A multi-channel differential input low-power MCU wake-up circuit

Abstract

This invention provides a multi-channel differential input low-power MCU wake-up circuit, including an MCU control unit and a multi-channel differential wake-up communication circuit. Each differential wake-up communication circuit includes a main signal line RS485A and RS485B, an optocoupler U1, and a WKUP signal line. The main signal lines RS485A and RS485B are respectively connected to the common communication port of the MCU control unit, and the main signal lines RS485A and RS485B are connected to the input terminal of the optocoupler U1. The operation of the optocoupler U1 is controlled by the main signal line RS485B being at a high or low level. When the bus is idle, the optocoupler does not operate. If the control unit has entered a low-power sleep mode, the control unit will not be woken up when idle. When there is data communication on the RS485 bus, the optocoupler will operate, and the WKUP signal line will be at a high level, thereby waking up the MCU.

Description

Technical Field

[0001] This utility model relates to the field of low-power circuit technology, specifically to a multi-channel differential input low-power MCU wake-up circuit. Background Technology

[0002] In many mobile products and battery-powered products, battery management is often very important, especially power loss management, which is why various low-power circuits are seen in circuit design.

[0003] Taking a multi-source system as an example, the MCU (Microcontroller Unit) consumes tens of milliamps of current during normal operation and several milliamps even when idle. Combined with the power supply from several differential chips, the total circuit consumes over ten milliamps of current when idle, which is a significant drain on a battery-powered system. Therefore, a switching device is needed to ensure that both the communication and control circuits enter a low-power mode in idle mode. Since the control system is located in a confined space, there is no additional wake-up device, and only one external communication port. Thus, providing a circuit structure that can both communicate normally and wake up in low-power mode is particularly important. Utility Model Content

[0004] In view of the deficiencies in the existing technology, the purpose of this utility model is to provide a multi-channel differential input low-power MCU wake-up circuit that can both communicate normally and wake up in low-power mode.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0006] This application provides a multi-channel differential input low-power MCU wake-up circuit, including an MCU control unit and a multi-channel differential wake-up communication circuit. Each differential wake-up communication circuit includes a main signal line RS485A and RS485B, an optocoupler U1, and a WKUP signal line. The main signal lines RS485A and RS485B are respectively connected to the common communication port of the MCU control unit. The main signal lines RS485A and RS485B are connected to the input terminal of the optocoupler U1. One end of the WKUP signal line is connected to the output terminal of the optocoupler U1, and the other end of the WKUP signal line is connected to the MCU control unit.

[0007] Furthermore, each differential wake-up communication circuit also includes a diode D1, the output terminal of the optocoupler U1 is connected to the positive terminal of the diode D1, and the negative terminal of the diode D1 is connected to one end of the WKUP signal line.

[0008] Furthermore, the input terminal of the optocoupler U1 is connected in series with resistors R7 and R9.

[0009] Furthermore, a capacitor C29 and a resistor R19 are connected in parallel to one end of the positive terminal of the diode D1.

[0010] The beneficial effects of this utility model are as follows:

[0011] By employing the aforementioned multi-channel differential input low-power MCU wake-up circuit, the operation of optocoupler U1 is controlled by whether the main signal line RS485B is high or low. When the bus is idle, the optocoupler does not operate. If the control unit has already entered low-power sleep mode, the control unit will not be woken up during idle periods. When there is data communication on the RS485 bus, the optocoupler will operate, and the WKUP signal line will go high, thus waking up the MCU. Once the MCU is woken up, it turns on the power supply to the communication chip, and data transmission and reception begin, thus completing the wake-up of the control unit during communication. When idle, it enters low-power mode. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the circuit principle of the multi-channel differential input low-power MCU wake-up circuit in the embodiments of this application.

[0013] Figure 2 This is a schematic diagram of the differential wake-up communication circuit in the embodiments of this application. Detailed Implementation

[0014] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0015] See appendix Figure 1 As shown, this embodiment provides a multi-channel differential input low-power MCU wake-up circuit, including an MCU control unit and a multi-channel differential wake-up communication circuit, such as a four-channel differential wake-up communication circuit. Each of the multi-channel differential wake-up communication circuits is connected to a common communication port of the MCU control unit. The structures of the multi-channel differential wake-up communication circuits are all the same; only one of the differential wake-up communication circuits will be described below.

[0016] See attached document Figure 2 As shown, specifically, each differential wake-up communication circuit includes main signal lines RS485A and RS485B, optocoupler U1, and WKUP signal line. The multiple main signal lines RS485A and RS485B are connected to the common communication port of the MCU control unit, the main signal lines RS485A and RS485B are connected to the input terminal of optocoupler U1, one end of the WKUP signal line is connected to the output terminal of optocoupler U1, and the other end of the WKUP signal line is connected to the MCU control unit.

[0017] When idle, RS485 bus signal lines RS485A are at a high level and RS485B is at a low level. Optocoupler U1 does not operate when the bus is idle. If the MCU control unit has already entered low-power sleep mode, the MCU control unit will not be woken up when idle.

[0018] When there is data communication on the RS485 bus, RS485B will be at a high level and RS485A will be at a low level. At this time, the optocoupler will activate. After the optocoupler U1 is activated, the WKUP signal line will be at a high level, thereby waking up the MCU control unit. After the MCU control unit is woken up, the power supply system of the communication chip is turned on, and data transmission and reception begin. This completes the communication wake-up of the control unit. When idle, it enters a low-power mode.

[0019] See attached document Figure 2 As shown, each differential wake-up communication circuit also includes a diode D1. The output terminal of the optocoupler U1 is connected to the positive terminal of the diode D1, and the negative terminal of the diode D1 is connected to one end of the WKUP signal line.

[0020] Continue to refer to the appendix Figure 2 As shown, resistors R7 and R9 are connected in series at the input terminal of optocoupler U1. By connecting resistors R7 and R9 in series, the light-emitting diode in optocoupler U1 can be protected from overcurrent damage.

[0021] In addition, a capacitor C29 and a resistor R19 are connected in parallel at the positive terminal of diode D1. The capacitor C29 and the resistor R19 form a buffer circuit to protect the diode D1 from damage caused by harmful voltage spikes, high-speed voltage changes and high-frequency oscillations during the switching process.

[0022] Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this utility model and their equivalents, this utility model also intends to include these modifications and variations.

Claims

1. A multi-channel differential input low-power MCU wake-up circuit, characterized in that, The device includes an MCU control unit and multiple differential wake-up communication circuits. Each differential wake-up communication circuit includes a main signal line RS485A and RS485B, an optocoupler U1, and a WKUP signal line. The main signal lines RS485A and RS485B are connected to the common communication port of the MCU control unit. The main signal lines RS485A and RS485B are connected to the input terminal of the optocoupler U1. One end of the WKUP signal line is connected to the output terminal of the optocoupler U1, and the other end of the WKUP signal line is connected to the MCU control unit.

2. The multi-channel differential input low-power MCU wake-up circuit according to claim 1, characterized in that, Each differential wake-up communication circuit also includes a diode D1. The output terminal of the optocoupler U1 is connected to the positive terminal of the diode D1, and the negative terminal of the diode D1 is connected to one end of the WKUP signal line.

3. A multi-channel differential input low-power MCU wake-up circuit according to claim 1 or 2, characterized in that, The input terminal of the optocoupler U1 is also connected in series with resistors R7 and R9.

4. The multi-channel differential input low-power MCU wake-up circuit according to claim 2, characterized in that, A capacitor C29 and a resistor R19 are connected in parallel to one end of the positive terminal of the diode D1.

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