An open / short detection circuit for FM / AM antennas

Abstract

The utility model provides a kind of FM / AM antenna's open short circuit detection circuit, including power unit, processor U3, comparator U2 and FM / AM antenna unit, power unit is respectively connected with processor U3, comparator U2 and FM / AM antenna unit electricity;It further includes sampling resistance R5, one end of sampling resistance R5 is connected with the output terminal of power unit, the other end of sampling resistance is connected the input terminal of FM / AM antenna unit, diode D2 is connected between the input terminal of power unit enable end and FM / AM antenna, sampling resistance R5 is connected with the input terminal of comparator U2, comparator U2 is also connected with processor U3.It is introduced sampling resistance R5 and comparator U2, it is judged by the voltage drop condition of sampling resistance R5 and transmission to processor U3 by comparator U2 collection, can quickly judge antenna state, realize accurate positioning of fault point;Diode D2 can be quickly cut off when antenna short circuit, limit loop current, can avoid that the voltage drop on resistance R5 is too large, and bring the risk of burnout.

Description

Technical Field

[0001] This utility model relates to the field of automotive electronic equipment technology, and in particular to an open / short circuit detection circuit for an FM / AM antenna. Background Technology

[0002] With the accelerated advancement of intelligent passenger vehicles, smart cockpits have become a market standard, and in-car radios, as one of their core functions, are being used more and more frequently. In the operation and maintenance of smart cockpits, FM / AM antenna status monitoring is particularly important, as it helps maintenance personnel quickly and accurately locate faults, shorten troubleshooting cycles, and improve user experience. However, most current solutions have significant shortcomings in this area: First, most systems lack automatic fault detection mechanisms, so even if common faults such as loose antennas or short circuits occur, the system cannot detect them in a timely manner and provide feedback to users or maintenance personnel; second, even if some solutions add self-resetting fuses at the antenna input, they can only provide very limited overcurrent protection. This approach reveals two major problems in practical applications: First, when a fault occurs, the system cannot automatically report the fault to the user or backend, let alone accurately locate the fault point. Maintenance personnel often have to check components such as antennas, wiring, and radio modules one by one, resulting in a significant waste of manpower and time. Second, when the output current is too high, the self-resetting fuse activates, generating high impedance to protect the downstream circuit. If the short circuit persists or the current remains very high, the fuse may blow, thus preventing the high current from damaging the downstream circuit. However, the function will be permanently damaged, affecting not only the radio function but also potentially triggering a chain reaction of other electronic component failures, further threatening the stability and safety of the vehicle's electronic system, such as... Figure 1 As shown. Utility Model Content

[0003] To address the aforementioned problems, the purpose of this invention is to provide an open / short circuit detection circuit for FM / AM antennas.

[0004] This utility model is implemented using the following method: an open / short circuit detection circuit for an FM / AM antenna, including a power supply unit, a processor U3, a comparator U2, and an FM / AM antenna unit. The power supply unit is electrically connected to the processor U3, the comparator U2, and the FM / AM antenna unit. It also includes a sampling resistor R5, one end of which is connected to the output terminal of the power supply unit, and the other end of which is connected to the input terminal of the FM / AM antenna unit. A diode D2 is connected between the enable terminal of the power supply unit and the input terminal of the FM / AM antenna. The sampling resistor R5 is connected to the input terminal of the comparator U2, which is also connected to the processor U3. The comparator U2 collects and judges the voltage drop across the sampling resistor and outputs the result to the processor U3 to determine whether the FM / AM antenna unit is in a normal connection state, a short circuit state, or an open circuit state. Preferably, one end of the sampling resistor is connected to the positive input terminal of the comparator U2, and the other end of the sampling resistor is connected to the negative input terminal of the comparator U2. The negative input terminal of the comparator U2 is connected to the second pin of the processor U3, and the signal output terminal of the comparator U2 is connected to the third pin of the processor U3. The comparator U2 compares the voltage across the sampling resistor R5 to determine the state of the FM / AM antenna unit based on the high or low level output by the comparator U2.

[0005] Preferably, it also includes resistors R6 and R7. One end of the sampling resistor R5 is connected to one end of the FM / AM antenna unit, and the other end of the resistor R6 is connected to one end of the resistor R7 and the negative input terminal of the comparator U2. The other end of the resistor R7 is grounded.

[0006] Preferably, a resistor R3 is connected in series between the other end of the sampling resistor R5 and the positive input terminal of the comparator U2, and the positive input terminal of the comparator U2 is connected to ground via a resistor R4.

[0007] Preferably, a diode D1 is connected between the other end of the resistor R5 and the input terminal of the FM / AM antenna unit.

[0008] Preferably, the fourth pin of the processor U3 is grounded.

[0009] Preferably, the power supply unit includes an LDO chip U1, which is connected to a power source. The sampling resistor R5 is connected in series between the third pin of the LDO chip U1 and the input terminal of the FM / AM antenna unit. The anode of the diode D2 is connected to the second pin of the LDO chip U1, and the cathode of the diode D2 is connected to the input terminal of the FM / AM antenna unit.

[0010] Preferably, a resistor R1 is connected between the power supply unit and the first pin of the LDO chip U1, and a resistor R2 is connected between the power supply unit and the second pin of the LDO chip U1.

[0011] Preferably, the fifth pin of the comparator U2 is grounded.

[0012] Preferably, the second pin of the comparator U2 outputs a 3.3V voltage and is connected to the first pin of the processor U3.

[0013] The beneficial effects of this utility model are as follows: This utility model provides an open / short circuit detection circuit for an FM / AM antenna. Compared with the prior art, this utility model has at least the following technical effects: 1. By introducing a sampling resistor R5 and a comparator U2, the comparator U2 collects the voltage drop of the sampling resistor R5 and transmits it to the processor U3 for judgment, which can quickly determine the antenna status, realize the accurate location of the fault point, and improve maintenance efficiency; Diode D2 is connected between the enable terminal of the power supply unit and the input terminal of the FM / AM antenna unit, which can quickly cut off when the antenna is short-circuited, limit the loop current, avoid the risk of burning out due to the continuous excessive voltage drop on R5, and avoid the problem of permanent damage to components caused by the fuse breaking the circuit. 2. A precision sampling resistor R5 is used. The FM / AM antenna unit is connected to this resistor, generating a voltage drop. The two ends of the sampling resistor are connected to the positive and negative input terminals of comparator U2. Comparator U2 compares the voltage at the input and output terminals of the sampling resistor, outputting a high or low level based on the magnitude. Processor U3 then collects and determines the antenna connection status, thus indicating the state of the FM / AM antenna unit. 3. Resistors R6 and R7 form a voltage divider network. When the output of comparator U2 is not high, and processor U3 collects the voltage divided by resistors R6 and R7 from the power supply unit, the antenna is in an open-circuit state. Attached Figure Description

[0014] Figure 1 This is the circuit schematic of an existing solution using a self-resetting fuse.

[0015] Figure 2 This is a circuit diagram of an open / short circuit detection circuit for an FM / AM antenna according to this utility model. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0017] Please see Figure 2An open / short circuit detection circuit for an FM / AM antenna includes a power supply unit, a processor U3, a comparator U2, and an FM / AM antenna unit. The power supply unit is electrically connected to the processor U3, the comparator U2, and the FM / AM antenna unit. It also includes a sampling resistor R5, one end of which is connected to the output terminal of the power supply unit, and the other end of which is connected to the input terminal of the FM / AM antenna unit. A diode D2 is connected between the enable terminal of the power supply unit and the input terminal of the FM / AM antenna unit. The sampling resistor R5 is connected to the input terminal of the comparator U2, which is also connected to the processor U3. The comparator U2 collects and judges the voltage drop across the sampling resistor and outputs the result to the processor U3 to determine whether the FM / AM antenna unit is in a normal connection state, a short circuit state, or an open circuit state. By introducing a sampling resistor R5 and a comparator U2, the voltage drop across the sampling resistor R5 is collected by the comparator U2 and transmitted to the processor U3 for judgment. This allows for rapid determination of the antenna status, accurate fault location, and improved maintenance efficiency. Diode D2 is connected between the enable terminal of the power supply unit and the input terminal of the FM / AM antenna unit. It can quickly cut off when the antenna is short-circuited, limiting the loop current and preventing the voltage drop across R5 from becoming too large, which could lead to burnout. This also avoids permanent damage to components caused by a blown fuse cutting off the circuit.

[0018] Please see Figure 2 Preferably, one end of the sampling resistor is connected to the positive input terminal of the comparator U2, and the other end of the sampling resistor is connected to the negative input terminal of the comparator U2. The negative input terminal of the comparator U2 is connected to the second pin of the processor U3 (ADC0 acquires the voltage at the negative input terminal of the comparator U2). The signal output terminal of the comparator U2 is connected to the third pin of the processor U3 (GPIO0, used to transmit the high or low level of the comparison result of the comparator U2 to the processor U3). The comparator U2 compares the voltage across the sampling resistor R5 to determine the state of the FM / AM antenna unit based on the high or low level output of the comparator U2. A precision sampling resistor R5 is used to connect the FM / AM antenna unit. A voltage drop is generated across the sampling resistor. The two ends of the sampling resistor are connected to the positive and negative input terminals of comparator U2. The output of comparator U2 can accurately determine whether the FM / AM antenna is properly connected. A high output indicates proper connection. At the same time, processor U3 can determine whether the FM / AM antenna is short-circuited by acquiring data through an ADC. Then, by combining the output of comparator U2 and the acquired value of the ADC, it can be determined whether the FM / AM antenna is open-circuited.

[0019] Please see Figure 2Preferably, it also includes resistors R6 and R7. One end of the sampling resistor R5 is connected to one end of the FM / AM antenna unit, and the other end of the resistor R6 is connected to one end of the resistor R7 and the negative input terminal of the comparator U2. The other end of the resistor R7 is grounded. Resistors R6 and R7 form a voltage divider network. When the output of the comparator U2 is not high, and the processor U3 acquires the voltage of the power supply unit divided by resistors R6 and R7, the antenna is in an open-circuit state.

[0020] Please see Figure 2 Preferably, a resistor R3 is connected in series between the other end of the sampling resistor R5 and the positive input terminal of the comparator U2, and the positive input terminal of the comparator U2 is connected to ground via a resistor R4. The resistor R3, connected in series between the sampling resistor R5 and the positive input terminal of the comparator U2, limits the current flowing into the comparator U2. When an abnormally large signal occurs in the circuit (such as a sudden voltage change across the sampling resistor R5 caused by a momentary strong interference signal from the antenna, thus increasing the current flowing into the comparator U2), the resistor R3 can share some of the voltage, reducing the current and preventing damage to the comparator U2 due to excessive current surges. Connecting the positive input terminal of the comparator U2 to ground provides a stable reference potential for the positive input terminal of the comparator U2, helping to stabilize the static operating point of the comparator U2. When the circuit is subjected to external noise interference, the resistor R4 can reduce the impact of noise on the potential of the positive input terminal of the comparator U2, reducing the possibility of misjudgment.

[0021] Please see Figure 2 Preferably, a diode D1 is connected between the other end of the resistor R5 and the input terminal of the FM / AM antenna unit. This prevents current surges when the antenna unit is connected in reverse, protecting the sampling resistor and comparator U2. Diode D1 is a germanium diode with a low voltage drop. Please see Figure 2 Preferably, the fourth pin of the processor U3 is grounded.

[0022] Please see Figure 2 Preferably, the power supply unit includes an LDO chip U1, which is connected to a power source. A sampling resistor R5 is connected in series between the third pin of the LDO chip U1 and the input terminal of the FM / AM antenna unit. The anode of diode D2 is connected to the second pin of the LDO chip U1, and the cathode of diode D2 is connected to the input terminal of the FM / AM antenna unit. The second pin of the LDO chip U1 is the enable pin of the power supply unit. Diode D2 cuts off reverse current when short-circuited, preventing circuit overload damage.

[0023] Please see Figure 2Preferably, a resistor R1 is connected between the power supply unit and the first pin of the LDO chip U1, and a resistor R2 is connected between the power supply unit and the second pin of the LDO chip U1. Resistors R1 and R2 can limit the current flowing into the LDO chip U1 and prevent power supply voltage fluctuations from impacting the LDO chip U1.

[0024] Please see Figure 2 Preferably, pin 5 of comparator U2 is grounded. This provides a stable level reference for comparator U2, ensuring the accuracy of the output level (e.g., 3.3V for high level and 0V for low level).

[0025] Please see Figure 2 Preferably, the second pin of the comparator U2 outputs a 3.3V voltage and is connected to the first pin of the processor U3. The processor U3 provides a stable reference voltage to ensure that the processor U3 correctly identifies the output signal of the comparator U2 (such as high-level judgment threshold matching).

[0026] Please see Figure 2 Preferably, a resistor R8 is connected between the signal output terminal of the comparator U2 and the third pin of the processor U3 to perform impedance matching. This allows the output signal of the comparator U2 to be transmitted more effectively to subsequent circuits (such as the processor U3), reducing signal reflection and loss during transmission and ensuring signal integrity. It also limits the current flowing from the output terminal of the comparator U2 to a certain extent, protecting the comparator U2 and preventing damage due to excessive current when driving subsequent circuits.

[0027] The working principle of this utility model is as follows: The power supply circuit unit regulates the input voltage through the LDO chip U1 and then supplies power to the processor U3, comparator U2 and FM / AM antenna unit. When the FM / AM antenna unit is connected normally, the current flows into the antenna unit through the LDO chip U1 and the sampling resistor R5. A voltage drop is generated across R5. At this time, the voltage at the positive input terminal of the comparator U2 is higher than that at the negative input terminal (reference voltage), and the output is high to the third pin (GPIO0) of the processor U3. The processor U3 determines that the antenna status is normal. When the FM / AM antenna unit is short-circuited, the loop current surges, the voltage drop across resistor R5 increases significantly, the output level of comparator U2 jumps to low, and simultaneously pulls down the EN pin of LDO chip U1 through diode D2 (under specific conditions (such as a short circuit causing current and voltage changes to meet certain conditions), diode D2 will conduct, directing current to the EN pin of U1, thereby pulling down the level of the EN pin. The EN pin of LDO chip U1 is the enable pin; normally, when it is high, the chip works normally and outputs a stable voltage. When the EN pin is pulled low, LDO chip U1 stops working, cutting off its power supply to subsequent circuits (such as comparator U2, antenna unit, etc.), preventing excessive current from continuously flowing through these circuit components, and preventing them from being permanently damaged by prolonged exposure to excessive current, thus achieving overcurrent protection for the circuit). Processor U3 determines that a short circuit has occurred based on the output of comparator U2 and the ADC sampling. When the FM / AM antenna unit is open-circuited, there is no current in the circuit and no voltage drop across R5. Comparator U2 outputs a low level. When processor U3 combines the output of comparator U2 with the voltage divider voltage of resistors R6 and R7 collected by ADC0, it can be determined that the circuit is open.

[0028] Several points should be noted: First, in the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installation", "connection" and "linkage" should be interpreted broadly, and can be mechanical or electrical connection, or internal connection between two components, or direct connection. "Up", "down", "left", "right", etc. are only used to indicate relative positional relationship. When the absolute position of the described object changes, the relative positional relationship may change.

[0029] Secondly: The accompanying drawings of the embodiments disclosed in this utility model only involve the structures involved in the embodiments disclosed in this utility model. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this utility model can be combined with each other.

[0030] Finally, the above description is only a preferred embodiment of the present utility model. The protection scope of the present utility model is not limited to the above embodiments. All technical solutions that fall within the scope of the present utility model are protected by the present utility model.

[0031] It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of this utility model should also be considered within the scope of protection of this utility model.

Claims

1. An open / short circuit detection circuit for an FM / AM antenna, comprising a power supply unit, a processor U3, a comparator U2, and an FM / AM antenna unit, wherein the power supply unit is electrically connected to the processor U3, the comparator U2, and the FM / AM antenna unit respectively; characterized in that: It also includes a sampling resistor R5, one end of which is connected to the output terminal of the power supply unit, and the other end of which is connected to the input terminal of the FM / AM antenna unit. A diode D2 is connected between the enable terminal of the power supply unit and the input terminal of the FM / AM antenna. The sampling resistor R5 is connected to the input terminal of the comparator U2, which is also connected to the processor U3. The comparator U2 collects and judges the voltage drop of the sampling resistor and outputs it to the processor U3 to determine whether the FM / AM antenna unit is in a normal access state, a short circuit state, or an open circuit state.

2. The open / short circuit detection circuit for an FM / AM antenna according to claim 1, characterized in that: One end of the sampling resistor is connected to the positive input terminal of the comparator U2, and the other end of the sampling resistor is connected to the negative input terminal of the comparator U2. The negative input terminal of the comparator U2 is connected to the second pin of the processor U3, and the signal output terminal of the comparator U2 is connected to the third pin of the processor U3. The comparator U2 compares the voltage across the sampling resistor R5 to determine the state of the FM / AM antenna unit based on the high or low level output of the comparator U2.

3. The open / short circuit detection circuit for an FM / AM antenna according to claim 2, characterized in that: It also includes resistors R6 and R7. One end of the sampling resistor R5 is connected to one end of the FM / AM antenna unit, and the other end of the resistor R6 is connected to one end of the resistor R7 and the negative input terminal of the comparator U2. The other end of the resistor R7 is grounded.

4. The open / short circuit detection circuit for an FM / AM antenna according to claim 3, characterized in that: The other end of the sampling resistor R5 is connected in series with a resistor R3 between it and the positive input terminal of the comparator U2. The positive input terminal of the comparator U2 is connected to ground via a resistor R4.

5. The open / short circuit detection circuit for an FM / AM antenna according to claim 4, characterized in that: A diode D1 is connected between the other end of the resistor R5 and the input terminal of the FM / AM antenna unit.

6. The open / short circuit detection circuit for an FM / AM antenna according to claim 1, characterized in that: The fourth pin of the processor U3 is grounded.

7. The open / short circuit detection circuit for an FM / AM antenna according to claim 1, characterized in that: The power supply unit includes an LDO chip U1, which is connected to a power source. The sampling resistor R5 is connected in series between the third pin of the LDO chip U1 and the input terminal of the FM / AM antenna unit. The anode of the diode D2 is connected to the second pin of the LDO chip U1, and the cathode of the diode D2 is connected to the input terminal of the FM / AM antenna unit.

8. The open / short circuit detection circuit for an FM / AM antenna according to claim 7, characterized in that: A resistor R1 is connected between the power supply unit and the first pin of the LDO chip U1, and a resistor R2 is connected between the power supply unit and the second pin of the LDO chip U1.

9. The open / short circuit detection circuit for an FM / AM antenna according to claim 1, characterized in that: The fifth pin of the comparator U2 is grounded.

10. The open / short circuit detection circuit for an FM / AM antenna according to claim 1, characterized in that: The second pin of the comparator U2 outputs a voltage of 3.3V and is connected to the first pin of the processor U3.

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