CN110890738A - Charging interface overcurrent turn-off protection circuit - Google Patents
Charging interface overcurrent turn-off protection circuit Download PDFInfo
- Publication number
- CN110890738A CN110890738A CN201811042496.3A CN201811042496A CN110890738A CN 110890738 A CN110890738 A CN 110890738A CN 201811042496 A CN201811042496 A CN 201811042496A CN 110890738 A CN110890738 A CN 110890738A
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- current
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- load
- overcurrent
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
Abstract
The invention discloses an overcurrent turn-off protection circuit for a charging interface, which comprises a current detection circuit, a current detection circuit and a voltage detection circuit, wherein the current detection circuit is used for sampling the output current of the interface and converting the output current into a voltage form for output; the control circuit is used for controlling the state of the current switch, controlling the current switch to be switched off when the circuit load is over-current, protecting the charging interface and the load, and controlling the current switch to be switched on and normally charged when the current of the circuit load is normal; the current switch is used for realizing the on and off of the charging of the load; the locking turn-off and recovery circuit is used for providing a locking signal for the control circuit after the circuit load is over-current and the current switch is disconnected; and the reference circuit is used for providing a reference comparison voltage for the control circuit and providing a reference current for the locking shutdown and recovery circuit. The invention can carry out overcurrent locking turn-off protection on various charging interfaces, recovers charging after a fault is removed, and is convenient to adjust the protection threshold current, thereby effectively ensuring the safety and stability of the charging interfaces and loads.
Description
Technical Field
The invention belongs to the technical field of integrated circuit design, and particularly relates to an overcurrent turn-off protection circuit.
Background
The portable electronic equipment is increasingly popularized and gradually becomes a necessity in life, and charging accessory products thereof are rapidly developed, such as various USB and TYPE-C interface charging products, so that how to effectively protect the charging and charged equipment during charging is a problem to be solved by the invention.
In the technical field of traditional circuits, an overcurrent protection circuit is a circuit which effectively protects a load and the whole circuit when the load current exceeds a threshold current. One conventional overcurrent protection method is to use a resettable fuse, which fuses to open a current path when a current exceeds the maximum current capacity of the resettable fuse, and then recovers to close the current path after a short-circuit fault is removed. The overcurrent protection measures adopting the restorable fuse have relatively weak protection reliability due to long fuse fusing time, and are inconvenient to adjust the overcurrent protection threshold point. Another common overcurrent protection is a hiccup protection mode, that is, when the current exceeds a threshold protection point, protection is performed through a sampling-comparing-switch-off (toff delay off time) -sampling-comparing-switch-on circulating mode, which has a certain protection capability on the load, but if the short-circuit fault is not eliminated, the hiccup protection is performed all the time, the load is continuously impacted, and meanwhile, the current switch continuously acts, and the temperature accumulation of the device rises, so that the reliability becomes low and even the device burns out. Therefore, in order to solve the above-mentioned deficiencies of the two conventional overcurrent protection methods, the present invention provides a method in which when a load is overcurrent, a circuit immediately turns off a current path and locks a switch to an off state, and only when a fault is removed, the switch is closed, and the load resumes a normal charging operation.
Disclosure of Invention
In order to overcome the defects of the overcurrent protection technology, the invention provides a locking turn-off and recovery circuit which is simple in structure, convenient to realize, capable of effectively protecting each device on a load and a current path and guaranteeing the safety and reliability of equipment.
The specific scheme disclosed by the invention is as follows:
a charging interface over-current turn-off protection circuit, the protection circuit comprising: current detection circuit, control circuit, locking turn-off and restore circuit, current switch, reference circuit, its characterized in that:
the current detection circuit is used for sampling and detecting the output current of the charging interface, converting the output current into a voltage signal and feeding the voltage signal back to the comparison control circuit;
the control circuit is used for controlling the on-off state of the load current, and when the load current is smaller than a set threshold value, the control circuit controls the on-off state of the current switch to normally charge; when the load current exceeds a set threshold value, the current switch is controlled to be switched off, and only after the overcurrent fault is eliminated, the control circuit controls the current switch to be switched on and recovers charging;
the locking turn-off and recovery circuit is used for providing a locking signal for the control circuit when the load is in overcurrent, locking the off state of the current switch and avoiding the current switch from being subjected to overcurrent impact due to repeated on-off of the current switch; when the overcurrent fault is eliminated, a recovery signal is provided for the comparison control circuit, the state of the current switch is switched, and normal charging is recovered;
the current switch is used for executing the on and off actions of load charging, the switch is closed when the load is charged normally, and the switch is opened when the load is over-current;
the reference circuit is used for providing a precise reference voltage for the comparator of the control circuit; meanwhile, the reference circuit provides a precise current for realizing the overcurrent protection threshold current.
Further, the current detection circuit is a sampling resistor Rs connected in series between the current switch NMOS transistor and the ground and flows through the sampling resistor RSCurrent multiplied by resistance RSConverted into voltage, and the voltage signal is finally superposed and fed back to the negative input end of the comparator of the control circuit.
Furthermore, the control circuit is a comparator COMP, the output signal of the comparator controls the state of the current switch, and the positive input end of the comparator is connected with a reference threshold voltage V in a plus modeTHThe negative input end of the comparator is connected with the output signal V of the locking shut-off and recovery circuitS。
Further, the locking shut-off and recovery circuit is composed of a resistor R1、R2、RSAnd a current source IrefComposition, resistance R1And a resistor R2And a sampling resistor RSForming a series circuit and adjusting the resistance R2The magnitude of the resistor R is used for adjusting the overcurrent protection threshold current1Is connected with the output end of the load, and a resistor R1Negative terminal of and resistor R2Positive terminal "+" connected, R2Negative terminal '-' connectedTo RSPositive terminal "+", current source IrefCurrent output terminal of R2Positive resistance "+" and resistance R1A voltage signal V is led out from the negative end "-"STo lock the turn-off and restore signals, VSTo the negative input of the comparator "-".
Furthermore, the current switch is an NMOS current switch on the load current path, a drain terminal D of the NMOS transistor is connected to the output terminal of the load, and a source terminal S of the NMOS transistor is connected to the sampling resistor RSThe positive end of the NMOS transistor is "+", the grid G of the control end NMOS of the switch is connected with the output end of the comparator, and in order to enhance the current conducting capability of the NMOS switch and reduce the conducting resistance of the NMOS switch, the width and the length of the NMOS transistor are designed to be larger than the size as much as possible.
Further, the reference circuit mainly provides a reference voltage and a reference current, the reference voltage VTHThe positive input end "+" of the comparator and the reference current I are connectedrefIs connected with the resistor R2Plus "+".
Compared with the prior art, the invention has the following advantages:
the overcurrent turn-off protection circuit designed by the method of the invention is locked and turned off when overcurrent occurs, thereby better and effectively protecting the load; the overcurrent turn-off protection circuit designed by the method can adjust the resistance value R2The overcurrent protection threshold current is convenient to set; the overcurrent turn-off protection circuit designed by the method can effectively recover to a normal charging state after overcurrent faults are removed; the overcurrent turn-off protection circuit designed by the method can effectively eliminate the impact of the traditional hiccup protection on the load and the switch tube; the overcurrent turn-off protection circuit designed by the method has a simple structure, and can effectively save the chip area and the cost by adopting a standard CMOS electronic device.
Drawings
Fig. 1 is a schematic diagram of a basic structure of an overcurrent shutdown protection circuit according to the present invention.
Fig. 2 is a schematic diagram of an embodiment of an overcurrent shutdown protection circuit according to the invention.
Detailed Description
The following detailed description of the charging interface overcurrent shutdown protection circuit according to the present invention is made with reference to the accompanying drawings, and is not intended to limit the scope of the present invention.
As shown in fig. 1 and 2, an overcurrent shutdown protection circuit according to the present invention includes: the circuit comprises a current detection circuit, a control circuit, a locking turn-off and recovery circuit, a current switch and a reference circuit.
The current detection circuit is a sampling resistor Rs connected in series between the current switch NMOS transistor and the ground and flows through the sampling resistor RSCurrent multiplied by resistance RSConverted into voltage, and the voltage signal is finally superposed and fed back to the negative input end of the comparator of the control circuit. The control circuit is a comparator COMP, the output signal of the comparator controls the state of a current switch, and the positive input end of the comparator is connected with a reference threshold voltage V in a plus modeTHThe negative input end of the comparator is connected with the output signal V of the locking shut-off and recovery circuitS. The locking turn-off and recovery circuit is composed of a resistor R1、R2、RSAnd a current source IrefComposition, resistance R1And a resistor R2And a sampling resistor RSForming a series circuit and adjusting the resistance R2The magnitude of the resistor R is used for adjusting the overcurrent protection threshold current1Is connected with the output end of the load, and a resistor R1Negative terminal of and resistor R2Positive terminal "+" connected, R2Negative terminal '-' is connected to RSPositive terminal "+", current source IrefCurrent output terminal of R2Positive resistance "+" and resistance R1A voltage signal V is led out from the negative end "-"STo lock the turn-off and restore signals, VSTo the negative input of the comparator "-". The current switch is an NMOS current switch on a load current path, a drain terminal D of an NMOS transistor is connected with an output terminal of a load, a source terminal S of the NMOS is connected with a plus terminal of the sampling resistor RS, a grid G of an NMOS at a control terminal of the switch is connected with an output terminal of the comparator, in order to enhance the current conduction capability of the NMOS switch and reduce the conduction resistance of the NMOS switch, the width and the length of the NMOS transistor are as much as possibleIs larger than the size design. The reference circuit mainly provides a reference voltage and a reference current, the reference voltage VTHThe positive input end "+" of the comparator and the reference current I are connectedrefIs connected with the resistor R2Plus "+".
The invention also relates to an overcurrent turn-off protection method, which comprises the following steps:
one end of the current sampling circuit is connected with the current switch, and the other end of the current sampling circuit is grounded, and the current sampling circuit is mainly used for sampling current on a load, outputting sampling voltage of the sampling current according to the linear relation between the current and the voltage, and feeding the sampling voltage back to the < - > input end of the comparator; as shown in fig. 2, the sampling resistor RSConnected in series between the current switch and ground. The sampling resistor is a low-resistance resistor, usually in the milliohm level, and aims to reduce sampling power consumption and voltage loss;
the controlled current switch, as shown in fig. 2, is connected in series between the load and the sampling resistor. Preferably, the controlled current switch may be an NMOS switch transistor, the drain of the NMOS switch transistor is connected to the load, the source is connected to the sampling resistor, and the gate is connected to the output of the comparator, but those skilled in the art should understand that the controlled current switch is not limited to the NMOS switch transistor, and in fact, other types of switches are also possible, such as an NPN switch transistor.
The latch circuit includes a 1 st resistor R12 nd resistance R2And the sampling resistor Rs described above. One end of the 1 st resistor is connected with the drain electrode of the NMOS, the other end of the 1 st resistor is connected with the 2 nd resistor in series, the 2 nd resistor is connected with the sampling resistor in series, meanwhile, a locking voltage signal line is led out from the serial connection position of the 1 st resistor and the 2 nd resistor, and the locking voltage signal line is input to the negative input end of the comparator.
The reference circuit, the present invention is not limited to various methods and specific voltage and current values for implementing a reference voltage and a reference current, the reference voltage mainly provides a comparison voltage to the comparator, and the reference current passes through R2And Rs resistance flows to ground.
The comparison circuit is used for comparing the sampling voltage output by the current sampling circuit (the sampling voltage output by the current sampling circuit passes through the Rth circuit2The resistor is fed back to the "-" input of the comparator) and the reference voltage (the reference voltage is connected with the "+" input V of the comparator)TH) And comparing, and when the output sampling voltage is greater than the reference voltage, outputting a high-level switch control signal by the comparator to control the switch to be switched off so as to achieve the purpose of carrying out open circuit protection on the whole circuit. In addition, when the overcurrent switch is disconnected, the load and the current switch are disconnected, the load is converted into series connection with the locking branch, and the current on the switch is zero due to the fact that the sum of series resistance values on the locking branch is large.
The above description is only a preferred embodiment of the present invention, and the values and ranges of values mentioned in the above description are not intended to limit the present invention, but only to provide a preferred embodiment of the present invention, and not to limit the present invention, and various modifications and variations of the present invention are possible to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. A charging interface over-current turn-off protection circuit, the protection circuit comprising: current detection circuit, control circuit, locking turn-off and restore circuit, current switch, reference circuit, its characterized in that:
the current detection circuit is used for sampling and detecting the output current of the charging interface, converting the output current into a voltage signal and feeding the voltage signal back to the comparison control circuit
The control circuit is used for controlling the on-off state of the load current, and when the load current is smaller than a set threshold value, the control circuit controls the on-off state of the current switch to normally charge; when the load current exceeds a set threshold value, the current switch is controlled to be switched off, and only after the overcurrent fault is eliminated, the control circuit controls the current switch to be switched on and recovers charging;
the locking turn-off and recovery circuit is used for providing a locking signal for the control circuit when the load is in overcurrent, locking the off state of the current switch and avoiding the current switch from being subjected to overcurrent impact due to repeated on-off of the current switch; when the overcurrent fault is eliminated, a recovery signal is provided for the comparison control circuit, the state of the current switch is switched, and normal charging is recovered;
the current switch is used for executing the on and off actions of load charging, the switch is closed when the load is charged normally, and the switch is opened when the load is over-current;
the reference circuit is used for providing a precise reference voltage for the comparator of the control circuit; meanwhile, the reference circuit provides a precise current for realizing the overcurrent protection threshold current.
2. The charging interface overcurrent turn-off protection circuit as claimed in claim 1, wherein the current detection circuit is a sampling resistor Rs connected in series between a current switch NMOS transistor and ground, and the sampling resistor R is flowed throughSCurrent multiplied by resistance RSConverted into voltage, and the voltage signal is finally superposed and fed back to the negative input end of the comparator of the control circuit.
3. The charging interface overcurrent turn-off protection circuit as claimed in claim 1 or 2, wherein the control circuit is a comparator COMP, an output signal of the comparator controls a current switch state, and a positive input terminal "+" of the comparator is connected to a reference threshold voltage VTHThe negative input end of the comparator is connected with the output signal V of the locking shut-off and recovery circuitS。
4. The charging interface overcurrent turn-off protection circuit as claimed in claim 1 or 2, wherein the latch turn-off and recovery circuit is composed of a resistor R1、R2、RSAnd a current source IrefComposition, resistance R1And a resistor R2And a sampling resistor RSForming a series circuit and adjusting the resistance R2The magnitude of the resistor R is used for adjusting the overcurrent protection threshold current1Is connected with the output end of the load, and a resistor R1Negative terminal of and resistor R2Positive terminal "+" connected, R2Negative terminal '-' is connected to RSPositive terminal"+", current source IrefCurrent output terminal of R2Positive resistance "+" and resistance R1A voltage signal V is led out from the negative end "-"STo lock the turn-off and restore signals, VSTo the negative input of the comparator "-".
5. The charging interface overcurrent turn-off protection circuit as claimed in claim 1 or 2, wherein the current switch is an NMOS current switch on a load current path, a drain terminal D of the NMOS transistor is connected to an output terminal of a load, a source terminal S of the NMOS transistor is connected to a plus terminal "+" of the sampling resistor RS, and a gate G of an NMOS transistor at a control terminal of the switch is connected to an output terminal of the comparator, so as to enhance a current conduction capability of the NMOS switch, reduce an on-resistance thereof, and design a width-to-length ratio of the NMOS transistor as large as possible compared with a size.
6. The charging interface overcurrent turn-off protection circuit as claimed in claim 1 or 2, wherein the reference circuit mainly provides a reference voltage and a reference current, and the reference voltage V isTHThe positive input end "+" of the comparator and the reference current I are connectedrefIs connected with the resistor R2Plus "+".
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811042496.3A CN110890738A (en) | 2018-09-07 | 2018-09-07 | Charging interface overcurrent turn-off protection circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811042496.3A CN110890738A (en) | 2018-09-07 | 2018-09-07 | Charging interface overcurrent turn-off protection circuit |
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| Publication Number | Publication Date |
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| CN110890738A true CN110890738A (en) | 2020-03-17 |
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| CN201811042496.3A Pending CN110890738A (en) | 2018-09-07 | 2018-09-07 | Charging interface overcurrent turn-off protection circuit |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112366651A (en) * | 2020-11-03 | 2021-02-12 | 航天科技控股集团股份有限公司 | Intelligent safety circuit |
| CN112737055A (en) * | 2021-01-13 | 2021-04-30 | 南昌嘉信高科技有限公司 | Charging protection circuit and electronic equipment |
| CN116087825A (en) * | 2022-12-05 | 2023-05-09 | 江苏帝奥微电子股份有限公司 | Charging interface foreign matter short circuit detection chip, detection device and method |
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| CN103633617A (en) * | 2013-12-02 | 2014-03-12 | 嘉兴中润微电子有限公司 | Overcurrent protection detection circuit applied to high-power motor drive chips |
| CN206180563U (en) * | 2016-11-22 | 2017-05-17 | 亿嘉和科技股份有限公司 | Load current foldback circuit |
| CN206865122U (en) * | 2017-06-06 | 2018-01-09 | 株洲珠华水工业科技开发有限公司 | A kind of overload protecting circuit for telecommunication circuit |
| CN207677424U (en) * | 2017-12-26 | 2018-07-31 | 广安职业技术学院 | A kind of current foldback circuit |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103390877A (en) * | 2013-08-07 | 2013-11-13 | 北京经纬恒润科技有限公司 | Overcurrent detection and protection circuit |
| CN103633617A (en) * | 2013-12-02 | 2014-03-12 | 嘉兴中润微电子有限公司 | Overcurrent protection detection circuit applied to high-power motor drive chips |
| CN206180563U (en) * | 2016-11-22 | 2017-05-17 | 亿嘉和科技股份有限公司 | Load current foldback circuit |
| CN206865122U (en) * | 2017-06-06 | 2018-01-09 | 株洲珠华水工业科技开发有限公司 | A kind of overload protecting circuit for telecommunication circuit |
| CN207677424U (en) * | 2017-12-26 | 2018-07-31 | 广安职业技术学院 | A kind of current foldback circuit |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112366651A (en) * | 2020-11-03 | 2021-02-12 | 航天科技控股集团股份有限公司 | Intelligent safety circuit |
| CN112737055A (en) * | 2021-01-13 | 2021-04-30 | 南昌嘉信高科技有限公司 | Charging protection circuit and electronic equipment |
| CN112737055B (en) * | 2021-01-13 | 2022-11-01 | 南昌嘉信高科技有限公司 | Charging protection circuit and electronic equipment |
| CN116087825A (en) * | 2022-12-05 | 2023-05-09 | 江苏帝奥微电子股份有限公司 | Charging interface foreign matter short circuit detection chip, detection device and method |
| CN116087825B (en) * | 2022-12-05 | 2023-09-29 | 江苏帝奥微电子股份有限公司 | Charging interface foreign matter short circuit detection chip, detection device and method |
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Application publication date: 20200317 |