CN109388601B

CN109388601B - Control method of OTG power supply and charging automatic switching module

Info

Publication number: CN109388601B
Application number: CN201710680475.3A
Authority: CN
Inventors: 杨文朗
Original assignee: Chengdu Shengcheng Tongyou Technology Co ltd
Current assignee: Chengdu Shengcheng Tongyou Technology Co ltd
Priority date: 2017-08-10
Filing date: 2017-08-10
Publication date: 2023-07-18
Anticipated expiration: 2037-08-10
Also published as: CN109388601A

Abstract

The invention discloses a control method of an OTG power supply and charging automatic switching module, which comprises a CMOS chip, a first interface for connecting Host equipment with an OTG function, a second interface for connecting a charger, and a third interface for connecting external equipment requiring OTG power supply; the CMOS chip comprises an E port, a Y port and a Z port, wherein the E port is electrically connected with the second interface, the Z port is grounded, and the Y port is electrically connected with the first interface. In the use process of the external equipment, the invention does not need a manual switch, and can ensure that the equipment supporting the OTG function can automatically switch the OTG power supply mode and the charging mode; the OTG equipment can be charged under the uninterrupted use state of the external equipment; meanwhile, the CMOS chip is used as a core device to automatically identify and control the switching of the OTG and the charging mode, so that the device is small in size, low in cost, almost negligible in power consumption, long in service life, high in cost performance, easy to integrate and beneficial to mass production.

Description

Control method of OTG power supply and charging automatic switching module

Technical Field

The invention relates to an OTG power supply and charging automatic switching module and a control method thereof, which are mainly used for OTG data/charging wires, OTG external equipment and the like.

Background

The development of USB technology has enabled PCs and peripheral devices to connect together devices of various data transmission speeds in a simple manner at moderate manufacturing costs. Is connected to the PC through the USB and exchanges data under the control of the PC. However, this convenient exchange method cannot be operated by the USB port between devices once leaving the PC, because none of the slave devices can act as a host for the PC.

OTG is an abbreviation of On-The-Go, a technology developed in recent years, and is mainly applied to The connection between various devices or mobile devices for data exchange. Such as Pad, cell phone, tablet, digital camera, video camera, printer, etc. OTG technology is to implement data transfer between devices without a PC. For example, a digital camera is directly connected to a printer, and is connected with a USB port between two devices through an OTG technology, so that a photographed photo is immediately printed; the data in the digital camera can be sent to the mobile hard disk of the USB interface through the OTG, so that the field operation does not need to carry an expensive memory card or carry a portable computer. USB devices are classified into HOST (master) and SLAVE, and data transfer can only be achieved when one HOST is connected to one SLAVE, and OTG devices are "EX" which can serve as both HOST and SLAVE. The conventional relay and manual switch are generally adopted by the conventional OTG equipment to perform normal work or switch the power supply mode, but in the actual use process, the manual switch is troublesome to operate, the relay needs to be matched with an MCU device and write a complex MCU control program, the cost is high, the equipment size is large, the power consumption is high, and the cost performance is low.

In the traditional scheme, the on-off relation between the S pin and the G pin is controlled by using a manual switch, so that the traditional scheme is inconvenient. In the process of manually controlling the switch, whether the OTG equipment is charged in an attempt and coordinated manner with the outside cannot be guaranteed, switching cannot be normally realized, system conflict can be caused, and even the normal working state can be recovered after the system is restarted. The patent scheme of simply using the relay has errors, can not ensure that the relay always works normally in the process of converting from charging to OTG state, has huge relay volume, limited use times and large power consumption, and can not be realized in products with high cost performance. The solution requiring an MCU must be self-powered to ensure that the MCU is always powered. And MCU is with high costs, programming is complicated, and in addition from electrified, bulky, be difficult to commercialize on a large scale.

For example, chinese patent 200810108684.1 discloses a data transmission device, a control circuit chip and a method for controlling working mode, which adopts a relay as an on-off switch and is designed by a circuit according to whether an external charging power supply exists or not

According to the on-off condition of the automatic switching relay. Firstly, the problem of circuit design of the patent cannot well realize the function of automatic switching; secondly, the relay itself has a number of drawbacks: the device has the advantages of large volume, large power consumption, poor reliability, easy damage and short service life, and cannot be truly applied to products with small volume and high cost performance.

As another example, the chinese patent with patent number 201410576624.8 discloses a method and apparatus for bidirectional balancing of electric power based on USB-OTG, which considers that the discrimination between OTG and non-OTG is based on the level of ID, and the system automatically determines the level of ID to determine whether to be in OTG state or charging state. But according to the working principle of OTG, the system should determine whether to be in OTG state or charged state by determining the resistance value between the ID pin and the ground pin (GND). Some designs on the market can not stably control the resistance value, so that the OTG/charging state of the product is unstable to switch, and once the system conflict occurs, the normal operation can be recovered even by restarting. Or may be different for some handsets than others.

Chinese patent No. 201310396425.4 discloses a USB OTG device, an electronic device and a method for implementing OTG function, which can determine the status of an external device through an MCU, but does not describe the next processing or make the application unclear.

Disclosure of Invention

The technical problem to be solved by the invention is to overcome the defects in the prior art, and provide an OTG power supply and charging automatic switching module with reasonable design and a control method thereof.

The technical scheme adopted by the invention for solving the technical problems is as follows: an OTG power supply, automatic switch-over module that charges, its characterized in that: the device comprises a CMOS chip, a first interface for connecting Host equipment with OTG function, a second interface for connecting charger, and a third interface for connecting external equipment requiring OTG power supply; the CMOS chip comprises an E port, a Y port and a Z port, wherein the E port is electrically connected with the second interface, the Z port is grounded, and the Y port is electrically connected with the first interface. The first interface is connected to a USB interface of Host equipment with OTG (on-the-go) function, such as a mobile phone, a tablet computer and the like; the second interface is connected to a USB interface of the charger; the third interface is used for connecting any external device which needs OTG power supply, such as a mobile hard disk, a printer and the like. The CMOS chip is a switch. The E port is the control of this switch and the Y and Z ports are the two ports of the switch. That is, pulling the E port up is equivalent to opening the switch, so the Y and Z ports are open, and pulling the E port down is equivalent to closing the switch, so the Y and Z ports are open. When the second interface is connected with the charger, the first interface is connected to a USB interface of equipment supporting the OTG function, an E port of an enabling end of the CMOS chip is pulled up, the CMOS chip is automatically disconnected, an open circuit is formed between a Y port and a Z port, the equipment connected with the first interface stops supplying power to the outside, and data transmission is carried out with external equipment through the first interface, the third interface. At the moment, the external equipment takes electricity from the charger through the second interface and the third interface; and simultaneously, the charger charges a host connected with the first interface. When the connection between the second interface and the charger is disconnected, the enabling end E port of the CMOS chip is pulled down, and the CMOS chip automatically

And closing, namely shorting the Y port and the Z port, enabling the equipment connected with the first interface to automatically enter an OTG power supply state, and supplying power to external equipment and carrying out data transmission through the first interface and the third interface.

The CMOS chip is used as a core device to automatically identify and control the switching of the OTG and the charging mode, the size is small, the cost is low, the power consumption is almost negligible, the service life is long, the cost performance is high, the integration is easy, and the large-scale production is facilitated. The manual operation is not needed, and an MCU device is not needed to be added and a complex MCU control program is not needed to be written.

The three interfaces of the invention comprise four pins V (vcc), D+ (data+), D- (data-), G (gnd), and the same pins are electrically connected with each other, wherein the interface I (J1) is also provided with a pin S (Sense).

The first interface and the third interface transmit data through D+ and D-pins and supply power through V pins; the power supply is carried out between the second interface and the third interface through a V pin. The Y port of the CMOS chip is electrically connected with the S pin and used for controlling the on-off between the S pin and the G pin in the first-number interface. The intelligent equipment supporting OTG external power supply such as a mobile phone determines whether to externally supply power or not by judging the on-off state between S and G pins at the USB interface of the intelligent equipment. And if S and G are conducted, power supply is started, and if S and G are disconnected, power supply is stopped.

The CMOS chip is connected with a capacitor, one end of the capacitor is grounded, and the other end of the capacitor is electrically connected with a V pin of the first interface. The capacitor is used for supplying power to the CMOS chip in a short time (the time between the external charging and the OTG power supply), so that the CMOS chip can continue to normally work in the time when the external power supply and the OTG power supply are not available.

The circuit connected between the first interface V pin and the second interface V pin is provided with a diode. The E port used for limiting the current direction can not flow from the OTG Host device to the CMOS chip, so that the current direction is limited, and the E port can not be pulled up by mistake due to OTG power supply.

The invention also provides a control method of the OTG power supply and charging automatic switching module, which is characterized in that: the control steps are as follows:

(1) When the module is used for the first time, the first interface (J1) is connected to a host with an OTG function, and the OTG power supply state is not entered at the moment;

(2) Connecting a charger to the second interface (J2), and charging the capacitor (C1), so that the CMOS chip (U1) enters a normal working state; at the moment, an enabling end E port of the CMOS chip (U1) is pulled up, the CMOS chip (U1) is automatically disconnected, and an open circuit is formed between a Y port and a Z port;

(3) Pulling out the charger, and pulling down an enabling end E of the CMOS chip (U1), wherein the CMOS chip (U1) is powered by the capacitor (C1) in a short time to keep normal switching to a closed state, and the Y port and the Z port are closed; at the moment, the host enters an OTG power supply state, and the power supply is started to the CMOS chip (U1) and the external equipment on the third interface (J3) is also powered; at this time, due to the function of the diode (D1) for limiting the current direction, the OTG power supply provided by the first interface (J1) cannot be erroneously operated to pull the enabling end E port of the CMOS chip (U1) high, so that the CMOS chip (U1) can be kept in a closed state, and the first interface (J1) is further ensured to be in an OTG power supply state;

(4) As long as the first interface (J1) is not disconnected, the CMOS chip (U1) can normally and automatically switch between the OTG power supply mode and the charging data mode according to whether the second interface (J2) is connected to the charger; if the second interface (J2) is connected with the charger, the enabling end E port of the CMOS chip (U1) is pulled up, the CMOS chip (U1) is automatically disconnected, an open circuit is formed between the Y port and the Z port, the host equipment connected with the first interface (J1) stops supplying power to the outside, and the host still performs data transmission with the external equipment through the first interface (J1) and the third interface (J3); at the moment, the external equipment takes electricity from the charger through a second interface (J2) and a third interface (J3); meanwhile, the charger charges a host connected with the first interface (J1); if the connection between the second interface (J2) and the charger is disconnected, an enabling end E port of the CMOS chip (U1) is pulled down, the CMOS chip (U1) is automatically closed, the Y port and the Z port are in short circuit, host equipment connected with the first interface (J1) automatically enters an OTG power supply state, and the host supplies power to external equipment through the first interface (J1) and the third interface (J3) and performs data transmission;

(5) If the first interface (J1) is disconnected or the first interface (J1) is completely powered off, the steps (1) - (3) above need to be repeated when the next time the connection is performed again.

Compared with the prior art, the invention has the following obvious effects: in the using process of the external equipment, the module of the invention does not need a manual switch, so that the equipment supporting the OTG function can automatically switch the OTG power supply mode and the charging mode; the OTG equipment can be charged under the uninterrupted use state of the external equipment; the module can be widely used in OTG data/charging wires, OTG external equipment and the like; meanwhile, the CMOS chip is used as a core device to automatically identify and control the switching of the OTG and the charging mode, so that the device is small in size, low in cost, almost negligible in power consumption, long in service life, high in cost performance, easy to integrate and beneficial to large-scale production; the manual operation is not needed, and an MCU device is not needed to be added and a complex MCU control program is not needed to be written.

Drawings

Fig. 1 is a circuit diagram of the present invention.

Detailed Description

The invention is further illustrated by way of example with reference to the accompanying drawings.

Examples: referring to fig. 1, the present embodiment includes a CMOS chip U1, an interface J1 for connecting a Host device with OTG function, an interface J2 for connecting a charger, and an interface J3 for connecting an external device requiring OTG power supply. The first interface J1 is connected to a USB interface of Host equipment with an OTG function, such as a mobile phone, a tablet computer and the like; the second interface J2 is connected to a USB interface of the charger; the third interface J3 is used for connecting any external device requiring OTG power supply, such as a mobile hard disk, a printer, and the like.

The three interfaces comprise four pins V (vcc), D+ (data+), D- (data-), G (gnd), and the same pins are electrically connected with each other, wherein the first interface J1 (J1) is also provided with a pin S (Sense).

Data are transmitted between the first interface J1 and the third interface J3 through the D+ pin and the D-pin, and power is supplied through the V pin; the power supply between the second interface J2 and the third interface J3 is realized through a V pin.

The CMOS chip U1 comprises an E port, a Y port and a Z port, wherein the E port is electrically connected with the second interface J2, the Z port is grounded, and the Y port is electrically connected with the first interface J1.

The Y port of the CMOS chip U1 is electrically connected with the S pin and used for controlling the on-off between the S pin and the G pin in the first-number interface J1. The intelligent equipment supporting OTG external power supply such as a mobile phone determines whether to externally supply power or not by judging the on-off state between S and G pins at the USB interface of the intelligent equipment. And if S and G are conducted, power supply is started, and if S and G are disconnected, power supply is stopped.

The CMOS chip U1 is used as a core device to automatically identify and control the switching of the OTG and the charging mode, and the device is small in size, low in cost, almost negligible in power consumption, long in service life, high in cost performance, easy to integrate and beneficial to mass production. The manual operation is not needed, and an MCU device is not needed to be added and a complex MCU control program is not needed to be written.

In this embodiment, a capacitor C1 is connected to the CMOS chip U1, one end of the capacitor C1 is grounded, and the other end is electrically connected to the V pin of the first interface J1. The capacitor C1 is used for supplying power to the CMOS chip U1 in a short time (the time between the conversion from external charging to OTG power supply), so as to ensure that the CMOS chip U1 can continue to operate normally in the time when no external power supply is available and no OTG power supply is available.

In this embodiment, a diode D1 is disposed in a circuit between the V pin of the first interface J1 and the V pin of the second interface J2. The device is used for limiting the current direction to flow from the OTG Host device to the E port of the CMOS chip U1, so that the current direction is limited, and the E port cannot be pulled up by mistake due to OTG power supply.

The control steps of this embodiment are as follows:

(1) When the module is used for the first time, the first interface J1 (J1) is connected to a host with an OTG function, and the OTG power supply state is not entered at the moment;

(2) Connecting a charger to the second interface J2 (J2), and charging the capacitor C1 (C1), so that the CMOS chip U1 (U1) enters a normal working state; at this time, the enabling end E port of the CMOS chip U1 (U1) is pulled up, the CMOS chip U1 (U1) is automatically disconnected, and an open circuit is formed between the Y port and the Z port;

(3) Pulling out the charger, and pulling down the enabling end E of the CMOS chip U1 (U1), wherein the CMOS chip U1 (U1) is powered by the capacitor C1 (C1) in a short time to keep normal switching to a closed state, and the Y port and the Z port are closed; at this time, the host enters an OTG power supply state, and not only the CMOS chip U1 (U1) starts to supply power, but also external equipment on the third interface J3 (J3) is powered; at this time, due to the function of the diode D1 (D1) for limiting the current direction, the OTG power supply provided from the first interface J1 (J1) will not be erroneously operated to pull the enable end E port of the CMOS chip U1 (U1) high, so the CMOS chip U1 (U1) may be kept in a closed state, thereby ensuring that the first interface J1 (J1) is in an OTG power supply state;

(4) As long as the first interface J1 (J1) is not disconnected, the CMOS chip U1 (U1) can normally and automatically switch between the OTG power supply mode and the charging data mode according to whether the second interface J2 (J2) is connected to the charger; if the second interface J2 (J2) is connected with the charger, the enabling end E port of the CMOS chip U1 (U1) is pulled up, the CMOS chip U1 (U1) is automatically disconnected, an open circuit is formed between the Y port and the Z port, the host equipment connected with the first interface J1 (J1) stops supplying power to the outside, and the host still performs data transmission with the external equipment through the first interface J1 (J1) and the third interface J3 (J3); at the moment, the external equipment takes electricity from the charger through a second interface J2 (J2) and a third interface J3 (J3); meanwhile, the charger charges a host connected with the interface J1 (J1); if the connection between the second interface J2 (J2) and the charger is disconnected, the enabling end E port of the CMOS chip U1 (U1) is pulled down, the CMOS chip U1 (U1) is automatically closed, the Y port and the Z port are in short circuit, the host equipment connected with the first interface J1 (J1) automatically enters an OTG power supply state, and the host supplies power to the external equipment through the first interface J1 (J1) and the third interface J3 (J3) and performs data transmission;

(5) If the first interface J1 (J1) is disconnected or the first interface J1 (J1) is completely powered off, the steps (1) to (3) above need to be repeated when the next reconnection is performed.

In addition, it should be noted that all equivalent or simple changes of the structure, features and principles described in the inventive concept are included in the scope of the present invention.

Claims

1. A control method of an OTG power supply and charging automatic switching module is characterized by comprising the following steps of: the OTG power supply and charging automatic switching module comprises a CMOS chip (U1), a first interface (J1) for connecting Host equipment with an OTG function, a second interface (J2) for connecting a charger, and a third interface (J3) for connecting external equipment requiring OTG power supply; the CMOS chip (U1) comprises an E port, a Y port and a Z port, wherein the E port is electrically connected with a second interface (J2), the Z port is grounded, the Y port is electrically connected with a first interface (J1), the second interface (J2) and a third interface (J3) respectively comprise V, D +, D and G pins, and the same pins are electrically connected with each other; the first interface (J1) is also provided with a pin S, and a Y port of the CMOS chip is electrically connected with the pin S; the CMOS chip (U1) is connected with a capacitor (C1), one end of the capacitor (C1) is connected with a Z pin of the CMOS chip (U1) and a G pin of the first interface (J1) to be grounded, and the other end of the capacitor is connected with a power pin of the CMOS chip and a V pin of the first interface (J1); a diode (D1) is arranged in a circuit connected between the V pins of the first interface (J1) and the V pins of the second interface (J2); the control steps are as follows: