Serial port enabling power supply structure

Abstract

The utility model discloses a serial port enabling power supply structure, which comprises an MCU (Microprogrammed Control Unit) processor, a functional device, an external power supply and a power switch circuit, the TXD pin of the MCU processor is connected with the RXD pin of the functional device, and the RXD pin of the MCU processor is connected with the TXD pin of the functional device; the control end of the power switch circuit is connected with a TXD pin of the MCU processor, the input end of the power switch circuit is connected with the power output end of the external power supply, and the output end of the power switch circuit is connected with a VCC pin of the functional device. According to the utility model, whether the external power supply supplies power to the functional device or not can be controlled through the TXD pin of the MCU processor, so that the requirement on the IO port of the MCU processor is reduced.

Description

Technical Field

[0001] The utility model relates to a serial port enabling power supply structure. Background Art

[0002] Among existing communication methods between different devices, serial ports have become the preferred method due to their simplicity and ubiquity. Many MCU processors and functional devices use serial ports for communication. In power-sensitive applications such as battery-powered devices, the MCU processor enters sleep mode when idle, shutting down the serial port module and peripheral power to reduce power consumption. However, small or low-cost MCUs have limited I / O ports and often lack an I / O port for controlling peripheral power supply to functional devices.

[0003] In view of the existence of the above problems, it is necessary to study a serial port enabled power supply structure, which can control whether the peripheral power supply supplies power to the functional device through the TXD pin of the MCU processor. Utility Model Content

[0004] The purpose of the utility model is to provide a serial port enabled power supply structure, which can control whether the peripheral power supply supplies power to the functional device through the TXD pin of the MCU processor.

[0005] In order to achieve the above objectives, the solution of the present invention is:

[0006] A serial port enabled power supply structure includes an MCU processor, a functional device, an external power supply, and a power switch circuit; the TXD pin of the MCU processor is connected to the RXD pin of the functional device, and the RXD pin of the MCU processor is connected to the TXD pin of the functional device; the control end of the power switch circuit is connected to the TXD pin of the MCU processor, the input end of the power switch circuit is connected to the power output end of the external power supply, and the output end of the power switch circuit is connected to the VCC pin of the functional device; the power switch circuit includes a resistor R1, a resistor R2, a capacitor C1, a diode D1, a PMO S transistor M1 and NMOS transistor M2; the anode of diode D1 is connected to the control end of the power switch circuit, the cathode of diode D1 is connected to the first end of capacitor C1, the first end of resistor R2 and the gate of NMOS transistor M2, the second end of capacitor C1, the second end of resistor R2 and the source of NMOS transistor M2 are grounded, the drain of NMOS transistor M2 is connected to the gate of PMOS transistor M1 and the first end of resistor R1, the source of PMOS transistor M1 and the second end of resistor R1 are connected to the input end of the power switch circuit, and the drain of PMOS transistor M1 is connected to the output end of the power switch circuit.

[0007] The power switch circuit also includes a resistor R3. The cathode of the diode D1 is connected to the first end of the capacitor C1, the first end of the resistor R2, and the gate of the NMOS transistor M2 through the resistor R3. The first end of the resistor R3 is connected to the cathode of the diode D1. The second end of the resistor R3 is connected to the first end of the capacitor C1, the first end of the resistor R2, and the gate of the NMOS transistor M2.

[0008] After adopting the above scheme, the working principle of the utility model is:

[0009] According to the communication specification of the serial port, when there is no data transmission, the level of the TXD pin of the MCU processor is high; while during the data transmission process, the level of the TXD pin of the MCU processor is high or low; when the data transmission is completed, the level of the TXD pin of the MCU processor turns high;

[0010] When the serial port module of the MCU processor is turned off, the TXD pin of the MCU processor outputs a low level. At this time, the gate of the NMOS transistor M2 cannot obtain voltage and the NMOS transistor M2 is in the cut-off state, which makes the gate voltage of the PMOS transistor M1 equal to the output voltage of the peripheral power supply. At this time, the PMOS transistor M1 is also in the cut-off state, so that the power switch circuit is in the off state, and the peripheral power supply does not supply power to the VCC pin of the functional device;

[0011] When the serial port module of the MCU processor is enabled and the MCU processor does not send data, the TXD pin of the MCU processor outputs a high level. The high level output by the TXD pin of the MCU processor charges the capacitor C1 through the diode D1 (charging time is about 1ms). After the charging of the capacitor C1 is completed, the gate level of the NMOS tube M2 changes from a low level to a high level, making the NMOS tube M2 turned on and pulling the gate level of the PMOS tube M1 down to a low level, thereby making the PMOS tube M1 turned on. In this way, the power switch circuit is in the on state, and the peripheral power supply supplies power to the VCC pin of the functional device;

[0012] When the serial port module of the MCU processor is enabled and the MCU processor is sending data, if the TXD pin of the MCU processor outputs a low level (i.e., sending data 0), diode D1 is turned off. At this time, capacitor C1 needs to discharge through resistor R2 for a period of time (the discharge time is approximately 100ms) before NMOS transistor M2 is turned off, and then PMOS transistor M1 is turned off, so that the peripheral power supply does not supply power to the VCC pin of the functional device. However, since the MCU processor pulls the level of the TXD pin of the MCU processor to a high level after completing the transmission of each byte of data, capacitor C1 is quickly charged through diode D1. Based on the foregoing, it can be seen that during the period when the MCU processor sends data, due to the fast charging and slow discharging characteristics of capacitor C1, the gate level of NMOS transistor M2 will not drop to a low level, thereby keeping NMOS transistor M2 in the on state, and thus keeping PMOS transistor M1 in the on state, thereby ensuring that the peripheral power supply continuously supplies power to the VCC pin of the functional device, allowing the MCU processor and the peripheral power supply to communicate normally.

[0013] When the serial port module of the MCU processor switches from the enabled state to the disabled state, the TXD pin of the MCU processor outputs a low level, turning off the diode D1. At this time, the capacitor C1 needs to discharge through the resistor R2 for a period of time (the discharge time is about 100ms) to turn off the NMOS tube M2, and then turn off the PMOS tube M1, so that the peripheral power supply automatically delays for a period of time before stopping powering the VCC pin of the functional device.

[0014] In summary, the present invention can control whether the peripheral power supply supplies power to the functional device through the TXD pin of the MCU processor, thereby reducing the demand for the IO port of the MCU processor; in particular, the present invention can automatically enable the peripheral power supply to supply power to the functional device when the serial port module of the MCU processor is enabled; and when the serial port module of the MCU processor is converted from an enabled state to a disabled state, the present invention can automatically delay the disconnection for a period of time before disconnecting the peripheral power supply to the functional device, thereby ensuring that the functional device is shut down normally. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a circuit diagram of the utility model. DETAILED DESCRIPTION

[0016] In order to further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0017] like Figure 1As shown, the utility model discloses a serial port enabled power supply structure, which includes an MCU processor, a functional device, an external power supply, and a power switch circuit; the TXD pin of the MCU processor is connected to the RXD pin of the functional device, and the RXD pin of the MCU processor is connected to the TXD pin of the functional device; the control end of the power switch circuit is connected to the TXD pin of the MCU processor, the input end of the power switch circuit is connected to the power output end of the external power supply, and the output end of the power switch circuit is connected to the VCC pin of the functional device; the power switch circuit includes a resistor R1, a resistor R2, a capacitor C1, and a diode D 1. PMOS transistor M1 and NMOS transistor M2; the anode of diode D1 is connected to the control end of the power switch circuit, the cathode of diode D1 is connected to the first end of capacitor C1, the first end of resistor R2, and the gate of NMOS transistor M2, the second end of capacitor C1, the second end of resistor R2, and the source of NMOS transistor M2 are grounded, the drain of NMOS transistor M2 is connected to the gate of PMOS transistor M1 and the first end of resistor R1, the source of PMOS transistor M1 and the second end of resistor R1 are connected to the input end of the power switch circuit, and the drain of PMOS transistor M1 is connected to the output end of the power switch circuit.

[0018] The working principle of this utility model is:

[0019] According to the communication specification of the serial port, when there is no data transmission, the level of the TXD pin of the MCU processor is high; while during the data transmission process, the level of the TXD pin of the MCU processor is high or low; when the data transmission is completed, the level of the TXD pin of the MCU processor turns high;

[0020] When the serial port module of the MCU processor is turned off, the TXD pin of the MCU processor outputs a low level. At this time, the gate of the NMOS transistor M2 cannot obtain voltage and the NMOS transistor M2 is in the cut-off state, which makes the gate voltage of the PMOS transistor M1 equal to the output voltage of the peripheral power supply. At this time, the PMOS transistor M1 is also in the cut-off state, so that the power switch circuit is in the off state, and the peripheral power supply does not supply power to the VCC pin of the functional device;

[0021] When the serial port module of the MCU processor is enabled and the MCU processor does not send data, the TXD pin of the MCU processor outputs a high level. The high level output by the TXD pin of the MCU processor charges the capacitor C1 through the diode D1 (charging time is about 1ms). After the charging of the capacitor C1 is completed, the gate level of the NMOS tube M2 changes from a low level to a high level, making the NMOS tube M2 turned on and pulling the gate level of the PMOS tube M1 down to a low level, thereby making the PMOS tube M1 turned on. In this way, the power switch circuit is in the on state, and the peripheral power supply supplies power to the VCC pin of the functional device;

[0022] When the serial port module of the MCU processor is enabled and the MCU processor is sending data, if the TXD pin of the MCU processor outputs a low level (i.e., sending data 0), diode D1 is turned off. At this time, capacitor C1 needs to discharge through resistor R2 for a period of time (the discharge time is approximately 100ms) before NMOS transistor M2 is turned off, and then PMOS transistor M1 is turned off, so that the peripheral power supply does not supply power to the VCC pin of the functional device. However, since the MCU processor pulls the level of the TXD pin of the MCU processor to a high level after completing the transmission of each byte of data, capacitor C1 is quickly charged through diode D1. Based on the foregoing, it can be seen that during the period when the MCU processor sends data, due to the fast charging and slow discharging characteristics of capacitor C1, the gate level of NMOS transistor M2 will not drop to a low level, thereby keeping NMOS transistor M2 in the on state, and thus keeping PMOS transistor M1 in the on state, thereby ensuring that the peripheral power supply continuously supplies power to the VCC pin of the functional device, allowing the MCU processor and the peripheral power supply to communicate normally.

[0023] When the serial port module of the MCU processor switches from the enabled state to the disabled state, the TXD pin of the MCU processor outputs a low level, turning off the diode D1. At this time, the capacitor C1 needs to discharge through the resistor R2 for a period of time (the discharge time is about 100ms) to turn off the NMOS tube M2, and then turn off the PMOS tube M1, so that the peripheral power supply automatically delays for a period of time before stopping powering the VCC pin of the functional device.

[0024] In summary, the present invention can control whether the peripheral power supply supplies power to the functional device through the TXD pin of the MCU processor, thereby reducing the demand for the IO port of the MCU processor; in particular, the present invention can automatically enable the peripheral power supply to supply power to the functional device when the serial port module of the MCU processor is enabled; and when the serial port module of the MCU processor is converted from an enabled state to a disabled state, the present invention can automatically delay the disconnection for a period of time before disconnecting the peripheral power supply to the functional device, thereby ensuring that the functional device is shut down normally.

[0025] In an embodiment of the present utility model, the power switch circuit further includes a resistor R3. The cathode of the diode D1 is connected to the first end of the capacitor C1, the first end of the resistor R2, and the gate of the NMOS transistor M2 through the resistor R3. The first end of the resistor R3 is connected to the cathode of the diode D1. The second end of the resistor R3 is connected to the first end of the capacitor C1, the first end of the resistor R2, and the gate of the NMOS transistor M2. The resistor R3 can play a role in current limiting protection.

[0026] In an embodiment of the present invention, the resistance value of the resistor R2 may be 10KΩ, the resistance value of the resistor R3 may be 220KΩ, the resistance value of the resistor R3 may be 1KΩ, and the capacitance value of the capacitor C1 may be 1uF.

[0027] The above embodiments and drawings do not limit the product form and style of the present invention. Any appropriate changes or modifications made by ordinary technicians in the relevant technical field should be deemed to be within the patent scope of the present invention.

Claims

1. A serial port enabled power supply structure, characterized in that: Includes MCU processor, functional device, peripheral power supply, and power switch circuit; The TXD pin of the MCU processor is connected to the RXD pin of the functional device, and the RXD pin of the MCU processor is connected to the TXD pin of the functional device; the control end of the power switch circuit is connected to the TXD pin of the MCU processor, the input end of the power switch circuit is connected to the power output end of the peripheral power supply, and the output end of the power switch circuit is connected to the VCC pin of the functional device; The power switch circuit includes a resistor R1, a resistor R2, a capacitor C1, a diode D1, a PMOS transistor M1, and an NMOS transistor M2; the anode of the diode D1 is connected to the control terminal of the power switch circuit, the cathode of the diode D1 is connected to the first terminal of the capacitor C1, the first terminal of the resistor R2, and the gate of the NMOS transistor M2, the second terminal of the capacitor C1, the second terminal of the resistor R2, and the source of the NMOS transistor M2 are grounded, the drain of the NMOS transistor M2 is connected to the gate of the PMOS transistor M1 and the first terminal of the resistor R1, the source of the PMOS transistor M1 and the second terminal of the resistor R1 are connected to the input terminal of the power switch circuit, and the drain of the PMOS transistor M1 is connected to the output terminal of the power switch circuit.

2. The serial port enabled power supply structure according to claim 1, wherein: The power switch circuit also includes a resistor R3. The cathode of the diode D1 is connected to the first end of the capacitor C1, the first end of the resistor R2, and the gate of the NMOS transistor M2 through the resistor R3. The first end of the resistor R3 is connected to the cathode of the diode D1. The second end of the resistor R3 is connected to the first end of the capacitor C1, the first end of the resistor R2, and the gate of the NMOS transistor M2.

Images