuit for a vehicle infotainment system according to claim 1, characterized in that, The two ends of inductor L2 are grounded through capacitors C32 and C33, respectively.

3. The ACC detection circuit for a vehicle infotainment system according to claim 2, characterized in that, The ACC power input terminal is grounded through bidirectional TVS diode D2.

4. The ACC detection circuit for a vehicle infotainment system according to claim 3, characterized in that, The collector of transistor Q3 is grounded through capacitor C30.

5. The ACC detection circuit for a vehicle infotainment system according to claim 4, characterized in that, The base of transistor Q3 is grounded through capacitor C31.

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