TWI698066B - Charging load detection circuit - Google Patents

Abstract

A charging load detection circuit includes a charging circuit, a frequency generation unit, and a control unit. The control unit controls the frequency generation unit to generate a pulse voltage with a fixed first frequency and a first amplitude, and the frequency generation unit provides the pulse voltage to an output end of the charging circuit. The control unit detects whether a load is coupled to the output end by detecting the first frequency and the first amplitude of the pulse voltage, and controls a charging path of the charging circuit to be short-circuit or open-circuit according to whether the load is coupled to the output end.

Description

Charging load detection circuit

The present invention relates to a charging load detection circuit, in particular to a charging load detection circuit that uses low-current pulse wave voltage to detect load types and load states.

In today's society, more and more batteries inside electronic products are used to maintain the power required for the operation of electronic products. Therefore, when the battery is dead, the charging technology of the charger must be used to charge the battery. However, because batteries are used in a wide range of fields and the types of battery management system functions used in each field are different, the charger must be able to recognize the state of the battery and give the correct charging mode, and also be able to respond to other Connect equipment, such as charging stations or other power supply requirements.

In the current charger industry, battery chargers need to use an internal controller to provide more than one additional pin to detect and display whether the battery is coupled to the charger and the type of battery. Virtually makes the charger in the no-load condition, the controller must continue to consume energy to perform battery detection, which increases the power consumption of the charger, so it cannot meet the low power consumption of the new US/European energy regulations or customer specifications Claim.

Therefore, how to design a charging load detection circuit to detect and display whether the battery is coupled to the charger and the type of battery, so that the controller inside the charger does not need to provide additional pins for battery detection. This is the author of this case A major topic for research.

In order to solve the above-mentioned problems, the present invention provides a charging load detection circuit to overcome the problems of the prior art. Therefore, the charging load detection circuit of the present invention includes a charging circuit, which provides a charging path including an input terminal and an output terminal, and the input terminal is coupled to the charger. The frequency generating unit is coupled to the output terminal through the charging path. And a control unit, coupled to the charging circuit and the frequency generating unit. Wherein, the control unit controls the frequency generating unit to generate a pulse voltage with a fixed first frequency and first amplitude, and the frequency generating unit provides the pulse voltage to the output terminal; the control unit detects the first frequency and the first amplitude of the pulse voltage Whether to change or not to know whether a load is coupled to the output terminal, and to control the short-circuit or open-circuit charging path according to whether the load is coupled to the output terminal.

In order to further understand the technology, means and effects of the present invention to achieve the intended purpose, please refer to the following detailed description and drawings of the present invention. I believe that the purpose, features and characteristics of the present invention can be obtained from this For specific understanding, the accompanying drawings are only provided for reference and illustration, and are not intended to limit the present invention.

100: Charging load detection system

1: charger

2. 2’: Charging load detection circuit

20: Charging circuit

202: Input

204: output

206: charging path

206-1: The first switch

206-A: The first drive unit

D1: junction diode

206-2: The second switch

206-B: second drive unit

208: output detection circuit

22: Frequency generating unit

220: third switch

222: third drive unit

24: control unit

3: load

Vp: pulse voltage

Vin: input voltage

Vo: output voltage

Io: charging current

T1~T4: interval

t1~t4: time

Fig. 1 is a block diagram of the charging load detection system of the present invention; Fig. 2A is a circuit diagram of the first embodiment of the charging load detection circuit of the present invention; Fig. 2B is a circuit diagram of the second embodiment of the charging load detection circuit of the present invention; Fig. 3A is the present invention The output voltage waveform diagram of the charging load detection circuit coupled to the battery with sleep mode; FIG. 3B is the output voltage waveform diagram of the battery for coupling the charging load detection circuit of the present invention; Fig. 3C is a waveform diagram of the output voltage of the charging load detection circuit of the present invention coupled to a fully charged battery; Fig. 3D is a waveform diagram of the output voltage of the charging load detection circuit of the present invention with a fully charged battery removed; Fig. 4A is a charging load detection circuit of the present invention coupled to charging The output voltage waveform diagram of the station; and FIG. 4B is the output voltage waveform diagram of the charging station removed from the charging load detection circuit of the present invention.

The technical content and detailed description of the present invention are described below with the drawings.

Please refer to FIG. 1 for a block diagram of the charging load detection system of the present invention. The charging load detection system 100 includes a charger 1 and a charging load detection circuit 2. The charger 1 is coupled to the charging load detection circuit 2, and the charging load detection circuit 2 detects whether the back end is coupled to the load 3. The charging load detection circuit 2 includes a charging circuit 20, a frequency generating unit 22 and a control unit 24. The charging circuit 20 provides a charging path 206 including an input terminal 202 and an output terminal 204, and the input terminal 202 is coupled to the charger 1. The frequency generating unit 22 is coupled to the output terminal 204 through the charging path 206, and the control unit 24 is coupled to the charging circuit 20 and the frequency generating unit 22.

Specifically, the control unit 24 controls the frequency generating unit 22 to generate a pulse voltage Vp with a fixed first frequency (for example, but not limited to, 100 Hz) and a first amplitude (for example, but not limited to, 16 volts), and the frequency generating unit 22 will The pulse voltage Vp is provided to the output terminal 204. The current value of the charging current Io provided by the output terminal 204 is less than 1 milliampere. Therefore, the internal controller of the charger 1 (not shown) does not need to add an additional pin to detect the charging state of the load. In this way, by using the charging load detection circuit 2 to provide a low current pulse voltage Vp, it is possible to know whether the load 3 is coupled or not, and the type of the load 3. Control unit 24 passes It is detected whether the first frequency and the first amplitude of the pulse voltage Vp are changed to determine whether the load 3 is coupled to the output terminal 204, and the charging path 206 is controlled to be short-circuited or disconnected according to whether the load 3 is coupled to the output terminal 204. When the first frequency and the first amplitude of the pulse voltage Vp remain unchanged, it means that the load 3 is not coupled to the output terminal 204. When the first frequency and the first amplitude of the pulse voltage Vp change, it means that a load 3 is coupled to the output terminal 204. At this time, the control unit 24 determines the type of the load 3 according to the voltage waveform of the output terminal 204, and further controls the charging mode of the charging load detection circuit 2 according to the type of the load 3.

Please refer to FIG. 2A for the circuit diagram of the charging load detection circuit of the present invention. The charging path 206 includes a first switch 206-1 and a second switch 206-2. The first switch 206-1 is coupled to the input terminal 202 and the control unit 24, and the first switch 206-1 is connected to the charging path 206 in series. The second switch 206-2 is coupled to the first switch 206-1, the control unit 24 and the output terminal 204, and the second switch 206-2 is connected to the charging path 206 in series. The control unit 24 is coupled to the first switch 206-1 through the first driving unit 206-A, and is coupled to the second switch 206-2 through the second driving unit 206-B. Specifically, when the control unit 24 wants to control to turn on the first switch 206-1, the control unit 24 controls the first driving unit 206-A to not couple the control terminal of the first switch 206-1 to the ground point, so that the first The switch 206-1 is turned on. Otherwise, the first switch 206-1 is not turned on. It is worth mentioning that the same is true for the second driving unit 206-B. Furthermore, the second switch 206-2 controls the short-circuit and disconnection of the charging path 206. When the control unit 24 controls the second switch 206-2 to be non-conductive, the charging path 206 is disconnected, so that the charger 1 is not coupled to the load 3. When the control unit 24 controls the second switch 206-2 to be turned on, the charging path 206 is short-circuited, so that the charger 1 is coupled to the load 3.

The frequency generating unit 22 includes a third switch 220, the third switch 220 is coupled to the control unit 24, and the third switch 220 is connected in parallel with the second switch 206-2. The control unit 24 is coupled to the third switch 220 through the third driving unit 222, and is coupled to the third switch 220 through the third driving unit 222. Specifically, when the control unit 24 wants to control the third switch 220 to be turned on, the control unit 24 controls the third driving unit 222 to disconnect the control terminal of the third switch 220 to the ground point, so that the third switch 220 is turned on. Otherwise, the third switch 220 is not turned on. Specifically, the control unit 24 turns on or off the third switch 220 to produce Generate pulse voltage Vp. When the control unit 24 switches on the third switch 220, the input voltage Vin of the input terminal 202 is provided to the output terminal 204 through the junction diode D1 of the first switch 206-1 and the path of the third switch 220. When the control unit 24 switches off the third switch 220, the input voltage Vin of the input terminal 202 cannot be provided to the output terminal 204 through the junction diode D1 of the first switch 206-1 and the third switch 220. At this time, through the conduction or non-conduction of the third switch 220, the output terminal 204 generates a low current pulse voltage Vp with a fixed first frequency and a first amplitude. Furthermore, when the control unit 24 controls the charging path 206 to be short-circuited, it means that the output terminal 204 is coupled to the load 3. At this time, the control unit 24 still controls the third switch 220 to switch on to continuously detect whether the load 3 is removed.

The charging circuit 20 further includes an output detection circuit 208, which is coupled between the output terminal 204 and the ground point to detect the voltage change of the output voltage Vo at the output terminal 204. The control unit 24 learns the voltage change of the output voltage Vo according to the output detection circuit 208 to control the conduction or non-conduction of the first switch 206-1, the second switch 206-2 and the third switch 220.

Please refer to FIG. 2B for the circuit diagram of the second embodiment of the charging load detection circuit of the present invention, and refer to 1~2A for compound coordination. The difference between the charging load detection circuit 2'of this embodiment and the charging load detection circuit 2 of FIG. 2A is that the third switch 220 is connected in parallel with the first switch 206-1 and the second switch 206-2. This means that one end of the third switch 220 is coupled to one end of the first switch 206-1, the other end of the third switch 220 is coupled to one end of the second switch 206-2, and the control end of the third switch 220 is coupled to the first switch One end of 206-1 connects the input voltage Vin of the input terminal 202 across the first switch 206-1 and the second switch 206-2. When the control unit 24 switches on the third switch 220, the input voltage Vin of the input terminal 202 is provided to the output terminal 204 through the path of the third switch 220. When the control unit 24 switches off the third switch 220, the input voltage Vin of the input terminal 202 cannot be provided to the output terminal 204 through the path of the third switch 220. At this time, through the conduction or non-conduction of the third switch 220, the output terminal 204 generates a low current pulse voltage Vp with a fixed first frequency and a first amplitude. It is worth mentioning that, except that the connection mode of the third switch 220 is different from that of FIG. 2A, the other element coupling modes and control modes are the same as those of FIG. 2A.

Please refer to FIG. 3A for the output voltage waveform diagram of the charging load detection circuit of the present invention coupled to the battery with sleep mode, and refer to 1~2B for compound coordination. In the interval T1 of FIG. 3A, since the load 3 is not yet coupled to the charging load detection circuit 2, the output voltage Vo is a pulse voltage Vp with a fixed first frequency and a first amplitude. At time t1, the battery with the sleep mode (that is, the load 3) is coupled to the charging load detection circuit 2, so the pulse voltage Vp of the output voltage Vo changes. Since the battery with sleep mode needs a trigger voltage (for example, but not limited to 5 volts) to wake up the battery, in interval T2, the pulse voltage Vp is provided to the battery with sleep mode, and the trigger voltage (with sleep mode) is gradually established. The battery usually uses a capacitive element to establish a trigger voltage), so that the voltage value of the output voltage Vo gradually rises, and a voltage waveform that increases in a capacitive charging curve is generated. The interval T2 is the first determination period (for example, but not limited to, 400 milliseconds) for the control unit 24 to determine whether the load 3 is coupled to the charging load detection circuit 2 and to determine the type of the load 3.

At time t2, the control unit 24 determines that the load 3 is a battery with a sleep mode, and the control unit 24 notifies the charger 1 so that the charger 1 performs a pre-charge mode on the load 3 (pre-charge mode). At this time, the control unit 24 controls to turn on the first switch 206-1 and the second switch 206-2, so that the charger 1 provides an output voltage Vo and a charging current Io (for example, but not limited to, a voltage value of 29 volts and a current value of 1 ampere) To load 3. In the interval T3, the voltage value of the battery gradually increases from a low voltage value (for example, but not limited to, 19 volts) to a wake-up value (for example, but not limited to, 23 volts). When the voltage value of the battery is greater than or equal to the wake-up value (time t3), the battery is awakened, so that after interval T3, the charger 1 charges the battery in a constant-current charging mode (Constant-Current mode, CC mode) (that is, charging The current Io gradually rises to a constant value).

Please refer to FIG. 3B for the output voltage waveform diagram of the battery for coupling the charging load detection circuit of the present invention, and refer to 1~3A for complex coordination. In the interval T1 of FIG. 3B, since the load 3 is not yet coupled to the charging load detection circuit 2, the output voltage Vo is a pulse voltage Vp with a fixed first frequency and a first amplitude. At time t1, the universal battery (that is, the load 3) is coupled to the charging load detection circuit 2, so the pulse voltage Vp of the output voltage Vo changes. The universal battery is the battery without sleep mode, so at time t1, the output The voltage of the output voltage Vo is changed from the pulse voltage Vp to the voltage value of the battery (increased to a fixed value, but not fully charged). The control unit 24 obtains a voltage waveform whose voltage value of the battery is approximately a fixed value (including loss) through the first judgment period of the interval T2, and judges that the load 3 is a general-purpose battery at time t2. The control unit 24 notifies the charger 1 to make the charger 1 perform the constant current charging mode for the load 3. At this time, the control unit 24 controls to turn on the first switch 206-1 and the second switch 206-2, so that the charger 1 uses a constant current The charging mode (CC mode) charges the battery (that is, the charging current Io gradually rises to a constant value).

Please refer to FIG. 3C for the output voltage waveform diagram of the charging load detection circuit of the present invention coupled to a fully charged battery. For details, refer to 1~3B. In the interval T1 of FIG. 3C, since the load 3 is not yet coupled to the charging load detection circuit 2, the output voltage Vo is the pulse voltage Vp with the first frequency and the first amplitude fixed. At time t1, the fully charged battery (that is, the load 3) is coupled to the charging load detection circuit 2, so the pulse voltage Vp of the output voltage Vo changes. The fully charged battery can be a battery with or without a sleep mode. At time t1, due to the full charge of the battery, the voltage of the output voltage Vo changes from the pulse voltage Vp to the voltage value of the battery (raising to the full charge value). The control unit 24 obtains a voltage waveform that the voltage value of the battery is substantially (including loss) showing a fully charged value through the first determination period of the interval T2, and determines that the load 3 is a fully charged battery at time t2. The control unit 24 notifies the charger 1 to make the charger 1 execute the low current charging mode for the load 3 (that is, the current value of the charging current Io is less than or equal to the threshold current value). At this time, the control unit 24 controls to turn on the first switch 206-1 and the second switch 206-2, so that the charger 1 charges the battery in a low current charging mode.

Furthermore, in the interval T3, the charger 1 continues to charge the load 3 in the low current charging mode (for example, but not limited to, the charging current Io is less than or equal to 0.25 amperes). Since the first switch 206-1 and the second switch 206-2 are still continuously conducting, when the fully charged battery is removed, the charger 1 still provides the output voltage Vo to the output terminal 204. In order to confirm whether the fully charged battery is removed, the control unit 24 controls the first switch 206-1 and the second switch 206-2 to enter a hiccup mode (hiccup mode) to determine whether the load 3 is removed. In the interval T3-1, the control unit 24 controls the first switch 206-1 and the second switch 206-2 to conduct, and in the interval T3-2, the control unit 24 controls the first switch 206-1 and the second switch 206- 2 unguided To continuously confirm whether the fully charged battery is still coupled to the charging load detection circuit 2. Since the fully charged battery is still coupled to the load, the voltage value of the output voltage Vo is the voltage value of the fully charged battery, so the voltage value of the output voltage Vo does not change. At this time, the control unit 24 determines that the fully charged battery is still coupled to charge Load detection circuit 2. Then, when the first switch 206-1 and the second switch 206-2 change from non-conduction to conduction, the charging current Io returns to the current value of the low-current charging mode (as shown in the interval T3-3).

Please refer to FIG. 3D for the output voltage waveform diagram of the charging load detection circuit of the present invention with the fully charged battery removed, and refer to 1~3C for compound coordination. In the blocking non-conduction mode (as shown in the interval T1), when the first switch 206-1 and the second switch 206-2 change from non-conduction to conduction, the voltage of the output voltage Vo is changed from the voltage value of the battery (current voltage When the value) drops to 0 volts (as shown at time t1), the control unit 24 learns that the fully charged battery may have been removed. At this time, since the control unit 24 must confirm whether the load 3 is removed, the control unit 24 obtains that the voltage value of the output terminal 204 is continuously less than or equal to the threshold voltage through the second judgment period (for example, but not limited to, 100 milliseconds) of the interval T2 value. At time t2, the control unit 24 determines that the fully charged battery is removed. At this time, the control unit 24 controls the first switch 206-1 and the second switch 206-2 to be non-conducting, and controls the third switch 220 to switch on, so that the interval After T3, the frequency generating unit 22 provides the pulse voltage Vp to the output terminal 204.

It is worth mentioning that in one embodiment of the present invention, when a battery that is not fully charged (a battery with or without a sleep mode) is removed, the charging current Io that is charging the battery will quickly drop to zero. The control unit 24 obtains a current waveform in which the charging current Io rapidly drops to zero through the second judgment period (for example, but not limited to, 100 milliseconds) of the interval T2. At time t2, the control unit 24 determines that the under-charged battery is removed. At this time, the control unit 24 controls the first switch 206-1 and the second switch 206-2 to be non-conducting, and controls the third switch 220 to be switched on. After the interval T3, the frequency generating unit 22 provides the pulse voltage Vp to the output terminal 204.

Please refer to FIG. 4A for the output voltage waveform diagram of the charging load detection circuit of the present invention coupled to the charging station. For details, please refer to 1~3D. In the interval T1 of FIG. 4A, since the load 3 is not yet coupled to the charging load The detection circuit 2, therefore, the output voltage Vo is a pulse voltage Vp with a fixed first frequency and a first amplitude. At time t1, the charging station (that is, the load 3) is coupled to the charging load detection circuit 2, so the pulse voltage Vp of the output voltage Vo changes. Since most of the input terminals of the charging station have capacitive or resistive elements, in the interval T2, the output voltage Vo generates a low-voltage fluctuating voltage waveform. The control unit 24 obtains the low-voltage fluctuating voltage waveform through the first judgment period of the interval T2, and judges that the load 3 is a charging station at time t2.

At time t2, the control unit 24 determines that the load 3 is a charging station, and the control unit 24 informs the charger 1 to make the charger 1 perform the POD mode on the load 3. At this time, the control unit 24 controls to turn on the second switch 206-2, and the first switch 206-1 is switched on or off. In the interval T3, the charger 1 provides the output voltage Vo to the charging station. At this time, since the first switch 206-1 is switched on, the input voltage Vin provided by the charger 1 can pass through the first switch 206-1 to the charging station , So that the voltage value of the output voltage Vo is a high-level voltage value (for example, but not limited to, a voltage value of 29 volts). When the first switch 206-1 is not conducting, the input voltage Vin provided by the charger 1 can only pass through the junction diode D1 of the first switch 206-1 to the charging station, so that the voltage value of the output voltage Vo is low The level voltage value (for example, but not limited to, the voltage value is 16 volts). Through the switching of the first switch 206-1 to be conductive or non-conductive, the output voltage Vo presents a voltage waveform with a fixed second frequency and a second amplitude. In this way, the output voltage Vo presents a voltage waveform with a fixed second frequency and a second amplitude, so that the control unit 24 can learn that the battery is connected to the charging station by changing the second amplitude of the voltage waveform. It is worth mentioning that since there is no battery access at this time, the charging station works at light load, and the charging current Io is low (for example, but not limited to, 1~2 mA).

Specifically, since the charging station has the lowest operating power, when the voltage value of the output voltage Vo provided by the output terminal 204 is lower than the lowest operating power, the charging station will stop operating. Therefore, the output voltage Vo provided by the output terminal 204 The voltage value must be higher than the minimum operating power (for example, 16 volts as described above). However, since the charging station does not contain a battery, when the charging station is coupled to the battery, if the voltage value of the battery exceeds the minimum operating power, a backflow phenomenon may occur. Therefore, in the first switch 206-1 cut When switching to non-conduction, the reverse bias of the junction diode D1 can prevent the voltage value of the battery from exceeding the minimum operating power and causing reverse flow.

Referring again to FIG. 4A, at time t3, the battery is connected to the charging station. At this time, the low-level voltage value will be pulled to the current voltage value of the battery, thereby changing the second amplitude of the voltage waveform. The control unit 24 obtains the voltage waveform changing the second amplitude through the third judgment period of interval T4 (for example, but not limited to, 200 milliseconds), and judges that the battery has been connected to the charging station at time t4. At this time, the control unit 24 controls the conduction The first switch 206-1 makes the charger 1 start to provide the charging current Io to charge the battery.

Please refer to FIG. 4B for the output voltage waveform diagram of the charging station removed from the charging load detection circuit of the present invention, and refer to 1~4A for compound coordination. In the interval T1, the output voltage Vo presents a voltage waveform with a fixed second frequency and a second amplitude, which means that the charging station is still coupled to the charging load detection circuit 2. At time t1, the charging station is removed, but since the voltage value of the output voltage Vo has not changed, the control unit 24 does not detect that the charging station has been removed. In interval T2, because the charging station is removed, the energy stored in the output voltage Vo at the high-level voltage value cannot be effectively consumed, causing the voltage waveform to drop when the control unit 24 controls the first switch 206-1 to not conduct The falling edge time of the edge is longer, and the slope is relatively gentle. Therefore, at least two judgment methods can be used to judge whether the charging station is removed.

One of the judgment methods is that, at time t2, the control unit 24 detects that the falling delay voltage of the voltage waveform is not lower than the threshold voltage during the threshold period (that is, the threshold period is the second judgment period, and for example, but Not limited to 100 milliseconds). Among them, the threshold voltage can be set at the voltage value of the low-level voltage (16 volts), and the falling delay voltage of the voltage waveform is not reduced from the high-level voltage value to the low-level voltage value (16 volts) in the second judgment period , Which means the charging station has been removed. At this time, the control unit 24 controls the first switch 206-1 and the second switch 206-2 to be non-conducting, and controls the third switch 220 to be switched on, so that after the interval T3, the frequency generating unit 22 provides the pulse voltage Vp to the output terminal 204 . Another judgment method is that at time t2, the control unit 24 detects that the falling edge period of the voltage waveform falling to the low-level voltage value is greater than the threshold period (that is, the threshold period is the second judgment period, and For example, but not limited to 100 milliseconds). That is, the period from the high-level voltage value to the low-level voltage value is the falling edge period. At this time, the control unit 24 controls the first switch 206-1 and the second switch 206-2 to be non-conducting, and controls the third switch 220 to be switched on, so that after the interval T3, the frequency generating unit 22 provides the pulse voltage Vp to the output terminal 204 .

It is worth mentioning that when the battery is coupled to the charger, but the charger is removed by the charging load detection circuit 2, the charging current Io that is charging the battery will quickly drop to zero. The control unit 24 obtains a current waveform in which the charging current Io rapidly drops to zero through the second judgment period (for example, but not limited to, 100 milliseconds) of the interval T2. At time t2, the control unit 24 determines that the under-charged battery is removed. At this time, the control unit 24 controls the first switch 206-1 and the second switch 206-2 to be non-conducting, and controls the third switch 220 to be switched on. After the interval T3, the frequency generating unit 22 provides the pulse voltage Vp to the output terminal 204.

It is worth mentioning that in one embodiment of the present invention, the number of seconds of the judgment period described in FIGS. 3A to 4B can be adjusted according to the actual requirements of the circuit. In addition, in an embodiment of the present invention, the first frequency and the first amplitude of the pulse voltage can also be adjusted according to the actual requirements of the circuit.

However, the above are only detailed descriptions and drawings of the preferred embodiments of the present invention. However, the features of the present invention are not limited thereto, and are not intended to limit the present invention. The full scope of the present invention should be referred to the following application The scope of the patent shall prevail. All embodiments that conform to the spirit of the scope of the patent application of the present invention and similar variations should be included in the scope of the present invention. Anyone familiar with the art in the field of the present invention can easily think of it. Changes or modifications can be covered in the following patent scope of this case.

100: Charging load detection system

1: charger

2: Charging load detection circuit

20: Charging circuit

202: Input

204: output

206: charging path

22: Frequency generating unit

24: control unit

3: load

Vp: pulse voltage

Io: charging current

Claims (14)

A charging load detection circuit includes: a charging circuit, providing a charging path including an input terminal and an output terminal, and the input terminal is coupled to a charger; a frequency generating unit coupled to the output terminal through the charging path; And a control unit, coupled to the charging circuit and the frequency generating unit; wherein the control unit controls the frequency generating unit to generate a pulse voltage with a fixed first frequency and a first amplitude, and the frequency generating unit provides the Pulse voltage to the output terminal of the charging circuit; the control unit determines whether there is a load coupled to the output terminal of the charging circuit by detecting whether the first frequency and the first amplitude of the pulse voltage are changed, and The control unit controls to short-circuit or open the charging path according to whether the load is coupled to the output terminal of the charging circuit. According to the charging load detection circuit described in claim 1, wherein the charging path includes: a first switch coupled to the input terminal and the control unit, and connected in series to the charging path; and a second switch, Is coupled to the first switch, the control unit and the output terminal, and is connected in series to the charging path; wherein, when the control unit controls the second switch to be non-conducting, the charging path is disconnected, and when the control unit controls the When the second switch is turned on, the charging path is short-circuited. The charging load detection circuit described in item 2 of the scope of patent application, wherein the control unit detects that the pulse wave voltage is changed from a pulse wave with the first frequency and the first amplitude fixed to a voltage that increases in a capacitive charging curve In the waveform, the control unit learns that the load is a battery with a sleep mode, and controls to turn on the first switch and the second switch. The charging load detection circuit described in item 2 of the scope of patent application, wherein the control unit detects that when the pulse wave voltage is changed from a pulse wave with the first frequency and the first amplitude fixed to a voltage waveform with a fixed value, The control unit learns that the load is a universal battery, and controls to turn on the first switch and the second switch. The charging load detection circuit described in item 2 of the scope of patent application, wherein the control unit is when the first switch and the second switch are turned on, and a current value of the output terminal is less than or equal to a threshold current value The first switch and the second switch are controlled to enter an isolated non-conduction mode. As for the charging load detection circuit described in item 5 of the scope of patent application, in the isolation non-conduction mode, when the control unit changes from non-conduction to conduction between the first switch and the second switch, and the output terminal When a voltage value is less than or equal to a threshold voltage value and the current value is less than or equal to the threshold current value, the control unit continuously controls the first switch and the second switch not to conduct, and controls the frequency generating unit to provide the pulse wave Voltage to this output terminal. The charging load detection circuit described in item 2 of the scope of patent application, wherein the control unit detects that when the pulse wave voltage is changed from a pulse wave with the first frequency and the first amplitude fixed to a voltage waveform showing a low voltage fluctuation, The control unit learns that the load is a charging station, and controls to turn on the second switch, and switch to turn on or off the first switch, so that the voltage waveform has a waveform with a fixed second frequency and a second amplitude. For the charging load detection circuit described in item 7 of the scope of patent application, when the control unit switches and does not turn on the first switch, an input voltage of the input terminal is provided to the first switch through a junction diode of the first switch The output terminal. For the charging load detection circuit described in item 7 of the scope of patent application, when the control unit detects the second amplitude change, the control unit controls to turn on the first switch. The charging load detection circuit described in item 7 of the scope of patent application, wherein the control unit detects that a falling delay voltage of the voltage waveform is not lower than a threshold voltage for a threshold period, the control The unit controls the first switch and the second switch not to conduct, and controls the frequency generating unit to provide the pulse voltage to the output terminal. The charging load detection circuit described in item 7 of the scope of patent application, wherein the control unit detects that a falling edge period of the voltage waveform is greater than a threshold period, the control unit controls the first switch and the second switch not to conduct And controlling the frequency generating unit to provide the pulse voltage to the output terminal. According to the charging load detection circuit described in item 2 of the scope of patent application, the frequency generating unit includes: a third switch coupled to the control unit and connected in parallel with the second switch; wherein the control unit is switched on or off The third switch causes an input voltage of the input terminal to generate the pulse voltage by switching between a junction diode of the first switch and the third switch to be conductive or non-conductive. According to the charging load detection circuit described in item 2 of the scope of patent application, the frequency generating unit includes: a third switch coupled to the control unit, and the first switch and the second switch are connected in parallel; wherein the control unit switches The third switch is turned on or not, so that an input voltage at the input terminal is connected across the first switch and the second switch, and is switched on or off with the third switch to generate the pulse voltage. For the charging load detection circuit described in item 12 of the scope of patent application, the control unit controls the third switch to switch on when the charging path is short-circuited by the control unit.

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