Anti-backcharge charging circuit and control method thereof

Abstract

The present invention relates to the field of circuit technology, and specifically to an anti-recharge charging circuit and a control method thereof. The circuit includes: a power supply, an anti-recharge circuit, a charging chip, a battery, a powered device, and an enabling circuit; the enabling circuit is used to detect a sampled voltage of the battery, and when it is determined that the sampled voltage is higher than a stop-charging voltage threshold, output a first level to the anti-recharge circuit; when it is determined that the sampled voltage is lower than a recharge voltage threshold, output a second level to the anti-recharge circuit; the anti-recharge circuit is used to cut off when receiving the first level input by the enabling circuit, triggering the charging chip to cut off the power supply input of the battery; and to turn on when receiving the second level input by the enabling circuit, triggering the charging chip to turn on the power supply input of the battery; the anti-recharge charging circuit provided by the present invention is compatible with various charging chips and has universal applicability.

Description

Technical Field

[0001] The present invention relates to the field of circuit technology, and in particular to an anti-backcharge charging circuit and a control method thereof. Background Art

[0002] When using batteries to power electronic devices, a variety of charging chips can generally be selected for charging circuit design. Once the charging circuit design is completed, if the model of the charging chip in the charging circuit is replaced, it may cause the charging circuit to recharge due to problems such as battery overcharging and floating charging. Therefore, the model of the charging chip cannot be changed at will, and its applicability is poor. Summary of the Invention

[0003] To solve the above problems, the present invention provides an anti-backcharge charging circuit and a control method thereof, which can prevent the charging circuit from backcharging and can be adapted to charging chips of different models, and has universal applicability.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A back-charging prevention charging circuit, comprising:

[0006] A power supply, an anti-recharge circuit, a charging chip, a battery, a powered device, and an enabling circuit; the power supply, the anti-recharge circuit, the charging chip, the battery, and the powered device are connected in sequence, the input end of the enabling circuit is connected to the power supply end of the battery, and the output end is connected to the input end of the anti-recharge circuit;

[0007] The enabling circuit is configured to detect a sampled voltage of the battery and output a first voltage level to the anti-recharge circuit when the sampled voltage is determined to be higher than a stop-charge voltage threshold; and output a second voltage level to the anti-recharge circuit when the sampled voltage is determined to be lower than a recharge voltage threshold; wherein the stop-charge voltage threshold is greater than the recharge voltage threshold;

[0008] The anti-recharge circuit is configured to be cut off when receiving the first level input by the enabling circuit, triggering the charging chip to cut off the power supply input of the battery; and to be turned on when receiving the second level input by the enabling circuit, triggering the charging chip to turn on the power supply input of the battery.

[0009] Furthermore, the anti-recharge circuit includes: a second MOS transistor, a third MOS transistor, a fourth MOS transistor, a triode and a fifth resistor, the drain of the second MOS transistor and the source of the fourth MOS transistor are commonly connected to the power supply, the drain of the second MOS transistor is connected to the drain of the third MOS transistor, the source of the third MOS transistor is connected to the input end of the charging chip, the gate of the second MOS transistor, the gate of the third MOS transistor, and the source of the fourth MOS transistor are commonly connected to one end of the fifth resistor, the other end of the fifth resistor is grounded, the gate of the fourth MOS transistor is connected to the collector of the triode, the emitter of the triode is grounded, and the base is connected to the output end of the enabling circuit.

[0010] Furthermore, the enabling circuit includes a hysteresis comparator, a reference voltage circuit and a sampling circuit, wherein the input end of the reference voltage circuit is connected to the power supply, and the input end of the sampling circuit is connected to the power supply end of the battery; the first input end of the hysteresis comparator is connected to the output end of the reference voltage circuit, the second input end is connected to the output end of the sampling circuit, and the output end of the hysteresis comparator is connected to the base of the transistor;

[0011] The reference voltage circuit is used to step down the voltage output by the power supply so that the first input terminal of the hysteresis comparator is maintained at the stop-charging voltage threshold value;

[0012] The sampling circuit is used to divide the voltage output by the battery to obtain a sampling voltage, and input the sampling voltage to the second input terminal of the hysteresis comparator; when the battery is fully charged, the sampling voltage is equal to the stop-charging voltage threshold;

[0013] The hysteresis comparator is configured to output a first level when the voltage value of the second input terminal is higher than the voltage value of the first input terminal; and output a second level when the voltage value of the second input terminal is lower than the voltage value of the first input terminal.

[0014] Furthermore, the reference voltage circuit includes: a reference voltage chip, a third resistor, a seventh resistor, a tenth resistor and a second capacitor, one end of the seventh resistor and the cathode of the reference voltage chip are commonly connected to one end of the third resistor, the other end of the third resistor is connected to the power supply, the other end of the seventh resistor is respectively connected to the reference pole of the reference voltage chip and one end of the tenth resistor, the anode of the reference voltage chip and the other end of the tenth resistor are commonly grounded, the second capacitor is arranged between the anode and cathode of the reference voltage chip, and the cathode of the reference voltage chip is also connected to the first input end of the hysteresis comparator.

[0015] Furthermore, the hysteresis comparator includes: an operational amplifier, an eighth resistor and an eleventh resistor, the inverting input terminal of the operational amplifier is connected to the cathode of the reference voltage chip, the non-inverting input terminal of the operational amplifier is connected to one end of the eleventh resistor, and the other end of the eleventh resistor is connected to the output end of the sampling circuit; the two ends of the eighth resistor are respectively connected to the non-inverting input terminal and the output end of the operational amplifier.

[0016] Furthermore, the sampling circuit includes: a twelfth resistor and a thirteenth resistor, one end of the twelfth resistor and one end of the thirteenth resistor are commonly connected to the other end of the eleventh resistor, the other end of the twelfth resistor is connected to the power supply end of the battery, and the other end of the thirteenth resistor is grounded.

[0017] Furthermore, the anti-recharge circuit further includes an OR gate circuit, one input end of the OR gate circuit is connected to the enabling circuit, the other input end is used to receive a level signal, and the output end of the OR gate circuit is connected to the anti-recharge circuit;

[0018] The OR gate circuit is configured to output the first level to the anti-recharge circuit when receiving the first level input by the enabling circuit or when the received level signal is the first level.

[0019] Furthermore, the anti-recharge circuit further includes a parallel circuit, a first input end of the parallel circuit is connected to the power supply, another input end is connected to the battery, and an output end of the parallel circuit is connected to the powered device.

[0020] Furthermore, the anti-recharge circuit further includes an isolation circuit, and the isolation circuit is provided between the power supply and the powered device.

[0021] A control method for an anti-recharge charging circuit is applied to any of the above-mentioned anti-recharge charging circuits, and the method comprises the following steps:

[0022] Step S100, enabling the circuit to detect the sampled voltage of the battery;

[0023] Step S200: When it is determined that the sampled voltage is higher than the stop-charging voltage threshold, the enabling circuit outputs a first level to the anti-recharge circuit; when the anti-recharge circuit receives the first level input by the enabling circuit, it is cut off, triggering the charging chip to cut off the power supply input of the battery;

[0024] Step S300: When it is determined that the sampled voltage is lower than the recharge voltage threshold, the enabling circuit outputs a second voltage level to the anti-recharge circuit; when the anti-recharge circuit receives the second voltage level input by the enabling circuit, it is turned on, triggering the charging chip to start the power supply input of the battery; wherein the stop-charging voltage threshold is greater than the recharge voltage threshold.

[0025] The beneficial effects of the present invention are as follows: the present invention provides an anti-recharge charging circuit and a control method thereof, which obtains the sampled voltage of the battery and compares the sampled voltage of the battery with a preset stop-charging voltage threshold and a pre-set recharge voltage threshold, and can directly control the charging chip to turn on or off the power supply input of the battery according to the comparison result. The anti-recharge circuit provided by the present application is compatible with various charging chips and has universal applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 This is a circuit block diagram of an anti-recharge circuit in an embodiment of the present invention;

[0028] Figure 2 This is a circuit diagram of an anti-recharge circuit in an embodiment of the present invention;

[0029] Figure 3 Schematic diagram of input and output characteristics of the hysteresis comparator in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0031] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0032] In the description of the present invention, if there are words such as "several", it means one or more, and "more" means more than two. Greater than, less than, and exceed are understood as not including the number itself, and above, below, and within are understood as including the number itself.

[0033] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0034] In the related art, when electronic devices are powered by batteries, they use a variety of charging chips. After the circuit design is completed, replacing different charging chips with different models may cause problems such as overcharging, floating charging, and back charging caused by small changes in battery voltage.

[0035] Based on this, the present invention provides an anti-backcharge charging circuit and a control method thereof, which directly controls the power supply input of the charging chip so that the circuit is compatible with various charging chips and has universal applicability.

[0036] refer to Figure 1 An embodiment of the present invention provides an anti-recharge charging circuit, comprising: a power supply 100, an anti-recharge circuit 200, a charging chip U1, a battery BAT, a powered device 400, and an enabling circuit 300; the power supply 100, the anti-recharge circuit 200, and the charging chip U1 are connected in sequence, the output end of the charging chip U1 and the power supply end of the battery BAT are commonly connected to the powered device 400, the input end of the enabling circuit 300 is connected to the power supply end of the battery BAT, and the output end is connected to the input end of the anti-recharge circuit 200;

[0037] The enabling circuit 300 is configured to detect a sampled voltage Uin of the battery BAT and output a first voltage level to the anti-recharge circuit 200 when the sampled voltage Uin is determined to be higher than a stop-charge voltage threshold UH; and output a second voltage level to the anti-recharge circuit 200 when the sampled voltage Uin is determined to be lower than a recharge voltage threshold UL; wherein the stop-charge voltage threshold UH is greater than the recharge voltage threshold UL.

[0038] The anti-backcharge circuit 200 is configured to be cut off when receiving the first level input from the enable circuit 300, triggering the charging chip U1 to cut off the power supply input to the battery BAT; and to be turned on when receiving the second level input from the enable circuit 300, triggering the charging chip U1 to turn on the power supply input to the battery BAT.

[0039] It should be noted that in the embodiments provided herein, the power supply 100 refers to an external power source provided to the circuit. The output of the power supply 100 outputs a DC power source. The charging chip U1 is a chip used to control the charging of the battery BAT, which has charge and discharge functions. The powered device 400 refers to a device that receives power from the power supply 100 or the battery BAT. The output of the charging chip U1 and the positive terminal of the battery BAT are both connected to the powered device 400, and the negative terminal of the battery BAT is grounded. The input of the enabling circuit 300 is connected to the output of the battery BAT, thereby detecting the sampled voltage Uin of the battery BAT. The output of the enabling circuit 300 is connected to the input of the anti-recharge circuit 200, thereby outputting a first voltage level and a second voltage level to the anti-recharge circuit 200.

[0040] In some embodiments, the enabling circuit 300 detects the sampled voltage Uin of the battery BAT and compares the sampled voltage Uin of the battery BAT with the stop-charging voltage threshold UH. When the sampled voltage Uin reaches the stop-charging voltage threshold UH, the enabling circuit 300 outputs a first level (e.g., a high level) to the anti-recharge circuit 200, so that the anti-recharge circuit 200 is turned off, thereby blocking the path from the power supply 100 to the charging chip U1, triggering the charging chip U1 to cut off the power supply input of the battery BAT; the stop-charging voltage threshold UH can be set according to actual conditions. For example, in order to ensure that the battery BAT is fully charged, the stop-charging voltage threshold UH is set to the full-charge voltage of the battery BAT, and the full-charge voltage is the voltage when the battery BAT is fully charged.

[0041] When the sampled voltage Uin reaches the recharge voltage threshold UL, a second level (e.g., a low level) is output to the anti-recharge circuit 200, causing the anti-recharge circuit 200 to conduct, thereby connecting the power supply 100 to the charging chip U1, triggering the charging chip U1 to start the power input to the battery BAT; the recharge voltage threshold UL can be set according to actual conditions, but it is necessary to ensure that the recharge voltage threshold UL is less than the stop-charging voltage threshold UH.

[0042] In the embodiment provided in the present application, the enabling circuit 300 compares the sampled voltage Uin of the battery BAT with the stop-charging voltage threshold UH. When the sampled voltage Uin reaches the stop-charging voltage threshold UH, the charging chip U1 is controlled to cut off the power supply input of the battery BAT, so that charging of the battery BAT is stopped after the battery BAT is fully charged, thereby preventing overcharging. The sampled voltage Uin of the battery BAT is compared with the recharge voltage threshold UL. When the sampled voltage Uin reaches the recharge voltage threshold UL, the charging chip U1 is controlled to turn on the power supply input of the battery BAT, so that the battery BAT is recharged after discharge, effectively preventing floating charge, so that the battery BAT can be maintained in a fully charged state without being overcharged.

[0043] By obtaining the sampled voltage Uin of the battery BAT and comparing the sampled voltage Uin of the battery BAT with the preset stop-charging voltage threshold UH and the resume-charging voltage threshold UL, the charging chip U1 can be directly controlled to turn on or off the power supply input of the battery BAT according to the comparison result. The anti-backcharge circuit 200 provided in this application is compatible with various charging chips U1 and has universal applicability.

[0044] refer to Figure 2 As a preferred embodiment of the above embodiment, the anti-backcharge circuit 200 includes: a second MOS transistor Q2, a third MOS transistor Q3, a fourth MOS transistor Q4, a transistor Q5, and a fifth resistor R5. The drain of the second MOS transistor Q2 and the source of the fourth MOS transistor Q4 are commonly connected to the power supply 100, the drain of the second MOS transistor Q2 is connected to the drain of the third MOS transistor Q3, the source of the third MOS transistor Q3 is connected to the input end of the charging chip U1, the gate of the second MOS transistor Q2, the gate of the third MOS transistor Q3, and the source of the fourth MOS transistor Q4 are commonly connected to one end of the fifth resistor R5, and the other end of the fifth resistor R5 is grounded. The gate of the fourth MOS transistor Q4 is connected to the collector of the transistor Q5, the emitter of the transistor Q5 is grounded, and the base is connected to the output end of the enabling circuit 300.

[0045] It should be noted that in the embodiment provided in the present application, the second MOS transistor Q2, the third MOS transistor Q3, and the fourth MOS transistor Q4 are all P-channel MOS transistors, and the transistor Q5 is an NPN-type transistor Q5. When the base of the transistor Q5 receives a high level, the transistor Q5 is turned on, and the fourth MOS transistor Q4 is turned on. Its conduction voltage drop Vds≈0V, so that Vgs of the second MOS transistor Q2 and the third MOS transistor Q3 is equal to Vds≈0V, the second MOS transistor Q2 and the third MOS transistor Q3 are turned off, and the anti-recharge circuit 200 is turned off; when the base of the transistor Q5 receives a low level, the transistor Q5 is turned off, and the fourth MOS transistor Q4 is turned off, so that the second MOS transistor Q2 and the third MOS transistor Q3 are turned on, and the anti-recharge circuit 200 is turned on. The anti-recharge circuit 200 provided in this embodiment can be turned off and on according to the level of the input.

[0046] As a preferred embodiment of the above embodiment, the anti-backcharge circuit 200 further includes: a fourth resistor R4, a sixth resistor R6, a ninth resistor R9, and a first capacitor C1. One end of the fourth resistor R4 and one end of the first capacitor C1 are commonly connected to the drain of the fourth MOS transistor Q4, the other end of the fourth resistor R4 and the other end of the first capacitor C1 are commonly connected to the gate of the fourth MOS transistor Q4, one end of the sixth resistor R6 and one end of the ninth resistor R9 are commonly connected to the base of the transistor Q5, the other end of the sixth resistor R6 is connected to the output end of the enabling circuit 300, and the other end of the ninth resistor R9 is grounded.

[0047] It should be noted that in the embodiment provided herein, the fourth resistor R4 is used to provide a gate-source voltage for the fourth MOS transistor Q4 and to limit the collector current of the transistor Q5. The voltage of the first capacitor C1 cannot change suddenly. By connecting the first capacitor C1 in parallel between the gate and source of the fourth MOS transistor Q4, the gate-source voltage of the fourth MOS transistor Q4 can be guaranteed not to change suddenly, thereby achieving slow turn-on and turn-off and preventing pulse interference. The sixth resistor R6 and the ninth resistor R9 are used for voltage division.

[0048] As a preferred embodiment of the above embodiment, the enabling circuit 300 includes a hysteresis comparator 320, a reference voltage circuit 310, and a sampling circuit 330. The input end of the reference voltage circuit 310 is connected to the power supply 100, and the input end of the sampling circuit 330 is connected to the power supply end of the battery BAT; the first input end of the hysteresis comparator 320 is connected to the output end of the reference voltage circuit 310, the second input end is connected to the output end of the sampling circuit 330, and the output end of the hysteresis comparator 320 is connected to the base of the transistor Q5;

[0049] The reference voltage circuit 310 is used to step down the voltage output by the power supply 100 so that the first input terminal of the hysteresis comparator 320 is maintained at the stop-charging voltage threshold value UH;

[0050] In this embodiment, the reference voltage circuit 310 is used to convert the voltage value output by the power supply 100 into a stop-charging voltage threshold value UH and keep it unchanged, so that the voltage value output to the hysteresis comparator 320 is maintained at the stop-charging voltage threshold value UH;

[0051] The sampling circuit 330 is used to divide the voltage output by the battery BAT to obtain a sampling voltage Uin, and input the sampling voltage Uin to the second input terminal of the hysteresis comparator 320; when the battery BAT is fully charged, the sampling voltage Uin is equal to the stop-charging voltage threshold value UH;

[0052] In some embodiments, the sampling circuit 330 is used to divide the voltage output by the battery BAT by a fixed ratio, thereby changing accordingly with the voltage output by the battery BAT, so that the voltage value output to the hysteresis comparator 320 can reflect the voltage change of the battery BAT. When the battery BAT is fully charged, the voltage output by the power supply end is stepped down by the sampling circuit 330 and input to the hysteresis comparator 320 to be equal to the stop-charging voltage threshold UH, thereby triggering the output level of the hysteresis comparator 320 to change from a low level to a high level.

[0053] The hysteresis comparator 320 is configured to output a first level when the voltage value of the second input terminal is higher than the voltage value of the first input terminal; and output a second level when the voltage value of the second input terminal is lower than the voltage value of the first input terminal.

[0054] In this embodiment, the voltage value of the first input terminal is used as a reference voltage. Since the voltage value of the first input terminal is maintained at the stop-charging voltage threshold value UH, the voltage value of the second input terminal is compared with the voltage value of the first input terminal. That is, the voltage value of the second input terminal is compared with the stop-charging voltage threshold value UH, and the first level or the second level is output according to the comparison result.

[0055] As a preferred embodiment of the above, the reference voltage circuit 310 includes: a reference voltage chip U3, a third resistor R3, a seventh resistor R7, a tenth resistor R10 and a second capacitor C2, one end of the seventh resistor R7 and the cathode of the reference voltage chip U3 are commonly connected to one end of the third resistor R3, the other end of the third resistor R3 is connected to the power supply 100, the other end of the seventh resistor R7 is respectively connected to the reference electrode of the reference voltage chip U3 and one end of the tenth resistor R10, the anode of the reference voltage chip U3 and the other end of the tenth resistor R10 are commonly grounded, the second capacitor C2 is arranged between the anode and cathode of the reference voltage chip U3, and the cathode of the reference voltage chip U3 is also connected to the first input end of the hysteresis comparator 320.

[0056] In one embodiment, the reference voltage chip U3 is of model SGM431, and the reference voltage chip U3 outputs an accurate charging stop voltage threshold value UH.

[0057] As a preferred embodiment of the above embodiment, the hysteresis comparator 320 includes: an operational amplifier U2, an eighth resistor R8 and an eleventh resistor R11, the inverting input terminal of the operational amplifier U2 is connected to the cathode of the reference voltage chip U3, the non-inverting input terminal of the operational amplifier U2 is connected to one end of the eleventh resistor R11, and the other end of the eleventh resistor R11 is connected to the output end of the sampling circuit 330; the two ends of the eighth resistor R8 are respectively connected to the non-inverting input terminal and the output end of the operational amplifier U2.

[0058] The input and output characteristics of the hysteresis comparator 320 are as follows: Figure 3 As shown;

[0059] As the sampling voltage Uin increases from the recharge voltage threshold UL to the stop-charge voltage threshold UH, the output level of operational amplifier U2 transitions from low to high. As the sampling voltage Uin decreases from ≥ the stop-charge voltage threshold UH, the output level of operational amplifier U2 remains high until the sampling voltage Uin falls below the recharge voltage threshold UL, at which point the output level of operational amplifier U2 transitions from high to low. By configuring the width of the region between the stop-charge voltage threshold UH and the recharge voltage threshold UL, the recharge voltage range △U of the battery BAT is adjusted, preventing the battery BAT circuit from overcharging, floating charging, and recharging caused by small voltage changes.

[0060] The recharge voltage threshold UL = the stop-charge voltage threshold UH - the recharge voltage range △U. For example, if the recharge voltage range △U = 0.1V, then the recharge voltage threshold UL = the stop-charge voltage threshold UH - 0.1V. The charging circuit will only recharge the battery BAT if the battery BAT voltage change is greater than or equal to the recharge voltage range △U, preventing recharge caused by small voltage changes in the battery BAT.

[0061] As a preferred embodiment of the above embodiment, the sampling circuit 330 includes: a twelfth resistor R12 and a thirteenth resistor R13, one end of the twelfth resistor R12 and one end of the thirteenth resistor R13 are commonly connected to the other end of the eleventh resistor R11, the other end of the twelfth resistor R12 is connected to the power supply end of the battery BAT, and the other end of the thirteenth resistor R13 is grounded.

[0062] Through the twelfth resistor R12 and the thirteenth resistor R13, the charging stop voltage threshold UH can be set as needed within the input voltage range allowed by the operational amplifier U2, and is compatible with different numbers of charging chips U1 and batteries BAT of different voltages.

[0063] The battery BAT voltage is sampled and stepped down through the twelfth resistor R12 and the thirteenth resistor R13 so that when the battery BAT is fully charged, the voltage output by the power supply end (the fully charged power supply VBAT) divided by the full power supply VBAT and input to the non-inverting input end of the operational amplifier U2 equals the stop-charging voltage threshold value UH.

[0064] When the battery BAT is fully charged and the voltage reaches the full-charge power supply VBAT, the corresponding input level to the non-inverting input terminal of the operational amplifier U2 is the stop-charge voltage threshold value UH, and the operational amplifier U2 outputs a high level to turn off the charging circuit to prevent the battery BAT from overcharging; when the battery BAT is discharged to make the input level of the non-inverting input terminal of the operational amplifier U2 equal to the stop-charge voltage threshold value UH-recharge voltage range △U, the operational amplifier U2 outputs a low level, the charging circuit is turned on, and the battery BAT is recharged, instead of charging the battery BAT immediately when the battery BAT voltage is lower than the full-charge power supply VBAT, effectively preventing the occurrence of floating charge and recharge caused by small voltage changes of the battery BAT.

[0065] As a preferred embodiment of the above embodiment, the anti-recharge circuit 200 further includes an OR gate circuit 500, one input end of the OR gate circuit 500 is connected to the enable circuit 300, the other input end is used to receive a level signal, and the output end of the OR gate circuit 500 is connected to the anti-recharge circuit 200;

[0066] The OR gate circuit 500 is configured to output the first level to the anti-recharge circuit 200 when receiving the first level input from the enabling circuit 300 or when the received level signal is the first level.

[0067] In some embodiments, the OR gate circuit 500 includes a second diode D2 and a third diode D3. The anode of the second diode D2 is connected to the input of the enable circuit 300, and the anode of the third diode D3 is connected to a controller. The controller is configured to send a first level to the OR gate circuit 500 when it detects that the battery BAT is not present, and send a second level to the OR gate circuit 500 when it detects that the battery BAT is present. The cathodes of the second diode D2 and the third diode D3 are connected to the input of the anti-recharge circuit 200. In another embodiment, the input of the anti-recharge circuit 200 is the sixth resistor R6, and the cathodes of the second diode D2 and the third diode D3 are connected to the other end of the sixth resistor R6. In one embodiment, when the first input receives a high level input from the enable circuit 300 or when the second input receives a high level sent by the controller, the OR gate circuit 500 outputs a high level to the anti-recharge circuit 200.

[0068] As a preferred embodiment of the above embodiment, the anti-recharge circuit 200 further includes a parallel circuit 600 , a first input end of the parallel circuit 600 is connected to the power supply 100 , another input end is connected to the battery BAT, and an output end of the parallel circuit 600 is connected to the powered device 400 .

[0069] In some embodiments, the parallel circuit 600 includes a first MOS transistor Q1, a first resistor R1, and a second resistor R2. One end of the first resistor R1 is connected to the power supply 100, and the other end is respectively connected to one end of the second resistor R2 and the gate of the first MOS transistor Q1. The other end of the second resistor R2 is grounded. The source of the first MOS transistor Q1 is connected to the power supply end of the battery BAT, and the drain is connected to the powered device 400.

[0070] By providing the first MOS transistor Q1, the power supply 100 can charge the powered device 400 and the battery BAT. When the voltage at the power supply end of the battery BAT is insufficient, the power supply 100 is enabled. When the battery BAT is supplying power to the powered device 400, the power supply path of the power supply 100 to the powered device 400 is blocked.

[0071] As a preference of the above embodiment, the anti-backcharge circuit 200 further includes an isolation circuit 700 , and the isolation circuit 700 is provided between the power supply 100 and the powered device 400 .

[0072] In some embodiments, the isolation circuit 700 includes a first diode D1 , wherein an anode of the first diode D1 is connected to the power supply 100 , and a cathode of the first diode D1 is connected to the powered device 400 .

[0073] Here's how this application works:

[0074] For the convenience of description, the first MOS transistor Q1, the second MOS transistor Q2, the third MOS transistor Q3, and the fourth MOS transistor Q4 are all P-channel MOS transistors, and Vgs and Vgs(th) both represent absolute values;

[0075] When the battery BAT is in place (not fully charged) and the power supply voltage DC_IN is input, the gate of the first MOS transistor Q1 is pulled up, Vgs<Vgs(th), the first MOS transistor Q1 is turned off, and the power supply 100 supplies power to the load;

[0076] The battery BAT is connected in parallel with the power supply 100 through the body diode of the first MOS transistor Q1. However, since the power supply voltage DC_IN of the power supply 100 is greater than the fully charged power voltage VBAT of the battery BAT, the body diode of the first MOS transistor Q1 is cut off, and the battery BAT does not supply power.

[0077] When the battery BAT is in place, the controller outputs a low level; and because the battery BAT voltage is not satisfied at this time, the voltage at the non-inverting input of the operational amplifier U2 is greater than the stop-charge voltage threshold UH, and the operational amplifier U2 outputs a low level. The anti-recharge circuit 200 is turned on;

[0078] The battery BAT starts charging;

[0079] When the battery BAT is fully charged to the full power supply VBAT, the voltage level input to the non-inverting input terminal of the operational amplifier U2 is the stop-charging voltage threshold UH, the operational amplifier U2 outputs a high level, the transistor Q5 is turned on, the fourth MOS transistor Q4 is turned on, and its conduction voltage drop Vds≈0V, so that the Vgs of the second MOS transistor Q2 and the third MOS transistor Q3 is equal to Vds≈0V, the second MOS transistor Q2 and the third MOS transistor Q3 are turned off, and the anti-recharge circuit 200 is turned off;

[0080] Since the battery BAT itself consumes current, the voltage of the battery BAT will slowly drop even when plugged into the external power supply 100. Due to the presence of the hysteresis comparator 320, only when the battery BAT voltage drops to a level that satisfies the input level of the non-inverting input terminal of the operational amplifier U2 within the full power supply VBAT - recharge voltage range △U, will the operational amplifier U2 output a low level again, re-opening the anti-recharge circuit 200 to charge the battery BAT. This effectively prevents the charging circuit from continuously floating-charging the battery BAT while the battery BAT itself is consuming current, and prevents recharge caused by small voltage changes in the battery BAT.

[0081] When the power input is removed, the gate of the first MOS transistor Q1 is pulled down to ground by the second resistor R2, making its Vgs>Vgs(th), the PMOS is turned on, and the battery BAT supplies power to the system. And because the Rds of the first MOS transistor Q1 is extremely small when it is turned on, the loss is very small;

[0082] At the same time, the inverting input terminal of the operational amplifier U2 is pulled down to ground by the seventh resistor R7 and the tenth resistor R10, and the operational amplifier U2 outputs a high level. The second MOS transistor Q2 and the third MOS transistor Q3 of the anti-backflow circuit 200 are cut off, effectively preventing the battery BAT from backflowing to the power input port through the charging circuit.

[0083] The first diode D1 can effectively prevent the battery BAT from backflowing to the power input port of the powered device 400.

[0084] When the controller detects that the battery BAT is not in place and the power voltage DC_IN is input, it outputs a high level, the anti-backcharge circuit 200 is turned off, and the first MOS tube Q1 is turned off, so that the charging circuit has no power input, which not only effectively reduces power consumption but also ensures that there is no voltage at the battery BAT socket, thereby improving safety.

[0085] If the controller detects that the battery BAT is fully charged, it can also output a high level battery BAT presence detection signal to shut down the anti-recharge circuit 200, thereby achieving dual control of software and hardware.

[0086] In addition, an embodiment of the present invention provides a control method for an anti-recharge charging circuit, which is applied to the anti-recharge charging circuit described in any of the above embodiments. The method includes the following steps:

[0087] Step S100: The enabling circuit 300 detects a sampled voltage Uin of the battery BAT;

[0088] Step S200: When it is determined that the sampled voltage Uin is higher than the stop-charging voltage threshold UH, the enabling circuit 300 outputs a first voltage level to the anti-recharge circuit 200; when the anti-recharge circuit 200 receives the first voltage level input by the enabling circuit 300, it is turned off, triggering the charging chip U1 to cut off the power supply input of the battery BAT;

[0089] Step S300: When it is determined that the sampled voltage Uin is lower than the recharge voltage threshold UL, the enabling circuit 300 outputs a second voltage level to the anti-recharge circuit 200; when the anti-recharge circuit 200 receives the second voltage level input by the enabling circuit 300, it is turned on, triggering the charging chip U1 to start the power supply input of the battery BAT; wherein the stop-charging voltage threshold UH is greater than the recharge voltage threshold UL.

[0090] Corresponding to the above-mentioned circuit embodiment, in the embodiment provided by the present application, the sampling voltage Uin of the battery BAT is compared with the stop-charging voltage threshold UH by the enabling circuit 300. When the sampling voltage Uin reaches the stop-charging voltage threshold UH, the charging chip U1 is controlled to cut off the power supply input of the battery BAT, so that charging of the battery BAT is stopped after the battery BAT is fully charged, thereby preventing overcharging; the sampling voltage Uin of the battery BAT is compared with the recharging voltage threshold UL. When the sampling voltage Uin reaches the recharging voltage threshold UL, the charging chip U1 is controlled to turn on the power supply input of the battery BAT, so that the battery BAT is recharged after discharge, effectively preventing floating charge, so that the battery BAT can be maintained in a fully charged state without being overcharged.

[0091] By obtaining the sampled voltage Uin of the battery BAT and comparing the sampled voltage Uin of the battery BAT with the preset stop-charging voltage threshold UH and the resume-charging voltage threshold UL, the charging chip U1 can be directly controlled to turn on or off the power supply input of the battery BAT according to the comparison result. The anti-backcharge circuit 200 provided in this application is compatible with various charging chips U1 and has universal applicability.

[0092] The embodiments described in the embodiments of the present invention are intended to more clearly illustrate the technical solutions of the embodiments of the present invention and do not constitute a limitation on the technical solutions provided by the embodiments of the present invention. Those skilled in the art will appreciate that with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of the present invention are also applicable to similar technical problems.

[0093] Those skilled in the art will understand that the technical solutions shown in the figures do not constitute a limitation on the embodiments of the present invention, and may include more or fewer steps than shown in the figures, or a combination of certain steps, or different steps.

[0094] The device embodiments described above are merely illustrative. The circuits described as separate components may or may not be physically separate, i.e., they may be located in one location or distributed across multiple network circuits. Some or all of the modules may be selected based on actual needs to achieve the objectives of this embodiment.

[0095] Those skilled in the art will appreciate that all or some of the steps in the methods, systems, and functional modules / circuits in the devices disclosed above may be implemented as software, firmware, hardware, or appropriate combinations thereof.

[0096] The terms "first," "second," "third," "fourth," and so forth (if any) in the description of the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate so that the embodiments of the present invention described herein can be implemented in orders other than those illustrated or described herein. In addition, the terms "including" and "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus that includes a series of steps or circuits is not necessarily limited to those steps or circuits explicitly listed, but may include other steps or circuits not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0097] It should be understood that in the present invention, "at least one (item)" refers to one or more, and "plurality" refers to two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can represent: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0098] In the several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the above circuits is merely a logical function division. In actual implementation, there may be other division methods, such as multiple circuits or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interface, device or circuit, which can be electrical, mechanical or other forms.

[0099] The circuits described above as separate components may or may not be physically separate, and the components shown as circuits may or may not be physical circuits, that is, they may be located in one place or distributed across multiple network circuits. Some or all of these circuits may be selected based on actual needs to achieve the objectives of this embodiment.

[0100] In addition, the functional circuits in various embodiments of the present invention may be integrated into a single processing circuit, each circuit may exist physically separately, or two or more circuits may be integrated into a single circuit. The aforementioned integrated circuits may be implemented in the form of hardware or software functional circuits.

[0101] The preferred embodiments of the embodiments of the present invention are described above with reference to the accompanying drawings, but the scope of the rights of the embodiments of the present invention is not limited thereby. Any modifications, equivalent substitutions and improvements made by those skilled in the art without departing from the scope and essence of the embodiments of the present invention should be within the scope of the rights of the embodiments of the present invention. Although the description disclosed in the present invention has been quite detailed and particularly describes several of the embodiments, it is not intended to be limited to any of these details or embodiments or any particular embodiment, but should be regarded as providing a broad possible interpretation for these claims by reference to the attached claims, taking into account the prior art, thereby effectively covering the intended scope disclosed by the present invention. In addition, the above description of the present invention is based on the embodiments that the inventor can foresee, and its purpose is to provide a useful description, and those non-substantial changes to the present invention that have not yet been foreseen may still represent equivalent changes to the present disclosure.

Claims

1. A charging circuit for preventing back-charge, characterized in that: include: A power supply (100), an anti-recharge circuit (200), a charging chip (U1), a battery (BAT), a powered device (400), and an enabling circuit (300); the power supply (100), the anti-recharge circuit (200), the charging chip (U1), the battery (BAT), and the powered device (400) are connected in sequence, and the input end of the enabling circuit (300) is connected to the power supply end of the battery (BAT), and the output end is connected to the input end of the anti-recharge circuit (200); The enabling circuit (300) is used to detect the sampling voltage (Uin) of the battery (BAT), and output a first level to the anti-recharge circuit (200) when it is determined that the sampling voltage (Uin) is higher than the stop-charge voltage threshold (UH); and output a second level to the anti-recharge circuit (200) when it is determined that the sampling voltage (Uin) is lower than the recharge voltage threshold (UL); wherein the stop-charge voltage threshold (UH) is greater than the recharge voltage threshold (UL); The anti-recharge circuit (200) is configured to be cut off when receiving a first level input from the enabling circuit (300), triggering the charging chip (U1) to turn off the power supply input of the battery (BAT); and to be turned on when receiving a second level input from the enabling circuit (300), triggering the charging chip (U1) to turn on the power supply input of the battery (BAT); The anti-recharge circuit (200) comprises: a second MOS transistor (Q2), a third MOS transistor (Q3), a fourth MOS transistor (Q4), a triode (Q5) and a fifth resistor (R5); the drain of the second MOS transistor (Q2) and the source of the fourth MOS transistor (Q4) are commonly connected to the power supply (100); the source of the second MOS transistor (Q2) is connected to the source of the third MOS transistor (Q3); the drain of the third MOS transistor (Q3) is connected to the input end of the charging chip (U1); the gate of the second MOS transistor (Q2), the gate of the third MOS transistor (Q3) and the drain of the fourth MOS transistor (Q4) are commonly connected to one end of the fifth resistor (R5); the other end of the fifth resistor (R5) is grounded; the gate of the fourth MOS transistor (Q4) is connected to the collector of the triode (Q5); the emitter of the triode (Q5) is grounded and the base is connected to the output end of the enabling circuit (300).

2. The anti-backcharge charging circuit according to claim 1, characterized in that: The enabling circuit (300) comprises a hysteresis comparator (320), a reference voltage circuit (310) and a sampling circuit (330), wherein the input end of the reference voltage circuit (310) is connected to the power supply (100), and the input end of the sampling circuit (330) is connected to the power supply end of the battery (BAT); the first input end of the hysteresis comparator (320) is connected to the output end of the reference voltage circuit (310), the second input end is connected to the output end of the sampling circuit (330), and the output end of the hysteresis comparator (320) is connected to the base of the transistor (Q5); The reference voltage circuit (310) is used to step down the voltage output by the power supply (100) so that the first input terminal of the hysteresis comparator (320) is maintained at a stop-charging voltage threshold value (UH); The sampling circuit (330) is used to divide the voltage output by the battery (BAT) to obtain a sampling voltage (Uin), and input the sampling voltage (Uin) to the second input terminal of the hysteresis comparator (320); when the battery (BAT) is fully charged, the sampling voltage (Uin) is equal to the stop-charging voltage threshold value (UH); The hysteresis comparator (320) is configured to output a first level when the voltage value of the second input terminal is higher than the voltage value of the first input terminal; When the voltage value of the second input terminal is lower than the voltage value of the first input terminal, a second level is output.

3. The anti-backcharge charging circuit according to claim 2, characterized in that: The reference voltage circuit (310) comprises: a reference voltage chip (U3), a third resistor (R3), a seventh resistor (R7), a tenth resistor (R10) and a second capacitor (C2); one end of the seventh resistor (R7) and the cathode of the reference voltage chip (U3) are commonly connected to one end of the third resistor (R3); the other end of the third resistor (R3) is connected to a power supply (100); the other end of the seventh resistor (R7) is respectively connected to the reference electrode of the reference voltage chip (U3) and one end of the tenth resistor (R10); the anode of the reference voltage chip (U3) and the other end of the tenth resistor (R10) are commonly grounded; the second capacitor (C2) is arranged between the anode and cathode of the reference voltage chip (U3); and the cathode of the reference voltage chip (U3) is also connected to the first input end of the hysteresis comparator (320).

4. The anti-backcharge charging circuit according to claim 3, characterized in that: The hysteresis comparator (320) comprises: an operational amplifier (U2), an eighth resistor (R8) and an eleventh resistor (R11); the inverting input terminal of the operational amplifier (U2) is connected to the cathode of the reference voltage chip (U3); the non-inverting input terminal of the operational amplifier (U2) is connected to one end of the eleventh resistor (R11); the other end of the eleventh resistor (R11) is connected to the output end of the sampling circuit (330); and the two ends of the eighth resistor (R8) are respectively connected to the non-inverting input terminal and the output end of the operational amplifier (U2).

5. The anti-backcharge charging circuit according to claim 4, characterized in that: The sampling circuit (330) comprises: a twelfth resistor (R12) and a thirteenth resistor (R13), one end of the twelfth resistor (R12) and one end of the thirteenth resistor (R13) are commonly connected to the other end of the eleventh resistor (R11), the other end of the twelfth resistor (R12) is connected to the power supply end of the battery (BAT), and the other end of the thirteenth resistor (R13) is grounded.

6. The anti-backcharge charging circuit according to claim 5, characterized in that: The anti-recharge circuit (200) further includes an OR gate circuit (500), one input end of the OR gate circuit (500) is connected to the enabling circuit (300), the other input end is used to receive a level signal, and the output end of the OR gate circuit (500) is connected to the anti-recharge circuit (200); The OR gate circuit (500) is used to output the first level to the anti-recharge circuit (200) when receiving the first level input by the enabling circuit (300) or when the received level signal is the first level.

7. The anti-backcharge charging circuit according to claim 6, characterized in that: The anti-recharge circuit (200) further comprises a parallel circuit (600), a first input end of the parallel circuit (600) being connected to the power supply (100), another input end being connected to the battery (BAT), and an output end of the parallel circuit (600) being connected to the powered device (400).

8. The anti-backcharge charging circuit according to claim 7, characterized in that: The anti-recharge circuit (200) further includes an isolation circuit (700), and the isolation circuit (700) is provided between the power supply (100) and the powered device (400).

9. A control method for an anti-backcharge charging circuit, characterized in that: The anti-recharge charging circuit according to any one of claims 1 to 8 is characterized in that the method comprises the following steps: Step S100, the enabling circuit (300) detects the sampled voltage (Uin) of the battery (BAT); Step S200: When it is determined that the sampled voltage (Uin) is higher than the stop-charging voltage threshold (UH), the enabling circuit (300) outputs a first electrical level to the anti-recharge circuit (200); when the anti-recharge circuit (200) receives the first electrical level input by the enabling circuit (300), it is cut off, triggering the charging chip (U1) to cut off the power supply input of the battery (BAT); Step S300: When it is determined that the sampling voltage (Uin) is lower than the recharge voltage threshold (UL), the enabling circuit (300) outputs a second level to the anti-recharge circuit (200); when the anti-recharge circuit (200) receives the second level input by the enabling circuit (300), it is turned on, triggering the charging chip (U1) to start the power supply input of the battery (BAT); wherein the stop charging voltage threshold (UH) is greater than the recharge voltage threshold (UL).

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