CN109450035B - Self-protection circuit for charging base and charging base - Google Patents
Self-protection circuit for charging base and charging base Download PDFInfo
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- CN109450035B CN109450035B CN201811497948.7A CN201811497948A CN109450035B CN 109450035 B CN109450035 B CN 109450035B CN 201811497948 A CN201811497948 A CN 201811497948A CN 109450035 B CN109450035 B CN 109450035B
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0042—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries characterised by the mechanical construction
- H02J7/0044—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries characterised by the mechanical construction specially adapted for holding portable devices containing batteries
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/0031—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits using battery or load disconnect circuits
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/007—Regulation of charging or discharging current or voltage
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- H02J7/0077—
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00302—Overcharge protection
Abstract
The invention discloses a self-protection circuit for a charging base and the charging base, comprising a charging column, a power switch, an AND gate, a Hall element and a controller; the power switch is connected in a charging current transmission line connected with the charging post; the Hall element is connected with a first input end of the AND gate, is set to be in a first state when a magnet in the electronic product is not sensed, and is set to be in a second state when the magnet is sensed; the controller is connected with the Hall element, and a first IO port of the controller is connected with a second input end of the AND gate; the controller controls the AND gate to output high level or low level according to the state change of the Hall element, and then controls the power switch to be connected or disconnected with the charging current transmission line so as to change the charging state of the charging column. According to the invention, when no electronic product is put in the charging base, the charging column in the charging base is controlled to be uncharged, so that potential safety hazards are eliminated; meanwhile, the overcharge damage of the electronic product can be avoided.
Description
Technical Field
The invention belongs to the technical field of charging devices, and particularly relates to a circuit design applied to a charging base.
Background
With the rapid development of electronic technology, electronic devices of wearable type, such as smart watches and smart bracelets, are increasingly more numerous, and great convenience is brought to people's daily lives. In the current wearable electronic devices, an internal rechargeable battery supplies power to a system circuit of the device, and an external charger (plug type or base type) can be utilized to charge and store energy for the rechargeable battery.
The charging base for smart watches and smart bracelets at present generally comprises a table top 1 for carrying the smart watch and smart bracelet, a charging post 2 mounted on the table top 1, and a USB interface 3 connected to a power adapter 4 or a USB data line, as shown in fig. 1. When placing intelligent wrist-watch and intelligent bracelet and charging on the base that charges, lay the charging electrode on intelligent wrist-watch and intelligent bracelet and can switch on with charging post 2 contact on the base that charges, make charging current introduce the internal circuit of intelligent wrist-watch and intelligent bracelet through charging post 2 and charging electrode then, charge for chargeable call in intelligent wrist-watch and the intelligent bracelet.
For such a charging base, the charging post 2 thereof is generally protruded from the table top 1 of the charging base and exposed to the environment, and after the charging base is connected with the power adapter 4, the charging post 2 thereof is always charged no matter whether the smart watch or the smart bracelet is placed on the charging base. The electrified state has potential safety hazards, short-circuit faults are easy to occur, and dangerous accidents such as burning of the charging base are further caused.
Disclosure of Invention
The invention aims to provide a self-protection circuit for a charging base, which can automatically control a charging column in the charging base to be uncharged when no electronic product is put in the charging base so as to eliminate potential safety hazards caused by charging the charging column; meanwhile, after the electronic product is fully charged, the power is automatically cut off, so that the overcharge damage of the electronic product is avoided.
In order to solve the technical problems, the invention is realized by adopting the following technical scheme:
in one aspect, the invention provides a self-protection circuit for a charging base, wherein the charging base charges an electronic product with a magnet inside; the self-protection circuit comprises a charging column, a power switch, an AND gate, a current detection circuit, a Hall element and a controller; the charging post is used for contacting with a charging electrode on the electronic product and transmitting charging current to the electronic product; the power switch is connected in a charging current transmission line connected with the charging post; the AND gate comprises a first input end, a second input end and an output end, wherein the output end is connected with the power switch and used for controlling the on-off of the power switch; the current detection circuit is connected to the charging current transmission line and is used for detecting the magnitude of charging current; the Hall element senses magnetic field change caused by the magnet, is set to be in a first state when the magnet is not sensed, and is set to be in a second state when the magnet is sensed; the Hall element is connected with the first input end of the AND gate; the controller is connected with the current detection circuit and detects the change of the charging current; a first IO port of the controller is connected with a second input end of the AND gate; when the controller detects that the Hall element is switched from a first state to a second state, the first IO port is set to be at a high level, the first input end of the AND gate is set to be at a high level through the Hall element, so that the AND gate outputs a high level, and the power switch is controlled to be communicated with the charging current transmission line; the controller keeps the high-level state of the first IO port until detecting that the charging current is close to zero, sets the first IO port to be low-potential, enables the AND gate to output low-level, controls the power switch to cut off the charging current transmission line, and enables the charging column to be uncharged.
As a first preferred embodiment of the hall element, the hall element comprises a first hall switch and a second hall switch, a first state of the first hall switch and the second hall switch is an open state, and a second state is a closed state; the first Hall switch is connected in series between a first IO port of the controller and a first input end of the AND gate, and the second Hall switch is connected between a second IO port and a third IO port of the controller; and when the level state of the third IO port is changed from low to high, the controller sets the first IO port to be high, keeps the high level state of the first IO port until detecting that the charging current is close to zero, and sets the first IO port to be low.
As a second preferred embodiment of the hall element, the hall element is a hall switch, the first state of the hall switch is an open state, and the second state is a closed state; the Hall switch is connected in series between the charging power supply and the first input end of the AND gate, the first input end of the AND gate is connected with the second IO port of the controller, and when the controller detects that the level state of the second IO port is changed from low to high, the controller sets the first IO port to be high level, keeps the high level state of the first IO port until detecting that the charging current is close to zero, and sets the first IO port to be low level.
The charging power supply is connected to the USB interface of the charging base, namely, the charging power supply is provided by the main equipment or provided by the power adapter.
Preferably, the power switch is an NMOS transistor, a source and a drain of the NMOS transistor are connected to the charging current transmission line, and a gate of the NMOS transistor is connected to an output end of the and gate.
In order to improve the accuracy and sensitivity of detection of the electronic product placed in the charging base, the Hall element is preferably arranged between a positive charging column and a negative charging column of the charging base; the magnets are preferably arranged between the positive and negative charging electrodes of the electronic product.
Preferably, the current detection circuit and the power switch are preferably connected between a power pin of the USB interface of the charging base and a positive charging column of the charging base.
In order to clearly indicate the working state of the charging base, a charging indicator lamp and a power-off indicator lamp are further arranged in the self-protection circuit, anodes of the charging indicator lamp and the power-off indicator lamp are respectively and correspondingly connected with a fourth IO port and a fifth IO port of the controller, and cathodes of the charging indicator lamp and the power-off indicator lamp are grounded; when the controller detects that the charging current is close to zero, a high level is output through the fifth IO port, and the power-off indicator lamp is controlled to be lightened; otherwise, outputting high level through the fourth IO port, and controlling the charging indicator lamp to be lightened.
In another aspect, the invention further provides a charging base, which is used for charging an electronic product with a built-in magnet, and comprises a charging column, a power switch, an AND gate, a current detection circuit, a Hall element and a controller; the charging post is used for contacting with a charging electrode on the electronic product and transmitting charging current to the electronic product; the power switch is connected in a charging current transmission line connected with the charging post; the AND gate comprises a first input end, a second input end and an output end, wherein the output end is connected with the power switch and used for controlling the on-off of the power switch; the current detection circuit is connected to the charging current transmission line and is used for detecting the magnitude of charging current; the Hall element senses magnetic field change caused by the magnet, is set to be in a first state when the magnet is not sensed, and is set to be in a second state when the magnet is sensed; the Hall element is connected with the first input end of the AND gate; the controller is connected with the current detection circuit and detects the change of the charging current; a first IO port of the controller is connected with a second input end of the AND gate; when the controller detects that the Hall element is switched from a first state to a second state, the first IO port is set to be at a high level, the first input end of the AND gate is set to be at a high level through the Hall element, so that the AND gate outputs a high level, and the power switch is controlled to be communicated with the charging current transmission line; the controller keeps the high-level state of the first IO port until detecting that the charging current is close to zero, sets the first IO port to be low-potential, enables the AND gate to output low-level, controls the power switch to cut off the charging current transmission line, and enables the charging column to be uncharged.
Preferably, a magnet is arranged in the charging base, the magnetism of the magnet is opposite to that of a magnet arranged in the electronic product, and when the electronic product is placed on the charging base, the electronic product is attracted with the charging base so as to prevent the electronic product from falling from the charging base.
Compared with the prior art, the invention has the advantages and positive effects that: the charging base can control the charging post on the charging base to be uncharged when no electronic product is put in, and automatically restore the charging state of the charging post when the electronic product is put on the charging base, so that the normal charging function of the charging base on the electronic product can be ensured, the short circuit fault easily caused by the charging of the charging post of the charging base can be avoided when no electronic product is put in, the potential safety hazard of the charging base is effectively eliminated, and the use safety and reliability of the charging base are improved. Meanwhile, the charging base can automatically cut off power after the electronic product is fully charged, so that the electronic product is prevented from being overcharged and damaged, and the electronic product is protected.
Other features and advantages of the present invention will become more apparent from the following detailed description of embodiments of the present invention, which is to be read in connection with the accompanying drawings.
Drawings
FIG. 1 is a schematic diagram of one embodiment of a prior art charging base for a smart watch or smart bracelet;
FIG. 2 is a schematic block circuit diagram of one embodiment of a self-protection circuit for a charging dock in accordance with the present invention;
fig. 3 is a schematic block circuit diagram of another embodiment of a self-protection circuit for a charging base according to the present invention.
Detailed Description
The following describes the embodiments of the present invention in further detail with reference to the drawings.
In order to add a self-protection function on the charging base, the charging post on the charging base can be in an uncharged state when no electronic product is placed on the charging base, so as to prevent short circuit fault, and a self-protection circuit is additionally arranged in the charging base, as shown in fig. 2, the charging base comprises main components of a hall element K, an AND gate U1, a power switch Q1, a controller MCU and the like. In order to detect the placement state of an electronic product by matching with the charging base of the embodiment, a magnet needs to be additionally arranged in the electronic product, when the electronic product approaches the charging base, the magnet in the electronic product can cause the magnetic field around the charging base to change, and the Hall element K distributed in the charging base is utilized to induce the magnetic field to change, so that the sensing of the charging base to the approaching state of the electronic product is realized.
In this embodiment, the hall element K may change its own state according to a magnetic field change, for example, when the proximity of the magnet is sensed, the hall element K is set to a second state (for example, a state in which a switch is closed or a high level is output, etc.); when the magnet is sensed to be away from or absent, the hall element K is set to a first state (e.g., a state in which the switch is off or outputs a low level, etc.). The hall element K is connected to the first input terminal IN1 of the and gate U1, and the configuration of the high-low level state on the first input terminal IN1 of the and gate U1 is realized by using the state change of the hall element K or further matching with the controller MCU.
One path of IO port, such as a first IO port IO1, of the controller MCU is connected to a second input end IN2 of the AND gate U1, and the high-low level state of the first IO port IO1 is configured by the controller MCU. The AND gate U1 outputs a high level when the first input end IN1 and the second input end IN2 of the AND gate U receive the high level; and outputs a low level when the first input terminal IN1 or the second input terminal IN2 is a low level.
The output end of the AND gate U1 is connected to the power switch Q1, the power switch Q1 is connected to a charging current transmission line in the charging base, the charging current transmission line is connected with a charging column of the charging base, and the charging column is preferably an anode charging column J+, so that the on-off state of the power switch Q1 can be changed by using the high and low levels output by the AND gate U1, and then the power switch Q1 is used for controlling the charging current transmission line to be connected or disconnected, so that the aim of changing the charging state of the charging column J+ is fulfilled.
Be provided with the USB interface on charging the base, preferably Micro USB interface utilizes Micro USB interface connection USB data line to connect outside master device through the USB data line, can utilize the charging source VBUS that master device provided to charge for the electronic product of placing on charging the base from this. Of course, the Micro USB interface can be externally connected with the power adapter to receive the charging power VBUS provided by the power adapter, so as to charge the electronic product placed on the charging base.
The charging power supply VBUS is connected to the charging base through a power pin of the Micro USB interface, and on one hand, the charging power supply VBUS supplies power to the controller MCU, so that the controller MCU starts to operate after the charging base is electrified; on the other hand, in the on state of the power switch Q1, the current is transmitted to the positive charging post j+ via the charging current transmission line, and the negative charging post J-is grounded together with the grounding pin of the Micro USB, so as to charge the charging post of the charging base.
In order to control the charging posts J+ and J-of the charging base to be uncharged when no electronic product is placed on the charging base, the embodiment configures the controller MCU to detect the level state of the Hall element K after power-on operation. If it is detected that the hall element K is switched from the first state to the second state, for example, from a default open state to a closed state, the state switching occurs, in which case, before the charging base is powered on, the electronic product is already placed on the charging base, and after the hall element K is powered on, the state is switched from the default open state to the closed state; in another case, when the hall element K detects that the electronic product approaches the charging base during the power-on standby process of the charging base, the state of the hall element K is switched from the open state to the closed state. When the controller MCU detects that the Hall element K is switched from the first state to the second state, the first IO port IO1 of the controller MCU is set to be at a high level, the first input end IN1 of the AND gate U1 is set to be at a high level through the Hall element K, and the second input end IN2 of the AND gate U1 is connected with the first IO port IO1 of the controller MCU, so that the second input end IN2 of the AND gate U1 is also at a high level. At this time, the AND gate U1 outputs a high level, controls the power switch Q1 to be turned on, and is communicated with a charging current transmission line connected between a power pin of the Micro USB interface and the positive charging post J+, so that the charging post J+ and J-are charged to charge an electronic product placed on the charging base. The controller MCU keeps the high level state of the first IO port IO1 until the Hall element K is switched to a first state, such as an off state, which indicates that the electronic product is removed, at the moment, the first input end IN1 of the AND gate U1 is low level, the AND gate U1 outputs low level, the power switch Q1 is controlled to be disconnected, and the charging current transmission line is cut off, so that the charging column J+ and J-is not electrified when no electronic product exists on the charging base.
If the state change of the hall element K from the first state to the second state is not detected after the controller MCU is powered on and operates, the first IO port IO1 of the hall element K may be set to a low level, so as to ensure that the charging posts j+ and J-of the charging base are not charged.
In order to realize accurate detection of state switching of the hall element K by the controller MCU, the following two preferred circuit designs are proposed for the hall element K in this embodiment.
As a first preferred circuit design of the hall element K, as shown in fig. 2, the hall element K includes two hall switches K1, K2, and the two hall switches K1, K2 are closed (second state) when the proximity of the magnet is sensed, and open (first state) when the proximity of the magnet is not sensed. The first Hall switch K1 is connected between a first IO port IO1 of the controller MCU and a first input end IN1 of the AND gate U1, and the second Hall switch K2 is connected between a second IO port IO2 and a third IO port IO3 of the controller MCU.
After the controller MCU is powered on and operates, the second IO port IO2 is set to be at a high level, and the second IO port IO2 is kept to output the high level all the time. Then, the controller MCU detects the level state of the third IO port IO3, if the level state of the third IO port IO3 jumps from the default low level to the high level, the second Hall switch K2 is switched from the open state to the closed state, and the electronic product is placed on the charging base. At this time, the controller MCU outputs a high level through the first IO port IO1 thereof, and sets the potential of the second input terminal IN2 of the and gate U1 to be high. Meanwhile, since the first hall switch K1 is also IN the closed state due to sensing the magnet IN the electronic product, the high level output by the controller MCU through the first IO port IO1 thereof is transmitted to the first input terminal IN1 of the and gate U1 via the first hall switch K1. At this time, the AND gate U1 outputs a high level, controls the power switch Q1 to switch on the charging current transmission line, charges the charging column J+, J-, and charges the electronic product by using the charging power supply VBUS.
If no electronic product is on the charging base, the first hall switch K1 is turned off, the first input terminal IN1 of the and gate U1 is at a low potential, at this time, the and gate U1 outputs a low level, and the power switch Q1 is controlled to cut off the charging current transmission line, so that the charging column j+ and J-are not charged, and short-circuit faults are prevented.
Therefore, the design purpose that the charging column J+ and J-on the charging base are not electrified when no electronic product is put in is achieved, and the charging column J+ and J-on the charging base only recover the electrified state when the electronic product is put in.
As a second preferred circuit design of the hall element K, as shown IN fig. 3, the hall element K includes a hall switch K3, the hall switch K3 is connected between the charging source VBUS and the first input terminal IN1 of the and gate U1, the first input terminal IN1 of the and gate U1 is connected to the second IO port IO2 of the controller MCU, the second input terminal IN2 of the and gate U1 is connected to the first IO port IO1 of the controller MCU, and the output terminal of the and gate U1 is connected to the power switch Q1.
After the charging base is connected with the charging power supply VBUS, the controller MCU is electrified to run, and the level state of the second IO port IO2 is detected. If the electronic product is put into the charging base, the Hall switch K3 is switched from an open state (a first state) to a closed state (a second state). At this time, the controller MCU detects that the second IO port IO2 jumps from the default low level to the high level, and controls the first IO port IO1 to output the high level, so that the potential of the second input terminal IN2 of the and gate U1 is high. Meanwhile, as the hall switch K3 is closed, the charging power supply VBUS acts on the first input end IN1 of the and gate U1 through the hall switch K3, so that the potential of the first input end IN1 of the and gate U1 is high, then the and gate U1 is controlled to output a high level, the charging current transmission line is controlled to be connected by the power switch Q1, and the charging posts j+, J-are charged, so that the electronic product can be charged by using the charging power supply VBUS.
If no electronic product is on the charging base, the hall switch K3 is turned off, the first input terminal IN1 of the and gate U1 is at a low potential, at this time, the and gate U1 outputs a low level, and the power switch Q1 is controlled to cut off the charging current transmission line, so that the charging column j+ and J-is not charged, and short-circuit fault is prevented.
Therefore, the design purpose that the charging column J+ and J-on the charging base is not electrified when no electronic product is put in the charging base, and the electrified state of the charging column J+ and J-is restored only when the electronic product is put in the charging base can be realized.
In order to further achieve the purpose that after the electronic product is fully charged, the charging base is automatically powered off, so as to prevent the electronic product from being damaged due to overcharging, in this embodiment, a current detection circuit A1 may be further disposed in the charging current transmission line of the charging base, as shown in fig. 2 and 3, and is connected to the controller MCU, so as to detect the magnitude of the charging current.
As a preferred circuit design of the current detection circuit A1, a sampling resistor R may be connected in series in the charging current transmission line, and the controller MCU may be used to detect the potential difference between two ends of the sampling resistor R, and calculate the magnitude of the charging current in combination with the resistance value of the sampling resistor R.
The design control strategy is as follows:
for the circuit design of the hall element K shown in fig. 2, after the controller MCU is powered on and operates, the second IO port IO2 is first set to be at a high level, and the second IO port IO2 is kept to output a high level all the time. Then, the controller MCU detects the level state of the third IO port IO3, if the level state of the third IO port IO3 jumps from the default low level to the high level, the second Hall switch K2 is switched from the open state to the closed state, and the electronic product is placed on the charging base. At this time, the controller MCU outputs a high level through the first IO port IO1 thereof, and sets the potential of the second input terminal IN2 of the and gate U1 to be high. Meanwhile, since the first hall switch K1 is also IN the closed state due to sensing the magnet IN the electronic product, the high level output by the controller MCU through the first IO port IO1 thereof is transmitted to the first input terminal IN1 of the and gate U1 via the first hall switch K1. At this time, the AND gate U1 outputs a high level, controls the power switch Q1 to switch on the charging current transmission line, charges the charging column J+, J-, and charges the electronic product by using the charging power supply VBUS.
The controller MCU maintains the high level state of the first IO port IO1 of the controller MCU, and simultaneously detects the magnitude of the charging current through the current detection circuit. If the charging current is larger and is higher than a preset current minimum value Io (the current minimum value Io can be determined according to the leakage current of the system, for example, io=5ma is set), the charging process of the electronic product is indicated, the controller MCU continuously outputs a high level through the first Io port Io1 thereof, the connection state of the charging current transmission line is maintained, and the continuous charging process is ensured. If the charging current becomes smaller, close to zero, for example, lower than the preset current minimum value Io, the electronic product is considered to be fully charged. At this time, the controller MCU may set the first IO port IO1 thereof to be at a low potential, so that the and gate U1 outputs a low level, and further control the power switch Q1 to cut off the charging current transmission line, so that the charging column j+ and J-of the charging base are not charged, and the charging process of the electronic product is terminated, thereby preventing overcharging of the electronic product.
When the electronic product is fully charged and is taken down from the charging base, the first Hall switch K1 and the second Hall switch K2 are disconnected, the first IO port IO1 of the controller MCU is kept to be low potential, the potential of the third IO port IO3 of the controller MCU is restored to be default low potential, and the electronic product entering the next round is put into a detection process.
If the electronic product is IN the normal charging process, the user suddenly removes the electronic product from the charging base, at this time, the first IO port IO1 of the controller MCU still outputs a high level, but the first hall switch K1 is turned off, so that the first input terminal IN1 of the and gate U1 is low, the and gate U1 outputs a low level, the power switch Q1 is controlled to cut off the charging current transmission line, and the charging column j+ and J-of the charging base are switched to an uncharged state, so that the potential safety hazard of the charging base is eliminated. Meanwhile, as the charging current transmission line is disconnected, the charging current detected by the current detection circuit is zero and lower than the preset current minimum value Io, the first IO port IO1 of the controller MCU is set to be low, and three IO ports IO1, IO2 and IO3 of the controller MCU are restored to a default level state.
Therefore, the design purposes that the charging column J+ and J-on the charging base are not electrified when no electronic product is put in, the charging column J+ and J-is restored to an electrified state when the electronic product is put in on the charging base, and the charging base is automatically powered off after the electronic product is fully charged are achieved.
For the circuit design of the hall element shown in fig. 3, after the charging base is connected to the charging power supply VBUS, the controller MCU is powered on to operate, sets the first IO port IO1 of the controller MCU to be in a default low-level state, and detects the level state of the second IO port IO2 of the controller MCU. If the electronic product is put into the charging base, the Hall switch K3 is switched from an open state (a first state) to a closed state (a second state). At this time, the controller MCU detects that the second IO port IO2 jumps from the default low level to the high level, and controls the first IO port IO1 to output the high level, so that the potential of the second input terminal IN2 of the and gate U1 is high. Meanwhile, as the hall switch K3 is closed, the charging power supply VBUS acts on the first input end IN1 of the and gate U1 through the hall switch K3, so that the potential of the first input end IN1 of the and gate U1 is high, then the and gate U1 is controlled to output high level, the power supply switch Q1 is controlled to switch on the charging current transmission line, the charging post j+ and J-are charged, and the charging power supply VBUS is used for charging electronic products.
The controller MCU maintains the high level state of the first IO port IO1 of the controller MCU, and simultaneously detects the magnitude of the charging current through the current detection circuit. If the charging current is larger and is higher than the preset current minimum value Io, the electronic product is in the charging process, the controller MCU continuously outputs a high level through the first IO port IO1 of the controller MCU, the communication state of the charging current transmission line is maintained, and the continuous charging process is ensured. If the charging current becomes smaller and is close to zero, for example, lower than a preset current minimum value Io, it is determined that the electronic product is fully charged. At this time, the controller MCU sets the first IO port IO1 to be low potential, so that the AND gate U1 outputs low level, and then the power switch Q1 is controlled to cut off the charging current transmission line, so that the charging posts J+ and J-of the charging base are not charged any more, the charging process of the electronic product is finished, and the overcharge protection is realized on the electronic product.
When the electronic product is fully charged and is taken down from the charging base, the Hall switch K3 is disconnected, the first IO port IO1 of the controller MCU is kept at low potential, the potential of the second IO port IO2 of the controller MCU is restored to be the default low potential, and the electronic product of the next round enters the detection process.
If the electronic product is IN the normal charging process, the user suddenly removes the electronic product from the charging base, at this time, the first IO port IO1 of the controller MCU still outputs a high level, but the hall switch K3 is turned off, so that the first input terminal IN1 of the and gate U1 is low, the and gate U1 outputs a low level, the power switch Q1 is controlled to cut off the charging current transmission line, and the charging column j+ J-of the charging base is switched to an uncharged state, so that the potential safety hazard of the charging base is eliminated. Meanwhile, as the charging current transmission line is disconnected, the charging current detected by the current detection circuit is zero and lower than the preset current minimum value Io, the first IO port IO1 of the controller MCU is set to be low, and the two IO ports IO1 and IO2 of the controller MCU are restored to a default low-level state.
Therefore, the design purposes that the charging column J+ and J-on the charging base are not electrified when no electronic product is put in, the charging column J+ and J-is electrified when the electronic product is put in on the charging base, and the charging base is automatically powered off after the electronic product is fully charged can also be realized.
In this embodiment, the power switch Q1 may be implemented by using a switching device such as an NMOS transistor or a thyristor. Taking an NMOS tube as an example for illustration, the source electrode of the NMOS tube Q1 can be connected to the positive charging post J+ of the charging base, the drain electrode of the NMOS tube Q1 is communicated with the power pin of the Micro USB interface through the current detection circuit, and the grid electrode of the NMOS tube Q1 is connected with the output end of the AND gate U1. When the AND gate U1 outputs a high level, the NMOS tube Q1 is saturated and conducted, and a charging current transmission line between the positive charging column J+ and a power supply pin of the Micro USB interface is communicated, so that the positive charging column J+ is electrified; when the AND gate U1 outputs a high level, the NMOS tube Q1 is cut off, and a charging current transmission line between the positive charging column J+ and a power supply pin of the Micro USB interface is cut off, so that the positive charging column J+ is not electrified.
In order to clearly indicate the working state of the charging base, the embodiment is further provided with an indicator light module in the charging base, as shown in fig. 2 and 3. A charge indicator LED2 (e.g. a green light emitting diode) and a power down indicator LED1 (e.g. a red light emitting diode) may be provided in the indicator module. And the anodes of the charge indicator LED2 and the power-off indicator LED1 are respectively connected with a fourth IO port IO4 and a fifth IO port IO5 of the controller MCU in a one-to-one correspondence manner, and the cathodes of the charge indicator LED2 and the power-off indicator LED1 are grounded. When the controller MCU detects that the charging current is close to zero (namely, lower than the current minimum value Io), a high level is output through the fifth IO port IO5, and the fourth IO port IO4 is juxtaposed to be low level, at the moment, the outage indicator lamp LED1 is turned on, the charging indicator lamp LED2 is turned off, and the charging column J+ and J-of the current charging base are indicated to be uncharged. Otherwise, when the controller MCU detects that the charging current is greater than the current minimum value Io, the electronic product is in a charging state. At this time, the controller MCU outputs a high level through the fourth IO port IO4 and is juxtaposed with the fifth IO port IO5 to be a low level, controls the power-off indicator light LED1 to be turned off, and the charging indicator light LED2 to be turned on, so as to indicate that the charging column J+ and J-of the current charging base are charged.
In addition, in order to improve the accuracy and sensitivity of the detection of the electronic product placed on the charging base, the embodiment preferably arranges the hall element K between the positive charging post j+ and the negative charging post J-of the charging base, and arranges the magnet in the electronic product between the positive charging electrode pin+ and the negative charging electrode PIN-of the electronic product.
Meanwhile, magnets can be arranged in the charging base, and the magnetism of the magnets is opposite to that of magnets arranged in the electronic product. Therefore, when the electronic product is placed on the charging base, the stability of the electronic product placed on the charging base can be improved by utilizing the attraction effect of the magnets arranged in the electronic product and the charging base, so that the electronic product is prevented from falling from the charging base. The design is particularly suitable for being applied to a charging base matched with a smart watch (or a smart bracelet).
It should be understood that the above description is not intended to limit the invention to the particular embodiments disclosed, but to limit the invention to the particular embodiments disclosed, and that other variations, modifications, additions and substitutions are possible, without departing from the scope of the invention as disclosed in the accompanying claims.
Claims (10)
1. The self-protection circuit for the charging base is used for charging an electronic product with a built-in magnet; characterized by comprising the following steps:
a charging post for contacting a charging electrode on the electronic product to deliver a charging current to the electronic product;
a power switch connected in a charging current transmission line connected with the charging post;
the AND gate comprises a first input end, a second input end and an output end, wherein the output end is connected with the power switch and used for controlling the on-off of the power switch;
a current detection circuit connected to the charging current transmission line for detecting the magnitude of the charging current;
a hall element that senses a change in a magnetic field caused by the magnet, and that is set to a first state when the magnet is not sensed, and that is set to a second state when the magnet is sensed; the Hall element is connected with the first input end of the AND gate;
a controller connected to the current detection circuit and detecting a change in the charging current; a first IO port of the controller is connected with a second input end of the AND gate; when the controller detects that the Hall element is switched from a first state to a second state, the first IO port is set to be at a high level, the first input end of the AND gate is set to be at a high level through the Hall element, so that the AND gate outputs a high level, and the power switch is controlled to be communicated with the charging current transmission line; the controller keeps the high-level state of the first IO port until detecting that the charging current is close to zero, sets the first IO port to be low-potential, enables the AND gate to output low-level, controls the power switch to cut off the charging current transmission line, and enables the charging column to be uncharged.
2. The self-protection circuit for a charging base of claim 1, wherein the hall element comprises a first hall switch and a second hall switch, a first state of the first hall switch and the second hall switch being an open state, a second state being a closed state; the first Hall switch is connected in series between a first IO port of the controller and a first input end of the AND gate, and the second Hall switch is connected between a second IO port and a third IO port of the controller; and when the level state of the third IO port is changed from low to high, the controller sets the first IO port to be high, keeps the high level state of the first IO port until detecting that the charging current is close to zero, and sets the first IO port to be low.
3. The self-protection circuit for a charging base of claim 1, wherein the hall element is a hall switch, a first state of the hall switch being an open state and a second state being a closed state; the Hall switch is connected in series between the charging power supply and the first input end of the AND gate, the first input end of the AND gate is connected with the second IO port of the controller, and when the controller detects that the level state of the second IO port is changed from low to high, the controller sets the first IO port to be high level, keeps the high level state of the first IO port until detecting that the charging current is close to zero, and sets the first IO port to be low level.
4. The self-protection circuit for a charging dock of claim 3, wherein the charging power source is accessed by a USB interface of the charging dock.
5. The self-protection circuit for a charging base according to claim 1, wherein the power switch is an NMOS transistor, a source and a drain of the NMOS transistor are connected in the charging current transmission line, and a gate of the NMOS transistor is connected to an output terminal of the and gate.
6. The self-protection circuit for a charging base of claim 1, wherein the hall element is disposed between a positive charging post and a negative charging post of the charging base; the magnet is arranged between a positive charging electrode and a negative charging electrode of the electronic product.
7. The self-protection circuit for a charging dock of any one of claims 1 to 6, wherein the current detection circuit and power switch are connected between a power pin of a USB interface of the charging dock and a positive charging post of the charging dock.
8. The self-protection circuit for a charging base according to any one of claims 1 to 6, further comprising a charging indicator light and a power-off indicator light, anodes of the charging indicator light and the power-off indicator light being respectively connected with a fourth IO port and a fifth IO port of the controller, cathodes of the charging indicator light and the power-off indicator light being grounded;
when the controller detects that the charging current is close to zero, a high level is output through the fifth IO port, and the power-off indicator lamp is controlled to be lightened; otherwise, outputting high level through the fourth IO port, and controlling the charging indicator lamp to be lightened.
9. A charging base comprising a self-protection circuit for a charging base as claimed in any one of claims 1 to 8.
10. The charging base of claim 9, wherein magnets are disposed in the charging base, the magnets having a magnetic property opposite to that of magnets disposed in the electronic product, the electronic product being attracted to the charging base when the electronic product is placed on the charging base.
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| CN109450035B true CN109450035B (en) | 2024-01-26 |
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| CN111555383A (en) * | 2020-04-22 | 2020-08-18 | 宁波吉利汽车研究开发有限公司 | Vehicle-mounted charging device and charging method |
| CN111697655A (en) * | 2020-06-18 | 2020-09-22 | 东莞新能安科技有限公司 | Electrochemical device and battery charge-discharge control system |
| CN112260357A (en) * | 2020-10-14 | 2021-01-22 | 卢祖雄 | External equipment of charger |
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