Automobile power signal switch circuit

Abstract

The present invention provides an automobile power signal switch circuit, comprising: a constant power input terminal, a functional power input terminal, a first diode, an RC energy storage circuit, a first resistor, a second resistor, a first switch tube, a third resistor, a second switch tube, a protection circuit, an anti-reverse connection circuit and a functional power output. The automobile power signal switch circuit of the present invention can obtain a control circuit of a stable output voltage from other constant power sources by collecting PWM signals, and has outstanding advantages in response speed and anti-interference ability, and is low in cost and convenient and reliable to implement.

Description

Technical Field

[0001] The invention relates to the field of power switch circuits, and in particular to an automobile power signal switch circuit. Background Art

[0002] The car power supply is dual power supply of battery and generator. When it reaches the car electronic control parts through BCM (body control module), if it is continuous power supply, the controller can work normally. However, when BCM supplies PWM (usually around 100HZ) power to the car electronic control parts, some car electronic control parts cannot work normally. If the OEM cannot modify the BCM control mode for some reason, it will inevitably cause the embarrassment that the car electronic control parts cannot work normally. Summary of the invention

[0003] In view of the deficiencies in the above-mentioned prior art, the present invention provides an automobile power signal switching circuit, which can obtain a control circuit for a stable output voltage from other constant power sources by collecting PWM signals. The circuit has outstanding advantages in response speed and anti-interference ability, and is low in cost and easy and reliable to implement.

[0004] In order to achieve the above object, the present invention provides an automobile power signal switch circuit, comprising:

[0005] A constant power input terminal;

[0006] A functional power input terminal;

[0007] a first diode, wherein an anode of the first diode is connected to the functional power input terminal;

[0008] an RC energy storage circuit; the RC energy storage circuit is connected to the cathode of the first diode;

[0009] a first resistor connected between the cathode of the first diode and a ground terminal;

[0010] a second resistor, a first end of the second resistor being connected to the RC energy storage circuit;

[0011] a first switch tube, wherein a gate of the first switch tube is connected to the second end of the second resistor, and a source of the first switch tube is connected to the cathode of the first diode;

[0012] a third resistor, a first end of the third resistor being connected to the drain of the first switch tube;

[0013] a second switch tube, wherein a gate of the second switch tube is connected to the second end of the third resistor, and a drain of the second switch tube is connected to the constant power input end;

[0014] a protection circuit connected between the gate of the second switch tube and the constant power input terminal;

[0015] an anti-reverse connection circuit connected between the functional power input terminal and the source of the second switch tube; and

[0016] A functional power output terminal, wherein the functional power output terminal is connected to the source of the second switch tube.

[0017] Preferably, the RC energy storage circuit comprises:

[0018] a second diode, wherein an anode of the second diode is connected to a cathode of the first diode;

[0019] a fourth resistor, wherein a first end of the fourth resistor is connected to the anode of the second diode, and a second end of the fourth resistor is connected to the first end of the second resistor;

[0020] a fifth resistor; and

[0021] A capacitor, the fifth resistor and the capacitor are connected in parallel between the first end of the second resistor and the ground end.

[0022] Preferably, the protection circuit includes a sixth resistor and a third diode, and the sixth resistor and the third diode are connected in parallel between the constant power supply input terminal and the gate of the second switch tube; the positive electrode of the third diode is connected to the gate of the second switch tube, and the negative electrode of the third diode is connected to the constant power supply input terminal.

[0023] The present invention adopts the above technical solution, so it has the following beneficial effects:

[0024] 1. By collecting PWM signals, a stable output voltage is obtained from other constant power sources. Its response speed and anti-interference ability have outstanding advantages, and it is low-cost, convenient and reliable to implement;

[0025] 2. When the functional power input terminal is at a high level, the power switch circuit chooses to use the functional power supply. When the functional power supply is suspended or at a low level, the power switch circuit chooses to use a constant power supply. This power supply method can supply high-power loads with low heat generation and high working efficiency.

[0026] 3. It will not cause the problem of BCM false alarm (BCM will only detect whether the output current meets the specifications when outputting functional power). When BCM outputs functional power, the power switch circuit uses the functional power issued by BCM for power supply.

[0027] 4. The power switch circuit outputs power in a short time. When the functional power is input, continuous functional power output can be obtained immediately at the output end of the power switch circuit.

[0028] 5. The power switch circuit has strong anti-interference ability and can withstand automotive-grade power supply and electromagnetic interference in space, with stable and reliable performance.

[0029] 6. When the functional power input is disconnected, the functional power output of the power switch circuit will disconnect the output in time after a short delay of ms. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A circuit diagram of an automotive power signal switch circuit according to an embodiment of the present invention;

[0031] Figure 2 It is a comparison diagram of the constant power supply, functional power supply input and functional power supply output signals of an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following is based on the attached Figure 1 and Figure 2 , give the preferred embodiments of the present invention, and describe them in detail so that the functions and features of the present invention can be better understood.

[0033] See also Figure 1 An automotive power signal switch circuit according to an embodiment of the present invention comprises: a constant power input terminal P1, a functional power input terminal P2, a first diode D1, an RC energy storage circuit 1, a first resistor R1, a second resistor R4, a first switch tube Q2, a third resistor R5, a second switch tube Q1, a protection circuit 2, an anti-reverse connection circuit 3 and a functional power output terminal P3; the positive electrode of the first diode D1 is connected to the functional power input terminal P2; the RC energy storage circuit 1 is connected to the negative electrode of the first diode D1; the first resistor R1 is connected between the negative electrode of the first diode D1 and a ground terminal; the first of the second resistor R4 The first end of the first switch tube Q2 is connected to the RC energy storage circuit 1; the gate of the first switch tube Q2 is connected to the second end of the second resistor R4, and the source of the first switch tube Q2 is connected to the cathode of the first diode D1; the first end of the third resistor R5 is connected to the drain of the first switch tube Q2; the gate of the second switch tube Q1 is connected to the second end of the third resistor R5, and the drain of the second switch tube Q1 is connected to the constant power input terminal P1; the protection circuit 2 is connected between the gate of the second switch tube Q1 and the constant power input terminal P1; the anti-reverse connection circuit 3 is connected between the functional power input terminal P2 and the source of the second switch tube Q1; the functional power output terminal P3 is connected to the source of the second switch tube Q1.

[0034] The RC energy storage circuit 1 includes: a second diode D2, a fourth resistor R2, a fifth resistor R3 and a capacitor C1. The anode of the second diode D2 is connected to the cathode of the first diode D1; the first end of the fourth resistor R2 is connected to the anode of the second diode D2, and the second end of the fourth resistor R2 is connected to the first end of the second resistor R4; the fifth resistor R3 and the capacitor C1 are connected in parallel between the first end of the second resistor R4 and the ground end.

[0035] In this embodiment, the protection circuit 2 includes a sixth resistor R6 and a third diode D3, and the sixth resistor R6 and the third diode D3 are connected in parallel between the constant power input terminal P1 and the gate of the second switch tube Q1; the anode of the third diode D3 is connected to the gate of the second switch tube Q1, and the cathode of the third diode D3 is connected to the constant power input terminal P1.

[0036] In an embodiment of the present invention, a car power signal switch circuit, a second diode D2, a fourth resistor R2, a fifth resistor R3 and a capacitor C1 form an RC energy storage circuit 1. When a PWM signal of a functional power input terminal P2 arrives, the PWM signal is converted into a stable DC signal through the circuit to turn on the first switch tube Q2. The presence of the third diode D3 makes the RC energy storage circuit 1 have only one discharge loop, and discharge is performed through the second resistor R4 and the first switch tube Q2, which can greatly reduce the RC parameters in the RC energy storage circuit 1 and reduce the device packaging.

[0037] Due to the existence of the RC energy storage circuit 1, the impact interference of high power pulse or ESD existing when the functional power is input can be resisted.

[0038] The sixth resistor R6 and the third diode D3 are used to protect the second switch tube Q1 (for example, the second switch tube Q1 is a PMOS tube).

[0039] The fourth resistor R2 and the fifth resistor R3 form a voltage divider circuit. Since the on-state voltage of the first switch tube Q2 is low, in order to resist the voltage increase caused by interference from the functional power input terminal P2 or other reasons, a voltage divider circuit is required to filter out low voltage signals below a certain level.

[0040] The second resistor R4 is a series resistor of the discharge circuit of the filter circuit, and determines the closing speed of the first switch tube Q2.

[0041] The anti-reverse connection circuit 3 is used to prevent the backflow of power from triggering the BCM alarm when the functional power supply has voltage output but the functional power supply input has no high voltage input.

[0042] When a negative pulse appears at the functional power input terminal P1, point B is still at a high level due to filtering and energy storage, which will cause the first switch tube Q2 to be mis-turned on instantly. The second diode D2 effectively blocks the invasion of negative pulses.

[0043] The first switch tube Q2 and the second switch tube Q1 may be any controlled switch tubes. For example, in this embodiment, the first switch tube Q2 is a triode, and the second switch tube Q1 is a MOS tube.

[0044] See also Figure 1 and Figure 2 For high-power loads, large currents passing through the first power supply branch 4 and the second power supply branch 5 will generate heat loss. However, since the first power supply branch 4 and the second power supply branch 5 work alternately, heat will not be concentrated on one device, which can greatly alleviate the heating of the power supply open tube.

[0045] When the functional power input of the functional power input terminal P2 is at a high level, the first switch tube Q2 will not be turned on because the conduction condition is not met. The functional power input passes through the anti-reverse connection circuit 3 and is output from the functional power output terminal P3. The voltage difference between the functional power input terminal P2 and the functional power output terminal P3 is the voltage drop of the anti-reverse connection circuit 3.

[0046] When the functional power input of the functional power input terminal P2 is at a low level or suspended within the PWM cycle, the first switch tube Q2 starts to conduct due to the action of the RC energy storage circuit 1, and at the same time, the second switch tube Q1 is also turned on, and the functional power is output. The voltage difference between the functional power input terminal P2 and the functional power output terminal P3 is the voltage difference of the second switch tube Q1.

[0047] When the functional power input returns to a high level, the second switch tube Q1 and the first switch tube Q2 will be turned off immediately, and then the functional power input passes through the anti-reverse connection circuit 3 and is output from the functional power output terminal P3. The tracking speed is very timely.

[0048] When the functional power input is continuously at a low level or is suspended, the RC energy storage circuit 1 is discharged ( Figure 2 The medium delay time can be determined by the parameters of the fourth resistor R2, the fifth resistor R3, the capacitor C1 and the second resistor R4), the second switch tube Q1 and the first switch tube Q2 are turned off, and the output of the functional power output terminal P3 is disconnected.

[0049] The present invention is described in detail above in conjunction with the embodiments of the accompanying drawings. A person skilled in the art can make various variations of the present invention according to the above description. Therefore, certain details in the embodiments should not constitute a limitation of the present invention, and the scope of protection of the present invention shall be defined by the scope of the attached claims.

Claims

1. An automotive power signal switch circuit, characterized in that: include: A constant power input terminal; A functional power input terminal; a first diode, wherein an anode of the first diode is connected to the functional power input terminal; an RC energy storage circuit; the RC energy storage circuit is connected to the cathode of the first diode; a first resistor connected between the cathode of the first diode and a ground terminal; a second resistor, a first end of the second resistor being connected to the RC energy storage circuit; a first switch tube, wherein a gate of the first switch tube is connected to the second end of the second resistor, and a source of the first switch tube is connected to the cathode of the first diode; a third resistor, a first end of the third resistor being connected to the drain of the first switch tube; a second switch tube, wherein a gate of the second switch tube is connected to the second end of the third resistor, and a drain of the second switch tube is connected to the constant power input end; a protection circuit connected between the gate of the second switch tube and the constant power input terminal; an anti-reverse connection circuit connected between the functional power input terminal and the source of the second switch tube; and a functional power supply output terminal, wherein the functional power supply output terminal is connected to the source of the second switch tube; The functional power input terminal receives a PWM signal.

2. The automotive power signal switch circuit according to claim 1, characterized in that: The RC energy storage circuit comprises: a second diode, wherein an anode of the second diode is connected to a cathode of the first diode; a fourth resistor, wherein a first end of the fourth resistor is connected to the cathode of the second diode, and a second end of the fourth resistor is connected to the first end of the second resistor; a fifth resistor; and A capacitor, the fifth resistor and the capacitor are connected in parallel between the first end of the second resistor and the ground end.

3. The automotive power signal switch circuit according to claim 2, characterized in that: The protection circuit includes a sixth resistor and a third diode, and the sixth resistor and the third diode are connected in parallel between the constant power supply input terminal and the gate of the second switch tube; the positive electrode of the third diode is connected to the gate of the second switch tube, and the negative electrode of the third diode is connected to the constant power supply input terminal.

Images