CN112234689B - Charge-discharge protection circuit and lithium battery protection system - Google Patents
Charge-discharge protection circuit and lithium battery protection system Download PDFInfo
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- CN112234689B CN112234689B CN202011461568.5A CN202011461568A CN112234689B CN 112234689 B CN112234689 B CN 112234689B CN 202011461568 A CN202011461568 A CN 202011461568A CN 112234689 B CN112234689 B CN 112234689B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00308—Overvoltage protection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/18—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for batteries; for accumulators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00302—Overcharge protection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00306—Overdischarge protection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/0031—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits using battery or load disconnect circuits
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- Power Engineering (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
- Protection Of Static Devices (AREA)
Abstract
The invention discloses a charging and discharging protection circuit and a lithium battery protection system, which comprise a battery protection circuit, a battery, a charger or a load and an RC filter circuit, wherein the battery protection circuit is connected with the charger or the load; the RC filter circuit comprises a first resistor and a first capacitor, one end of the first resistor is connected with one end of the first capacitor and then connected with a VDD end of the battery protection circuit, and the other end of the first resistor is connected with the anode of the battery; the battery protection circuit comprises a charging voltage protection circuit or a discharging voltage protection circuit, and further comprises a basic protection circuit, an AND gate, a driving circuit and a first MOS (metal oxide semiconductor) tube, wherein the charging voltage protection circuit or the discharging voltage protection circuit and the basic protection circuit are connected with the input end of the AND gate. According to the invention, through the cooperation of the second delay circuit and the counter, the output of the latch circuit controls the output of the logic circuit, and the locking of the charge-discharge loop is realized by closing the first MOS tube, so that the situation that the battery is damaged due to repeated charge-discharge is avoided.
Description
Technical Field
The invention relates to the technical field of lithium battery protection, in particular to a charging and discharging protection circuit and a lithium battery protection system.
Background
In the prior art, lithium battery protection systems are widely used, in particular, for the miniaturization of battery capacity, for example, the existing battery capacity is only dozens of mAh, even 20 mAh.
At present, the charging current is rarely 0.5C (10 mA for 20mAH battery) or 1C, most of the charging current is larger than 1C, especially the improvement of the quick charging technology, the battery is charged by the current of 2C or even more than 5C in the quick charging stage, and the damage of the battery is caused. After the battery is used for a period of time, the capacity of the battery is reduced, the parasitic internal resistance of the battery is increased, the battery is charged by large current, if the charging overcurrent setting of the lithium battery protection is larger, and the charging current is lower than the charging overcurrent protection current value, the battery is very easy to be charged to the overcharge voltage protection, when the overcharge voltage protection is achieved and the corresponding overcharge protection delay is carried out, the charging path is cut off, the charging current is reduced to zero, at this time, the voltage drop of the battery parasitic resistance is reduced to be lower than the overcharge recovery voltage, the charging can be continued, when the battery is charged again, the voltage of the battery is charged to be higher than the overcharge voltage, and after the corresponding overcharge protection delay, the charging path is cut off again, the charging current is reduced to zero, and because the voltage drop of the battery parasitic resistance is reduced to be zero, the battery voltage is lower than the overcharge recovery voltage and starts to be charged, this results in charging, shutting down, switching the charging path back and forth, possibly tens or even hundreds of times back and forth. This accelerates the damage of the battery, and it is highly possible to directly damage the battery, resulting in the battery bulging or firing.
Meanwhile, the same situation and problem exist during discharging, the discharge protection current is rarely 1C (20 mA for a 20mAH battery) or less, and the performance or the service life of the battery is affected by a large discharge capacitance. Especially after a period of use, the capacity of the battery is reduced, the internal resistance of the battery is increased, at this time, the battery is discharged by using large current, the discharge current is lower than the discharge overcurrent protection current value, the voltage of the battery is pulled below the over-discharge protection voltage, after the over-discharge protection time delay, the chip enters the over-discharge protection state, the power MOS tube is turned off, the voltage drop on the parasitic resistance of the battery is reduced to zero without the discharge current, the voltage of the battery is increased to be higher than the over-discharge recovery voltage, the discharge is started, the voltage of the battery is pulled below the over-discharge protection voltage after the discharge is started, after the over-discharge protection time delay, the over-discharge protection state is entered, the power MOS tube is turned off, the voltage drop on the parasitic resistance of the battery is reduced to zero without the discharge current, the voltage of the battery is higher than the over-discharge recovery voltage, the discharge is started, The discharge path is turned off, turned on and off back and forth, and can be discharged back and forth tens of times or even hundreds of times. This also accelerates the damage of the battery, or directly damages the battery.
Disclosure of Invention
In order to solve the above problems, the present invention provides a charging/discharging protection circuit and a lithium battery protection system, so as to solve the problem of battery damage acceleration or battery damage directly caused by repeated charging or repeated discharging of the existing battery.
The technical scheme adopted by the invention is as follows:
the application provides a charging voltage protection circuit, including overcharge voltage judgement circuit, first delay circuit, second delay circuit, counter, logic circuit, latch circuit and discharge detection circuit, wherein:
the overcharge voltage judging circuit comprises a second resistor, a third resistor, a fourth resistor, a first switch, a second switch and a first comparator, wherein the second end of the first switch is connected with the second end of the second switch and then connected with the inverting end of the first comparator, the inverting end of the first comparator is connected with a Vref end, the second switch is initially in a closed state, the output end of the first comparator is connected with the input end of a first delay circuit, and the overcharge voltage judging circuit is used for judging whether the voltage of the battery exceeds a set overcharge voltage value or not;
the first delay circuit is used for outputting the output voltage of the overcharge voltage judging circuit in a delay way;
the counter is used for recording the times of changing the first delay circuit from a high level to a low level;
the discharge detection circuit is used for detecting whether the battery is in a discharge state;
the latch circuit is used for latching the counter result meeting the condition;
the logic circuit is used for combining the output of the latch circuit and the output of the first delay circuit and outputting a logic control signal;
the output end of the first delay circuit is connected with the input end of the logic circuit, the input end of the second delay circuit and the input end of the counter, the output end of the second delay circuit, the output end of the counter and the output end of the discharge detection circuit are connected with the input end of the latch circuit, the output end of the second delay circuit is connected with the input end of the second delay circuit, the input end of the counter and the input end of the latch circuit, the output end of the counter and the output end of the discharge detection circuit are connected with the input end of the latch circuit, and the output end of the latch circuit is connected with the input.
Preferentially, one end of the second resistor is connected with a VDD end, and the other end of the second resistor is connected with one end of the third resistor and the first end of the first switch; the other end of the third resistor is connected with one end of a fourth resistor and the first end of a second switch, and the other end of the fourth resistor is connected with a VGND end; the second end of the first switch is connected with the second end of the second switch, and the switch end of the first switch is connected with the output end of the first comparator.
The application also provides a discharge voltage protection circuit, including overdischarge voltage judgement circuit, first delay circuit, second delay circuit, counter, logic circuit, latch circuit and charge detection circuit, wherein:
the over-discharge voltage judgment circuit comprises a fifth resistor, a sixth resistor, a seventh resistor, a third switch, a fourth switch and a second comparator, wherein the second end of the third switch is connected with the second end of the fourth switch and then connected with the in-phase end of the second comparator, the inverting end of the second comparator is connected with the Vref end, the third switch is initially in a closed state, and the output end of the second comparator is connected with the input end of the first delay circuit;
the over-discharge voltage judging circuit is used for judging whether the battery voltage is lower than a set over-discharge voltage value or not;
the charging detection circuit is used for detecting whether the battery is in a charging state;
the first time delay circuit is used for outputting the output voltage of the over-discharge voltage judging circuit in a time delay way;
the counter is used for recording the times of changing the first delay circuit from a high level to a low level;
the latch circuit is used for latching the counter result meeting the condition;
the logic circuit is used for combining the output of the latch circuit and the output of the first delay circuit and outputting a logic control signal;
the output end of the first delay circuit is connected with the input end of the logic circuit, the input end of the second delay circuit and the input end of the counter, the output end of the counter and the output end of the charging detection circuit are connected with the input end of the latch circuit, the output end of the second delay circuit is connected with the input end of the second delay circuit, the input end of the counter and the input end of the latch circuit, and the output end of the latch circuit is connected with the input end of the logic circuit.
Preferably, one end of the fifth resistor is connected to the VDD terminal, and the other end of the fifth resistor is connected to one end of the sixth resistor and the first end of the third switch; the other end of the sixth resistor is connected with one end of a seventh resistor and the first end of a fourth switch, and the other end of the seventh resistor is connected with a VGND end; and the second end of the third switch is connected with the second end of the fourth switch, and the switch end of the third switch is connected with the output end of the second comparator.
Based on the charging voltage protection circuit and the discharging voltage protection circuit, the application also provides a lithium battery protection system, which comprises a battery protection circuit, a battery, a charger or a load and an RC filter circuit, wherein the battery protection circuit is connected with the charger or the load;
the RC filter circuit comprises a first resistor and a first capacitor, one end of the first resistor is connected with one end of the first capacitor and then connected with a VDD end of the battery protection circuit, and the other end of the first resistor is connected with a battery anode and a charger or a load anode;
the battery protection circuit comprises the charging voltage protection circuit or the discharging voltage protection circuit, and further comprises a basic protection circuit, an AND gate, a driving circuit and a first MOS tube, wherein the charging voltage protection circuit or the discharging voltage protection circuit and the basic protection circuit are connected with the input end of the AND gate, the output end of the AND gate is connected with the input end of the driving circuit, the output end of the driving circuit is connected with the grid electrode of the first MOS tube, one end of a source electrode or a drain electrode of the first MOS tube is connected with the cathode of the battery, and the other end of the source electrode or the drain electrode of the first MOS tube is connected with the cathode of the charger or.
Based on the battery protection circuit, the application also provides a lithium battery protection chip which comprises the battery protection circuit.
The invention has the beneficial effects that: when the output of the first delay circuit is changed from high level to low level, the second delay circuit starts to work, and when the second delay circuit is charged, if the counting times set by the counter are not reached within the time set by the second delay circuit, the latch circuit maintains the original state, the output is low level, and the output of the logic circuit is not influenced; if the counting times set by the counter are reached within the time set by the second delay circuit, the output of the latch circuit is low, the output of the control logic circuit is low and is only controlled by the output of the latch circuit, the first MOS tube is closed and cannot be charged, the condition that the battery is damaged by charging the charger back and forth is avoided, and similarly, the discharging is also based on the same principle, and the battery is prevented from being damaged by discharging the load back and forth.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a circuit diagram of an overcharge voltage determination circuit of the present invention;
fig. 2 is a circuit diagram of an over-discharge voltage judging circuit of the present invention;
FIG. 3 is a schematic diagram of the connection of the charge voltage protection circuit of the present invention;
FIG. 4 is a schematic diagram of the connection of the discharge voltage protection circuit of the present invention;
FIG. 5 is a schematic view of a connection of the lithium battery protection system of the present invention;
fig. 6 is a schematic diagram of the connection of the counter, the second delay circuit, the latch circuit, and the logic circuit of the present invention.
Labeled as: 1. the circuit comprises an overcharge voltage judging circuit, 2 an overdischarge voltage judging circuit, 3 a first delay circuit, 4 a second delay circuit, 5 a counter, 6 a logic circuit, 7 a latch circuit, 8 a discharge detection circuit, 9 a charge detection circuit, 10 a battery protection circuit, 11 a basic protection circuit, 12 an AND gate, 13 a driving circuit, 14 a battery, 15 a charger or a load and 16 an RC filter circuit.
Detailed Description
As shown in fig. 1 and fig. 3, the present application provides a charging voltage protection circuit, which includes an overcharge voltage determination circuit 1, a first delay circuit 3, a second delay circuit 4, a counter 5, a logic circuit 6, a latch circuit 7, and a discharge detection circuit 8, wherein:
the overcharge voltage judging circuit 1 comprises a second resistor R2, a third resistor R3, a fourth resistor R4, a first switch K1, a second switch K2 and a first comparator COMP1, wherein one end of the second resistor R2 is connected with a VDD terminal, and the other end of the second resistor R2 is connected with one end of the third resistor R3 and a first end of a first switch K1; the other end of the third resistor R3 is connected with one end of a fourth resistor R4 and the first end of a second switch K2, and the other end of the fourth resistor R4 is connected with the VGND end; the second end of the first switch K1 is connected with the second end of the second switch K2, the switch end of the first switch K1 is connected with the output end of the first comparator COMP1, the second end of the first switch K1 is connected with the second end of the second switch K2 and then connected with the inverting end of the first comparator COMP1, the inverting end of the first comparator COMP1 is connected with the Vref end, the second switch K2 is initially in a closed state, the output end of the first comparator COMP1 is connected with the input end of the first delay circuit 3, the overcharging voltage judging circuit 1 is used for judging whether the voltage of the battery 14 exceeds a set overcharging voltage value, if not, a high level is output, and if not, a low level is output;
during charging, the non-inverting terminal of the first comparator COMP1 is connected to the reference voltage terminal of the battery protection circuit 10, during normal operation, the voltage at the VDD terminal is lower, the voltage at the non-inverting terminal of the first comparator COMP1 is higher than the voltage at the inverting terminal, the output terminal of the first comparator COMP1 outputs high level and controls the second switch K2 to be switched on, and the first switch K1 is switched off; when the voltage of the battery 14 rises and the voltage at the VDD terminal exceeds a set voltage value, the voltage is generally set to 4.3V, the output end of the first comparator COMP1 changes from high level to low level, the first switch K1 is turned on, the second switch K2 is turned off, and at this time, the voltage of the corresponding battery 14 when the output end of the first comparator COMP1 changes to high level is an overcharge recovery voltage, which is generally 4.1V; when the internal resistance and the charging current of the battery 14 in the battery protection circuit 10 are both large, the voltage of the battery 14 is higher than 4.3V when the battery is fully charged, and when the charging is stopped, the voltage of the battery 14 is lower than 4.1V because the voltage drop of the parasitic resistance in the battery 14 is reduced to 0V, and the charging is started again, so that the charging is repeated.
The first delay circuit 3 is used for performing delay output on the output voltage of the overcharge voltage judging circuit 1, when the output of the overcharge voltage judging circuit 1 is changed from a high level to a low level, the low level is output after delay set by the first delay circuit 3, and the delay is generally 100ms to 1 s; when the output of the overcharge voltage judgment circuit 1 changes from low level to high level, the high level is output after the delay set by the first delay circuit 3, the delay is generally 10 mus to 10ms, the time for entering the protection is longer than the time for releasing, the misoperation is prevented from entering the protection state, and the quick release is needed once the release condition is reached.
When the output of the first delay circuit 3 changes from high level to low level, the second delay circuit 4 starts to work and starts to set delay, and when the set delay is passed, the output end of the second delay circuit 4 changes from high level to low level, and the output end of the second delay circuit 4 is at low level, the second delay circuit 4, the counter 5 and the latch circuit 7 are reset.
The counter 5 is used for recording the number of times that the first delay circuit 3 changes from a high level to a low level in each counting period of the second delay circuit 4;
the discharge detection circuit 8 is used for detecting a discharge state and judging a recovery condition of the overcharge protection;
the latch circuit 7 is used for latching the result of the counter 5 meeting the condition in each counting period of the second delay circuit 4;
the logic circuit 6 is configured to combine the output of the latch circuit 7 and the output of the first delay circuit 3, and output a logic control signal.
The output end of the first delay circuit 3 is connected with the input end of the logic circuit 6, the input end of the second delay circuit 4 and the input end of the counter 5, the output end of the second delay circuit 4 is connected with the input end of the second delay circuit 4, the input end of the counter 5 and the input end of the latch circuit 7, the output end of the counter 5 and the output end of the discharge detection circuit 8 are both connected with the input end of the latch circuit 7, and the output end of the latch circuit 7 is connected with the input end of the logic circuit 6.
As shown in fig. 2 and fig. 4, the present application further provides a discharge voltage protection circuit, which includes an overdischarge voltage determination circuit 2, a first delay circuit 3, a second delay circuit 4, a counter 5, a logic circuit 6, a latch circuit 7, and a charge detection circuit 9, wherein:
the over-discharge voltage judging circuit 2 comprises a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a third switch K3, a fourth switch K4 and a second comparator COMP2, one end of the fifth resistor R5 is connected with a VDD end, and the other end of the fifth resistor R5 is connected with one end of the sixth resistor R6 and a first end of a third switch K3; the other end of the sixth resistor R6 is connected with one end of a seventh resistor R7 and the first end of a fourth switch K4, and the other end of the seventh resistor R7 is connected with the VGND end; a second end of the third switch K3 is connected with a second end of the fourth switch K4, a switch end of the third switch K3 is connected with an output end of the second comparator COMP2, a second end of the third switch K3 is connected with a second end of the fourth switch K4 and then connected with a non-inverting end of the second comparator COMP2, an inverting end of the second comparator COMP2 is connected with a Vref end, the third switch K3 is initially in a closed state, and an output end of the second comparator COMP2 is connected with an input end of the first delay circuit 3;
when the discharge is normal, the voltage of the VDD terminal is high, the fourth switch K4 is disconnected, the third switch K3 is connected, the voltage of the non-inverting terminal of the second comparator COMP2 is higher than the voltage of the inverting terminal, and the output end of the second comparator COMP2 is at a high level; when the voltage of the battery 14 is reduced and the voltage of the VDD terminal is lower than the set voltage value, the voltage is generally set to 2.8V, the output end of the second comparator COMP2 is at a low level, the third switch K3 is turned off, and the fourth switch K4 is turned on, at this time, when the output end of the second comparator COMP2 is to be at a high level, the corresponding voltage of the battery 14 is an over-discharge recovery voltage, which is generally 3.0V; when the internal resistance of the battery protection circuit 10 is large and the discharge current is relatively large, the voltage of the battery 14 during overdischarge is lower than 2.8V, when the discharge is stopped, the voltage of the battery 14 is higher than 3.0V due to the fact that the voltage drop of the parasitic resistor in the battery 14 is reduced to 0V, the discharge is started again, the discharge is below the overdischarge protection voltage and then is higher than 3.0V, and therefore the circular discharge is achieved.
The over-discharge voltage judging circuit 2 is used for judging whether the voltage of the battery 14 is lower than a set over-discharge voltage value;
the charge detection circuit 9 is used for detecting a charge state;
the first delay circuit 3 is used for outputting the output voltage of the over-discharge voltage judging circuit 2 in a delay way;
the counter 5 is used for recording the times of changing the first delay circuit 3 from high level to low level;
the latch circuit 7 is used for latching the counter 5 result meeting the condition;
the logic circuit 6 is used for combining the output of the latch circuit 7 and the output of the first delay circuit 3 and outputting a logic control signal;
the output end of the first delay circuit 3 is connected with the second input end of the logic circuit 6, the second input end of the second delay circuit 4 and the first input end of the counter 5, the output end of the second delay circuit 4 is connected with the second input end of the counter 5, the first input end of the second delay circuit 4 and the second input end of the latch circuit 7, the output end of the counter 5 is connected with the first input end of the latch circuit 7, the output end of the charging detection circuit 9 is connected with the third input end of the latch circuit 7, and the output end of the latch circuit 7 is connected with the first input end of the logic circuit 6.
As shown in fig. 3, 4 and 6, the counter 5 includes a third flip-flop D3 to a sixth flip-flop D6 and an or gate I1, the second delay circuit 4 includes a first flip-flop D1, a second flip-flop D2 to an nth flip-flop DN, and the latch circuit 7 includes a seventh flip-flop D7, where N is the total number of flip-flops, the flip-flops are all D flip-flops, the CLK terminal of the D flip-flop is triggered at a low level, i.e., the D terminal signal of the D flip-flop is transmitted to the Q terminal from a high level to a low level, the Set terminal is active at a high level, and the CLK is the oscillator output in the battery protection circuit 10. The logic circuit 6 includes an and gate I2.
In the initial state, the initial state of the Q terminal of the first flip-flop D1 in the second delay circuit 4 is low level, the Set terminals of the second flip-flop D2 to the nth flip-flop DN are low level, the second delay circuit 4 does not calculate delay, the QN terminal of the output terminal of the nth flip-flop DN is high level, and the first flip-flop D1, the third flip-flop D3 to the sixth flip-flop D6 start to operate;
when the output of the overcharge voltage judging circuit 1 or the overdischarge voltage judging circuit 2 is changed from the high level to the low level for the first time during charging or discharging, the output is the low level after the delay of the first delay circuit 3, and at this time, the output of the logic circuit 6 is only controlled by the output of the first delay circuit 3;
meanwhile, the second delay circuit 4 and the counter 5 start to operate, the counter 5 starts to count the number of times that the first delay circuit 3 changes from high to low, the Q terminal of the first flip-flop D1 changes from low to high, the Set terminals of the second flip-flop D2 to the nth flip-flop DN are at high, CLK is counted as delay, and when the QN terminal of the nth flip-flop DN changes to low, the counting period ends. When the QN terminal is at a low level, the Set terminal of the first flip-flop D1 is at a low level, and the Q terminal of the first flip-flop D1 is at a low level, then the Set terminals of the second flip-flop D2 to the nth flip-flop DN are at a low level, and the second delay circuit 4 and the counter 5 are reset.
1) Within the time set by the second delay circuit 4, that is, when the QN end of the nth flip-flop DN is at a high level, the output of the discharge detection circuit 8 is at a high level, and does not reach the count number set by the counter 5, for example, the delay set by the second delay circuit 4 is 10min, the count number set by the counter 5 is 10, the or gate I1 of the counter 5 always outputs a high level, the latch circuit 7 maintains the original state, and always outputs a high level, which does not affect the output of the logic circuit 6, that is, the output of the logic circuit 6 is only controlled by the output of the first delay circuit 3;
2) the counting number set by the counter 5 is reached within the time set by the second delay circuit 4, the output of the or gate I1 of the counter 5 changes from high level to low level after the counting number reaches the set number, at this time, the output of the QN end of the nth flip-flop DN remains at high level, the output of the latch circuit 7 changes from high level to low level, the output of the logic circuit 6 is fixed at low level, the output of the logic circuit 6 is only controlled by the output of the latch circuit 7, and is not affected by the output of the first delay circuit 3. After passing through the and gate 12 and the driving circuit 13, the first MOS transistor M1 is turned off, and charging or discharging cannot be performed at this time, so that the situation that the battery 14 is damaged due to charging back and forth or repeated discharging of the charger is avoided; when the Set end signal of the latch circuit 7 changes from high level to low level, the output of the latch circuit 7 changes to high level, and the output of the logic circuit 6 is controlled by the output of the first delay circuit 3 again;
3) for the charging state, when the latch circuit 7 is locked and can not be charged, the charger is removed at this time, or the charger is removed and connected with a load, and the charging state is entered, the discharge detection circuit 8 outputs a low level at this time, the latch circuit 7 is closed, the output of the logic circuit 6 is only controlled by the output of the first delay circuit 3, and the normal working state is recovered;
4) for the discharging state, when the latch circuit 7 is locked and can not discharge, the charger is connected and charged at this time, the charging state is entered, the charge detection circuit 9 outputs low level at this time, the latch circuit 7 is closed, and the output of the logic circuit 6 is only controlled by the output of the first delay circuit 3 and is recovered to the normal working state.
As shown in fig. 5, based on the charging voltage protection circuit and the discharging voltage protection circuit, the present application also provides a lithium battery protection system, which includes a battery protection circuit 10, a battery 14, a charger or a load 15, and an RC filter circuit 16, wherein;
the RC filter circuit 16 comprises a first resistor R1 and a first capacitor C1, one end of the first resistor R1 is connected with one end of the first capacitor C1 and then connected with the VDD end of the battery protection circuit 10, and the other end of the first resistor R1 is connected with the anode of the battery 14;
the battery protection circuit 10 includes the above-mentioned charge voltage protection circuit or the above-mentioned discharge voltage protection circuit, or includes the above-mentioned charge voltage protection circuit and the above-mentioned discharge voltage protection circuit at the same time, also include the basic protection circuit 11, and the gate 12, the drive circuit 13 and the first MOS transistor M1, the charge voltage protection circuit or the discharge voltage protection circuit and the basic protection circuit 11 are connected with the input end of the and gate 12, the output end of the and gate 12 is connected with the input end of the drive circuit 13, the output end of the drive circuit 13 is connected with the gate of the first MOS transistor M1, one end of the source or drain of the first MOS transistor M1 is connected with the negative pole of the battery 14, the other end of the source or drain of the first MOS transistor M1 is connected with the negative pole P-of the charger or load 15, and the positive.
As shown in fig. 5, based on the battery protection circuit 10, the present application also provides a lithium battery protection chip, which includes the battery protection circuit 10.
Based on the charging voltage protection circuit and the discharging voltage protection circuit, the application is also used for a single-section lithium battery protection system, a single-section positive lithium battery protection system and a multi-section lithium battery protection system of the double-control MOS tube.
The invention has the advantages that: through the cooperation of the second delay circuit and the counter, the output of the latch circuit controls the output of the logic circuit, and then the first MOS tube is closed, so that the locking of the charging loop and the discharging loop is realized, and the condition that the battery is damaged due to repeated charging or repeated discharging is avoided.
Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (4)
1. A charging voltage protection circuit, characterized by: including overcharge voltage judgement circuit, first delay circuit, second delay circuit, counter, logic circuit, latch circuit and discharge detection circuit, wherein:
the overcharge voltage judging circuit comprises a second resistor, a third resistor, a fourth resistor, a first switch, a second switch and a first comparator, wherein the second end of the first switch is connected with the second end of the second switch and then connected with the inverting end of the first comparator, the inverting end of the first comparator is connected with a Vref end, the second switch is initially in a closed state, the output end of the first comparator is connected with the input end of a first delay circuit, and the overcharge voltage judging circuit is used for judging whether the voltage of the battery exceeds a set overcharge voltage value or not;
the first delay circuit is used for outputting the output voltage of the overcharge voltage judging circuit in a delay way;
the counter is used for recording the times of changing the first delay circuit from a high level to a low level;
the discharge detection circuit is used for detecting a discharge state;
the latch circuit is used for latching the counter result meeting the condition;
the logic circuit is used for combining the output of the latch circuit and the output of the first delay circuit and outputting a logic control signal;
the output end of the first delay circuit is connected with the input end of the logic circuit, the input end of the second delay circuit and the input end of the counter, the output end of the second delay circuit is connected with the input end of the second delay circuit, the input end of the counter and the input end of the latch circuit, the output end of the counter and the output end of the discharge detection circuit are both connected with the input end of the latch circuit, and the output end of the latch circuit is connected with the input end of the logic circuit;
the charging voltage protection circuit is connected with an AND gate and a first input end of the AND gate, the output end of the AND gate is connected with a driving circuit and an input end of the driving circuit, and the output end of the driving circuit is connected with a first MOS (metal oxide semiconductor) tube and a grid electrode of the first MOS tube;
one end of the second resistor is connected with a VDD end, and the other end of the second resistor is connected with one end of a third resistor and a first end of a first switch; the other end of the third resistor is connected with one end of a fourth resistor and the first end of a second switch, and the other end of the fourth resistor is connected with a VGND end; the second end of the first switch is connected with the second end of the second switch, and the switch end of the first switch is connected with the output end of the first comparator.
2. A discharge voltage protection circuit, characterized by: including overdischarge voltage decision circuit, first delay circuit, second delay circuit, counter, logic circuit, latch circuit and charge detection circuit, wherein:
the over-discharge voltage judgment circuit comprises a fifth resistor, a sixth resistor, a seventh resistor, a third switch, a fourth switch and a second comparator, wherein the second end of the third switch is connected with the second end of the fourth switch and then connected with the in-phase end of the second comparator, the inverting end of the second comparator is connected with the Vref end, the third switch is initially in a closed state, and the output end of the second comparator is connected with the input end of the first delay circuit;
the over-discharge voltage judging circuit is used for judging whether the battery voltage is lower than a set over-discharge voltage value or not;
the charging detection circuit is used for detecting a charging state;
the first time delay circuit is used for outputting the output voltage of the over-discharge voltage judging circuit in a time delay way;
the counter is used for recording the times of changing the first delay circuit from a high level to a low level;
the latch circuit is used for latching the counter result meeting the condition;
the logic circuit is used for combining the output of the latch circuit and the output of the first delay circuit and outputting a logic control signal;
the output end of the first delay circuit is connected with the input end of the logic circuit, the input end of the second delay circuit and the input end of the counter, the output end of the second delay circuit, the output end of the counter and the output end of the charge detection circuit are all connected with the input end of the latch circuit, the output end of the second delay circuit is connected with the input end of the second delay circuit, the input end of the counter and the input end of the latch circuit, the output end of the counter and the output end of the charge detection circuit are both connected with the input end of the latch circuit, and the output end of the latch circuit is connected with;
the discharge voltage protection circuit is connected with an AND gate and a first input end of the AND gate, the output end of the AND gate is connected with a driving circuit and an input end of the driving circuit, and the output end of the driving circuit is connected with a first MOS (metal oxide semiconductor) tube and a grid electrode of the first MOS tube;
one end of the fifth resistor is connected with a VDD end, and the other end of the fifth resistor is connected with one end of a sixth resistor and a first end of a third switch; the other end of the sixth resistor is connected with one end of a seventh resistor and the first end of a fourth switch, and the other end of the seventh resistor is connected with a VGND end; and the second end of the third switch is connected with the second end of the fourth switch, and the switch end of the third switch is connected with the output end of the second comparator.
3. A lithium battery protection system is characterized in that: the device comprises a battery protection circuit, a battery, a charger or a load and an RC filter circuit, wherein;
the RC filter circuit comprises a first resistor and a first capacitor, one end of the first resistor is connected with one end of the first capacitor and then connected with a VDD end of the battery protection circuit, and the other end of the first resistor is connected with the anode of the battery;
the battery protection circuit comprises a charging voltage protection circuit as claimed in claim 1 or a discharging voltage protection circuit as claimed in claim 2, and further comprises a basic protection circuit, wherein one end of the source electrode or the drain electrode of the first MOS transistor is connected with the negative electrode of the battery, and the other end of the source electrode or the drain electrode of the first MOS transistor is connected with the negative electrode of the charger or the load.
4. A lithium battery protection chip is characterized in that: comprising a lithium battery protection system as claimed in claim 3.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011461568.5A CN112234689B (en) | 2020-12-14 | 2020-12-14 | Charge-discharge protection circuit and lithium battery protection system |
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| CN202011461568.5A CN112234689B (en) | 2020-12-14 | 2020-12-14 | Charge-discharge protection circuit and lithium battery protection system |
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| CN112234689A CN112234689A (en) | 2021-01-15 |
| CN112234689B true CN112234689B (en) | 2021-03-09 |
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| CN112582984B (en) * | 2021-02-23 | 2021-05-07 | 苏州赛芯电子科技股份有限公司 | Quick turn-off circuit and lithium battery protection system thereof |
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| JP4098279B2 (en) * | 2004-07-05 | 2008-06-11 | セイコーインスツル株式会社 | Battery protection circuit |
| JP5564955B2 (en) * | 2009-01-14 | 2014-08-06 | ミツミ電機株式会社 | Protection monitoring circuit, battery pack, secondary battery monitoring circuit, and protection circuit |
| CN102904219B (en) * | 2012-09-18 | 2014-12-31 | 株式会社理光 | Lithium battery charging and discharging protective circuit |
| CN109449891A (en) * | 2018-11-06 | 2019-03-08 | 苏州赛芯电子科技有限公司 | Improve the single-wafer battery protecting circuit and charge-discharge circuit of anti-peak voltage ability |
| CN112003355B (en) * | 2020-10-30 | 2021-01-08 | 苏州赛芯电子科技股份有限公司 | Lithium battery protection device and system with power-on self-locking function |
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