Automobile antenna dual-path power automatic switching device and method

Abstract

This disclosure relates to the field of automotive antenna technology, and particularly to an automatic switching device and method for dual-power supply in automotive antennas. To address the issues of mutual interference between power supplies in a dual-power supply system and the control of external power supplies by the internal power supply of the domain controller, this disclosure employs a discrete component design, including power input filtering, detection and switching, and output protection modules. An NPN transistor Q2 detects the internal DC10V status of the domain controller and controls the switching of the P-channel MOSFET Q1, achieving controlled switching of the external DC12V; Schottky diodes D1 and D2 are used to achieve reverse current isolation. This design utilizes the contactless switching characteristics of transistors to replace mechanical relays, achieving a switching speed in the microsecond range and an efficiency exceeding 96%. Furthermore, high anti-interference and stability are ensured through RC filtering and a voltage divider network. This disclosure features a compact structure, low cost, and high reliability, perfectly realizing controlled redundant power supply logic for internal control of external power supplies, and is suitable for automotive scenarios with stringent power continuity requirements.

Description

Technical Field

[0001] This disclosure relates to the field of automotive antenna technology, and in particular to an automatic switching device and method for dual power supplies of automotive antennas. Background Technology

[0002] In in-vehicle infotainment systems, the continuity and stability of the power supply to the radio and GPS antenna amplifiers directly determine signal quality and user experience. To prevent antenna failure due to a single point of failure, a dual-redundancy architecture with both external power and domain controller internal power supply is typically used.

[0003] The existing dual power supply switching scheme has three major drawbacks: First, mechanical relays are prone to wear, sparking, and slow switching, which can easily cause the load to restart after power failure; second, although dedicated power management chips have fast switching speed, they are expensive and their performance is overkill in simple scenarios; third, simple diode anti-reverse current circuits lack controlled logic and rely solely on high and low voltage to blindly supply power, which cannot achieve internal control of external circuits. When the host is abnormal, it can easily cause the antenna to spin idly or power crosstalk to damage the circuit.

[0004] In summary, there is an urgent need for a low-cost, compact, fast-switching dual-power switching circuit capable of implementing controlled redundancy logic to solve the interference and reliable switching problems in the dual-power supply of automotive antenna amplifiers. Summary of the Invention

[0005] To address the aforementioned issues, this disclosure provides an automatic switching device and method for dual-power supply of automotive antennas, which solves the problems of mutual interference between power supplies in a dual-power supply system and the control of external power supply by the internal power supply of the domain controller.

[0006] In a first aspect, a dual-power automatic switching device for an automotive antenna includes: The first power input terminal is used to connect to the first power supply. The second power input terminal is used to connect to the second power supply; wherein, the voltage of the first power supply is higher than the voltage of the second power supply. The power output terminal is used to connect the antenna load; The main switch Q1 is connected between the first power input terminal and the power output terminal, and is used to control the switching on and off of the power from the first power input terminal to the power output terminal. The control transistor Q2 has its base connected to the second power input terminal, its collector C connected to the control terminal of the main switch transistor Q1, and its emitter E grounded. It is used to detect the voltage status of the second power input terminal and control the conduction and cutoff of the main switch transistor Q1. The first diode D1 is connected in series between the main switch Q1 and the power output terminal; The second diode D2 is connected in series between the second power input terminal and the power output terminal.

[0007] Furthermore, when the first power input terminal and the second power input terminal are simultaneously powered normally, the second power input terminal normally powers on the control transistor Q2 and pulls down the control terminal voltage of the main switch transistor Q1, so that the main switch transistor Q1 is turned on, and the first power input terminal supplies power to the power output terminal through the main switch transistor Q1 and the first diode D1.

[0008] Furthermore, when the first power input terminal is de-energized and the second power input terminal is normally powered, the second power input terminal supplies power to the power output terminal via the second diode D2.

[0009] Furthermore, when the second power input is below the switching threshold, the control transistor Q2 is turned off, and the main switch Q1 is turned off.

[0010] When the second power input terminal is de-energized, the control transistor Q2 is cut off, the main switch transistor Q1 is turned off, and the power output terminal stops supplying power.

[0011] Furthermore, the main switch Q1 is a P-channel field-effect transistor, with its source connected to the first power input terminal, its drain connected to the anode of the first diode D1, and its gate, as the control terminal, connected to the collector of the control transistor Q2 through the first resistor R1.

[0012] Furthermore, it also includes a second resistor R2, which is connected between the source and gate of the P-channel MOSFET Q1 as a pull-up resistor. This resistor is used to pull the gate voltage of the P-channel MOSFET Q1 up to the source voltage when the control transistor Q2 is turned off, so as to ensure that the P-channel MOSFET Q1 is reliably turned off.

[0013] Furthermore, it also includes a voltage divider network, which is connected between the second power input terminal and ground, and the base of the control transistor Q2 is connected to the voltage divider node of the voltage divider network.

[0014] Furthermore, the voltage divider network includes a third resistor R3 and a fourth resistor R4 connected in series. One end of the third resistor R3 is connected to the second power input terminal, and the other end is connected to the base of the control transistor Q2 and one end of the fourth resistor R4. The other end of the fourth resistor R4 is grounded.

[0015] Furthermore, both the first diode D1 and the second diode D2 are Schottky diodes, and the cathodes of both diodes D1 and D2 are connected to the power output terminal.

[0016] Furthermore, it also includes a filtering unit, which includes: The second capacitor C2 is connected between the first power input terminal and ground. The first capacitor C1 is connected between the second power input terminal and ground.

[0017] Furthermore, it also includes a fourth capacitor C4, which is connected between the gate and source of the P-channel MOSFET Q1 to filter out the ripple of the control signal.

[0018] Secondly, a method for automatic switching of dual power supplies for automotive antennas, using the aforementioned automatic switching device for dual power supplies for automotive antennas to supply power to the automotive antenna.

[0019] Thirdly, a domain control system includes the aforementioned dual-power automatic switching device for an automotive antenna, wherein the second power input terminal is electrically connected to the internal power module of the domain control system.

[0020] Fourthly, an automotive antenna employs the aforementioned dual-power automatic switching device to power the automotive antenna.

[0021] Fifthly, a vehicle includes the aforementioned vehicle antenna dual-power automatic switching device.

[0022] This disclosure includes at least the following beneficial effects: This disclosure achieves automatic switching and stable output of dual power supplies using discrete components, featuring a compact structure, low cost, and high reliability, making it suitable for scenarios with high requirements for power continuity. This disclosure utilizes the switching characteristics of transistors to achieve contactless switching, avoiding the wear and tear problems of mechanical relays, while simultaneously improving power quality through filtering and protection circuits.

[0023] Other features and advantages of this disclosure will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the disclosure. The objects and other advantages of this disclosure may be realized and obtained by means of the structures pointed out in the description and the accompanying drawings. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the architecture of the dual-power automatic switching device according to an embodiment of this disclosure.

[0026] In the diagram, C1, C2, C3, and C4 are the first, second, third, and fourth capacitors, respectively; R1, R2, R3, and R4 are the first, second, third, and fourth resistors, respectively; D1 and D2 are the first and second diodes, respectively; Q1 is a MOSFET; and Q2 is a transistor. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0028] like Figure 1 As shown, an automatic dual-power switching device for automotive antennas includes: The first power input terminal is used to connect to the first power supply. The second power input terminal is used to connect to the second power supply; wherein, the voltage of the first power supply is higher than the voltage of the second power supply. The power output terminal is used to connect the antenna load; The main switch Q1 is connected between the first power input terminal and the power output terminal, and is used to control the switching on and off of the power from the first power input terminal to the power output terminal. The control transistor Q2 has its base connected to the second power input terminal, its collector C connected to the control terminal of the main switch transistor Q1, and its emitter E grounded. It is used to detect the voltage status of the second power input terminal and control the conduction and cutoff of the main switch transistor Q1. The first diode D1 is connected in series between the main switch Q1 and the power output terminal; The second diode D2 is connected in series between the second power input terminal and the power output terminal.

[0029] In practical implementation, the main switch Q1 (AO3401A, P-channel MOSFET) is the main gate of the entire power switching circuit, responsible for controlling whether the DC12V power supply can flow to the output terminal DC_ANT. Because a P-channel MOSFET is used, it not only acts as a switch but also achieves low-loss (low voltage drop) power switching.

[0030] Turn-on condition: The characteristic of a P-MOSFET is that it turns on when the gate (G) voltage is lower than the source (S) voltage by a threshold value.

[0031] Source (S): Connect to the DC12V input after being filtered by C2.

[0032] Gate (G): Connected to the collector of Q2 (via the first resistor R1). When Q2 is turned on, the gate of Q1 is pulled low to ground (0V), and Q1 is fully turned on; when Q2 is turned off, the gate is pulled high through the pull-up resistor R2 to near the source voltage of 12V, and Q1 is turned off.

[0033] P-MOSFETs have an internal parasitic diode pointing from D to S.

[0034] The main switch Q1 achieves high-efficiency transmission. Compared with using ordinary diodes to step down the voltage (voltage drop of 0.4V~0.7V), Q1 has extremely low internal resistance when it is turned on (the on-resistance of AO3401A is only tens of milliohms). When supplying power to the output with DC12V, it generates almost no voltage drop and power consumption, ensuring the stability of the output voltage and the power efficiency.

[0035] The main switch Q1 adopts controlled switching to realize intelligent access of DC12V. DC12V output is only allowed when DC10V is in normal condition, thus avoiding disordered parallel connection of dual power supplies.

[0036] The control transistor Q2 (NPN type) is the brain of the entire circuit. It is responsible for detecting the state of DC10V and issuing control commands to the main switch Q1 to turn on or off based on the detection results.

[0037] Base (B) detection: The DC10V input is divided by R3 and R4 and filtered by C1 before being connected to the base of Q2. When the DC10V is present, the base receives sufficient current.

[0038] When DC10V is normal, the current flows into the base through R3, Q2 is saturated and turned on, the collector (C) and emitter (E) are approximately short-circuited, pulling the gate voltage of Q1 down to ground, forcing Q1 to turn on, and DC12V is switched to the output terminal.

[0039] When DC10V is abnormal (such as power failure or low voltage), there is no base current, Q2 is cut off, the collector is in a high-resistance state, the gate voltage of Q1 is pulled up, Q1 is turned off, and DC12V is cut off.

[0040] R1 serves as the load resistor / pull-up resistor for the collector of Q2, and works in conjunction with the switching action of Q2 to achieve level conversion.

[0041] The control transistor Q2 achieves real-time monitoring of the DC10V power supply through state sensing and automatic switching, and automatically shuts off the DC12V power supply when the DC10V is abnormal, without the need for manual intervention or additional control chips.

[0042] The control transistor Q2 implements logic protection, ensuring the logic safety of power switching and preventing conflicts between the two power supplies under abnormal conditions.

[0043] The first diode D1 (SK54, Schottky diode) is located on the DC12V input side to prevent the voltage at the output terminal DC_ANT from flowing back to the DC12V input terminal, thus providing unidirectional isolation.

[0044] When forward biased, when Q1 is on, DC12V flows to the output terminal through Q1 and D1. At this time, D1 is forward biased and conducts, with a voltage drop of about 0.4V.

[0045] When reverse-biased, if the output DC_ANT voltage is higher than the DC12V input voltage for some reason (such as a higher external voltage or the DC10V side being powered), D1 is reverse-biased and cut off, cutting off the path of current flowing back from the output to DC12V.

[0046] The first diode D1 prevents reverse current flow, protecting the DC12V power supply from damage caused by abnormal voltage at the output terminal, and preventing the body diode inside Q1 from being reverse-broken or forming a leakage current loop when it is turned off.

[0047] The first diode D1, together with Q1, achieves perfect turn-off. Without D1, even if Q1 is turned off, the high voltage at the output terminal may flow back to the DC12V side through the body diode of Q1. The presence of D1 completely blocks this reverse path.

[0048] The second diode D2 (SK54, Schottky diode) is located on the DC10V input side to prevent the voltage at the output terminal (DC_ANT) from flowing back to the DC10V input terminal, and at the same time to prevent voltage crosstalk from the DC12V side to the DC10V input side, thus playing a unidirectional isolation role.

[0049] When forward conduction occurs, if DC10V is normal and the voltage is higher than the output terminal, DC10V will pass through R3 (to provide detection current for Q2) and the possible direct supply path (to supply power to the output terminal through D2). At this time, D2 will be forward biased and conduct.

[0050] When reverse biased, if DC10V is de-energized and DC12V supplies power to the output through Q1 and D1, the output voltage will be approximately 12V. This voltage is much higher than the DC10V input side (which is 0V at this time), and D2 will be reverse biased and cut off.

[0051] The second diode D2 provides power isolation, ensuring that when powered by DC12V, current will not flow in reverse through the output terminal into the de-energized DC10V network. This prevents the DC10V side circuit from being damaged by abnormal power supply and also prevents the base of Q2 from being mis-energized by reverse voltage.

[0052] The second diode D2 eliminates crosstalk, achieving physical electrical isolation between the two input power supplies and ensuring the independence and stability of the dual power supply system.

[0053] This disclosure uses a P-MOSFET (Q1) as the main switch, in conjunction with a Schottky diode (D1). Compared with the traditional "dual diode OR gate" power switching circuit, it significantly reduces the voltage drop and heat generation on the main power supply (DC12V) path, and improves power utilization and system reliability.

[0054] In this embodiment, when the first power input terminal and the second power input terminal are simultaneously powered normally, the second power input terminal normally powers on the control transistor Q2 and pulls down the control terminal voltage of the main switch transistor Q1, so that the main switch transistor Q1 is turned on, and the first power input terminal supplies power to the power output terminal through the main switch transistor Q1 and the first diode D1.

[0055] In this embodiment, when the first power input terminal is de-energized and the second power input terminal is powered normally, the second power input terminal supplies power to the power output terminal via the second diode D2.

[0056] In this embodiment, when the second power input terminal is lower than the switching threshold, the control transistor Q2 is turned off and the main switch Q1 is turned off; when the second power input terminal is de-energized, the control transistor Q2 is turned off, the main switch Q1 is turned off, and the power output terminal stops supplying power.

[0057] In practice, Q2 is disconnected and Q1 is disconnected when the DC10V second power supply drops below the switching threshold of 1.4V.

[0058] The first power supply (DC12V) has a higher power supply priority than the second power supply (DC10V). When both are present, the first power supply is given priority through the low-loss MOSFET path.

[0059] State 1: When both power supplies are normal, the first power supply takes priority.

[0060] When the first power input terminal and the second power input terminal are powered normally at the same time, the second power input terminal normally powers on the control transistor Q2 and pulls down the control terminal voltage of the main switch transistor Q1, so that the main switch transistor Q1 is turned on, and the first power input terminal supplies power to the power output terminal through the main switch transistor Q1 and the first diode D1.

[0061] During the detection and control phase, the second power supply (DC10V) injects current into the base of Q2 (NPN) through resistor R3, causing Q2 to saturate and conduct, with its collector and emitter approximately short-circuited.

[0062] During the main switch-on phase, the gate (G) of Q1 (P-MOSFET) is pulled low to ground (0V) by the conducting Q2. At this time, the source (S) of Q1 is connected to the first power supply (12V), and the gate (G) is 0V, which is far below its turn-on threshold, so Q1 is fully turned on.

[0063] During the power supply path establishment phase, the first power supply (12V) current passes through the conducting Q1 (extremely low internal resistance), then through D1 (Schottky diode), and reaches the power output terminal.

[0064] During the reverse isolation phase, the output voltage is approximately 12V. This voltage is higher than the second power supply (10V), so D2 is reverse biased and cut off, preventing current from the second power supply from flowing to the output.

[0065] This disclosure achieves low-loss main power supply by using a MOSFET (Q1) as the main switch, avoiding the voltage drop and heat generation problems of 0.7V or even higher caused by directly using a diode to step down the voltage, thus ensuring efficient power transmission of the first power supply.

[0066] This disclosure implements priority arbitration, opens the path of the first power supply through the second power supply, and naturally blocks the second power supply by utilizing the voltage drop difference between D1 and D2, thereby achieving absolute priority power supply of the first power supply.

[0067] This disclosure achieves backflow prevention. D1 prevents the output voltage from flowing back to the first power supply, and D2 prevents the output voltage from flowing back to the second power supply, thus achieving complete electrical isolation between the two inputs.

[0068] State 2: When the first power supply is off and the second power supply is normal, the second power supply takes over the power supply.

[0069] When the first power input terminal is de-energized and the second power input terminal is powered normally, the second power input terminal supplies power to the power output terminal via the second diode D2.

[0070] During the main switch turn-off phase, the first power supply is de-energized (0V). Even if Q2 is still conducting and pulls the gate of Q1 down to 0V, Q1 loses the conduction condition and turns off because the source of Q1 is also 0V.

[0071] During the backup circuit establishment phase, the second power supply (DC10V) current flows through D2 to the power supply output terminal.

[0072] During the reverse isolation phase, the output voltage is approximately 10V. Since Q1 is turned off and D1 is reverse biased, the voltage cannot flow back to the de-energized first power input terminal through D1 and Q1.

[0073] This disclosure enables seamless backup switching. In an emergency where the main power supply is unavailable, the backup power supply directly takes over the system power supply through the simplest diode path, with an extremely fast response speed (nanosecond level) and no control logic delay, ensuring uninterrupted power supply to the downstream loads. D1 effectively blocks leakage or backflow from the backup power supply to the main power supply side, protecting the circuitry on the primary power supply side.

[0074] State 3: When the second power source fails, the system stops supplying power.

[0075] When the second power input terminal is de-energized, the control transistor Q2 is cut off, the main switch transistor Q1 is turned off, and the power output terminal stops supplying power.

[0076] During the failure detection phase, the second power supply (DC10V) is de-energized, no current flows through R3, the base of Q2 loses its driving current, and Q2 changes from the conducting state to the cut-off state.

[0077] During the main switch turn-off phase, after Q2 is turned off, its collector is in a high-resistance state, and the gate (G) voltage of Q1 is pulled up to the same potential as the source (S), thus turning off Q1. The first power supply path is physically cut off.

[0078] With the backup circuit failing and the second power supply itself de-energized, there is no voltage at the input of D2, so it cannot supply power.

[0079] This disclosure employs complete power-off protection. When the second power source (serving as both a control signal source and a backup power source) disappears, the system determines that "no backup is available" and actively cuts off the output of the first power source. This design is for safe shutdown scenarios, where the backup power source not only provides power but its existence is also a prerequisite for the system to allow output. It prevents abnormal output and avoids the first power source from uncontrolled direct output in the event of control logic failure (second power source failure), thus ensuring the safety of the entire power supply chain.

[0080] After Q1 is turned off, the leakage current from the first power supply to the output terminal is limited to the microampere level (only the leakage current of the MOSFET), and the output voltage returns to zero, realizing zero-power safe standby of the system.

[0081] This disclosure cleverly utilizes a design where the backup power supply functions as both a power source and a control signal: (1) The main power supply is allowed to output only when the backup power supply is available (Q2 is turned on and Q1 is enabled). (2) When the main power supply is on, the main power supply will prioritize low-loss output (the voltage drop difference causes D2 to be cut off naturally). (3) When the main power supply is not available, the backup power supply is used (D2 is conducting to supply power). (4) The backup power supply is not available, and the main power supply is forcibly blocked (Q2 is cut off, causing Q1 to be turned off).

[0082] In this embodiment, the main switch Q1 is a P-channel field-effect transistor, with its source connected to the first power input terminal, its drain connected to the anode of the first diode D1, and its gate connected to the collector of the control transistor Q2 as a control terminal.

[0083] In this embodiment, a second resistor R2 is also included. The second resistor R2 is connected between the source and gate of the P-channel field-effect transistor Q1 as a pull-up resistor. It is used to pull the gate voltage of the P-channel field-effect transistor Q1 up to the source voltage when the control transistor Q2 is turned off, so as to ensure that the P-channel field-effect transistor Q1 is reliably turned off.

[0084] In practice: State 1: When Q2 is off (R2 is in operation), the power output terminal stops supplying power.

[0085] When the second power supply (DC10V) is de-energized, the control transistor Q2 is cut off, and its collector (C) and emitter (E) are effectively disconnected (high impedance state). At this time, the gate (G) of Q1 loses its low-impedance path to ground and is in a "floating" state.

[0086] Since R2 connects the source (12V) and the gate, the 12V power supply will charge the gate capacitor of Q1 through R2, quickly pulling the gate voltage up to a potential almost equal to that of the source.

[0087] At this time, the gate-source voltage difference of Q1 does not meet the turn-on condition of the P-MOSFET, so Q1 is reliably turned off.

[0088] State 2: When Q2 is on (R2 is in the compliant state), the power supply output is stopped.

[0089] When Q2 is turned on, the gate of Q1 is pulled low to ground (0V) by Q2. At this time, R2 is connected to 12V (source) and 0V (gate) respectively, and a small current will flow from the source through R2 to Q2 and then to ground. However, since the resistance of R2 is usually large (e.g., 100kΩ), this current is extremely small (about 0.12mA~1.2mA), and will not affect Q2 from pulling the gate low, nor will it cause significant power loss.

[0090] The presence of R2 resolves several critical vulnerabilities in MOSFET control, resulting in the following significant technical advantages: (1) Eliminating floating state and ensuring reliable turn-off. The gate (G) of a MOSFET is a high-impedance input terminal, which is equivalent to a very small capacitor inside. If only Q2 is connected to the gate of Q1 without R2, the gate is essentially floating when Q2 is turned off. A floating gate will act like an antenna, easily absorbing electromagnetic interference (EMI) from the surrounding environment, or the gate voltage may be uncertain or slowly charged due to leakage current inside the MOSFET. This can easily cause Q1 to turn on falsely, resulting in DC12V leaking to the output terminal when it should not be output, causing system logic chaos or even short circuit. R2 provides a clear static bias, firmly "locking" the gate to a high level, ensuring absolute reliability of turn-off.

[0091] (2) Provides a discharge circuit to accelerate the turn-off process. The gate of a MOSFET has a parasitic capacitance, which is charged when Q1 is turned on. When Q2 turns from on to off, the charge on the gate capacitance needs to be released before Q1 can be turned off. Without R2, the charge can only be released through the tiny leakage current of Q2 or the air, making the turn-off process extremely slow. With R2, the gate capacitance can quickly discharge to the source (12V power supply) through R2, forming a low-resistance circuit, thereby accelerating the turn-off process of Q1, reducing switching losses, and preventing the MOSFET from overheating and burning out due to being in the linear region (semi-conducting state) for a long time.

[0092] In this embodiment, a voltage divider network is also included, which is connected between the second power input terminal and ground, and the base of the control transistor Q2 is connected to the voltage divider node of the voltage divider network.

[0093] In this embodiment, the voltage divider network includes a third resistor R3 and a fourth resistor R4 connected in series. One end of the third resistor R3 is connected to the second power input terminal, and the other end is connected to the base of the control transistor Q2 and one end of the fourth resistor R4. The other end of the fourth resistor R4 is grounded.

[0094] In this embodiment, both the first diode D1 and the second diode D2 are Schottky diodes, and the cathodes of both the first diode D1 and the second diode D2 are connected to the power output terminal.

[0095] In this embodiment, a filtering unit is also included, which includes: The second capacitor C2 is connected between the first power input terminal and ground. The first capacitor C1 is connected between the second power input terminal and ground.

[0096] In this embodiment, a fourth capacitor C4 is also included. The fourth capacitor C4 is connected between the gate and source of the P-channel field-effect transistor Q1 and is used to filter out the ripple of the control signal.

[0097] In practice, R2 and C4 together form the RC filter network for the gate of the P-channel MOSFET Q1.

[0098] To absorb high-frequency ripple (low impedance bypass), the basic characteristic of a capacitor is that it "passes AC and blocks DC" and the voltage across its terminals cannot change abruptly. When a high-frequency AC ripple or voltage spike appears at the gate due to a control signal (from the collector of Q2) or external interference, these high-frequency AC components will preferentially flow back to the source through C4 because C4 presents extremely low impedance to high-frequency signals, without causing drastic fluctuations in the gate DC potential.

[0099] Smoothing the control signal (charge / discharge buffer): When Q2 is turned on and pulls the gate low, C4 is charged; when Q2 is turned off, C4 is discharged through R2. The presence of C4 forces the gate voltage change to undergo a charge / discharge process, thus smoothing out the potentially steep control signal edges.

[0100] The addition of C4 is mainly to solve the problem that MOSFETs are easily interfered with and damaged in complex electromagnetic environments, which is specifically reflected in the following four aspects: (1) Filtering out control signal ripple to prevent Q1 from being mis-turned on. If there is power supply ripple on the DC10V side, or if the base of Q2 is subject to spatial electromagnetic interference, these fluctuations will be conducted to the gate of Q1 through Q2. Without C4, high-frequency ripple will be directly superimposed on the gate, which may momentarily drop below the turn-on threshold, causing Q1 to turn on momentarily and resulting in output voltage jitter. C4 utilizes the low impedance characteristic of capacitors to high frequencies to short-circuit these ripples back to the source, locking the DC potential of the gate, which greatly improves the anti-interference capability of the circuit.

[0101] (2) Absorbing voltage spikes and protecting the gate oxide layer of Q1. The gate (G) and source (S) of a MOSFET are separated by a very thin silicon dioxide insulating layer (which is easily broken down). In actual circuits, due to the parasitic inductance of PCB traces or the influence of external static electricity (ESD), instantaneous high voltage spikes can easily appear on the gate. C4, as a local bypass capacitor, can quickly absorb these transient spike energies, preventing the gate and source from being damaged by overvoltage, thus protecting the MOSFET.

[0102] In this embodiment, a third capacitor C3 is also included, which is connected between the power output terminal and ground.

[0103] In practice, after the power supply undergoes switching in the front stage (Q1's switching action) and diode transfer (D1 / D2), the output is often superimposed with high-frequency switching noise, spikes generated by diode reverse recovery, and electromagnetic interference (EMI) from the external environment. C3, as a high-frequency decoupling capacitor, presents extremely low impedance to high-frequency signals, bypassing these high-frequency AC components to ground. This ensures that the output is left with a smooth, clean DC voltage, guaranteeing the stable operation of downstream loads (such as MCUs and sensors).

[0104] When a sudden change occurs in the back-end load (e.g., a microcontroller suddenly wakes up from sleep mode, instantly increasing the current), the parasitic inductance and resistance of the power supply line itself will hinder the instantaneous rise in current, causing a momentary drop in output voltage. At the moment of the sudden change in load current, C3 can instantly release its stored charge, providing a transient pulse current to the load, filling the power supply gap, thereby maintaining the stability of the output voltage and preventing the system from resetting or crashing due to voltage drops.

[0105] In dual power supply switching circuits (such as switching between DC12V and DC10V), there may be a very short dead zone or voltage fluctuation at the moment of switching. C3 is fully charged before switching and can maintain the output voltage at the moment of switching, ensuring that the back-end system is "powered up" during the power switching process and achieving seamless switching.

[0106] This disclosure provides a method for automatic switching of dual power supplies for automotive antennas, which uses the aforementioned automatic switching device for dual power supplies to power the automotive antenna.

[0107] In practice: This disclosure employs a discrete component design, including power input filtering, detection switching, and output protection modules. An NPN transistor Q2 detects the internal DC 10V status of the domain controller and controls the switching of the P-channel MOSFET Q1, achieving controlled switching of the external DC 12V. Schottky diodes D1 and D2 provide reverse current protection isolation. This design utilizes the contactless switching characteristics of transistors to replace mechanical relays, achieving microsecond-level switching speeds and efficiencies exceeding 96%. Furthermore, RC filtering and a voltage divider network ensure high anti-interference and stability. This disclosure features a compact structure, low cost, and high reliability, perfectly realizing controlled redundant power supply logic for internal control of external power supplies. It solves the problems of power supply interference in dual-power supply systems and the control of external power supplies by the domain controller's internal power supply, making it suitable for automotive scenarios with stringent power continuity requirements.

[0108] This disclosure implements precise internal control and external controlled redundancy logic. It breaks away from the blind dominance of the traditional dual power supply with the higher voltage, granting the domain controller's internal power supply (DC10V) absolute priority decision-making power. When the internal power supply is abnormal, even if the external power supply (DC12V) is normal, it can actively cut off the external power supply circuit, avoiding ineffective idling or uncontrollable interference of the antenna amplifier when the host is down, and achieving system-level self-protection and isolation control.

[0109] This disclosure employs microsecond-level contactless switching with zero power supply interruption. By utilizing the electronic switching characteristics of a MOSFET (Q1) to replace the traditional mechanical relay, contact sparking, bounce, and mechanical wear are completely eliminated. The switching time constant is determined by the RC parameters and controlled at the microsecond level, far exceeding the millisecond-level switching speed of conventional relays. This extremely short switching time ensures that the downstream antenna amplifier can maintain voltage using its own capacitance during power switching, achieving uninterrupted power supply with "zero load awareness."

[0110] This disclosure employs highly efficient power transfer with extremely low losses. The main circuit losses originate solely from the forward voltage drop of the isolation Schottky diodes (D1 / D2). The extremely high energy conversion rate reduces heat generation, eliminating the need for additional heat dissipation design, perfectly meeting the requirements of low-power devices.

[0111] This disclosure provides strong anti-interference and backflow prevention stability. Physical isolation and crosstalk prevention are achieved by D1 and D2 forming a unidirectional anti-theft door, completely cutting off the reverse backflow path between the two power sources at a physical level, ensuring that the two sources do not interfere with each other. Fluctuation resistance and accidental touch prevention are achieved by the precision voltage divider network composed of R3 and R4 providing a stable base threshold for Q2, combined with multi-stage high-frequency filter capacitors (C1, C2, C3) at the input / output terminals, effectively suppressing voltage transients and noise interference in the complex electromagnetic environment of automobiles, eliminating switching jitter or malfunctions caused by voltage fluctuations.

[0112] This disclosure optimizes cost-effectiveness and space utilization, eliminating expensive dedicated power management chips and bulky mechanical relays. Using only one MOSFET, one transistor, and a few inexpensive discrete components such as resistors, capacitors, and diodes, it achieves complex functions integrating voltage detection, logic judgment, power switching, and isolation protection. This significantly reduces BOM cost and PCB footprint, achieving a perfect balance between high reliability and low cost.

[0113] This disclosure provides a domain control system, including the aforementioned dual-power automatic switching device for automotive antennas, wherein the second power input terminal is electrically connected to the internal power module of the domain control system.

[0114] This disclosure provides an automotive antenna that uses the aforementioned dual-power automatic switching device to power the automotive antenna.

[0115] This disclosure provides a vehicle including the aforementioned vehicle antenna dual-power automatic switching device.

[0116] To enable those skilled in the art to better understand this disclosure, the principles of this disclosure are explained below in conjunction with the accompanying drawings: Currently, circuit design utilizes high-cost multi-channel power supply chips. These chips are expensive, and their availability is sometimes constrained by market demands, impacting development cycles. For example... Figure 1 As shown, the circuit disclosed herein utilizes a P-channel MOSFET (AO3401) to control the on / off state of a 12V DC power supply, achieving a large output current while also serving as an external power supply control circuit. To ensure reliable power supply for the car radio and GPS antenna amplifiers, two power supply methods are used simultaneously: external and internal power supply to the domain controller. This disclosed circuit solves the problem of two power supplies simultaneously powering the antenna without interference, while the power supply inside the domain controller can also control the external power supply.

[0117] This disclosed circuit achieves automatic switching and stable output of dual power supplies using simple discrete components. It features a compact structure, low cost, and high reliability, making it suitable for scenarios with high requirements for power continuity. Its core advantage lies in utilizing the switching characteristics of transistors to achieve contactless switching, avoiding the wear and tear problems of mechanical relays. Simultaneously, filtering and protection circuits improve power quality.

[0118] The circuit composition and component functions are introduced below: C1, C2, C3, and C4 are the first, second, third, and fourth capacitors, respectively, and are ceramic capacitors; R1, R2, R3, and R4 are the first, second, third, and fourth resistors, respectively; D1 and D2 are the first and second diodes, respectively, and are Schottky diodes; Q1 is a MOSFET, and Q2 is a transistor.

[0119] The power input and filtering module has the following parameters: DC12V input: After high-frequency ripple is filtered out by C2 (100nF / 50V ceramic capacitor), it is connected to the control circuit. DC10V input: High-frequency interference is filtered out by C1 (100nF / 50V ceramic capacitor), and then current is limited by R3 (10kΩ / 1% precision resistor) before being connected to the control circuit.

[0120] Power detection and switching module Q1 (AO3401A): P-channel MOSFET, used as the main switch. It turns on when the gate (G) voltage is lower than the source (S) voltage, switching DC12V to the output.

[0121] Transistor Q2 (NPN type): Together with R3 and R4 (10kΩ / 1%), it forms a voltage comparator circuit to detect the DC10V status. When DC10V is normal, it conducts, pulling down the gate voltage of Q1 to turn Q1 on; when DC10V is abnormal, it is cut off, the gate voltage of Q1 rises, and Q1 turns off.

[0122] Diodes D1 and D2 (SK54): Schottky diodes with a forward voltage drop of approximately 0.4V, used to prevent reverse crosstalk between the two power supplies and to isolate the output and input terminals.

[0123] Output protection and filtering module, C3 (100nF / 50V): High-frequency filter capacitor at the output end to suppress ripple.

[0124] DC_ANT: The final output terminal, providing a stable DC power supply.

[0125] The workflow is as follows: Normal operating condition: When both DC12V and DC10V are powered normally, Q2 is turned on, the gate voltage of Q1 is pulled low, Q1 is turned on, DC12V powers DC_ANT through D1, and the DC10V branch serves as a redundant backup, while charging C3.

[0126] DC12V failure state: After DC12V is powered off, Q1 is cut off. At this time, DC10V supplies power to DC_ANT through its own filter circuit and D2, ensuring that the load is not interrupted.

[0127] DC10V Failure State: When the DC10V voltage is below the threshold, Q2 is turned off, the gate voltage of Q1 increases, Q1 is turned off, and the DC10V output is interrupted. At this time, Q1 is turned off, and there is no voltage output from DC_ANT.

[0128] Overvoltage protection mechanism: If the input voltage exceeds the component's withstand voltage (e.g., DC12V exceeds 25V), C2 and C1 will break down due to overvoltage protection circuit to prevent damage to subsequent components.

[0129] The key parameters and design are as follows: Power switching threshold calculation, Q2 turn-on condition: base voltage (VB) > emitter voltage (VE) - 0.7V (NPN diode turn-on voltage drop). When DC10V is normal (10V), VB≈0.7V (considering the voltage divider of R3 and diode voltage drop), Q2 turns on.

[0130] Filter capacitor selection: C2 (100nF): Filters high-frequency ripple from the DC12V input to ensure stable input voltage. C1 and C3 (100nF): Ceramic capacitors are used to achieve low-impedance filtering for high-frequency interference (such as switching noise), improving power supply purity.

[0131] For parameter matching, Q1 (AO3401A) has a withstand voltage of 30V and an on-resistance of 0.01Ω, meeting the DC12V / DC10V voltage requirements, and has low conduction loss (P=I²R, P≈0.01W when I≈1A). Q2 must meet the following requirements: collector-emitter voltage (Vce) ≥15V and current amplification factor (β) ≥100 to ensure reliable transmission of control signals.

[0132] Circuit performance evaluation is as follows: (1) Switching speed: The gate capacitor charging / discharging time constant of AO3401A (τ=R×C≈10kΩ×100nF=1μs) can control the switching time in microseconds, which meets the sensitivity requirements of most electronic devices to power interruption.

[0133] (2) Efficiency analysis: Under normal conditions (DC10V output): efficiency η≈(10V-0.4V) / 10V=96% (excluding the forward voltage drop of D2). Under standby conditions (DC12V output): efficiency η≈(12V-0.4V) / 12V=96.7%, the overall efficiency is relatively high, which is suitable for low power consumption devices.

[0134] (3) Stability verification: The voltage divider network of R3 (10kΩ) and R4 (10kΩ) ensures the stability of the base voltage of Q2 and avoids false switching due to input voltage fluctuations; the filtering effect of C2 and C3 further suppresses noise interference and improves the anti-interference capability of the circuit.

[0135] Although the present disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. An automatic switching device for dual power supplies of an automotive antenna, characterized in that, include: The first power input terminal is used to connect to the first power supply. The second power input terminal is used to connect to the second power supply; wherein, the voltage of the first power supply is higher than the voltage of the second power supply. The power output terminal is used to connect the antenna load; The main switch Q1 is connected between the first power input terminal and the power output terminal, and is used to control the switching on and off of the power from the first power input terminal to the power output terminal. The control transistor Q2 has its base connected to the second power input terminal, its collector C connected to the control terminal of the main switch transistor Q1, and its emitter E grounded. It is used to detect the voltage status of the second power input terminal and control the conduction and cutoff of the main switch transistor Q1. The first diode D1 is connected in series between the main switch Q1 and the power output terminal; The second diode D2 is connected in series between the second power input terminal and the power output terminal.

2. The automatic switching device for dual power supplies of an automotive antenna according to claim 1, characterized in that, When the first power input terminal and the second power input terminal are powered normally at the same time, the second power input terminal normally powers on the control transistor Q2 and pulls down the control terminal voltage of the main switch transistor Q1, so that the main switch transistor Q1 is turned on, and the first power input terminal supplies power to the power output terminal through the main switch transistor Q1 and the first diode D1.

3. The automatic switching device for dual power supplies of an automotive antenna according to claim 1, characterized in that, When the first power input terminal is de-energized and the second power input terminal is powered normally, the second power input terminal supplies power to the power output terminal via the second diode D2.

4. The automatic switching device for dual power supplies of an automotive antenna according to claim 1, characterized in that, When the second power input is below the switching threshold, the control transistor Q2 is turned off, and the main switch transistor Q1 is turned off.

5. The automatic switching device for dual power supplies of an automotive antenna according to claim 1, characterized in that, The main switch Q1 is a P-channel field-effect transistor. Its source is connected to the first power input terminal, its drain is connected to the anode of the first diode D1, and its gate is connected to the collector of the control transistor Q2 through the first resistor R1.

6. The automatic switching device for dual power supplies of an automotive antenna according to claim 5, characterized in that, It also includes a second resistor R2, which is connected between the source and gate of the P-channel field-effect transistor Q1 as a pull-up resistor. When the control transistor Q2 is turned off, the gate voltage of the P-channel field-effect transistor Q1 is pulled up to the source voltage to ensure that the P-channel field-effect transistor Q1 is reliably turned off.

7. The automatic switching device for dual power supplies of an automotive antenna according to claim 1, characterized in that, It also includes a voltage divider network, which is connected between the second power input terminal and ground, and the base of the control transistor Q2 is connected to the voltage divider node of the voltage divider network.

8. The automatic switching device for dual power supplies of an automotive antenna according to claim 7, characterized in that, The voltage divider network includes a third resistor R3 and a fourth resistor R4 connected in series. One end of the third resistor R3 is connected to the second power input terminal, and the other end is connected to the base of the control transistor Q2 and one end of the fourth resistor R4. The other end of the fourth resistor R4 is grounded.

9. The automatic switching device for dual power supplies of an automotive antenna according to claim 1, characterized in that, Both the first diode D1 and the second diode D2 are Schottky diodes, and the cathodes of both diodes D1 and D2 are connected to the power output terminal.

10. The automatic switching device for dual power supplies of an automotive antenna according to claim 1, characterized in that, It also includes a filtering unit, which includes: The second capacitor C2 is connected between the first power input terminal and ground. The first capacitor C1 is connected between the second power input terminal and ground.

11. The automatic switching device for dual power supplies of an automotive antenna according to claim 5, characterized in that, It also includes a fourth capacitor C4, which is connected between the gate and source of the P-channel field-effect transistor Q1 to filter out the ripple of the control signal.

12. A method for automatic switching of dual power supplies for an automotive antenna, characterized in that, The vehicle antenna is powered by an automatic dual-power switching device as described in any one of claims 1 to 11.

13. A domain control system, characterized in that, The device includes an automatic dual-power switching device for an automotive antenna as described in any one of claims 1 to 11, wherein the second power input terminal is electrically connected to the internal power module of the domain control system.

14. A car antenna, characterized in that, The vehicle antenna is powered by an automatic dual-power switching device as described in any one of claims 1 to 11.

15. A car, characterized in that, Includes an automatic dual-power switching device for automotive antennas as described in any one of claims 1 to 11.

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