CN117293972A - Protection circuit for preventing battery equipment from overdischarging - Google Patents

Protection circuit for preventing battery equipment from overdischarging Download PDF

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Publication number
CN117293972A
CN117293972A CN202311515985.7A CN202311515985A CN117293972A CN 117293972 A CN117293972 A CN 117293972A CN 202311515985 A CN202311515985 A CN 202311515985A CN 117293972 A CN117293972 A CN 117293972A
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CN
China
Prior art keywords
power
protection circuit
triode
voltage
resistor
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Pending
Application number
CN202311515985.7A
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Chinese (zh)
Inventor
苏晨
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Vanstone Electronic Beijing Co Ltd
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Vanstone Electronic Beijing Co Ltd
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Application filed by Vanstone Electronic Beijing Co Ltd filed Critical Vanstone Electronic Beijing Co Ltd
Priority to CN202311515985.7A priority Critical patent/CN117293972A/en
Publication of CN117293972A publication Critical patent/CN117293972A/en
Pending legal-status Critical Current

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Classifications

    • 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
    • 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
    • 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
    • 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
    • H02J7/0063—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with circuits adapted for supplying loads from the battery
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The embodiment of the disclosure provides a protection circuit for preventing overdischarge of a battery device, the circuit comprising: the power supply comprises a power supply input end, a power supply output end, a recovery circuit, a delay protection circuit and a power switch; the recovery circuit is used for conducting the power switch when the voltage of the power input end is larger than or equal to a first threshold value; the delay protection circuit is used for keeping the power switch on when the voltage of the power input end is smaller than a first threshold value and larger than or equal to a second threshold value in the on state of the protection circuit; the power switch is used for switching on and off the power input end and the power output end. The protection circuit of the embodiment of the disclosure is a circuit which is composed of passive devices and has a simple logic structure and is self-recovered after power-on, and aims to provide a multiple and final discharge defense line, and after a battery is charged, the protection circuit can be immediately communicated with a later stage so as to enable the circuit to normally work.

Description

Protection circuit for preventing battery equipment from overdischarging
Technical Field
The embodiment of the disclosure relates to the technical field of electronic circuits, in particular to a protection circuit for preventing overdischarge of battery equipment.
Background
The battery device discharge protection circuit is widely applied to various portable electronic devices, such as smart phones, tablet computers, notebook computers, POS machines and the like. These devices are typically powered by lithium ion batteries or polymer lithium ion batteries, as well as by power tools and electric vehicles, and are typically operated by battery power, and by incorporating a discharge protection circuit, the occurrence of overdischarge of the battery, etc., can be prevented, improving the safety and life of the battery. The battery is prevented from being damaged, so that the battery discharge protection circuit plays a key role.
However, the existing discharge protection circuits basically use chips for protection, convert the battery voltage into digital quantity by adopting AD conversion, and then monitor the digital quantity by comparing the digital quantity with a threshold value set by a main control chip. The basic logic of the existing circuit is the same, but the logic of the design is that before the battery is fast and dead, a voltage value higher than the shutdown voltage value of the normal operation of the chip is set, so the shutdown voltage value of the equipment is higher than the normal dead voltage value of the battery, although the protection is achieved, the equipment is only suitable for light load occasions, or occasions where software logic is not problematic, or occasions where the voltage ripple of the battery is light, if the load is too heavy, the power supply is not clean, the ripple is large, or the software logic is bug, once the voltage is lower than a software set value or the instantaneous voltage is lower than the software set value, or the ripple of the power supply is large, the voltage value lower than the shutdown voltage value set by the chip does not periodically occur, the chip cannot normally operate because of the voltage is too low, but the rear stage is not disconnected, the battery still continues to supply power, the situation of overdischarge of the battery occurs, and people know that a lot of extra problems occur, such as incapacitation, or long-time charge is needed, or the service life of the battery is lost, or the battery is damaged, and the like, thus causing the problem that the equipment cannot work after maintenance or damage is larger.
Disclosure of Invention
An object of an embodiment of the present disclosure is to provide a protection circuit for preventing overdischarge of a battery device, thereby solving the aforementioned problems in the prior art.
In order to achieve the above objective, the technical solution adopted in the embodiments of the present disclosure is as follows:
the embodiment of the disclosure provides a protection circuit for preventing overdischarge of a battery device, the circuit comprising: the power supply comprises a power supply input end, a power supply output end, a recovery circuit, a delay protection circuit and a power switch;
the recovery circuit is used for conducting the power switch when the voltage of the power input end is larger than or equal to a first threshold value;
the delay protection circuit is used for keeping the power switch on when the voltage of the power input end is smaller than a first threshold value and larger than or equal to a second threshold value in the on state of the protection circuit;
the power switch is used for switching on and off the power input end and the power output end.
Illustratively, the restoration circuit includes: the second zener diode D2, the resistor R5, the resistor R6 and the second triode Q2; the cathode of the second zener diode D2 is connected with the power input end, and the anode of the second zener diode D2 is sequentially connected with the resistor R6 and the resistor R5 in series and then grounded;
the base electrode of the second triode Q2 is connected between the resistor R5 and the resistor R6, the collector electrode of the second triode Q2 is respectively connected with the power input end and the first end of the power switch, and the emitter electrode of the second triode Q2 is grounded; the second end of the power switch is connected with the power input end, and the third end of the power switch is connected with the power output end;
the cut-off voltage value of the second zener diode D2 is a first threshold value.
Illustratively, the restoration circuit further includes: the first capacitor C1 is connected with the resistor R1 in parallel, the first ends of the first capacitor C1 and the resistor R1 are respectively connected with the power input end, and the second ends of the first capacitor C1 and the resistor R1 are respectively connected with the collector electrode of the second triode Q2.
When the voltage of the power input end is greater than the first threshold, the second zener diode D2 works, the base electrode of the second triode Q2 has a voltage, the collector electrode and the emitter electrode of the second triode Q2 are conducted, the first end of the power switch is pulled down, and the second end and the third end of the power switch are conducted, so that the power output end stably outputs.
Illustratively, the first threshold value ranges from 3.5V to 3.0V.
Illustratively, the delay protection circuit includes: the first voltage stabilizing diode D1, the resistor R2, the resistor R3 and the first triode Q1; the cathode of the first zener diode D1 is connected with the power output end, and the anode of the first zener diode D1 is sequentially connected with the resistor R3 and the resistor R2 in series and then grounded;
the collector of the first triode Q1 is connected with the first end of the power switch, the emitter of the first triode Q1 is grounded, and the base of the first triode Q1 is connected between the resistor R2 and the resistor R3;
the cut-off voltage of the first zener diode D1 is a second threshold.
When the circuit is in a conducting state, the voltage at the power supply input end is larger than the second threshold value and smaller than the first threshold value, the second zener diode D2 does not work, the first zener diode D1 works, the base electrode of the first triode Q1 has voltage, the collector electrode and the emitter electrode of the first triode Q1 are conducted, the first end of the power supply switch is pulled down, the second end and the third end of the power supply switch are conducted, and the power supply output end is kept to stably output.
Illustratively, the second threshold ranges from less than 3.0V to 2.8V or more.
The power switch includes a PMOS transistor Q3, where a gate of the PMOS transistor Q3 is connected to the recovery circuit and the delay protection circuit, a drain of the PMOS transistor Q3 is connected to the power output terminal, and a source of the PMOS transistor Q3 is connected to the power input terminal.
Illustratively, the circuit further includes a second capacitor C4, a first end of the second capacitor C4 is connected to the power input terminal, and a second end of the second capacitor C4 is grounded.
The beneficial effects of the embodiment of the disclosure are that:
the protection circuit for preventing the over-discharge of the battery equipment is simple in structure, high in reliability and low in cost; the power supply can be effectively protected, under the condition of excessively high instantaneous load, the instantaneous voltage is excessively reduced, so that the chip is in an abnormal working voltage, at the moment, a later-stage circuit can be timely disconnected, the loss caused by the over-discharge of a battery is reduced or avoided, or under the condition of continuous power supply of the battery, if other reasons cause that software fails to timely turn off the circuit; the voltage can be effectively solved when the later stage load is unstable, and the voltage is repeatedly oscillated in a certain interval, so that the power switch is repeatedly turned on and off, and the output of the later stage circuit is unstable.
Drawings
Fig. 1 is a schematic configuration diagram of a protection circuit for preventing overdischarge of a battery device according to an embodiment of the present disclosure.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure more apparent, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings. It should be understood that the detailed description is merely illustrative of the disclosed embodiments and is not intended to limit the disclosed embodiments.
As shown in fig. 1, an embodiment of the present disclosure provides a protection circuit for preventing overdischarge of a battery device, the circuit including: a power input terminal VBAT/VIN10, a power output terminal VBUS/VOUT20, a recovery circuit 30, a delay protection circuit 40, and a power switch 50;
the recovery circuit 30 is configured to turn on the power switch 50 when the voltage at the power input terminal is greater than or equal to a first threshold;
the delay protection circuit 40 is configured to keep the power switch 50 turned on when the voltage at the power input terminal is less than a first threshold and equal to or greater than a second threshold in a conducting state of the protection circuit;
the power switch 50 is configured to switch on and off the power input terminal and the power output terminal.
In the embodiment of the disclosure, the power supply may be a battery, where the positive electrode of the battery is connected to VBAT or VIN and the negative electrode of the battery is used as a power supply input end, or the negative electrode of the battery is connected to VBAT or VIN and the positive electrode of the battery is connected to the ground as a power supply input end, and the rear stage is connected to VBUS or VOUT and is connected to the load output. The recovery circuit 30 is not conducted when the voltage of the power input end is lower than the first threshold value; when the voltage of the power input end reaches or exceeds the first threshold value, the recovery circuit 30 is conducted to conduct the power switch 50, the power input end is connected with the power output end in a conducting way, and the protection circuit is automatically recovered. The delay protection circuit 40 is not turned on when the voltage of the power input end is lower than a second threshold value, but when the voltage of the power input end is higher than or equal to the second threshold value, the delay protection circuit 40 can be turned on, but in the circuit of the embodiment of the disclosure, the power switch 50 is not independently turned on, only when the voltage of the power input end is higher than or equal to a first threshold value, the power switch 50 is turned on through the recovery circuit 30, after the power input end is connected and turned on with the power output end, when the voltage of the power supply drops to some extent and drops to be lower than the first threshold value, the recovery circuit is turned off, but the voltage of the power supply is still higher than or equal to the second threshold value, the delay protection circuit 40 is kept in a turned-on state, so that the power switch 50 is kept on, the power input end is connected with the power output end, and the delay protection circuit 40 is connected with the recovery circuit 30 in parallel and is connected with the power input end; when the power supply input voltage drops below the second threshold, the delay protection circuit 40 is turned off and the power switch 50 is turned off. The first threshold is greater than the second threshold.
The embodiment of the disclosure provides an overdischarge automatic protection and incoming call self-recovery protection circuit of battery equipment, which realizes a hysteresis circuit switching function through a delay protection circuit and provides protection for the circuit under extreme conditions.
The protection circuit of the embodiment of the disclosure is suitable for the field of working of all battery equipment, and has the characteristics of simple circuit, high reliability and low cost. Under the condition of excessively high instantaneous load, the instantaneous voltage is reduced excessively, so that the chip is in an abnormal working voltage, the back-stage circuit can be disconnected in time at the moment, the loss caused by the over-discharge of the battery is reduced or avoided, or under the condition of continuous power supply of the battery, if the software fails to turn off the circuit in time due to other reasons, the back-stage circuit can be compensated, the voltage of the battery is increased after the battery is charged, the set threshold value is reached, the connection of the back-stage circuit can be automatically restored, and the circuit can continue to work normally. And avoid the back-end load unstable when, voltage is in certain interval and is vibrate repeatedly, lead to switch on and off repeatedly for the unstable condition of back-end circuit output. For example, when the voltage of the power input end is repeatedly oscillated between the first threshold value and the second threshold value in the conducting state of the protection circuit, the power switch can be kept on all the time, so that the unstable condition of the load of the later stage is avoided.
The protection circuit of the embodiment of the disclosure is suitable for platforms such as POS machines and card swiping machines, can be applied to common consumer electronics fields such as tablet computers and smart phones with battery operation, and can also be used in industrial control fields such as industrial monitoring with batteries, data detection and smart home, and the like.
As a specific example of the recovery circuit, the recovery circuit 30 includes: the second zener diode D2, the resistor R5, the resistor R6 and the second triode Q2; the cathode of the second zener diode D2 is connected with the power input end, and the anode of the second zener diode D2 is sequentially connected with the resistor R6 and the resistor R5 in series and then grounded;
the base electrode of the second triode Q2 is connected between the resistor R5 and the resistor R6, the collector electrode of the second triode Q2 is respectively connected with the power input end and the first end of the power switch 50, and the emitter electrode of the second triode Q2 is grounded; a second end of the power switch 50 is connected with the power input end, and a third end of the power switch 50 is connected with the power output end;
the cut-off voltage value of the second zener diode D2 is a first threshold value.
As a specific example of the recovery circuit, the recovery circuit 30 further includes: the first capacitor C1 is connected with the resistor R1 in parallel, the first ends of the first capacitor C1 and the resistor R1 are respectively connected with the power input end, and the second ends of the first capacitor C1 and the resistor R1 are respectively connected with the collector electrode of the second triode Q2.
In the disclosed embodiment, the first capacitor C1 is used to prevent the circuit from being turned off when the load is just connected, such as a motor, or the load is loaded with a large filter capacitor, and the circuit is turned off when the voltage falls below the first threshold, at this time, the effect of C1 is to avoid the instant voltage drop caused when the load with the instant large current is turned on by the later stage, at this time, the circuit is theoretically not turned off, the power switch is maintained to be turned on, the short difficult time is helped, and the repetitive oscillation is avoided.
As a specific example of the first threshold value, the range of the first threshold value is 3.5V or less and 3.0V or more.
As an operation example of the protection circuit, when the voltage of the power input terminal is greater than the first threshold, the second zener diode D2 is operated, the base of the second triode Q2 has a voltage, the collector and the emitter of the second triode Q2 are conducted, the first terminal of the power switch 50 is pulled down, and the second terminal and the third terminal of the power switch 50 are conducted, so that the power output terminal stably outputs.
As a specific example of the delay protection circuit, the delay protection circuit 40 includes: the first voltage stabilizing diode D1, the resistor R2, the resistor R3 and the first triode Q1; the cathode of the first zener diode D1 is connected with the power output end, and the anode of the first zener diode D1 is sequentially connected with the resistor R3 and the resistor R2 in series and then grounded;
the collector of the first triode Q1 is connected with the first end of the power switch 50, the emitter of the first triode Q1 is grounded, and the base of the first triode Q1 is connected between the resistor R2 and the resistor R3;
the cut-off voltage of the first zener diode D1 is a second threshold.
As a specific example of the operation of the circuit, when the circuit is in a conducting state and the voltage of the power input end is greater than the second threshold value and smaller than the first threshold value, the second zener diode D2 does not operate, the first zener diode D1 operates, the base electrode of the first triode Q1 has a voltage, the collector electrode of the first triode Q1 is conducted with the emitter electrode, the first end of the power switch is pulled down, the second end of the power switch is conducted with the third end, and the stable output of the power output end is maintained.
As a specific example of the second threshold value, the second threshold value ranges from less than 3.0V to 2.8V or more.
In the embodiment of the disclosure, the second pin of the power switch 50 is connected to the second end of the power switch 50, i.e. the second end of the power switch 50 is connected to the power input end VBAT/VIN10, the third pin of the power switch 50 is connected to the third end of the power switch 50, i.e. the third end of the power switch 50 is connected to the power output end vbus/VOUT, and the first pin of the power switch 50 is connected to the collectors of the first triode Q1 and the second triode Q2 respectively.
As a specific example of the power switch, the power switch 50 includes a PMOS transistor Q3, a gate of the PMOS transistor Q3 is connected to the recovery circuit 30 and the delay protection circuit 40, a drain of the PMOS transistor Q3 is connected to the power supply output terminal, and a source of the PMOS transistor Q3 is connected to the power supply input terminal.
That is, the source of the field effect PMOS transistor Q3 is connected to VBAT/VIN, the drain of the field effect PMOS transistor Q3 is connected to VBUS/VOUT, and the gate of the field effect PMOS transistor is connected to the collectors of the first transistor Q1 and the second transistor Q2.
As a specific example of the protection circuit, the circuit further includes a second capacitor C4, a first end of the second capacitor C4 is connected to the power input terminal, and a second end of the second capacitor C4 is grounded.
The second capacitor C4 in the embodiment of the present disclosure is connected to the side of the power battery and is used as a bypass filter capacitor, and is suitable for filtering some small clutter of the power battery.
The resistors R1 and R2 and R3 and R5 and R6 in the embodiment of the disclosure are relatively large in resistance, so that the overall power consumption of the circuit is reduced, and the resistors are theoretically negligible below the microampere level. The parameter value of the field effect transistor, namely the PMOS transistor Q3, is selected according to the maximum current characteristic of the protection circuit and is larger than the maximum current of the whole protection circuit. The characteristic values of the first zener diode D1 and the second zener diode D2 are selected to have small floating differences as much as possible. The first triode Q1 and the second triode Q2 are common triodes.
In the following, a single lithium battery is taken as an example of the principle of the circuit of the present disclosure, the working power supply of the protection circuit is a single lithium battery, the full voltage is 4.2V, the minimum voltage for the normal operation of the protection circuit is 3.3V, and the power-off protection voltage is set to be 3V, because the battery has damage to the service life after the battery is lower than 3V.
VBAT is battery terminal, i.e. the power input end, VBUS is the back level work circuit end, i.e. the power output end, when protection circuit normally works, along with the consumption of electric quantity, battery voltage gradually drops, when voltage is lower than 3.3V, still be higher than 3V, second zener diode D2 does not work, second triode Q2 does not switch on, first zener diode D1 still works, first triode Q1 base has voltage to switch on, so 2 foot and 3 foot switch on of first triode Q1 are put lowly, then the grid level of PMOS transistor Q3 is low level, source and drain electrode switch on, the work of back level normal power supply, so the circuit normally works, when battery voltage continues to drop below 3V, second zener diode D2 does not switch on, the base level of triode Q2 is grounded by the resistance, second triode Q2 does not switch on, first triode Q1' S base is pulled down, first triode Q1 does not switch on, the grid level is then turned off by PMOS transistor Q3 from the low level to the drain electrode, the drain electrode is disconnected from the high level, then the grid level is not cut off.
If the battery is in a critical shutdown voltage, the voltage is increased to be 3V along with current recovery, the PMOS transistor Q3 is turned on again, the later stage connection is enabled, if the load is unstable, the repeated on-off situation can occur, the combination of the second diode D2 and the second triode Q2 is protected by adding a hysteresis, the set voltage is assumed to be 3.3V, namely, if the voltage is reduced to be 3V due to the instantaneous large current caused by the heavy load, the voltage is gradually increased and then is required to be higher than 3.3V, the second diode D2 can work, then the base stage of the second triode Q2 has high voltage, the collector and the transmitter of the second triode Q2 can be conducted and pulled down, the grid electrode of the PMOS transistor Q3 is conducted due to the low level, and the later stage circuit recovers output.
Therefore, the situation that the output of the post-stage circuit is unstable due to the fact that the PMOS transistor Q3 is repeatedly switched on and off as the voltage is repeatedly oscillated around 3V when the post-stage load is unstable can be avoided. When the voltage is higher than the set voltage by more than 3V, the power supply output is normal, when the voltage is lower than 3V, the rear-stage circuit is disconnected, and when the voltage is raised to 3.3V, the system starts to work normally.
The following details the state of the power input voltage from 3.3V or more to 3V or less:
when the battery voltage is above 3.3V, the power input end VBAT and the power output end VBUS are connected in a conducting mode.
When the battery voltage is still above 3.3V, the second zener diode D2 works, there is conduction current to the resistors R5 and R6, there is voltage on the resistor R5, that is, there is voltage on the base of the second triode Q2, the collector and the emitter of the second triode Q2 are conducted, the emitter of the second triode Q2 is grounded, the gate of the field effect transistor, that is, the PMOS transistor Q3 is also pulled down, the drain D and the source S are also conducted because of the PMOS transistor, the first zener diode D1 is seen again, there is a current flowing through the resistor R2 and the resistor R3 because the voltage is greater than 3V, there is a voltage drop on the resistor R2, the collector and the emitter of the first triode Q1 are also conducted, the collector and the gate of the PMOS transistor Q1 are also pulled down, the gate of the PMOS transistor Q1 is connected together, the gate of the PMOS transistor is pulled down, and the feedback output is continued to be equivalent to negative.
When the battery voltage drops below 3.3V, 3V or above.
The first zener diode D1 continues to work normally, the current flows through R2 and R3, there is a voltage drop across the resistor R2, the base of the first triode Q1 continues to conduct if there is a voltage, the collector and emitter of the first triode Q1 continue to conduct to ground, so the gate voltage of the PMOS transistor Q3 continues to be low, the D and S stages of the field effect PMOS transistor Q3 continue to conduct because the voltage is higher than the characteristic value of the first zener diode D1, which stabilizes the voltage. The second zener diode D2 is not conducted, no current exists in the circuits of the resistors R5 and R6, the base electrode of the second triode Q2 is connected with the resistor R5 to the ground, the collector electrode of the second triode Q2 is disconnected from the emitter, the second triode Q2 is disconnected, and the first triode Q1 is conducted, so that the field effect transistor PMOS is continuously low level and continuously and stably output.
When the battery voltage continues to drop below 3V.
The second zener diode D2 is not operated because the characteristic value is higher than 3V, the second zener diode D2 is not conducted, no current is applied to the circuits of the resistors R5 and R6, the base electrode of the second triode Q2 is connected to the resistor R5 to the ground, the collector electrode of the second triode Q2 is disconnected from the emitter electrode, the voltage regulator D1 is seen again, the first triode Q1 is conducted because the front is in a working state, the grid electrode of the field effect transistor PMOS is still in a low level state, the PMOS is conducted at the front, when the voltage is lower than 3V, the first zener diode D1 is not conducted, the base electrode of the first triode Q1 is pulled down to the ground by the resistor R2, the collector electrode of the first triode Q1 is disconnected from the emitter electrode, the two first triodes Q1 and the second triodes Q2 are both not conducted, the grid electrode of the field effect transistor PMOS is pulled up only by the resistor R1, the D stage and the S stage of the field effect transistor PMOS are disconnected, and no output is generated at the rear stage. The battery can be disconnected from the later-stage circuit at 3V, and the battery is not over-discharged due to continuous electric quantity loss.
When the battery voltage starts to rise back, if it rises above 3V and below 3.3V.
The characteristic value of the second zener diode D2 is higher than the voltage at this time, and still does not work, so that the resistors R5 and R6 do not have current, the base of the second triode Q2 is pulled down by the resistor R5, the second triode Q2 cannot be turned on, the gate of the field effect transistor PMOS cannot be turned on, and no output is provided at the later stage.
When the battery voltage continues to rise, if it rises above 3.3V.
The characteristic value of the second zener diode D2 is lower than the current voltage, the conduction operation is started, the current flows through the resistors R5 and R6, the base level of the second triode Q2 is pulled high by the resistor R5, the collector and emitter of the second triode Q2 are conducted, the grid level of the field effect transistor PMOS is pulled low, the PMOS starts to conduct, the output starts to exist, the characteristic value of the first zener diode D1 is lower than the current voltage, the conduction operation is started, the current flows through the resistors R2 and R3, the base level of the first triode Q1 is pulled high by the resistors R2 and R3, the collector and emitter of the first triode Q1 are conducted, the collector level is pulled low, the grid of the field effect transistor is equivalent to negative feedback, and the PMOS continues to conduct. And the subsequent stage outputs normally.
By adopting the technical scheme disclosed by the embodiment of the disclosure, the following beneficial effects are obtained:
the protection circuit of the embodiment of the disclosure has the advantages that the logic basic circuit formed by the resistor-capacitor, the triode, the voltage stabilizing tube and the field effect tube which are passive devices is simple and stable in structure, compared with other existing chip-controlled discharge protection circuits, the device is fewer, the structure is simpler, the stability is better than that of a complex micro control unit (Microcontroller Unit, MCU) which needs software to control an IO circuit, the circuit design is simpler, and the cost is lower under the condition of reliability.
The foregoing is merely a preferred implementation of the embodiments of the disclosure, and it should be noted that, for a person skilled in the art, several improvements and modifications may be made without departing from the principles of the embodiments of the disclosure, which should also be considered as protective scope of the embodiments of the disclosure.

Claims (10)

1. A protection circuit for preventing overdischarge of a battery device, the circuit comprising: the power supply comprises a power supply input end, a power supply output end, a recovery circuit, a delay protection circuit and a power switch;
the recovery circuit is used for conducting the power switch when the voltage of the power input end is larger than or equal to a first threshold value;
the delay protection circuit is used for keeping the power switch on when the voltage of the power input end is smaller than a first threshold value and larger than or equal to a second threshold value in the on state of the protection circuit;
the power switch is used for switching on and off the power input end and the power output end.
2. The protection circuit of claim 1, wherein the recovery circuit comprises: the second zener diode D2, the resistor R5, the resistor R6 and the second triode Q2; the cathode of the second zener diode D2 is connected with the power input end, and the anode of the second zener diode D2 is sequentially connected with the resistor R6 and the resistor R5 in series and then grounded;
the base electrode of the second triode Q2 is connected between the resistor R5 and the resistor R6, the collector electrode of the second triode Q2 is respectively connected with the power input end and the first end of the power switch, and the emitter electrode of the second triode Q2 is grounded; the second end of the power switch is connected with the power input end, and the third end of the power switch is connected with the power output end;
the cut-off voltage value of the second zener diode D2 is a first threshold value.
3. The protection circuit of claim 2, wherein the recovery circuit further comprises: the first capacitor C1 is connected with the resistor R1 in parallel, the first ends of the first capacitor C1 and the resistor R1 are respectively connected with the power input end, and the second ends of the first capacitor C1 and the resistor R1 are respectively connected with the collector electrode of the second triode Q2.
4. A protection circuit according to claim 3, wherein when the voltage at the power supply input terminal is greater than the first threshold value, the second zener diode D2 is operated, the base of the second triode Q2 has a voltage, the collector and the emitter of the second triode Q2 are conducted, the first terminal of the power supply switch is pulled down, and the second terminal and the third terminal of the power supply switch are conducted, so that the power supply output terminal stably outputs.
5. The protection circuit according to any one of claims 1 to 4, wherein the first threshold value ranges from 3.5V or less to 3.0V or more.
6. The protection circuit according to any one of claims 1 to 4, wherein the delay protection circuit includes: the first voltage stabilizing diode D1, the resistor R2, the resistor R3 and the first triode Q1; the cathode of the first zener diode D1 is connected with the power output end, and the anode of the first zener diode D1 is sequentially connected with the resistor R3 and the resistor R2 in series and then grounded;
the collector of the first triode Q1 is connected with the first end of the power switch, the emitter of the first triode Q1 is grounded, and the base of the first triode Q1 is connected between the resistor R2 and the resistor R3;
the cut-off voltage of the first zener diode D1 is a second threshold.
7. The protection circuit of claim 6, wherein when the circuit is in a conductive state, the voltage at the power supply input terminal is greater than the second threshold value and less than the first threshold value, the second zener diode D2 is not operated, the first zener diode D1 is operated, the base of the first triode Q1 has a voltage, the collector of the first triode Q1 is conducted with the emitter, the first terminal of the power supply switch is pulled down, the second terminal of the power supply switch is conducted with the third terminal, and the stable output of the power supply output terminal is maintained.
8. The protection circuit of claim 6, wherein the second threshold value ranges from less than 3.0V to 2.8V.
9. The protection circuit according to any one of claims 1 to 4, wherein the power switch comprises a PMOS transistor Q3, a gate of the PMOS transistor Q3 is connected to the recovery circuit and the delay protection circuit, respectively, a drain of the PMOS transistor Q3 is connected to the power supply output terminal, and a source of the PMOS transistor Q3 is connected to the power supply input terminal.
10. The protection circuit according to any one of claims 1 to 4, further comprising a second capacitor C4, wherein a first end of the second capacitor C4 is connected to the power input terminal, and a second end of the second capacitor C4 is grounded.
CN202311515985.7A 2023-11-14 2023-11-14 Protection circuit for preventing battery equipment from overdischarging Pending CN117293972A (en)

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CN202311515985.7A CN117293972A (en) 2023-11-14 2023-11-14 Protection circuit for preventing battery equipment from overdischarging

Applications Claiming Priority (1)

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CN202311515985.7A CN117293972A (en) 2023-11-14 2023-11-14 Protection circuit for preventing battery equipment from overdischarging

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117526543A (en) * 2024-01-03 2024-02-06 成都汉度科技有限公司 Power supply system adopting solar panel and battery dual power supply

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117526543A (en) * 2024-01-03 2024-02-06 成都汉度科技有限公司 Power supply system adopting solar panel and battery dual power supply
CN117526543B (en) * 2024-01-03 2024-03-22 成都汉度科技有限公司 Power supply system adopting solar panel and battery dual power supply

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