A mobile luminaire battery under-voltage protection circuit

Abstract

The utility model provides a kind of mobile lamps and lanterns battery under-voltage protection circuit, including linear three-terminal voltage regulator chip U1, double voltage comparator U2, MOS tube Q1, triode Q2, voltage dividing resistor R2, voltage dividing resistor R3, voltage dividing resistor R5, voltage dividing resistor R6 and current-limiting resistor R8, one end of the current-limiting resistor R8 is connected with battery anode, the other end of the current-limiting resistor R8 is connected with the pin 3 of linear three-terminal voltage regulator chip U1, the pin 1 of linear three-terminal voltage regulator chip U1 is grounded, the pin 2 of linear three-terminal voltage regulator chip U1 is connected with the pin 8 of double voltage comparator U2.The beneficial effects of the utility model are: provide a kind of mobile lamps and lanterns battery under-voltage protection circuit, can be closed by MOS tube Q1 when battery power remaining is less (for example 20%), turn off mobile lamps and lanterns current, prevent lithium battery overdischarge, to prolong the service life of lithium battery.

Description

Technical Field

[0001] This utility model relates to lighting devices, and more particularly to a battery undervoltage protection circuit for a portable lamp. Background Technology

[0002] Existing portable lights typically use replaceable lithium batteries for power. During use, there's a possibility that users might leave the lights on after use (e.g., forgetting to turn them off), leading to over-discharge and deep battery depletion. Deep battery depletion is a "battery killer," and its damage is irreversible. Users should strictly adhere to the 20%-80% charge range and avoid charging and discharging in extreme high / low temperature environments. Electrode material damage: Deep discharge causes excessive lithium-ion intercalation and deintercalation, triggering the collapse of the positive and negative electrode material structures (such as graphite layer peeling and metal oxide lattice distortion), resulting in irreversible capacity loss. Experimental data: Discharging to below 10% of the charge can cause a single deep discharge to reduce capacity by 0.5%-2%; repeated deep discharges can shorten battery life by more than 30%. Summary of the Invention

[0003] To address the problems in the prior art, this utility model provides a battery undervoltage protection circuit for mobile lighting fixtures.

[0004] This utility model provides a battery undervoltage protection circuit for a mobile lamp, including a linear three-terminal voltage regulator chip U1, a dual voltage comparator U2, a MOSFET Q1, a transistor Q2, voltage divider resistors R2, R3, R5, and R6, and a current-limiting resistor R8. One end of the current-limiting resistor R8 is connected to the positive terminal of the battery, and the other end of the current-limiting resistor R8 is connected to pin 3 of the linear three-terminal voltage regulator chip U1. Pin 1 of the linear three-terminal voltage regulator chip U1 is grounded, and pin 2 of the linear three-terminal voltage regulator chip U1 is connected to pin 8 of the dual voltage comparator U2. One end of the voltage divider resistor R2 is connected to the positive terminal of the battery, and the other end of the voltage divider resistor R2 is connected to pin 3 of the dual voltage comparator U2. One end of resistor R3 is connected to pin 3 of the dual voltage comparator U2, and the other end of the voltage divider resistor R3 is grounded. One end of voltage divider resistor R5 is connected to pin 2 of the linear three-terminal voltage regulator chip U1, and the other end of voltage divider resistor R5 is connected to pin 2 of the dual voltage comparator U2. One end of voltage divider resistor R6 is connected to pin 2 of the dual voltage comparator U2, and the other end of voltage divider resistor R6 is grounded. The base of transistor Q2 is connected to pin 1 of the dual voltage comparator U2, the emitter of transistor Q2 is grounded, the collector of transistor Q2 is connected to the gate of MOSFET Q1, the source of MOSFET Q1 is connected to the positive terminal of the battery, and the drain of MOSFET Q1 is connected to the portable lamp.

[0005] As a further improvement of this utility model, the undervoltage protection circuit for the mobile lamp battery also includes a resistor R1, one end of which is connected to the source (S) terminal of the MOSFET Q1, and the other end of which is connected to the collector terminal of the transistor Q2.

[0006] As a further improvement of this utility model, the undervoltage protection circuit for the mobile lamp battery also includes a current-limiting resistor R4. One end of the current-limiting resistor R4 is connected to the base of the transistor Q2, and the other end of the current-limiting resistor R4 is connected to pin 1 of the dual voltage comparator U2.

[0007] As a further improvement of this utility model, the mobile lamp battery undervoltage protection circuit also includes a feedback resistor R9. One end of the feedback resistor R9 is connected to pin 1 of the dual voltage comparator U2, and the other end of the feedback resistor R9 is connected to pin 3 of the dual voltage comparator U2.

[0008] As a further improvement of this utility model, the undervoltage protection circuit for the mobile lamp battery also includes a power supply capacitor C1. One end of the power supply capacitor C1 is connected to pin 3 of the linear three-terminal voltage regulator chip U1, and the other end of the power supply capacitor C1 is grounded.

[0009] As a further improvement of this utility model, the undervoltage protection circuit for the mobile lamp battery also includes a filter capacitor C2. One end of the filter capacitor C2 is connected to pin 2 of the linear three-terminal voltage regulator chip U1, and the other end of the filter capacitor C2 is grounded.

[0010] As a further improvement of this utility model, the linear three-terminal voltage regulator chip U1 is model number LM7805.

[0011] As a further improvement of this utility model, the dual voltage comparator U2 is model number LM393.

[0012] As a further improvement of this utility model, the MOS transistor Q1 is a P-channel MOS transistor.

[0013] As a further improvement of this utility model, the transistor Q2 is an NPN transistor.

[0014] The beneficial effects of this utility model are as follows: The above solution provides a mobile lamp battery undervoltage protection circuit. Because the voltage of a lithium battery will drop during the discharge process, the voltage corresponding to 20% capacity of the lithium battery can be calculated. When the remaining battery power is low (e.g., 20%), the voltage corresponding to the undervoltage protection point is reached and the MOSFET Q1 is turned off, cutting off the current of the mobile lamp, preventing deep discharge of the lithium battery, and ensuring that the battery capacity is in the range of >20%, thereby extending the service life and cycle number of the lithium battery. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other solutions can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a circuit diagram for undervoltage protection of a mobile lamp battery according to this utility model. Detailed Implementation

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0018] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0019] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0021] like Figure 1As shown, a mobile lighting battery undervoltage protection circuit includes a linear three-terminal voltage regulator chip U1, a dual voltage comparator U2, a MOSFET Q1, a transistor Q2, voltage divider resistors R2, R3, R5, and R6, and a current-limiting resistor R8. One end of the current-limiting resistor R8 is connected to the positive terminal of the battery, and the other end of the current-limiting resistor R8 is connected to pin 3 of the linear three-terminal voltage regulator chip U1. Pin 1 of the linear three-terminal voltage regulator chip U1 is grounded, and pin 2 of the linear three-terminal voltage regulator chip U1 is connected to pin 8 of the dual voltage comparator U2. One end of the voltage divider resistor R2 is connected to the positive terminal of the battery, and the other end of the voltage divider resistor R2 is connected to pin 3 of the dual voltage comparator U2. One end of the voltage divider resistor R3 is connected to the positive terminal of the battery. Pin 3 of the dual voltage comparator U2 is connected; the other end of the voltage divider resistor R3 is grounded; one end of the voltage divider resistor R5 is connected to pin 2 of the linear three-terminal regulator chip U1; the other end of the voltage divider resistor R5 is connected to pin 3 of the dual voltage comparator U2; one end of the voltage divider resistor R6 is connected to pin 3 of the dual voltage comparator U2; the other end of the voltage divider resistor R6 is grounded; the base of the transistor Q2 is connected to pin 1 of the dual voltage comparator U2; the emitter of the transistor Q2 is grounded; the collector of the transistor Q2 is connected to the gate of the MOSFET Q1; the source of the MOSFET Q1 is connected to the positive terminal of the battery; and the drain of the MOSFET Q1 is connected to the portable lamp.

[0022] Voltage divider resistors R2 and R3 are the voltage divider resistors at the non-inverting input of the dual voltage comparator U2.

[0023] Voltage divider resistors R5 and R6 are the voltage divider resistors at the inverting input of the dual voltage comparator U2.

[0024] The current-limiting resistor R8 is the current-limiting resistor for the linear three-terminal voltage regulator chip U1.

[0025] The undervoltage protection circuit for the mobile lamp battery also includes a resistor R1, one end of which is connected to the source (S) terminal of the MOSFET Q1, and the other end of which is connected to the collector terminal of the transistor Q2.

[0026] Resistor R1 is the discharge resistor between the gate and source of MOSFET Q1, and the current limiting resistor after transistor Q2 is turned on.

[0027] The undervoltage protection circuit for the mobile lamp battery also includes a current-limiting resistor R4. One end of the current-limiting resistor R4 is connected to the base of the transistor Q2, and the other end of the current-limiting resistor R4 is connected to pin 1 of the dual voltage comparator U2.

[0028] The current-limiting resistor R4 is the current-limiting resistor for transistor Q2.

[0029] The undervoltage protection circuit for the mobile lamp battery also includes a feedback resistor R9. One end of the feedback resistor R9 is connected to pin 1 of the dual voltage comparator U2, and the other end of the feedback resistor R9 is connected to pin 3 of the dual voltage comparator U2.

[0030] The feedback resistor R9 is the feedback resistor between the output terminal and the non-inverting terminal of the dual voltage comparator U2.

[0031] The undervoltage protection circuit for the mobile lamp battery also includes a power supply capacitor C1. One end of the power supply capacitor C1 is connected to pin 3 of the linear three-terminal voltage regulator chip U1, and the other end of the power supply capacitor C1 is grounded.

[0032] The power supply capacitor C1 is the input power supply capacitor for the linear three-terminal voltage regulator chip U1.

[0033] The undervoltage protection circuit for the mobile lamp battery also includes a filter capacitor C2. One end of the filter capacitor C2 is connected to pin 2 of the linear three-terminal voltage regulator chip U1, and the other end of the filter capacitor C2 is grounded.

[0034] The filter capacitor C2 is the output filter capacitor of the linear three-terminal voltage regulator chip U1.

[0035] The linear three-terminal voltage regulator chip U1 is model LM7805.

[0036] The LM7805 is a commonly used three-terminal voltage regulator with an input voltage range typically from 7V to 35V. Within this range, the regulator can operate normally, stably converting the input voltage to a 5V output voltage.

[0037] The dual voltage comparator U2 is model LM393.

[0038] The LM393 is a dual differential comparator that supports single or dual power supply operation, with an operating voltage range of 2V to 36V. Internally, the LM393 chip contains two independent high-precision voltage comparators capable of comparing two input signals and outputting the corresponding comparison result, which can be used to control other circuits. When the voltage at the non-inverting input is greater than the voltage at the inverting input, the output is high; when the voltage at the non-inverting input is less than the voltage at the inverting input, the output is low.

[0039] The MOSFET Q1 is a P-channel MOSFET.

[0040] A P-channel MOSFET is a type of MOSFET with an n-type substrate and a p-channel, which carries current through the flow of holes. MOSFETs are technically called metal-oxide-semiconductor field-effect transistors (MOSFETs). P-channel MOSFETs are often referred to as PMOSFETs or PMOS. Here, it functions as a switch; when the gate (G) is low, the PMOS is turned on, and current flows from the source (S) to the drain (D). When the gate (G) is high, the PMOS is turned off, current is cut off, and the lamp is not powered on.

[0041] The transistor Q2 is an NPN transistor.

[0042] The operating principle of an NPN transistor is primarily based on current amplification and switching. Here, it's used for switching; the operating principle of an NPN transistor is primarily based on current amplification and switching.

[0043] This utility model provides a battery undervoltage protection circuit for a portable lamp. A linear three-terminal voltage regulator chip U1 provides a stable 5V voltage to a dual voltage comparator U2. A stable reference voltage is provided to the inverting input through voltage divider resistors R5 and R6. The non-inverting input of the dual voltage comparator U2 is divided by voltage divider resistors R2 and R3 to provide a single voltage. The dual voltage comparator U2 compares the voltages at pin 3 (non-inverting input) and pin 2 (inverting input) to output different levels. When the voltage at pin 3 is greater than the voltage at pin 2, output pin 1 outputs a high level, transistor Q2 conducts, and current flows through resistor R1 to the negative terminal of the battery via transistor Q2. At this time, the gate (G) of MOSFET Q1 becomes low, MOSFET Q1 conducts, and the portable lamp is powered normally. Conversely, when the voltage at pin 3 is less than the voltage at pin 2, the output pin 1 outputs a low level, transistor Q2 is cut off, the current through resistor R1 flows to the gate of MOSFET Q1 at a high level, MOSFET Q1 is turned off, and the L moving lamp is powered off and extinguished, thereby preventing the lithium battery from being over-discharged and thus extending the life of the lithium battery.

[0044] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the protection scope of the present invention.

Claims

1. A battery undervoltage protection circuit for a portable lighting fixture, characterized in that: The system includes a linear three-terminal voltage regulator chip U1, a dual voltage comparator U2, a MOSFET Q1, a transistor Q2, voltage divider resistors R2, R3, R5, and R6, and a current-limiting resistor R8. One end of the current-limiting resistor R8 is connected to the positive terminal of the battery, and the other end is connected to pin 3 of the linear three-terminal voltage regulator chip U1. Pin 1 of the linear three-terminal voltage regulator chip U1 is grounded, and pin 2 of the linear three-terminal voltage regulator chip U1 is connected to pin 8 of the dual voltage comparator U2. One end of the voltage divider resistor R2 is connected to the positive terminal of the battery, and the other end is connected to pin 3 of the dual voltage comparator U2. One end of the voltage divider resistor R3 is connected to the dual voltage comparator U2. Pin 3 of voltage comparator U2 is connected; the other end of voltage divider resistor R3 is grounded; one end of voltage divider resistor R5 is connected to pin 2 of linear three-terminal regulator chip U1; the other end of voltage divider resistor R5 is connected to pin 2 of dual voltage comparator U2; one end of voltage divider resistor R6 is connected to pin 2 of dual voltage comparator U2; the other end of voltage divider resistor R6 is grounded; the base of transistor Q2 is connected to pin 1 of dual voltage comparator U2; the emitter of transistor Q2 is grounded; the collector of transistor Q2 is connected to the gate of MOSFET Q1; the source of MOSFET Q1 is connected to the positive terminal of the battery; and the drain of MOSFET Q1 is connected to the portable lamp.

2. The undervoltage protection circuit for mobile lighting batteries according to claim 1, characterized in that: The undervoltage protection circuit for the mobile lamp battery also includes a resistor R1, one end of which is connected to the source (S) terminal of the MOSFET Q1, and the other end of which is connected to the collector terminal of the transistor Q2.

3. The undervoltage protection circuit for mobile lighting battery according to claim 1, characterized in that: The undervoltage protection circuit for the mobile lamp battery also includes a current-limiting resistor R4. One end of the current-limiting resistor R4 is connected to the base of the transistor Q2, and the other end of the current-limiting resistor R4 is connected to pin 1 of the dual voltage comparator U2.

4. The undervoltage protection circuit for mobile lighting battery according to claim 1, characterized in that: The undervoltage protection circuit for the mobile lamp battery also includes a feedback resistor R9. One end of the feedback resistor R9 is connected to pin 1 of the dual voltage comparator U2, and the other end of the feedback resistor R9 is connected to pin 3 of the dual voltage comparator U2.

5. The undervoltage protection circuit for mobile lighting battery according to claim 1, characterized in that: The undervoltage protection circuit for the mobile lamp battery also includes a power supply capacitor C1. One end of the power supply capacitor C1 is connected to pin 3 of the linear three-terminal voltage regulator chip U1, and the other end of the power supply capacitor C1 is grounded.

6. The undervoltage protection circuit for mobile lighting batteries according to claim 1, characterized in that: The undervoltage protection circuit for the mobile lamp battery also includes a filter capacitor C2. One end of the filter capacitor C2 is connected to pin 2 of the linear three-terminal voltage regulator chip U1, and the other end of the filter capacitor C2 is grounded.

7. The undervoltage protection circuit for mobile lighting battery according to claim 1, characterized in that: The linear three-terminal voltage regulator chip U1 is model LM7805.

8. The undervoltage protection circuit for mobile lighting battery according to claim 1, characterized in that: The dual voltage comparator U2 is model LM393.

9. The undervoltage protection circuit for mobile lighting battery according to claim 1, characterized in that: The MOSFET Q1 is a P-channel MOSFET.

10. The undervoltage protection circuit for mobile lighting battery according to claim 1, characterized in that: The transistor Q2 is an NPN transistor.

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