Low-power-consumption wake-up circuit

Abstract

The utility model discloses a low power consumption wake-up circuit, which comprises a first input circuit, a diode, a triode and a second input circuit, the first input circuit is externally connected with a switch, the first input circuit is connected with a first power supply, the output end of the first input circuit is connected with the negative electrode of the diode, the positive electrode of the diode is connected with the base electrode of the triode, and the negative electrode of the triode is connected with the second input circuit. The emitter of the triode is connected with a second power supply, and the collector of the triode is output to a second input circuit which is connected with the MCU. According to the scheme, no current is consumed when the wake-up circuit is in constant power, so that the requirement for lower sleep current is met.

Description

Technical Field

[0001] The utility model relates to the technical field of automotive electronic control, and particularly relates to a low-power wake-up circuit. Background Art

[0002] The trend of modern automotive electronics is becoming more and more obvious, which makes more and more ECUs installed in vehicles. For this reason, the vehicle manufacturers have higher requirements for the power consumption of each ECU. On the other hand, the trend of automotive ECU integration is also becoming more and more obvious, which increases the input and output circuits. And for each ECU to achieve a certain target of sleep current, the requirements for hardware design and software design are also higher.

[0003] Among them, the MCU intermittent working mode is as Figure 1 shown.

[0004] Generally, after the MCU is powered on, it runs at high speed for a period of time first. After meeting the sleep requirements, it enters the Toff stage. Before entering Toff, a low-power timer needs to be turned on as a wake-up source so that the MCU can be periodically woken up during the Toff stage. For example, set the period of the low-power timer to 50 ms, as Figure 1 shown, that is, Toff + Ton = 50 ms.

[0005] At the same time, as Figure 2 can be seen, the difference between it and the MCU intermittent working mode is that there is an additional T1 time. In fact, the MCU intermittent working mode is to achieve the ECU intermittent working mode. And the ECU intermittent working mode is to be able to intermittently check whether the switch state has changed during the ECU sleep period, such as whether the door handle switch is pressed.

[0006] Generally, the wake-up circuit design is as Figure 3 shown.

[0007] Switch1 is externally connected to a switch to the ground. The circuit inputs the switch state to the MCU through a voltage dividing circuit, that is, Switch1_MCU is connected to the IO port of the MCU. The EN signal is controlled by the IO of the MCU. When the circuit needs to work, the EN signal outputs a high level to make VCC12V_PU1 12V to supply power to the wake-up input circuit. Switch1 is the input of a low-level effective switch. Once the switch is pressed (grounded at Switch1), Switch1_MCU becomes low level.

[0008] When the ECU is in the intermittent working mode, the EN signal needs to output a high level intermittently during the T1 time period, and then the MCU reads the Switch state through the IO port. If the switch signal is invalid, the MCU goes to sleep again. If it is valid, the entire ECU wakes up and enters the high-speed working state.

[0009] However, see Figure 3 It can be seen that once the VCC12V_PU1 outputs a 12V voltage, there will be a charging process for the voltage at Switch1, that is, the voltage here has a process of gradually increasing.

[0010] At the same time, in the existing wake-up circuit, a control circuit ( Figure 3 the upper part) is required. When the automotive ECU is in the intermittent working mode, it periodically outputs a high level to enable it to work. When it is not needed, it shuts off the power supply of the relevant circuit through it.

[0011] Secondly, due to the existence of the capacitor C223, it is necessary to charge for a period of time each time before the input switch state can be collected, and this time needs to be considered in the software design.

[0012] In addition, the capacitor C223 needs to be charged periodically. Once the EN control signal becomes low, the capacitor C223 will discharge to the ground through the resistors R351 and R355. It needs to be charged again during the next T1 time, resulting in the power consumption of the input circuit not being only the power consumption of the three adjacent resistors. In fact, the current is consumed when charging the capacitor, and after the wake-up input circuit is turned off, it is released through the resistor.

[0013] The three resistors R349, R351, and R355 divide the 12V voltage, resulting in the voltage at Switch1_MCU being significantly higher than 5V. Therefore, the IO port of the MCU needs to have the voltage clamping ability to be able to work normally when the voltage of the IO port exceeds 5V. ( Figure 3 This circuit design needs to consider the situation where the 12V power supply voltage becomes lower, such as being able to normally collect the input switch state when it is 8V.)

[0014] Therefore, the ECU and the MCU need to work in the intermittent mode to collect the wake-up input switch state, which consumes a relatively large current.

[0015] It can be seen that the existing wake-up circuit design has low reliability due to the above-mentioned technical problems. Therefore, how to improve the reliability of the wake-up circuit is a problem to be solved in this field. Summary of the Invention

[0016] Aiming at the technical problem that the existing wake-up circuit has low reliability due to the above-mentioned technical problems, the purpose of the present invention is to provide a low-power wake-up circuit, which can effectively overcome the problems existing in the prior art and greatly improve the reliability of the wake-up circuit.

[0017] To achieve the above object, the present utility model provides a low-power wake-up circuit, which includes a first input circuit, a diode, a triode, and a second input circuit. The first input circuit is externally connected to a switch, the first input circuit is connected to a first power supply, the output end of the first input circuit is connected to the negative electrode of the diode, the positive electrode of the diode is connected to the base of the triode, the emitter of the triode is connected to a second power supply, the collector of the triode outputs to the second input circuit, and the second input circuit is connected to the MCU.

[0018] Further, a first capacitor is connected to the output end of the first input circuit.

[0019] Further, a first resistor is connected in series between the output end of the first input circuit and the first power supply.

[0020] Further, a second resistor is connected in series between the diode and the triode.

[0021] Further, a third resistor is provided between the second power supply and the triode.

[0022] Further, a fourth resistor is connected in series between the collector of the triode and the ground.

[0023] Further, a fifth resistor is connected in series between the collector of the triode and the second input circuit.

[0024] Further, a second capacitor is connected to the input end of the second input circuit.

[0025] The low-power wake-up circuit provided by the present utility model has almost no current consumption in the circuit, further reducing the sleep current of the ECU.

[0026] Secondly, with its constant power supply design, whether the ECU is working normally or in sleep mode, this circuit always has power (VCC12 and VCC5), and there is no need to consider switching these circuits during software design.

[0027] At the same time, due to the existence of the triode and the 5V power supply connected to its emitter, the voltage of the 12V input voltage reaching the MCU IO port can be maintained between 0V and 5V after passing through the designed circuit, and an MCU without voltage clamping ability at the port can be used.

[0028] In addition, due to the constant power supply design, the ECU and the MCU do not need to work in the intermittent mode. When the ECU is in sleep mode, the state of the Switch2_MCU can be changed by operating the state of the input switch. Therefore, the IO port interrupt function of the MCU can be used to collect the wake-up signal, improving the response speed of the ECU. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present utility model will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0030] Figure 1 Schematic diagram of the existing MCU intermittent working mode;

[0031] Figure 2 Schematic diagram of the existing ECU intermittent working mode;

[0032] Figure 3 Schematic diagram of the existing wake-up input circuit;

[0033] Figure 4 Schematic diagram of this low-power wake-up circuit. Detailed implementation mode

[0034] In order to make the technical means, creative features, achieved purposes and effects realized by the present utility model easy to understand, the present utility model will be further described below with reference to specific drawings.

[0035] The low-power wake-up circuit provided by the present utility model is shown in Figure 4 , which includes a first input circuit Switch2, a first capacitor C30, a first power supply VCC12, a diode D200, a triode Q9, a second power supply VCC5, a second capacitor C42 and a second input circuit Switch2_MCU.

[0036] The first input circuit Switch2 is externally connected to a switch. Its input end is externally connected to the switch, and the output end is connected to the negative electrode of the diode D200. The positive output of the diode D200 is connected to the base of the triode Q9. The emitter of the triode Q9 is connected to the second power supply VCC5, the collector is grounded and the amplified output is sent to the second input circuit Switch2_MCU, and the second input circuit Switch2_MCU is connected to the IO port of the MCU.

[0037] Furthermore, a first capacitor C30 is connected in the first input circuit Switch2. The output end of the first capacitor C30 is grounded, and it is used to absorb the static electricity generated by the connector of the PCB board where this circuit is located, preventing static electricity from entering the PCB and causing potential damage to the electronic components on the PCB board.

[0038] Secondly, a first power supply VCC12 is connected in the first input circuit Switch2. The first power supply VCC12 is at a 12V level, and a first resistor R41 is provided between the first power supply VCC12 and the first input circuit Switch2 to protect this power supply circuit.

[0039] A second resistor R46 is connected in series between the diode D200 and the triode Q9 for current limiting and protecting the circuit.

[0040] The second power supply VCC5 is at a 5V level, and a third resistor R56 is provided in the input circuit of the triode Q9 and the second power supply VCC5 to regulate the voltage provided by the second power supply.

[0041] A fourth resistor R58 is connected in series between the collector of the triode Q9 and the ground for current limiting and protecting the circuit. A fifth resistor R59 is provided between the collector output terminal of the triode Q9 and the second input circuit Switch2_MCU for current limiting and protecting the circuit.

[0042] A second capacitor C42 is connected between the fifth resistor R59 and the second input circuit Switch2_MCU, and the output terminal of the second capacitor C42 is grounded. The signal input to the second input circuit Switch2_MCU is filtered through the second capacitor to ensure the stability of the signal.

[0043] For the low-power wake-up circuit composed of the above scheme, the working process in specific applications is illustrated as follows, and the specific working principle is as follows:

[0044] When the switch externally connected to Switch2 is not pressed, Switch2 is connected to the 12V power supply through the first resistor R41 and maintains a 12V level state.

[0045] At this time, the voltage at the base of the triode Q9 is higher than the voltage at the emitter, and the triode Q9 operates in the cut-off state.

[0046] Since the triode Q9 is in the cut-off state, no loop is formed from VCC5 to the ground. At the same time, due to the unidirectional conduction of the diode D200, no loop is formed from VCC12 to the ground either. Similarly, due to the existence of the diode D200, no loop is formed between VCC12 and VCC5.

[0047] Therefore, when the switch externally connected to Switch2 is not pressed, the entire circuit consumes almost no current. At this time, the level collected by Switch2_MCU from the MCU is a low level.

[0048] When the switch externally connected to Switch2 is pressed, Switch2 is grounded and becomes a low level, and the triode Q9 operates in the saturation state.

[0049] At this time, the level collected by Switch2_MCU is a 5V high level, which is close to the power supply voltage of the MCU. Therefore, it can be used as a switch input circuit, and this circuit design meets the functional requirements.

[0050] Since the emitter of the triode Q9 is connected to the 5V power supply, when the first input circuit Switch2 inputs a 12V voltage, the voltage reaching the MCU IO port after passing through the triode Q9 remains between 0V and 5V, and an MCU without voltage clamping ability at the port can be used.

[0051] For the low-power wake-up circuit provided by the above solution, in its main power supply design, whether the ECU is working normally or in sleep mode, this circuit always has the main power supply (VCC12 and VCC5). When designing the software, there is no need to consider switching these circuits.

[0052] Secondly, due to the main power supply design, the ECU and the MCU do not need to work in the intermittent mode. When the ECU is in sleep mode, the state of the operating input switch can be used to change the state of Switch2_MCU. Therefore, the IO port interrupt function of the MCU can be used to collect the wake-up signal, which improves the response speed of the ECU.

[0053] Finally, the circuit has almost no current consumption, which further reduces the sleep current of the ECU.

[0054] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A low power consumption wake-up circuit, characterized in that: It includes a first input circuit, a diode, a transistor, and a second input circuit. The first input circuit is externally connected to a switch, the first input circuit is connected to a first power supply, the output end of the first input circuit is connected to the cathode of the diode, the anode of the diode is connected to the base of the transistor, the emitter of the transistor is connected to the second power supply, the collector of the transistor is output to the second input circuit, and the second input circuit is connected to an MCU.

2. A low power consumption wake-up circuit according to claim 1, characterized in that: The output end of the first input circuit is connected to a first capacitor.

3. A low power consumption wake-up circuit according to claim 1, characterized in that: A first resistor is connected in series between the output end of the first input circuit and the first power supply.

4. The low power consumption wake-up circuit according to claim 1, characterized in that: A second resistor is connected in series between the diode and the triode.

5. A low power consumption wake-up circuit according to claim 1, characterized in that: A third resistor is provided between the second power supply and the transistor.

6. A low power consumption wake-up circuit according to claim 1, characterized in that: A fourth resistor is connected in series between the transistor collector and the ground.

7. The low power consumption wake-up circuit according to claim 1, characterized in that: A fifth resistor is connected in series between the transistor collector and the second input circuit.

8. The low power consumption wake-up circuit according to claim 1, characterized in that: The input terminal of the second input circuit is connected to a second capacitor.

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