0V charging forbidding circuit

Abstract

The utility model discloses a 0V charging forbidding circuit, which comprises a battery end, a low potential end, a detection circuit, a master control circuit and an output circuit, the sampling end of the detection circuit is electrically connected with the battery end, the input end of the master control circuit is electrically connected with the output end of the detection circuit, and the output end of the master control circuit is electrically connected with the output end of the detection circuit. The output circuit comprises a first input end and a second input end, the first input end is electrically connected with the battery end, the second input end is electrically connected with the low-potential end, and the controlled end of the output circuit is electrically connected with the main control circuit, so that when the voltage of the battery end is reduced to 0V, a charging loop of the battery is disconnected, and the condition that the battery end is still charged when the voltage of the battery end is 0V is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of charging, in particular to a circuit for prohibiting 0V charging. Background Art

[0002] In various portable electronic products, lithium battery terminals are the main power suppliers. When the lithium battery terminal is discharged below the over-discharge value, in order to protect the battery terminal from damage, the over-discharge protection function will be triggered and the discharge process will be automatically cut off. However, it is worth noting that the lithium battery terminal protection chip will still have a small self-consumption after over-discharge. This means that if the battery terminal is left for a long time without charging, the voltage of the lithium battery terminal may gradually drop to close to 0V.

[0003] When the battery terminal drops to 0V, the chemical substances inside the battery terminal may be in an unstable state. If charging is performed at this time, the battery terminal may not be able to accept the charge normally, resulting in charging failure or damage to the battery terminal. In addition, the 0V battery terminal may produce abnormal reactions during the charging process, such as overheating and short circuit. These abnormal reactions may cause safety risks such as fire and explosion, posing a threat to the user's personal safety. Utility Model Content

[0004] The main purpose of the utility model is to provide a 0V charging prohibition circuit, which is intended to disconnect the charging circuit of the battery when the voltage at the battery terminal drops to 0V, so as to avoid continuous charging when the voltage at the battery terminal is 0V.

[0005] In order to achieve the above object, the utility model proposes a 0V charging prohibition circuit, the 0V charging prohibition circuit includes a battery terminal and a low potential terminal, and is characterized in that the 0V charging prohibition circuit also includes:

[0006] A detection circuit, wherein a sampling end of the detection circuit is electrically connected to the battery end, and the detection circuit is used to detect the voltage of the battery end and output a corresponding detection signal;

[0007] A main control circuit, wherein an input end of the main control circuit is electrically connected to an output end of the detection circuit;

[0008] an output circuit, the output circuit comprising a first input terminal and a second input terminal, the first input terminal being electrically connected to the battery terminal, the second input terminal being electrically connected to the low potential terminal, and the controlled terminal of the output circuit being electrically connected to the main control circuit;

[0009] The main control circuit is used to control the output end of the output circuit to output the voltage of the battery end or the voltage of the low potential end according to the detection signal.

[0010] Optionally, the detection circuit includes:

[0011] A first switch tube, a first resistor and a second resistor, wherein the input end of the first switch tube is electrically connected to the battery end, the first end of the first resistor is electrically connected to the battery end, the controlled end of the first switch tube is electrically connected to the second end of the first resistor, the output end of the first switch tube is electrically connected to the input end of the main control circuit, the first end of the second resistor is electrically connected to the battery end, and the second end of the second resistor is electrically connected to the input end of the main control circuit.

[0012] Optionally, the detection circuit further includes:

[0013] A second switch tube, wherein the input end of the second switch tube is electrically connected to the second end of the first resistor, the controlled end of the second switch tube is electrically connected to the controlled end of the first switch tube and the input end of the second switch tube respectively, and the output end of the second switch tube is grounded.

[0014] Optionally, the output circuit includes:

[0015] A voltage output end, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a third switch tube and a fourth switch tube, wherein the first end of the third resistor is electrically connected to the battery end, the second end of the third resistor is electrically connected to the controlled end of the third switch tube, the controlled end of the third switch tube is also electrically connected to the output end of the main control circuit, the input end of the third switch tube is electrically connected to the battery end, the output end of the third switch tube is electrically connected to the first end of the fourth resistor, the second end of the fourth resistor is electrically connected to the voltage output end, the voltage output end is electrically connected to the first end of the fifth resistor, the second end of the fifth resistor is electrically connected to the output end of the fourth switch tube, the input end of the fourth switch tube is electrically connected to the low potential end, the controlled end of the fourth switch tube is electrically connected to the first end of the sixth resistor and the output end of the main control circuit respectively, and the second end of the sixth resistor is electrically connected to the low potential end.

[0016] Optionally, the main control circuit includes:

[0017] A first inverter, a first push-pull output circuit, a second push-pull output circuit, a fifth switch tube, a seventh resistor and an eighth resistor, wherein the input end of the first inverter is used to access a high level or a low level, the first end of the first push-pull output circuit is electrically connected to the output end of the detection circuit, the controlled end of the first push-pull output circuit is electrically connected to the output end of the first inverter, the second end of the first push-pull output circuit is grounded, the output end of the first push-pull output circuit is electrically connected to the controlled end of the fifth switch tube, the input end of the fifth switch tube is electrically connected to the battery end, and the output end of the fifth switch tube is electrically connected to the battery end. The first end of the eighth resistor is electrically connected, the second end of the eighth resistor is electrically connected to the controlled end of the fourth switch tube and the first end of the sixth resistor respectively, the first end of the seventh resistor is electrically connected to the controlled end of the fifth switch tube, and the second end of the seventh resistor is electrically connected to the low potential end; the output end of the first push-pull output circuit is also electrically connected to the controlled end of the second push-pull output circuit, the first end of the second push-pull output circuit is electrically connected to the battery end, the second end of the second push-pull output circuit is grounded, and the output end of the second push-pull output circuit is electrically connected to the controlled end of the fifth switch tube.

[0018] Optionally, the first push-pull output circuit includes:

[0019] a sixth switch tube and a seventh switch tube, wherein the input end of the sixth switch tube is electrically connected to the output end of the detection circuit, the input end of the seventh switch tube is electrically connected to the output end of the sixth switch tube, the controlled end of the sixth switch tube and the controlled end of the seventh switch tube are both electrically connected to the output end of the first inverter, the output end of the sixth switch tube is electrically connected to the controlled end of the fifth switch tube, and the output end of the seventh switch tube is grounded;

[0020] The second push-pull output circuit comprises:

[0021] An eighth switch tube and a ninth switch tube, wherein the input end of the eighth switch tube is electrically connected to the battery end, the output end of the eighth switch tube is electrically connected to the input end of the ninth switch tube, the output end of the ninth switch tube is grounded, the controlled end of the eighth switch tube and the controlled end of the ninth switch tube are both electrically connected to the output end of the eighth switch tube, and the output end of the eighth switch tube is electrically connected to the controlled end of the third switch tube.

[0022] Optionally, the output circuit further includes:

[0023] A tenth switch tube, the second end of the sixth resistor is electrically connected to the output end of the tenth switch tube, the input end of the tenth switch tube is electrically connected to the low potential end, and the controlled end of the tenth switch tube is electrically connected to the input end of the tenth switch tube.

[0024] Optionally, the 0V charging prohibition circuit further includes:

[0025] An eleventh switch tube and a ninth resistor, wherein the input end of the eleventh switch tube is electrically connected to the battery end, the output end of the eleventh switch tube is electrically connected to the second end of the seventh resistor and the first end of the ninth resistor respectively, and the second end of the ninth resistor is electrically connected to the low potential end.

[0026] The technical scheme of the utility model includes a detection circuit, a main control circuit and an output circuit. The detection circuit is used for detecting the voltage of the battery terminal and outputting a corresponding detection signal. The main control circuit determines whether the voltage of the battery terminal is close to 0 according to the detection signal, and controls the output circuit to output the voltage of the battery terminal or the voltage of the low potential terminal. The output terminal of the output circuit is used for being electrically connected to an external main control. When the external main control receives the normal voltage of the battery terminal, it controls or maintains the electrical connection of the path between the power supply and the battery so that the battery can be charged normally under normal conditions; when the external main control receives the voltage of the low potential terminal, the external main control controls the path between the power supply and the battery to be disconnected so that the battery cannot be charged when the voltage is basically 0. With such an arrangement, in actual application, when the battery terminal voltage is basically 0, the technical solution of the utility model can promptly disconnect the loop between the battery terminal and the power supply and connect a low voltage to the battery terminal, so that the battery terminal voltage cannot be charged when it is 0V; when the battery terminal voltage is greater than 0, the technical solution of the utility model conducts the path between the power supply and the battery terminal, so that the battery terminal voltage can be charged normally when it is greater than 0. The utility model ensures that the battery terminal operates within the normal voltage range, thereby avoiding the problem of sudden shutdown or performance degradation of the corresponding equipment due to excessively low battery terminal voltage, thereby improving the stability and reliability of the equipment to which the utility model is applied. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0028] Figure 1 This is a schematic diagram of a module of an embodiment of the utility model;

[0029] Figure 2 This is a schematic diagram of the circuit structure of another embodiment of the utility model.

[0030] Description of Figure Numbers:

[0031] Label name Label name 10 Detection circuit 22 Second push-pull output circuit 20 Main control circuit 30 Output Circuit 21 First push-pull output circuit

[0032] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0034] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0035] In addition, the descriptions of "first", "second", etc. in the present utility model are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0036] In various portable electronic products, lithium battery terminals are the main power suppliers. When the lithium battery terminal is discharged below the over-discharge value, in order to protect the battery terminal from damage, the over-discharge protection function will be triggered and the discharge process will be automatically cut off. However, it is worth noting that the lithium battery terminal protection chip will still have a small self-consumption after over-discharge. This means that if the battery terminal is left for a long time without charging, the voltage of the lithium battery terminal may gradually drop to close to 0V.

[0037] When the battery terminal drops to 0V, the chemical substances inside the battery terminal may be in an unstable state. If charging is performed at this time, the battery terminal may not be able to accept the charge normally, resulting in charging failure or damage to the battery terminal. In addition, the 0V battery terminal may produce abnormal reactions during the charging process, such as overheating and short circuit. These abnormal reactions may cause safety risks such as fire and explosion, posing a threat to the user's personal safety.

[0038] To this end, the main purpose of the utility model is to provide a 0V charging prohibition circuit, which is intended to disconnect the charging circuit at the battery end when the voltage at the battery end drops to 0V, so as to avoid continued charging when the battery terminal voltage is 0V.

[0039] refer to Figure 1 In one embodiment of the utility model, a 0V charging prohibition circuit is provided, the 0V charging prohibition circuit comprises a battery terminal and a low potential terminal, and the 0V charging prohibition circuit further comprises:

[0040] A detection circuit 10, wherein a sampling end of the detection circuit 10 is electrically connected to the battery end, and the detection circuit 10 is used to detect the voltage of the battery end and output a corresponding detection signal;

[0041] A main control circuit 20, wherein an input end of the main control circuit 20 is electrically connected to an output end of the detection circuit 10, and a controlled end of the main control circuit 20 is used to receive a disconnection signal or a conduction signal;

[0042] An output circuit 30, the output circuit 30 comprises a first input terminal and a second input terminal, the first input terminal is electrically connected to the battery terminal, the second input terminal is electrically connected to the low potential terminal, and the controlled terminal of the output circuit 30 is electrically connected to the output terminal of the main control circuit 20;

[0043] When the controlled end of the main control circuit 20 receives the conduction signal and is turned on, the output end of the output circuit 30 outputs the voltage of the battery end or the voltage of the low potential end according to the detection signal.

[0044] In this embodiment, the output end of the output circuit 30 is used to be electrically connected to the external main control. When the external main control receives the voltage at the battery end, it controls or maintains the path between the power supply and the battery to be connected, so that the battery can be charged normally under normal conditions; when the external main control receives the voltage at the low potential end, it controls the path between the power supply and the battery to be disconnected, so that the battery cannot be charged when the voltage is 0.

[0045] In this embodiment, the detection circuit 10 can be implemented by a voltage sensor such as a Hall voltage sensor, a voltage divider sensor or a resistor voltage divider. The voltage sensor can be directly used to detect the voltage of the battery terminal and output a corresponding detection signal, and the voltage sensor has a high detection accuracy, so that the technical solution of the utility model can timely disconnect the path between the battery terminal and the battery terminal when the battery terminal voltage is 0, which helps to ensure that the battery terminal will not be charged when the voltage is too low; the detection circuit 10 can also be implemented by at least one switch tube and at least one resistor, the input end of the switch tube is electrically connected to the battery terminal, and the controlled end of the switch tube is electrically connected to the battery terminal through the resistor. The output end of the switch tube is electrically connected to the main control circuit 20. When the voltage at the battery end is greater than the conduction threshold of the switch tube (the battery voltage is greater than 0), the switch tube is turned on, and the main control circuit 20 controls the output circuit 30 to output the voltage at the battery end according to the voltage at the battery end obtained through the switch tube; when the voltage at the battery end is less than the conduction threshold of the switch tube (the battery voltage is 0), the switch tube is turned off, and the main control circuit 20 controls the output circuit 30 to output the voltage at the low potential end according to the low voltage obtained through the switch tube. The material cost and occupied area of ​​the detection circuit 10 composed of the switch tube and the resistor are low. The detection circuit 10 can be selected according to the actual application and is not limited here.

[0046] In this embodiment, the main control circuit 20 can be implemented by a main controller, such as an MCU (Microcontroller Unit), a DSP (Digital Signal Process), an FPGA (Field Programmable Gate Array), a SOC (System On Chip), etc.; the main control circuit 20 can also be implemented by a logic circuit composed of multiple switching tubes. The main control circuit 20 can be selected according to the actual application and is not limited here.

[0047] In this embodiment, the output circuit 30 can be implemented by a multiplexer, the first input end of the multiplexer is electrically connected to the battery end, the second input end of the multiplexer is electrically connected to the low potential end, and the multiplexer outputs the voltage of the low potential end or the voltage of the battery end according to the control signal output by the main control circuit 20, such as 00 or 01; the output circuit 30 can also be implemented by two switching tubes, the input end of one switching tube is electrically connected to the battery end, and the input end of the other switching tube is electrically connected to the low potential end. When the battery voltage is greater than 0, the main control circuit 20 controls one of the switching tubes to be turned on and the other switching tube to be turned off, and one of the switching tubes outputs the voltage of the battery end. When the battery voltage is 0, the main control circuit 20 controls one of the switching tubes to be turned off and the other switching tube to be turned on, and the other switching tube outputs the voltage of the low potential end. The output circuit 30 can be selected according to actual applications and is not limited here.

[0048] Specifically, the technical solution of the utility model includes a detection circuit 10, a main control circuit 20 and an output circuit 30. The detection circuit 10 is used to detect the voltage at the battery end and output a corresponding detection signal. The main control circuit 20 determines whether the voltage at the battery end is close to 0 according to the detection signal, and controls the output circuit 30 to output the voltage at the battery end or the voltage at the low potential end. The output end of the output circuit 30 is used to be electrically connected to an external main control. When the external main control receives the normal voltage at the battery end, it controls or maintains the electrical connection of the path between the power supply and the battery so that the battery can be charged normally under normal conditions; when the external main control receives the voltage at the low potential end, the external main control controls the path between the power supply and the battery to be disconnected so that the battery cannot be charged when the voltage is basically 0. With such an arrangement, in actual application, when the battery terminal voltage is basically 0, the technical solution of the utility model can promptly disconnect the loop between the battery terminal and the power supply and connect a low voltage to the battery terminal, so that the battery terminal voltage cannot be charged when it is 0V; when the battery terminal voltage is greater than 0, the technical solution of the utility model conducts the path between the power supply and the battery terminal, so that the battery terminal voltage can be charged normally when it is greater than 0. The utility model ensures that the battery terminal operates within the normal voltage range, thereby avoiding the problem of sudden shutdown or performance degradation of the corresponding equipment due to excessively low battery terminal voltage, thereby improving the stability and reliability of the equipment to which the utility model is applied.

[0049] refer to Figure 2 In one embodiment of the present utility model, the detection circuit 10 comprises:

[0050] A first switch tube Q1, a first resistor R1 and a second resistor R2, wherein the input end of the first switch tube Q1 is electrically connected to the battery end, the first end of the first resistor R1 is electrically connected to the battery end, the controlled end of the first switch tube Q1 is electrically connected to the second end of the first resistor R1, the output end of the first switch tube Q1 is electrically connected to the input end of the main control circuit 20, the first end of the second resistor R2 is electrically connected to the battery end, and the second end of the second resistor R2 is electrically connected to the input end of the main control circuit 20.

[0051] In this embodiment, the first switch tube Q1 is a PMOS tube. When the voltage at the battery terminal is greater than the conduction threshold of the first switch tube Q1 (the battery voltage is greater than 0), the first switch tube Q1 is turned on, and the main control circuit 20 determines that the battery voltage is greater than 0 at this time according to the larger voltage obtained by the first switch tube Q1, and controls the output circuit 30 to output the voltage at the battery terminal, so that the battery can be charged normally under normal conditions; when the voltage at the battery terminal is less than the conduction threshold of the first switch tube Q1, the first switch tube Q1 is turned off. Since the resistance value of the second resistor R2 is extremely large, the main control circuit 20 determines that the battery voltage is 0 at this time according to the smaller voltage obtained by the second resistor R2, and controls the output circuit 30 to output the voltage at the low potential terminal. With such a configuration, compared with the detection circuit 10 using a voltage sensor, the technical solution of the utility model can detect the battery voltage through one switch tube and two resistors, so that the material cost required for the product applied by the utility model is lower and the area utilization rate is higher.

[0052] When designing a single-cell lithium battery protection chip, the charger connection port often generates a peak voltage below -28V when the charger is plugged in or out. With the advancement of technology, in many processes, only the drain and source (VDS) of the high-voltage MOS can withstand high voltage, but the voltage between the gate and the source (VGS) cannot withstand high voltage. For example, in the above embodiment, the controlled end of the first switch tube Q1 is electrically connected to the battery end via the first resistor R1, and the voltage between the gate and the source of the first switch tube Q1 cannot withstand a voltage as high as 28V.

[0053] In this embodiment, the detection circuit 10 further includes:

[0054] A second switch tube Q2, wherein an input end of the second switch tube Q2 is electrically connected to the second end of the first resistor R1, a controlled end of the second switch tube Q2 is electrically connected to the controlled end of the first switch tube Q1 and the input end of the second switch tube Q2 respectively, and an output end of the second switch tube Q2 is grounded.

[0055] In this embodiment, the second switch tube Q2 is an NMOS tube. Since the gate and drain of the second switch tube Q2 are short-circuited, as long as the second switch tube Q2 is in the on state (V GS >V TH ), the second switch tube Q2 is always in saturation state, so: Where V TH is the conduction threshold, W and L are width and length respectively, μ n is the electron mobility, C ox is the gate oxide capacitance per unit area, and is a constant. Since the gate and drain of the second switch tube Q2 are short-circuited, there is no body effect, so V TH is also a constant, V GS by IDS (current from drain to source) is determined by adjusting the resistance value of the first resistor R1 to control I DS The size of the gate-drain voltage difference V of the second switch tube Q2 can be controlled to achieve a voltage difference between the battery terminal (VDD) and the low potential terminal (VM) of no more than 28V. GS The gate of the second switch tube Q2 is electrically connected to the gate of the first switch tube Q1, so the V GS It will not exceed 5V, so that the first switch tube Q1 can still work normally under the high voltage of 28V. This setting avoids damage to the switch tube when the voltage at the battery end is too high when the charger is plugged in or out, thereby extending the service life of the switch tube and improving the stability of the entire circuit.

[0056] refer to Figure 2 In one embodiment of the present utility model, the output circuit 30 includes:

[0057] a voltage output terminal VOUT, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a third switch tube Q3 and a fourth switch tube Q4, wherein a first end of the third resistor R3 is electrically connected to the battery terminal, a second end of the third resistor R3 is electrically connected to a controlled end of the third switch tube Q3, the controlled end of the third switch tube Q3 is also electrically connected to an output end of the main control circuit 20, an input end of the third switch tube Q3 is electrically connected to the battery terminal, an output end of the third switch tube Q3 is electrically connected to a first end of the fourth resistor R4, a second end of the fourth resistor R4 is electrically connected to the voltage output terminal, the voltage output terminal is electrically connected to a first end of the fifth resistor R5, a second end of the fifth resistor R5 is electrically connected to an output end of the fourth switch tube Q4, an input end of the fourth switch tube Q4 is electrically connected to the low potential end, a controlled end of the fourth switch tube Q4 is electrically connected to a first end of the sixth resistor R6 and an output end of the main control circuit 20 respectively, and a second end of the sixth resistor R6 is electrically connected to the low potential end.

[0058] In this embodiment, the third switch tube Q3 is a PMOS tube, and the fourth switch tube Q4 is an NMOS tube. When the battery voltage is 0, the main control circuit 20 outputs a corresponding control signal (high level) to the third switch tube Q3 and the fourth switch tube Q4, the third switch tube Q3 is turned off and the fourth switch tube Q4 is turned on. Since the input end of the fourth switch tube Q4 is electrically connected to the low potential end, the voltage output end outputs the voltage of the low potential end; when the battery voltage is greater than 0, the main control circuit 20 outputs a corresponding control signal (low level) to the third switch tube Q3 and the fourth switch tube Q4, the third switch tube Q3 is turned on and the fourth switch tube Q4 is turned off. Since the input end of the third switch tube Q3 is electrically connected to the battery end, the voltage output end outputs the voltage of the battery end.

[0059] refer to Figure 2 In one embodiment of the present utility model, the main control circuit 20 includes:

[0060] A first inverter D1, a first push-pull output circuit 21, a second push-pull output circuit 22, a fifth switch tube Q5, a seventh resistor R7 and an eighth resistor R8, wherein the input end of the first inverter D1 is used to access a high level or a low level, the first end of the first push-pull output circuit 21 is electrically connected to the output end of the detection circuit 10, the controlled end of the first push-pull output circuit 21 is electrically connected to the output end of the first inverter D1, the second end of the first push-pull output circuit 21 is grounded, the output end of the first push-pull output circuit 21 is electrically connected to the controlled end of the fifth switch tube Q5, the input end of the fifth switch tube Q5 is electrically connected to the battery end, and the output end of the fifth switch tube Q5 is electrically connected to the battery end. The first end of the first push-pull output circuit 21 is electrically connected to the controlled end of the second push-pull output circuit 22, the first end of the second push-pull output circuit 22 is electrically connected to the battery end, the second end of the second push-pull output circuit 22 is grounded, and the output end of the second push-pull output circuit 22 is electrically connected to the controlled end of the fifth switch tube Q5.

[0061] In this embodiment, the fifth switch tube Q5 is a PMOS tube. When the product to which the technical solution of the utility model is applied is started, the input end of the first inverter D1 is connected to a high level, and the controlled end of the first push-pull output circuit 21 receives a low level. When the battery voltage is greater than 0, the first push-pull output circuit 21 outputs the detection circuit 10 to output the corresponding detection signal (high level) to the fifth switch tube Q5 and the second push-pull output circuit 22. The fifth switch tube Q5 is turned off and the second push-pull output circuit 22 is turned off. Since the third switch tube Q3 is a PMOS tube, the second push-pull output circuit 22 is disconnected, and therefore the third switch tube Q3 is turned on, and the battery voltage is transmitted through the third switch tube Q3 and the first push-pull output circuit 22. The four resistors R4 and the power output terminal VOUT are output to the external main control; when the battery voltage is 0, the first push-pull output circuit 21 outputs the corresponding detection signal (low level) to the fifth switch tube Q5 and the second push-pull output circuit 22, and the fifth switch tube Q5 and the second push-pull output circuit 22 are both turned on. Since the battery voltage (high level) is output to the third switch tube Q3 via the second push-pull output circuit 22, the third switch tube Q3 is turned off, and the battery voltage is also transmitted to the controlled end of the fourth switch tube Q4 via the fifth switch tube Q5. The fourth switch tube Q4 is turned on, and the voltage of the low potential end (VM) is output to the external main control via the fourth switch tube Q4, the fifth resistor R5 and the voltage output end. When the product used in the utility model is not started, the input end of the first inverter D1 receives a low level signal, and the first push-pull output circuit 21 receives the detection signal, so the fifth switch tube Q5 and the second push-pull output circuit 22 are both turned on, and the voltage output end outputs the voltage value of the low potential end to the external main control.

[0062] In this embodiment, the first push-pull output circuit 21 includes:

[0063] a sixth switch tube Q6 and a seventh switch tube Q7, wherein the input end of the sixth switch tube Q6 is electrically connected to the output end of the detection circuit 10, the input end of the seventh switch tube Q7 is electrically connected to the output end of the sixth switch tube Q6, the controlled end of the sixth switch tube Q6 and the controlled end of the seventh switch tube Q7 are both electrically connected to the output end of the first inverter D1, the output end of the sixth switch tube Q6 is electrically connected to the controlled end of the fifth switch tube Q5, and the output end of the seventh switch tube Q7 is grounded;

[0064] The second push-pull output circuit 22 comprises:

[0065] an eighth switch tube Q8 and a ninth switch tube Q9, wherein the input end of the eighth switch tube Q8 is electrically connected to the battery end, the output end of the eighth switch tube Q8 is electrically connected to the input end of the ninth switch tube Q9, the output end of the ninth switch tube Q9 is grounded, the controlled end of the eighth switch tube Q8 and the controlled end of the ninth switch tube Q9 are both electrically connected to the output end of the eighth switch tube Q8, and the output end of the eighth switch tube Q8 is electrically connected to the controlled end of the third switch tube Q3.

[0066] In this embodiment, the sixth switch tube Q6 and the eighth switch tube Q8 are both PMOS tubes, and the seventh switch tube Q7 and the ninth switch tube Q9 are NMOS tubes. When the product applied by the utility model is started, the input end of the first inverter D1 receives a high level, and the controlled ends of the sixth switch tube Q6 and the seventh switch tube Q7 both receive a low level, and the sixth switch tube Q6 is turned on. Therefore, the detection signal is transmitted to the controlled end of the fifth switch tube Q5, the controlled end of the eighth switch tube Q8, and the controlled end of the ninth switch tube Q9 through the sixth switch tube Q6. When the battery is charged, the detection signal is turned on. When the voltage is greater than 0, when the detection signal is at a high level, the ninth switch tube Q9 is turned on, while the fifth switch tube Q5 and the eighth switch tube Q8 are both turned off, and the voltage at the controlled end of the third switch tube Q3 is pulled down by the turned-on ninth switch tube Q9, so the third switch tube Q3 is turned on, and the voltage output end outputs the voltage at the battery end; when the battery voltage is 0, the detection signal is at a low level, the fifth switch tube Q5 and the eighth switch tube Q8 are both turned on, and the fourth switch tube Q4 is also turned on, and the voltage at the low potential end is transmitted to the voltage output end through the fourth switch tube Q4 and the fifth resistor R5.

[0067] refer to Figure 2 In one embodiment of the present utility model, when the main control circuit 20 includes a first push-pull output circuit 21, a second push-pull output circuit 22 and a third switch tube Q3, the output circuit 30 further includes:

[0068] The tenth switch tube Q10, the second end of the sixth resistor R6 is electrically connected to the output end of the tenth switch tube Q10, the input end of the tenth switch tube Q10 is electrically connected to the low potential end, and the controlled end of the tenth switch tube Q10 is electrically connected to the input end of the tenth switch tube Q10.

[0069] When designing a single-cell lithium battery protection chip, the charger connection port often generates a peak voltage below -28V when the charger is plugged in or out. With the advancement of technology, in many processes, only the drain and source (VDS) of the high-voltage MOS can withstand high voltage, but the voltage between the gate and the source (VGS) cannot withstand high voltage. For example, in the above embodiment, the controlled end of the fourth switch tube Q4 is electrically connected to the low potential end via the sixth resistor R6, and the voltage between the gate and the source of the fourth switch tube Q4 cannot withstand a voltage as high as 28V.

[0070] In the present embodiment, the tenth switch tube Q10 is an NMOS tube, whose gate and drain are short-circuited. The current from the drain to the source can be controlled by adjusting the size of the sixth resistor R6, so that the difference between the voltage at the battery end (VDD) and the low potential end (VM) is not greater than 28V, and the gate-drain voltage difference VGS of the tenth switch tube Q10 is controlled not to exceed its withstand voltage value of 5V. Since the gate of the fourth switch tube Q4 is electrically connected to the gate of the first switch tube Q1 through the sixth resistor R6, the VGS of the fourth switch tube Q4 will not exceed 5V, so that the fourth switch tube Q4 can still work normally under the high voltage scenario of 28V. The principle is the same as that of the second switch tube Q2 of the above-mentioned detection circuit 10, which will not be repeated here. Such a setting avoids damage to the switch tube when the voltage at the battery end is too large when the charger is plugged in and out, prolongs the service life of the switch tube and improves the stability of the entire circuit.

[0071] refer to Figure 2 In one embodiment of the present utility model, the 0V charging prohibition circuit further includes:

[0072] an eleventh switch tube Q11 and a ninth resistor R9, wherein the input end of the eleventh switch tube Q11 is electrically connected to the battery end, the output end of the eleventh switch tube Q11 is electrically connected to the second end of the seventh resistor R7 and the first end of the ninth resistor R9 respectively, and the second end of the ninth resistor R9 is electrically connected to the low potential end.

[0073] In the present embodiment, the eleventh switch tube Q11 is a PMOS tube, the gate and drain of the PMOS tube are short-circuited, which is similar to a load. When the voltage difference between the battery terminal (VDD) and the voltage at the low potential (VM) terminal reaches 0.7V or more, the eleventh switch tube Q11 will be turned on and in a saturation state. At this time, since the first end of the ninth resistor R9 is electrically connected to the output end of the eleventh switch tube Q11, the voltage at the first end of the ninth resistor R9 and the voltage at the second end of the seventh resistor R7 are always 0.7V or more lower than the voltage at the battery terminal (determined by the current flowing through the eleventh switch tube Q11). This arrangement avoids damage to the fifth switch tube Q5 caused by excessive voltage at the battery terminal when the charger is plugged in or out, thereby extending the service life of the switch tube and improving the stability of the entire circuit.

[0074] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A 0V charging prohibition circuit, the 0V charging prohibition circuit comprising a battery terminal and a low potential terminal, characterized in that: The 0V charging prohibition circuit further includes: A detection circuit, wherein a sampling end of the detection circuit is electrically connected to the battery end, and the detection circuit is used to detect the voltage of the battery end and output a corresponding detection signal; A main control circuit, wherein an input end of the main control circuit is electrically connected to an output end of the detection circuit; an output circuit, the output circuit comprising a first input terminal and a second input terminal, the first input terminal being electrically connected to the battery terminal, the second input terminal being electrically connected to the low potential terminal, and the controlled terminal of the output circuit being electrically connected to the main control circuit; The main control circuit is used to control the output end of the output circuit to output the voltage of the battery end or the voltage of the low potential end according to the detection signal.

2. The 0V charging prohibition circuit according to claim 1, characterized in that: The detection circuit comprises: A first switch tube, a first resistor and a second resistor, wherein the input end of the first switch tube is electrically connected to the battery end, the first end of the first resistor is electrically connected to the battery end, the controlled end of the first switch tube is electrically connected to the second end of the first resistor, the output end of the first switch tube is electrically connected to the input end of the main control circuit, the first end of the second resistor is electrically connected to the battery end, and the second end of the second resistor is electrically connected to the input end of the main control circuit.

3. The 0V charging prohibition circuit according to claim 2, characterized in that: The detection circuit also includes: A second switch tube, wherein the input end of the second switch tube is electrically connected to the second end of the first resistor, the controlled end of the second switch tube is electrically connected to the controlled end of the first switch tube and the input end of the second switch tube respectively, and the output end of the second switch tube is grounded.

4. The 0V charging prohibition circuit according to claim 1, characterized in that: The output circuit comprises: A voltage output end, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a third switch tube and a fourth switch tube, wherein the first end of the third resistor is electrically connected to the battery end, the second end of the third resistor is electrically connected to the controlled end of the third switch tube, the controlled end of the third switch tube is also electrically connected to the output end of the main control circuit, the input end of the third switch tube is electrically connected to the battery end, the output end of the third switch tube is electrically connected to the first end of the fourth resistor, the second end of the fourth resistor is electrically connected to the voltage output end, the voltage output end is electrically connected to the first end of the fifth resistor, the second end of the fifth resistor is electrically connected to the output end of the fourth switch tube, the input end of the fourth switch tube is electrically connected to the low potential end, the controlled end of the fourth switch tube is electrically connected to the first end of the sixth resistor and the output end of the main control circuit respectively, and the second end of the sixth resistor is electrically connected to the low potential end.

5. The 0V charging prohibition circuit according to claim 4, characterized in that: The main control circuit comprises: A first inverter, a first push-pull output circuit, a second push-pull output circuit, a fifth switch tube, a seventh resistor and an eighth resistor, wherein the input end of the first inverter is used to access a high level or a low level, the first end of the first push-pull output circuit is electrically connected to the output end of the detection circuit, the controlled end of the first push-pull output circuit is electrically connected to the output end of the first inverter, the second end of the first push-pull output circuit is grounded, the output end of the first push-pull output circuit is electrically connected to the controlled end of the fifth switch tube, the input end of the fifth switch tube is electrically connected to the battery end, and the output end of the fifth switch tube is electrically connected to the battery end. The first end of the eighth resistor is electrically connected, the second end of the eighth resistor is electrically connected to the controlled end of the fourth switch tube and the first end of the sixth resistor respectively, the first end of the seventh resistor is electrically connected to the controlled end of the fifth switch tube, and the second end of the seventh resistor is electrically connected to the low potential end; the output end of the first push-pull output circuit is also electrically connected to the controlled end of the second push-pull output circuit, the first end of the second push-pull output circuit is electrically connected to the battery end, the second end of the second push-pull output circuit is grounded, and the output end of the second push-pull output circuit is electrically connected to the controlled end of the fifth switch tube.

6. The 0V charging prohibition circuit according to claim 5, characterized in that: The first push-pull output circuit comprises: a sixth switch tube and a seventh switch tube, wherein the input end of the sixth switch tube is electrically connected to the output end of the detection circuit, the input end of the seventh switch tube is electrically connected to the output end of the sixth switch tube, the controlled end of the sixth switch tube and the controlled end of the seventh switch tube are both electrically connected to the output end of the first inverter, the output end of the sixth switch tube is electrically connected to the controlled end of the fifth switch tube, and the output end of the seventh switch tube is grounded; The second push-pull output circuit comprises: An eighth switch tube and a ninth switch tube, wherein the input end of the eighth switch tube is electrically connected to the battery end, the output end of the eighth switch tube is electrically connected to the input end of the ninth switch tube, the output end of the ninth switch tube is grounded, the controlled end of the eighth switch tube and the controlled end of the ninth switch tube are both electrically connected to the output end of the eighth switch tube, and the output end of the eighth switch tube is electrically connected to the controlled end of the third switch tube.

7. The 0V charging prohibition circuit according to claim 6, characterized in that: The output circuit further comprises: A tenth switch tube, the second end of the sixth resistor is electrically connected to the output end of the tenth switch tube, the input end of the tenth switch tube is electrically connected to the low potential end, and the controlled end of the tenth switch tube is electrically connected to the input end of the tenth switch tube.

8. The 0V charging prohibition circuit according to claim 7, characterized in that: The 0V charging prohibition circuit further includes: An eleventh switch tube and a ninth resistor, wherein the input end of the eleventh switch tube is electrically connected to the battery end, the output end of the eleventh switch tube is electrically connected to the second end of the seventh resistor and the first end of the ninth resistor respectively, and the second end of the ninth resistor is electrically connected to the low potential end.

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