Charging circuit, power adapter and charging system

Abstract

The present application discloses a charging circuit, a power adapter and a charging system, which belong to the field of charging technology. The charging circuit is applied to a power adapter and includes: a voltage conversion unit for processing the input alternating current to output a first pulsating DC voltage; a voltage sampling unit for sampling the pulsating DC voltage output by the voltage conversion unit to obtain a sampled voltage; a comparator unit, a negative input terminal connected to the output terminal of the voltage sampling unit, a positive input terminal connected to the reference voltage providing terminal, for comparing the sampled voltage with a preset reference voltage and outputting a comparison signal; a switch unit for conducting when the comparator unit outputs a low level so that the charging circuit outputs a voltage, and shutting down when the comparator unit outputs a high level so that the charging circuit does not output a voltage, wherein the voltage output by the charging circuit is a target pulsating DC voltage. The present application can reduce the volume of the adapter.

Description

Technical Field

[0001] The present application relates to the field of charging technology, and in particular to a charging circuit, a power adapter and a charging system. Background Art

[0002] At present, mobile terminals (such as smart phones) are becoming more and more popular among consumers, but mobile terminals consume a lot of power and need to be charged frequently. Usually, mobile terminals are charged through power adapters; wherein, the power adapter converts the input 220V AC power into a stable low-voltage DC power (such as 5V) suitable for the needs of the mobile terminal, and then provides it to the mobile terminal to charge the battery of the mobile terminal.

[0003] In the technical solutions of related power adapters, especially in the technical solutions of power adapters for charging mobile terminals, the power adapters are relatively large and inconvenient to carry around. Summary of the invention

[0004] The embodiments of the present application provide a charging circuit, a power adapter, and a charging system, which can reduce the size of the power adapter, making the power adapter easy to carry and improving the user experience.

[0005] In a first aspect, a charging circuit is provided, which is applied to a power adapter;

[0006] The charging circuit comprises:

[0007] A voltage conversion unit, used for processing the input alternating current to output a first pulsating direct current voltage;

[0008] a voltage sampling unit connected to the output end of the voltage conversion unit, and configured to sample the first pulsating DC voltage output by the voltage conversion unit to obtain a sampled voltage;

[0009] A comparator unit, one input end of the comparator unit is connected to the output end of the voltage sampling unit, the other input end of the comparator unit is connected to the reference voltage supply end, and the comparator unit is used to compare the sampled voltage with a preset reference voltage and output a comparison signal;

[0010] a switch unit connected to the output end of the comparator unit, configured to be turned on when the comparator unit outputs a low level so that the charging circuit outputs a voltage, and turned off when the comparator unit outputs a high level so that the output of the charging circuit is turned off;

[0011] Wherein, the voltage output by the charging circuit is a target pulsating DC voltage.

[0012] In a second aspect, a power adapter is provided, comprising the charging circuit as described above.

[0013] In a third aspect, a charging system is provided, the charging system comprising a power adapter and a device to be charged;

[0014] Wherein, the power adapter comprises:

[0015] A voltage conversion unit, used for processing the input alternating current to output a first pulsating direct current voltage;

[0016] a voltage sampling unit connected to the output end of the voltage conversion unit, and configured to sample the first pulsating DC voltage output by the voltage conversion unit to obtain a sampled voltage;

[0017] A comparator unit, one input end of the comparator unit is connected to the output end of the voltage sampling unit, the other input end of the comparator unit is connected to the reference voltage supply end, and the comparator unit is used to compare the sampled voltage with a preset reference voltage and output a comparison signal;

[0018] a switch unit connected to the output end of the comparator unit, configured to be turned on when the comparator unit outputs a low level so that the charging circuit outputs a voltage, and turned off when the comparator unit outputs a high level so that the output of the charging circuit is turned off;

[0019] Wherein, the voltage output by the charging circuit is a target pulsating DC voltage;

[0020] a first charging interface, connected to the switch unit, and configured to output the target pulsating DC voltage when the switch unit is turned on;

[0021] The device to be charged includes a second charging interface and a battery, and the second charging interface is connected to the battery. When the second charging interface is connected to the first charging interface, the target pulsating DC voltage output by the first charging interface is loaded to the battery through the second charging interface to charge the battery.

[0022] The beneficial effects brought by the technical solution provided by the embodiment of the present application include at least:

[0023] After adopting the above-mentioned charging circuit, power adapter and charging system, in the charging circuit of the power adapter, after the AC power of, for example, 220V is converted into a pulsating DC voltage through the voltage conversion unit, it is not directly output, but after voltage division through the voltage sampling unit, it is input into the comparator unit to compare the sampled voltage and the reference voltage; when the sampled voltage is greater than the reference voltage, the switch unit is turned on, and the charging circuit outputs the voltage normally to charge the battery of the device to be charged; when the sampled voltage is less than the reference voltage, the switch unit is controlled to be turned off to turn off the voltage output of the charging circuit.

[0024] That is to say, when the voltage of the pulsating DC voltage output by the voltage conversion unit is high, the output of the switch unit is turned on so that the charging circuit outputs the pulsating DC voltage normally, and when the corresponding voltage is low, the output of the switch unit is turned off so that the output of the charging circuit is turned off. Among them, when the output of the charging circuit is turned off, the load becomes resistive and does not need to draw a large current to keep the system working, so there is no need to use a large-capacity capacitor in the circuit to store energy, which can reduce the requirements for the capacitance of the capacitor in the power adapter, thereby reducing the size of the adapter and improving the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the structure of a charging system provided in an embodiment of the present application;

[0026] Figure 2 A schematic diagram of a charging circuit provided in an embodiment of the present application;

[0027] Figure 3 A schematic diagram of a charging circuit provided in an embodiment of the present application;

[0028] Figure 4 A schematic diagram of a charging circuit provided in an embodiment of the present application;

[0029] Figure 5 A waveform diagram of a first pulsating DC voltage or a second pulsating DC voltage provided in an embodiment of the present application;

[0030] Figure 6 A waveform diagram of a target pulsating DC voltage provided in an embodiment of the present application. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0032] To charge the device to be charged through a power adapter, the input 220V AC power needs to be converted into a stable low-voltage DC power suitable for the needs of the device to be charged, so as to provide it to the power management device and battery of the device to be charged, thereby realizing the charging of the device to be charged.

[0033] For details, please see Figure 1 , a schematic diagram of a power adapter for charging a device to be charged is given. The power adapter 100 is connected to 220V AC power, and the charging circuit 101 converts the 220V AC power into low-voltage DC power (for example, 5V, 15V, 25V or other voltage values) acceptable to the device to be charged 200, and outputs it through the first charging interface 1001 to charge the battery 201 of the device to be charged.

[0034] For further information, see Figure 2 , Figure 2 A schematic diagram of the charging circuit structure of the power adapter 300 of another embodiment is given. Specifically, the charging circuit includes a primary rectifier unit 301, a primary filter unit 302, a transformer unit 303, a secondary rectifier unit 304, a secondary filter unit 305, and a control unit 306. Among them, the AC end (mains power) inputs alternating current, which is a 220V sine wave, which is rectified by the primary rectifier unit 301 and outputs a steamed bun wave, and then the energy is stored by the filter capacitor of the primary filter unit 302 to supply power to the primary winding group of the transformer unit 303, which is modulated by the primary winding group of the transformer unit 303 into a pulsating wave (PWM wave, Pulse width modulation) with a higher frequency and adjustable duty cycle, which is transmitted to the secondary winding group of the transformer unit 303, and after being rectified by the secondary rectifier unit 304, the filter capacitor of the secondary filter unit 305 is charged and filtered, and finally output to charge the device to be charged.

[0035] However, in the scheme of the charging circuit of the above-mentioned power adapter, when the voltage of the input AC power is relatively low, a relatively large current needs to be drawn in order to output a constant power in this case, so that a large-capacity filter capacitor (i.e., an electrolytic capacitor) is required in the primary filter unit 302 and the secondary filter unit 305 to store capacity. In other words, in the above-mentioned scheme, the dependence on the electrolytic capacitor in the charging circuit is relatively large; that is, a high-voltage electrolytic capacitor is required on one side corresponding to the primary winding group of the transformer unit, and a relatively large-capacitance electrolytic capacitor is required on one side corresponding to the secondary winding group of the transformer unit, which results in a relatively large size of the power adapter and a relatively poor user experience.

[0036] See also Figure 3 and Figure 4, a specific structural diagram of an embodiment of the charging circuit of the power adapter provided in this embodiment is given. The charging circuit 101 of the power adapter 100 includes a first rectifier unit 102, a first filter unit 103, a transformer unit 104, a second rectifier unit 105, a second filter unit 106, a control unit 107, a voltage sampling unit 108, a comparator unit 109 and a switch unit 110.

[0037] in:

[0038] The first rectifying unit 102 rectifies the input AC power (mains power, such as a 220V sine wave) and outputs a pulsating DC voltage (a second pulsating DC voltage). Figure 5 The pulsating DC voltage outputted after the alternating current is rectified by the first rectifying unit 102 is as follows: Figure 5 As shown in FIG. 1 , the waveform of the pulsating DC voltage is a steamed bun waveform. Figure 4 The first rectifying unit may specifically be a full-bridge rectifying circuit composed of four diodes.

[0039] The pulsating DC voltage obtained after rectification by the first rectifying unit 102 is input to the first filtering unit 103, and is filtered by the first filtering unit 103 to output a pulsating DC voltage (referred to as the third pulsating DC voltage). Figure 4 The first filtering unit is a filtering capacitor C1, which can filter the second pulsating DC voltage.

[0040] The third pulsating DC voltage after filtering by the first filtering unit 103 is input to the primary side (i.e., the primary winding side) of the transformer unit 104, and is coupled to the secondary side (i.e., the secondary winding side) of the transformer unit 104. The corresponding pulsating DC voltage (recorded as the fourth pulsating DC voltage) is obtained through the transformer unit 104. The voltage value of the first pulsating DC voltage before passing through the transformer unit 104 is higher than the voltage value of the fourth pulsating DC voltage, and the specific voltage value is determined according to the turns ratio of the coils of the primary winding group and the secondary winding group of the transformer unit 104. Among them, the second pulsating DC voltage and the fourth pulsating DC voltage are synchronized in waveform, specifically referring to that the phases of the second pulsating DC voltage and the fourth pulsating DC voltage are kept consistent, and the amplitude change trends are consistent.

[0041] In one embodiment, the transformer unit 104 includes a primary winding group and a secondary winding group, one end of the primary winding group is connected to the first output end of the first filter unit, the second output end of the first filter unit is grounded, and the other end of the primary winding is connected to the control unit. The transformer unit 104 is used to output a fourth pulsating DC voltage according to the second pulsating DC voltage. The transformer unit 104 is a high-frequency transformer, and its operating frequency can be 50KHz-2MHz. The high-frequency transformer couples the modulated pulsating DC voltage to the secondary winding group side, and the secondary winding group outputs it.

[0042] In an embodiment of the present invention, a high-frequency transformer is used. The small size of the high-frequency transformer compared to the low-frequency transformer (the low-frequency transformer is also called the industrial frequency transformer, which is mainly used to refer to the frequency of the mains, such as 50Hz or 60Hz alternating current) can be utilized to achieve the miniaturization of the power adapter 100.

[0043] The fourth pulsating DC voltage output by the transformer unit 104 is rectified by the second rectifier unit 105, and the rectified pulsating DC voltage (recorded as the fifth pulsating DC voltage) is output. Figure 4 As shown, the second rectifying unit 105 includes a diode D1.

[0044] The fifth pulsating DC voltage rectified by the second rectifying unit 105 is input to the second filtering unit 106, and is filtered by the second filtering unit 106 to output a corresponding pulsating DC voltage (recorded as the sixth pulsating DC voltage). Figure 4 As shown, the second filtering unit 106 includes a second filtering capacitor C2.

[0045] The sixth pulsating DC voltage after rectification by the second rectifying unit 106 is a steamed bun waveform. Figure 5 The waveform diagram of the pulsating DC voltage is given. When the output voltage of this pulsating DC voltage is low, the output constant power load needs to draw a larger current, so the filter capacitors in the first filter unit C1 and the second filter unit C2 need to have a larger capacitance, store more energy, and withstand high voltage.

[0046] In one embodiment, the first rectifier unit 102, the first filter unit 103, the transformer unit 104, the second rectifier unit 105, the second filter unit 106, and the control unit 107 are used as a voltage conversion unit 110 to process the input alternating current to output a pulsating DC voltage (i.e., the sixth pulsating DC voltage output by the second filter unit 106), and the pulsating DC voltage output by the voltage conversion unit 111 is recorded as the first pulsating DC voltage (i.e., the sixth pulsating DC voltage is set to the first pulsating DC voltage).

[0047] If the first pulsating DC voltage output by the voltage conversion unit 111 is directly used as the output of the power adapter 100 to charge the battery 201 of the device to be charged 200, when the voltage is low, in order to maintain the operation of the system, the load needs to draw a large current, which leads to a large capacitance requirement for the filter capacitors C1 and C2, resulting in a large volume of the power adapter 100. Therefore, in the present application, in order to reduce the volume of the power adapter 100 and reduce the requirements for the filter capacitors C1 and C2, after the voltage conversion unit 111 outputs the first pulsating DC voltage, the first pulsating DC voltage needs to be further processed so that when the input voltage is low, it is not necessary to draw a large current.

[0048] For details, see Figure 3 and Figure 4 The charging circuit 101 further includes a voltage sampling unit 108 , a comparator unit 109 , and a switch unit 110 .

[0049] In one embodiment, the voltage sampling unit 108 is connected to the output end of the second filtering unit 106 (that is, the output end of the voltage conversion unit 111), and includes two voltage-dividing resistors R2 (first voltage-dividing resistor) and R3 (second voltage-dividing resistor), which are used to perform voltage sampling on the first pulsating DC voltage output by the voltage conversion unit 111 to obtain the corresponding sampling voltage Vs.

[0050] One input terminal of the comparator unit 109 is connected to a reference voltage supply terminal, and the other input terminal of the comparator unit 109 is connected to the output terminal of the voltage sampling unit 108. The comparator unit 109 is used to compare the sampled voltage Vs provided by the voltage sampling unit 108 with the reference voltage Vref provided by the reference voltage supply terminal. When the sampled voltage Vs is greater than the reference voltage Vref, the comparator unit 109 outputs a low level, and when the sampled voltage Vs is less than the reference voltage Vref, the comparator unit 109 outputs a high level.

[0051] The high level or low level output by the comparator unit 109 is loaded to the switch unit 110 to control the on or off of the switch unit 110 , so that the charging circuit 101 outputs a voltage or does not output a voltage.

[0052] Specifically, Figure 4As shown, the switch unit 110 includes a first triode Q1, a second triode Q2, and a MOS switch tube M1; wherein the drain of the MOS switch tube M1 is connected to the output end of the voltage conversion unit 111; the base of the first triode Q1 is connected to the output end of the voltage conversion unit, the collector of the first triode Q1 is connected to the source of the MOS switch tube M1, and the emitter of the first triode Q1 is grounded; the base of the second triode Q2 is connected to the collector of the first triode Q1, the collector of the second triode Q2 is connected to the gate of the MOS switch tube M1, and the emitter of the second triode Q2 is grounded. The first triode Q1 is an NPN triode, and the second triode Q2 is a PNP triode.

[0053] That is, when the comparator unit 109 outputs a high level, the voltage of the base of the first transistor Q1 is high, the first transistor Q1 is turned on, and the voltage of its collector is high, so that the base of the second transistor Q2 connected to the collector of the first transistor Q1 is high, the second transistor Q2 is not turned on, and its collector is grounded; the gate of the MOS switch tube M1 is low, and the source of the MOS switch tube connected to the collector of the first transistor Q1 is high, so that the gate of the MOS switch tube is pulled down, the MOS switch tube M1 is not turned on, and the output from the voltage conversion unit 111 to the charging circuit is turned off. That is, when the comparator 109 outputs a high level, the output of the charging circuit is turned off, and no current or voltage is output.

[0054] When the comparator unit 109 outputs a low level, the voltage of the base of the first transistor Q1 is low, the first transistor Q1 is not turned on, and the voltage of its collector is low, so that the voltage of the base of the second transistor Q2 connected to the collector of the first transistor Q1 is low, the second transistor Q2 is turned on, and its collector is not grounded; the gate of the MOS switch tube M1 is connected to the USBP terminal, the voltage is high, and the source of the MOS switch tube connected to the collector of the first transistor Q1 is low, so that the MOS switch tube is turned on, the MOS switch tube M1 is turned on, and the output from the voltage conversion unit 111 to the charging circuit is output normally. That is, when the comparator 109 outputs a low level, the normal output voltage and current of the charging circuit.

[0055] That is to say, when the sampling voltage Vs is less than the reference voltage Vref, it means that the voltage of the first pulsating DC voltage output from the voltage conversion unit 111 is relatively low; at this time, the comparator unit 109 outputs a low level, the switch unit 110 is controlled to be turned off, and the current and voltage output by the charging circuit 101 drop to 0. That is, when the input voltage is relatively low, the charging circuit 101 does not output current and voltage, so that the load is drawn into resistance, and a large current does not need to be drawn, that is, the aforementioned filter capacitors C1 and C2 do not need a large capacitance to store sufficient energy. When the sampling voltage Vs is greater than the reference voltage Vref, it means that the voltage of the first pulsating DC voltage output from the voltage conversion unit 111 meets the requirements and does not need to be processed. In this case, the comparator unit 109 outputs a high level, the switch unit 110 is controlled to be turned on, so that the charging circuit 101 outputs voltage normally.

[0056] See also Figure 6 , Figure 6 A waveform diagram of the target pulsating DC voltage output by the charging circuit after the output of the switch unit 110 is turned on and off is given. Figure 5 The pulsating DC voltage of the steamed bun waveform shown is reduced to 0 at the trough where the input voltage is smaller, and the output is temporarily shut down; that is, when the input voltage is small, there is no need to output constant power and there is no need to draw a large current.

[0057] In an embodiment of the present invention, by reasonably designing the voltage-dividing resistor ratio at the input end of the comparator unit 109, when the voltage value Vs of the pulsating DC voltage output by the second rectifier unit 106 is within a preset range (greater than the reference voltage Vref), the comparator unit 109 outputs a high-level signal, the voltage at the base of the first transistor Q1 is high, the first transistor Q1 is turned on, and the source voltage of the MOS switch tube connected to the collector of the first transistor Q1 is high; the voltage at the base of the second transistor Q2 connected to the collector of the first transistor Q1 is high, the second transistor Q2 is not turned on, the voltage at the corresponding resistors R3 and R6 is low, the gate of the MOS switch tube is pulled down, the MOS switch tube is not turned on, the output from the voltage conversion unit 111 to Vbus is turned off, and the output of the charging circuit is turned off.

[0058] On the contrary, when the voltage value Vs of the first pulsating DC voltage output by the voltage conversion unit 111 is not within the preset range (less than the reference voltage Vref), the comparator unit 109 outputs a low-level signal, the voltage at the base of the first transistor Q1 is low, the first transistor Q1 is not turned on, and the source voltage of the MOS switch tube connected to the collector of the first transistor Q1 is low; the voltage at the base of the second transistor Q2 connected to the collector of the first transistor Q1 is low, the second transistor Q2 is turned on, and the voltage at the corresponding resistors R3 and R6 is high, the gate of the MOS switch tube is normally unaffected, the MOS switch tube is turned on, and the output from the voltage conversion unit to Vbus is normal; in other words, the output of the charging circuit is the target pulsating DC voltage.

[0059] That is to say, after adopting the above charging circuit, when the input voltage is low, the output is turned off, so that the voltage position of the power adapter output is above a reasonable voltage value (determined by the reference voltage Vref). In other words, when the input energy is high, the energy is output normally, but when the input energy is low, the energy is not output to keep the power system working normally, thereby avoiding the need to draw a large current to maintain a constant power output when the input voltage is temporarily reduced, and also avoiding the use of capacitors with large capacitance to store energy to maintain the power system. Compared with Figure 2 As for the charging circuit shown in FIG. 1 , the capacitance of the filter capacitor in the charging circuit is reduced, thereby reducing the size of the power adapter.

[0060] As mentioned above, the second pulsating DC voltage and the fourth pulsating DC voltage are synchronized in waveform, and further, the two are also synchronized with the first pulsating DC voltage in waveform. That is to say, in the charging circuit 101, the input power and the output power change synchronously, and the situation of outputting a large power when the input voltage is small will not occur, thereby avoiding the requirement of storing a large amount of energy in the filter capacitors C1 and C2, that is, reducing the requirement on the capacitance of the filter capacitors C1 and C2.

[0061] In one embodiment, Figure 4 As shown, a varistor R1 is also connected in parallel between the input ends of the first rectifier unit 102 , and the varistor R1 is used to clamp the high voltage signal generated by the surge voltage impact to protect other units at the input end of the power adapter 100 and improve the safety of the power adapter 100 .

[0062] In one embodiment, the power adapter 100 may adopt a forward switching power supply, that is, the transformer unit adopts a forward transformer. In the case of adopting a forward transformer, the inductance requirement for the transformer is lower, and the volume of the power adapter 100 can be further reduced. In another embodiment, the power adapter 100 may also adopt a flyback switching power supply, that is, the transformer unit adopts a flyback transformer. In other embodiments, the power adapter 100 may also adopt a push-pull switching power supply, a half-bridge switching power supply or a full-bridge switching power supply, that is, the transformer unit may adopt a push-pull transformer, a half-bridge transformer or a full-bridge transformer. In other words, the power adapter 100 may adopt any one of a flyback switching power supply, a forward switching power supply, a push-pull switching power supply, a half-bridge switching power supply and a full-bridge switching power supply to output a pulsating waveform voltage.

[0063] Further, such as Figure 1 As shown, in the charging system 10, the device 200 to be charged includes a second charging interface 2001 and a battery 201, and the second charging interface 2001 is connected to the battery 201, wherein when the second charging interface 2001 is connected to the first charging interface 1001, the second charging interface 2001 loads the target pulsating DC voltage to the battery 201 to charge the battery 201.

[0064] It should be noted that, in the present embodiment, loading the target pulsating DC voltage to the battery 201 through the second charging interface 2001 may be to directly load the target pulsating DC voltage to the battery 201 (i.e., no longer undergo voltage conversion, such as boost or buck processing), to achieve charging in direct charging mode; in another embodiment, it may also be necessary to perform a conversion circuit to step down or boost the voltage before loading the voltage to the battery 201 (i.e., a conversion circuit for stepping down or boosting the voltage is also included between the second charging interface 2001 and the battery 201), and then load the pulsating DC voltage after the boost or step-down to the battery 201 to adapt to different charging modes.

[0065] Among them, a power line is also provided between the first charging interface 1001 and the second charging interface 1002, and the power line is used to output the target pulsating DC voltage output by the power adapter 100 to the second charging interface 1002 to realize charging of the battery 201. It should be noted that in this embodiment, the power line can not only transmit voltage and voltage, but also transmit data between the power adapter 100 and the device to be charged 200. For example, the device to be charged 200 collects status information of the battery 201, such as voltage value, etc., and transmits it to the power adapter 100 through the power line, so that the power adapter 100 adjusts the charging voltage, etc.

[0066] In this embodiment, the control unit 107 can modulate the pulsating DC voltage output by the transformer unit 104 so that the target pulsating DC voltage output by the power adapter 100 meets the charging requirements of the device to be charged 200 (for example, the requirements for charging power), that is, the target pulsating DC voltage meets the charging voltage and charging current when the battery 201 is charged. In a specific implementation, the control unit 107 can adjust the duty cycle of the control signal such as the PWM signal according to the sampled voltage and / or current output by the power adapter 100, adjust the output of the transformer unit 104 in real time, and implement closed-loop regulation control, so that the target pulsating DC voltage meets the charging requirements of the device to be charged 200, and ensures that the battery 201 is charged safely and reliably.

[0067] In a specific example of the present invention, the control unit 107 may be an MCU (Micro Controller Unit), that is, a microprocessor that integrates switch drive control function, synchronous rectification function, and voltage and current regulation control function.

[0068] According to one embodiment of the present invention, the control unit 107 is further used to adjust the frequency of the control signal according to the voltage sampling value and / or the current sampling value, that is, to control the PWM signal output to the first charging interface 1001 to continuously output for a period of time and then stop outputting, and to start the output of the PWM signal again after stopping for a predetermined time, so that the voltage loaded to the battery is intermittent, and intermittent charging of the battery is realized, thereby avoiding the safety hazard caused by severe heating of the battery during continuous charging, and improving the reliability and safety of battery charging.

[0069] In the above-mentioned charging circuit, power adapter and charging system, a pulsating DC voltage with a steamed wave envelope is obtained after voltage conversion of the input AC power; when the voltage can ensure the normal operation of the power adapter system (that is, when the voltage is greater than the reference voltage), the power adapter system is powered to ensure the normal operation of the system, and a pulsating DC voltage is output. Among them, the reference voltage can be set with reference to the minimum operating voltage of the power adapter system. For example, if the power supply voltage of the chip in the power adapter is 10V, the reference voltage is 10V or a value greater than 10V, so that the input voltage is maintained above a reasonable voltage value, thereby ensuring the normal operation of the power adapter system. Conversely, when the pulsating DC voltage after voltage conversion temporarily drops below a certain value (below the reference voltage), the filter capacitor in the charging circuit is used to store energy to power the system of the power adapter to ensure the normal operation of the system.

[0070] In a specific embodiment, assuming that the turns ratio of the transformer unit is 8:1, the 220V energy is input into the primary winding side of the transformer unit and then transmitted to the secondary winding side, and then the output is 27.5V. If the supply voltage of the chip in the power adapter is set to 10V, the output of the transformer unit between 10V-27.5V can ensure the normal operation of the power adapter system and output energy. When the output of the transformer unit is lower than 10V, if the output of the power adapter is not turned off, a capacitor is needed to store energy to maintain the normal operation of the system. When the capacitance value of the capacitor is small, the input voltage cannot be well maintained, and a large current needs to be drawn at the output end, resulting in the input voltage being pulled down to the point where the power adapter system cannot work normally; that is, by turning off the output of the power adapter when the voltage is low, a large-capacity capacitor can be used without using the normal operation of the power adapter system while ensuring the normal operation of the power adapter system, thereby reducing the size of the power adapter and improving the user experience.

[0071] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A charging circuit, characterized in that: The charging circuit is applied to a power adapter; The charging circuit comprises: A voltage conversion unit, used for processing the input alternating current to output a first pulsating direct current voltage; a voltage sampling unit connected to the output end of the voltage conversion unit, and configured to sample the first pulsating DC voltage output by the voltage conversion unit to obtain a sampled voltage; A comparator unit, one input end of the comparator unit is connected to the output end of the voltage sampling unit, the other input end of the comparator unit is connected to the reference voltage supply end, and the comparator unit is used to compare the sampled voltage with a preset reference voltage and output a comparison signal; a switch unit connected to the output end of the comparator unit, configured to be turned on when the comparator unit outputs a low level so that the charging circuit outputs a voltage, and turned off when the comparator unit outputs a high level so that the output of the charging circuit is turned off; Wherein, the voltage output by the charging circuit is a target pulsating DC voltage; When the sampling voltage is greater than the reference voltage, the comparator unit outputs a low level; When the sampling voltage is less than the reference voltage, the comparator outputs a high level; The switch unit includes a first triode, a second triode, and a MOS switch tube; Wherein, the drain of the MOS switch tube is connected to the output end of the voltage conversion unit; The base of the first transistor is connected to the output end of the voltage conversion unit, the collector of the first transistor is connected to the source of the MOS switch tube, and the emitter of the first transistor is grounded; The base of the second transistor is connected to the collector of the first transistor, the collector of the second transistor is connected to the gate of the MOS switch tube, and the emitter of the second transistor is grounded.

2. The charging circuit according to claim 1, characterized in that: The first transistor is an NPN transistor, and the second transistor is a PNP transistor.

3. The charging circuit according to claim 1, characterized in that: When the comparator unit outputs a high level, the first transistor is turned on, the second transistor is not turned on, the gate of the MOS switch tube is pulled low, and the switch unit is turned off; When the comparator unit outputs a low level, the first transistor is not turned on, the second transistor is turned on, and the MOS switch tube is turned on.

4. The charging circuit according to claim 1, characterized in that: The voltage conversion unit comprises: A first rectifying unit, used for rectifying the input alternating current and outputting a second pulsating direct current voltage; a first filtering unit, wherein an input end of the first filtering unit is connected to an output end of the first rectifying unit, and the first filtering unit is used to filter the initial pulsating DC voltage to obtain a third pulsating DC voltage after filtering; a transformer unit, wherein an input end of the transformer unit is connected to an output end of the first filter unit, and the transformer unit is used to generate a corresponding fourth pulsating DC voltage according to the third pulsating DC voltage; a second rectifying unit, wherein an input end of the second rectifying unit is connected to an output end of the transformer unit, and the second rectifying unit is used for rectifying the fourth pulsating DC voltage to generate a fifth pulsating DC voltage; A second filtering unit, wherein the input end of the second filtering unit is connected to the output end of the second rectifying unit, and the second filtering unit is used to filter the fifth pulsating DC voltage, and the pulsating DC voltage after filtering is the first pulsating DC voltage output by the voltage conversion unit.

5. The charging circuit according to claim 4, characterized in that: A varistor is also connected in parallel between the input ends of the first rectifying unit.

6. The charging circuit according to claim 4, characterized in that: The charging circuit further includes a control unit connected to the transformer unit, the voltage sampling unit and the switch unit.

7. The charging circuit according to claim 1, characterized in that: The voltage sampling unit includes a first voltage-dividing resistor and a second voltage-dividing resistor, one end of the first voltage-dividing resistor is connected to one end of the voltage conversion unit, and the other end of the first voltage-dividing resistor is connected to the second voltage-dividing resistor and an input end of the comparator; The first voltage-dividing resistor and the second voltage-dividing resistor are used to perform voltage-dividing processing on the first pulsating DC voltage input to the voltage sampling unit.

8. A charging system, characterized in that: The charging system includes a power adapter and a device to be charged; Wherein, the power adapter comprises: A voltage conversion unit, used for processing the input alternating current to output a first pulsating direct current voltage; a voltage sampling unit connected to the output end of the voltage conversion unit, and configured to sample the first pulsating DC voltage output by the voltage conversion unit to obtain a sampled voltage; A comparator unit, one input end of the comparator unit is connected to the output end of the voltage sampling unit, the other input end of the comparator unit is connected to the reference voltage supply end, and the comparator unit is used to compare the sampled voltage with a preset reference voltage and output a comparison signal; a switch unit connected to the output end of the comparator unit, and configured to be turned on when the comparator unit outputs a low level so that the charging circuit outputs a voltage; and turned off when the comparator unit outputs a high level so that the output of the charging circuit is turned off; Wherein, the voltage output by the charging circuit is a target pulsating DC voltage; a first charging interface, connected to the switch unit, and configured to output the target pulsating DC voltage when the switch unit is turned on; The device to be charged includes a second charging interface and a battery, wherein the second charging interface is connected to the battery. When the second charging interface is connected to the first charging interface, the target pulsating DC voltage output by the first charging interface is loaded to the battery through the second charging interface to charge the battery; When the sampling voltage is greater than the reference voltage, the comparator unit outputs a low level; When the sampling voltage is less than the reference voltage, the comparator outputs a high level; The switch unit includes a first triode, a second triode, and a MOS switch tube; Wherein, the drain of the MOS switch tube is connected to the output end of the voltage conversion unit; The base of the first transistor is connected to the output end of the voltage conversion unit, the collector of the first transistor is connected to the source of the MOS switch tube, and the emitter of the first transistor is grounded. The base of the second transistor is connected to the collector of the first transistor, the collector of the second transistor is connected to the gate of the MOS switch tube, and the emitter of the second transistor is grounded; The first transistor is an NPN transistor, and the second transistor is a PNP transistor.

9. The charging system according to claim 8, characterized in that: When the comparator unit outputs a high level, the first transistor is turned on, the second transistor is not turned on, the gate of the MOS switch tube is pulled low, and the switch unit is turned off; When the comparator unit outputs a low level, the first transistor is not turned on, the second transistor is turned on, and the MOS switch tube is turned on.

10. The charging system according to claim 8, characterized in that: The voltage conversion unit also includes: A first rectifying unit, used for rectifying the input alternating current and outputting a second pulsating direct current voltage; a first filtering unit, wherein an input end of the first filtering unit is connected to an output end of the first rectifying unit, and the first filtering unit is used for filtering the initial pulsating DC voltage and outputting a third pulsating DC voltage; a transformer unit, wherein an input end of the transformer unit is connected to an output end of the first filter unit, and the transformer unit is used to generate a corresponding fourth pulsating DC voltage according to the filtered third pulsating DC voltage; a second rectifying unit, wherein an input end of the second rectifying unit is connected to an output end of the transformer unit, and the second rectifying unit is used for rectifying the fourth pulsating DC voltage to output a fifth pulsating DC voltage; a second filtering unit, wherein an input end of the second filtering unit is connected to an output end of the second rectifying unit, and the second filtering unit is used for filtering the rectified fifth pulsating DC voltage and outputting the first pulsating DC voltage; The charging circuit further includes a control unit connected to the transformer unit, the voltage sampling unit and the switch unit.

11. The charging system according to claim 8, characterized in that: The voltage sampling unit includes a first voltage-dividing resistor and a second voltage-dividing resistor, one end of the first voltage-dividing resistor is connected to one end of the voltage conversion unit, and the other end of the first voltage-dividing resistor is connected to the second voltage-dividing resistor and an input end of the comparator; The first voltage-dividing resistor and the second voltage-dividing resistor are used to perform voltage-dividing processing on the first pulsating DC voltage input to the voltage sampling unit.

12. The charging system according to claim 8, characterized in that: The system further comprises: a power line, used to connect the first charging interface and the second charging interface, and transmit the target pulsating DC voltage to the second charging interface through the power line; The power line is used for data communication, so that the power adapter and the device to be charged perform data communication through the power line.

13. A power adapter, characterized in that: The charging circuit comprises a charging circuit as described in any one of claims 1 to 7.

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