阅读说明：本技术 过电流保护电路以及其方法 (Overcurrent protection circuit and method thereof ) 是由 黎永波 李永强 杨文龙 邱俊新 于 2018-08-20 设计创作，主要内容包括：一种过电流保护电路以及其方法。上述过电流保护方法适用于采用电源传输协议的一通用串行总线,上述过电流保护方法包括：将输入电压转换为第一电压以对第一电子装置供电,其中输入电压由第二电子装置所提供；判断第一电子装置所产生的工作电流是否大于第一既定值；判断第一电子装置所产生的工作电流是否大于第二既定值,其中第二既定值小于第一既定值；响应于工作电流大于第一既定值时,第一电流检测电路产生第一感测信号以关闭开关,使得第一电子装置与第二电子装置之间形成开路；以及响应于工作电流大于第二既定值时,停止将输入电压转换为第一电压。本发明可避免受电端的工作电流带来对供电端的电子装置的损害且避免保护机制被太过频繁的触发。(An over-current protection circuit and a method thereof. The overcurrent protection method is suitable for a universal serial bus adopting a power transmission protocol, and comprises the following steps: converting an input voltage to a first voltage to power a first electronic device, wherein the input voltage is provided by a second electronic device; judging whether the working current generated by the first electronic device is greater than a first preset value or not; judging whether the working current generated by the first electronic device is larger than a second preset value, wherein the second preset value is smaller than the first preset value; when the working current is larger than a first preset value, the first current detection circuit generates a first sensing signal to close the switch, so that an open circuit is formed between the first electronic device and the second electronic device; and stopping converting the input voltage into the first voltage in response to the working current being greater than a second predetermined value. The invention can avoid the damage of the working current of the power receiving end to the electronic device of the power supply end and avoid the frequent triggering of the protection mechanism.)

1. An over-current protection method for a Universal Serial Bus (USB) using a power transmission protocol, the over-current protection method comprising:

converting an input voltage into a first voltage to supply power to a first electronic device, wherein the input voltage is provided by a second electronic device;

judging whether a working current generated by the first electronic device is larger than a first preset value or not;

determining whether the operating current generated by the first electronic device is greater than a second predetermined value, wherein the second predetermined value is less than the first predetermined value;

when the working current is larger than the first preset value, a first current detection circuit generates a first sensing signal to close a switch, so that an open circuit is formed between the first electronic device and the second electronic device; and

and stopping converting the input voltage into the first voltage when the operating current is larger than the second preset value.

2. The overcurrent protection method as set forth in claim 1, further comprising:

determining, by a second current detection circuit, whether the operating current generated by the first electronic device is greater than a third predetermined value, wherein the third predetermined value is less than the second predetermined value;

in response to the operating current being greater than the third predetermined value, the second current detection circuit generates a second sensing signal;

starting timing after receiving the second sensing signal output by the second current detection circuit through a microcontroller; and

and when the microcontroller continuously receives the second sensing signal for more than a preset time, the microcontroller closes the switch.

3. The method according to claim 2, wherein the switch comprises a first metal oxide semiconductor transistor and a second metal oxide semiconductor transistor.

4. The method according to claim 3, wherein the first current detecting circuit and the second current detecting circuit respectively comprise a first comparator and a second comparator.

5. The method of claim 4, wherein the first MOS transistor has a first gate, a first drain and a first source and the second MOS transistor has a second gate, a second drain and a second source, the first drain is coupled to an output of a voltage converting chip, the first source is coupled to the second source, the first gate and the second gate are coupled to a first output of the first current detecting circuit and a signal output of the microcontroller, and the second gate is coupled to the first current detecting circuit, the second current detecting circuit and the first electronic device.

6. An over-current protection circuit for a universal serial bus (usb) using a power transfer protocol, the over-current protection circuit comprising:

the power receiving end is connected with a first electronic device;

the power supply end is connected with a second electronic device and provides an input voltage by the second electronic device;

the voltage conversion chip is used for converting the input voltage into a first voltage so as to supply power to the first electronic device;

a switch coupled between the receiving terminal and the voltage converting chip; and

a first current detection circuit, coupled between the power receiving terminal and the switch, for determining whether a working current generated by the first electronic device is greater than a first predetermined value;

wherein, when the working current of the first electronic device is greater than the first predetermined value, the first current detection circuit generates a first sensing signal to close the switch; and is

When the operating current of the first electronic device is greater than a second predetermined value, the voltage conversion chip stops converting the input voltage into the first voltage, wherein the second predetermined value is smaller than the first predetermined value.

7. The overcurrent protection circuit as set forth in claim 6, further comprising:

a second current detection circuit, coupled between the power receiving terminal and the switch, for determining whether the operating current generated by the first electronic device is greater than a third predetermined value, wherein the third predetermined value is smaller than the second predetermined value, and outputting a second sensing signal when the operating current is greater than the third predetermined value; and

a microcontroller coupled to the second current detection circuit and the switch for starting timing after receiving the second sensing signal;

and when the microcontroller continuously receives the second sensing signal for more than a preset time, the microcontroller closes the switch.

8. The overcurrent protection circuit of claim 7, wherein the switch comprises a first metal-oxide-semiconductor transistor and a second metal-oxide-semiconductor transistor.

9. The overcurrent protection circuit as recited in claim 8, wherein the first current detection circuit and the second current detection circuit respectively comprise a first comparator and a second comparator.

10. The over-current protection circuit as claimed in claim 9, wherein the first mos transistor has a first gate, a first drain and a first source and the second mos transistor has a second gate, a second drain and a second source, the first drain is coupled to an output terminal of the voltage converting chip, the first source is coupled to the second source, the first gate and the second gate are coupled to a first output terminal of the first current detecting circuit and a signal output terminal of the microcontroller, and the second gate is coupled to the first current detecting circuit, the second current detecting circuit and the power receiving terminal.

Technical Field

The present invention relates to an overcurrent protection circuit and a method thereof, and more particularly, to an overcurrent protection circuit and a method thereof that prevent a protection mechanism from being triggered too frequently.

Background

In order to meet the requirements of the continuously advancing electronic devices, the Power transmission capability and the data transmission speed of the transmission interface are increasingly required, and the universal serial bus adopting the Power Delivery (PD) protocol integrates the data transmission and the high-Power supply, so that the size of the connector becomes smaller and the use is more convenient. However, since the new transmission interface provides a charging function, in order to avoid damage to the electronic device caused by inrush current and further consider system compatibility, a perfect protection mechanism must be established to ensure the safety of the electronic device that supplies power.

Therefore, it is desirable to provide an overcurrent protection circuit and a method thereof to solve the above problems.

Disclosure of Invention

An embodiment of the present invention provides an overcurrent protection method, which is applicable to a universal serial bus using a power transmission protocol, and the overcurrent protection method includes: converting an input voltage into a first voltage to supply power to a first electronic device, wherein the input voltage is provided by a second electronic device; judging whether a working current generated by the first electronic device is larger than a first preset value or not; determining whether the operating current generated by the first electronic device is greater than a second predetermined value, wherein the second predetermined value is less than the first predetermined value; when the working current is larger than the first preset value, a first current detection circuit generates a first sensing signal to close a switch, so that an open circuit is formed between the first electronic device and the second electronic device; and stopping converting the input voltage into the first voltage in response to the operating current being greater than the second predetermined value.

Another embodiment of the present invention provides an overcurrent protection circuit, adapted to a universal serial bus using a power transmission protocol, the overcurrent protection circuit comprising: the power supply circuit comprises a power receiving end, a power supply end, a voltage conversion chip, a switch and a first current detection circuit; the power receiving end is connected with a first electronic device; the power supply end is connected with a second electronic device, and the second electronic device provides an input voltage; the voltage conversion chip is used for converting the input voltage into a first voltage so as to supply power to the first electronic device; the switch is coupled between the power receiving end and the voltage conversion chip; the first current detection circuit is coupled between the power receiving end and the switch and used for judging whether a working current generated by the first electronic device is larger than a first preset value or not; wherein, when the working current of the first electronic device is greater than the first predetermined value, the first current detection circuit generates a first sensing signal to close the switch; and when the operating current of the first electronic device is greater than a second predetermined value, the voltage conversion chip stops converting the input voltage into the first voltage, wherein the second predetermined value is smaller than the first predetermined value.

According to an embodiment of the present invention, the overcurrent protection circuit further includes: a second current detection circuit and a microcontroller. The second current detection circuit is coupled between the power receiving end and the switch and used for judging whether the working current generated by the first electronic device is larger than a third preset value or not, wherein the third preset value is smaller than the second preset value. And the microcontroller is coupled with the second current detection circuit and the switch and is used for starting timing after receiving the second sensing signal. The second current detection circuit outputs a second sensing signal when the working current is larger than a third predetermined value. And when the microcontroller continuously receives the second sensing signal for more than a preset time, the microcontroller closes the switch.

According to an embodiment of the present invention, the switch includes a first metal oxide semiconductor transistor and a second metal oxide semiconductor transistor.

According to an embodiment of the present invention, the first current detection circuit and the second current detection circuit respectively include a first comparator and a second comparator.

According to an embodiment of the present invention, the first metal oxide semiconductor transistor has a first gate, a first drain and a first source, and the second metal oxide semiconductor transistor has a second gate, a second drain and a second source, the first drain is coupled to an output terminal of the voltage conversion chip, the first source is coupled to the second source, the first gate and the second gate are coupled to a first output terminal of the first current detection circuit and a signal output terminal of the microcontroller, and the second gate is coupled to the first current detection circuit, the second current detection circuit and the power receiving terminal.

The invention can avoid the damage of the working current of the power receiving end to the electronic device of the power supply end, and can improve the compatibility of the system through the multiple protection mechanisms of a plurality of circuits so as to avoid the protection mechanism from being triggered too frequently.

Drawings

Fig. 1 is a system architecture diagram of an overcurrent protection circuit according to an embodiment of the invention.

Fig. 2 is a system architecture diagram of an overcurrent protection circuit according to another embodiment of the invention.

Fig. 3 is a system architecture diagram of an overcurrent protection circuit according to another embodiment of the invention.

Fig. 4A and 4B are flowcharts illustrating a current protection method according to another embodiment of the invention.

Description of the main component symbols:

100 overcurrent protection circuit

110. 210 voltage conversion chip

120. 220 switch

130. 230 first current detection circuit

240 second current detection circuit

250 microcontroller

310. 320 comparator

330 circuit for preventing current from flowing backwards

CADJ capacitor

Q1, Q2, Q3 MOS transistors

R1, R2, RS1, RS2, RS3 and RADJ resistor

S401-S410 flow

VBUS power receiving end

VIN power supply terminal

Detailed Description

Further areas of applicability of the overcurrent protection circuit and method of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the following detailed description and specific examples, while indicating exemplary embodiments of the over-current protection circuit and method, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

Fig. 1 is a system architecture diagram of an overcurrent protection circuit according to an embodiment of the invention. In this embodiment, the over-current protection circuit 100 is suitable for a universal serial bus (e.g. USB Type-C standard) using Power over fault (PD) protocol, and may include a Power receiving terminal VBUS and a Power supply terminal V_INA voltage conversion chip 110, a switch 120 and a first current detection circuit 130. Wherein, the USB adopting the power transmission protocol provides more advantages compared with the traditional USB standardHigh power transmission capability and data transmission speed, and the voltage and current indicator can be raised to 20V/5A, namely the maximum power of 100W. In other words, the power receiving terminal VBUS (also referred to as a power consuming terminal, Sink terminal) can be connected to an electronic device (hereinafter, generally referred to as a first electronic device) such as a notebook computer or a smart phone. Supply terminal V_INAlso called Source terminal (Source) for connecting with an electronic device (hereinafter, referred to as second electronic device) having a driving power Source (for example, connected to the mains or a built-in battery) to supply power to the first electronic device connected to the power receiving terminal VBUS. It should be noted that the first electronic device such as a notebook computer or a smart phone is only an example of the present invention, and the notebook computer with a power supply can also be used as the second electronic device and the power supply terminal V_INAnd (4) connecting.

The voltage conversion chip 110 is used for connecting the power supply terminal V_INThe input voltage is converted into a lower supply voltage (first voltage) to supply power to the first electronic device connected to the power receiving terminal VBUS. For example, in an embodiment of the invention, the second electronic device is a display screen, and the input voltage is provided by a power source of the display screen. The switch 120 is coupled between the receiving terminal VBUS and the voltage converting chip 110, and is controlled by the first current detecting circuit 130. The first current detection circuit 130 is coupled between the power receiving end VBUS and the switch 120, and is configured to determine whether an operating current generated by a first electronic device connected to the power receiving end VBUS is greater than a first predetermined value. Under the condition that the first electronic device is internally provided with the battery, when the first electronic device is started or connected with the second electronic device, the working current flowing from the first electronic device to the second electronic device is possibly generated. In response to the working current flowing from the first electronic device to the second electronic device being greater than the first predetermined value, the first current detection circuit 130 generates a first sensing signal to turn off the switch 120, i.e. to turn off the power supply terminal V_INAn open circuit is formed between the first electronic device and the power receiving end VBUS to avoid the influence of the excessive working current on the second electronic device. In some embodiments, the power supply terminal comprises a power receiving terminal VBUS and a power supply terminal V_INA voltage conversion chip 110, a switch 120 and a first switchThe over-current protection circuit 100 of the current detection circuit 130 can be integrated into a second electronic device.

In addition, the voltage conversion chip 110 also includes an overcurrent protection function. Similarly, in the case of the first electronic device having a built-in battery, when the first electronic device is powered on or connected to the second electronic device, if the working current flowing from the first electronic device to the second electronic device is greater than a second predetermined value, the voltage conversion chip 110 will be automatically turned off, that is, the voltage conversion chip 110 stops converting the input voltage into the supply voltage and does not supply power to the first electronic device. Wherein the first predetermined value is greater than the second predetermined value.

Fig. 2 is a system architecture diagram of an overcurrent protection circuit according to another embodiment of the invention. In this embodiment, the over-current protection circuit 100 includes a power receiving terminal VBUS and a power supply terminal V_INA voltage converting chip 210, a switch 220, a first current detecting circuit 230, a second current detecting circuit 240 and a microcontroller 250. The functions of the voltage converting chip 210, the switch 220 and the first current detecting circuit 230 are the same as the functions of the voltage converting chip 110, the switch 120 and the first current detecting circuit 130, and are not described herein for brevity. The second current detection circuit 240 is coupled between the power receiving end VBUS and the switch 220, and is configured to determine whether an operating current generated by the first electronic device connected to the power receiving end VBUS is greater than a third predetermined value. Wherein the second predetermined value is greater than the third predetermined value. The microcontroller 250 may be disposed in the second electronic device and at least has a timer for starting timing after receiving a second sensing signal outputted by the second current detecting circuit 240. In an embodiment of the present invention, the second electronic device is a display screen, and the microcontroller 250 can be a liquid crystal control (Scaler) chip of the display screen.

Wherein, under the condition that the first electronic device has a built-in battery, when the first electronic device is powered on or connected to the second electronic device, if the working current flowing from the first electronic device to the second electronic device is greater than a third predetermined value, the second current detection circuit 240 outputs a second sensing signal to the microcontroller250. The microcontroller 250 will cause the built-in timer to start timing after receiving the second sensing signal. In response to the microcontroller 250 continuously receiving the second sensing signal for more than a predetermined time (e.g., 10 ms), it outputs a turn-off signal to the switch 220 to turn off the switch 120, i.e., to make the power supply terminal V_INAn open circuit is formed between the first electronic device and the power receiving end VBUS to avoid the influence of improper working current on the second electronic device. It is noted that in response to the microcontroller 250 interrupting the reception of the second sensing signal, its built-in timer will be reset to zero to start timing from zero when the second sensing signal is received again. It should be noted that the predetermined time period can be defined according to the user's requirement, but the present invention is not limited thereto.

FIG. 3 is a diagram of a system architecture of an over-current protection circuit for USB Type-C according to an embodiment of the present invention. As shown in fig. 3, the voltage converting chip 210 comprises a DC/DC converter, a compensation circuit comprising a resistor RADJ and a capacitor CADJ, and a resistor RS3, and the voltage converting chip 210 stops converting the input voltage into the first voltage in response to the operating current flowing from the first electronic device to the second electronic device being greater than a second predetermined value (e.g. a current of the first electronic device exceeds 130% of a normal operating current). The switch 220 is composed of first and second transistor elements connected in series. In this embodiment, the switch 220 is composed of a first MOS transistor Q1 and a second MOS transistor Q2. A first drain D1 of the first mos transistor Q1 is coupled to an output terminal of the voltage converting chip 210, a first source S1 of the first mos transistor Q1 is coupled to a second source S2 of the second mos transistor Q2, and a second drain of the second mos transistor Q2 is coupled to the first current detecting circuit 230 and the second current detecting circuit 240. The first current detection circuit 230 is composed of a first detection resistor RS1 and a first comparator 310, and is responsive to the operating current flowing from the first electronic device to the second electronic device being greater than a first predetermined value (e.g., a current of the first electronic device exceeds positive)200% of the normal operating current), the first comparator 310 outputs a positive voltage level to the gate G1 of the first mos transistor Q1 and the gate G2 of the second mos transistor Q2, so that the first mos transistor Q1 and the second mos transistor Q2 form an open circuit to protect the power supply terminal V_INThe second electronic device of (1). The second current detection circuit 230 is composed of a second detection resistor RS2 and a second comparator 320, and in response to the operating current flowing from the first electronic device to the second electronic device being greater than a second predetermined value (e.g. the current of the first electronic device exceeds 110% of the normal operating current), the second current detection circuit 230 can output a positive voltage level or a negative voltage level to enable the microcontroller 250 to start timing according to the received positive voltage level or negative voltage level. In response to the current continuously exceeding 110% of the normal operating current for more than a predetermined time, the microcontroller 250 outputs a turn-off signal with a positive voltage level to the gate G1 of the first mos transistor Q1 and the gate G2 of the second mos transistor Q2, so that the first mos transistor Q1 and the second mos transistor Q2 form an open circuit. It should be noted that the switch 220 may also be formed by a single mos transistor, and is not limited to the structure of two mos transistors Q1 and Q2. In some embodiments, the first and second transistor elements in the switch 220 may also be designed to open in response to a turn-off signal having a negative voltage level. In addition, in some embodiments, when the overcurrent protection circuit is used in USB Type-C, a circuit 330 may be further included. The circuit 330 includes a resistor R1, a resistor R2, a transistor Q3, and a comparator, which mainly functions to prevent the reverse flow of current (as shown in fig. 3). It is noted that the circuit 300 is optional, and the circuit 330 shown in fig. 3 can be removed when the over-current protection circuit of the present invention is used in other usb architectures.

Fig. 4A and 4B are flowcharts illustrating an overcurrent protection method according to an embodiment of the invention. In step S401, the voltage conversion chip 210 converts an input voltage provided by a power supply module of the second electronic device into a first voltage to supply power to the first electronic device. In step S402, the first current detecting circuit 230 determines whether the operating current flowing from the first electronic device to the second electronic device is greater than a first predetermined value. In response to the working current being greater than the first predetermined value, the method proceeds to step S403, the first current detecting circuit 230 outputs a first sensing signal to the switch 220 to close the switch 220, so that the power supply terminal V is connected to the power supply terminal V_INAn open circuit is formed between the first power supply and the power receiving end VBUS to prevent the operation of the second electronic device from being affected by the excessive working current. In step S404, the voltage converting chip 210 determines whether the working current flowing from the first electronic device to the second electronic device is greater than a second predetermined value through the built-in over-current protection function. When the working current is greater than the second predetermined value, step S405 is performed, and the voltage conversion chip 210 is automatically turned off to protect the power supply module of the second electronic device. In step S406, the second current detecting circuit 240 determines whether the operating current flowing from the first electronic device to the second electronic device is greater than a third predetermined value. In response to the operating current being greater than the third predetermined value, step S407 is entered, and the third current detecting circuit 240 outputs the second sensing signal to the microcontroller 250, and starts timing according to the second sensing signal by the timer of the microcontroller 250. In step S408, the microcontroller 250 further determines whether the time for continuously receiving the second sensing signal exceeds a predetermined time. In some embodiments, the predetermined time may be, for example, 10 ms, but may be defined according to the user's requirement, but is not limited thereto. When the microcontroller 250 continuously receives the second sensing signal for more than the predetermined time, the process proceeds to step S409, and the microcontroller 250 outputs a turn-off signal to the switch 220 to turn off the switch 220, so that the power supply terminal V is connected to the power supply terminal V_INAn open circuit is formed between the first power supply and the power receiving end VBUS to prevent the working current from influencing the operation of the second electronic device. Otherwise, in response to the time that the microcontroller 250 continuously receives the second sensing signal being less than or equal to the predetermined time, the process proceeds to step S410, and the microcontroller 250 resets the counted seconds to start counting again when receiving the second sensing signal again. In certain embodiments, the firstThe predetermined value is greater than the second predetermined value, and the second predetermined value is greater than the third predetermined value. For example, the first predetermined value may be 200% of the operating current, the second predetermined value may be 130% of the operating current, and the third predetermined value may be 110% of the operating current, but may also be adjusted according to the user's requirement, but not limited thereto.

In summary, according to the over-current protection circuit and the method thereof of some embodiments of the present invention, through the over-current protection function built in the voltage conversion chip and the multiple protection mechanisms provided by the current detection circuit, the damage of the working current of the power receiving terminal to the electronic device of the power supply terminal can be avoided, and the multiple protection mechanisms of the multiple circuits can improve the compatibility of the system, so as to avoid the protection mechanism from being triggered too frequently.

The foregoing describes features of various embodiments so that others skilled in the art may readily understand the aspects of the present description. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.