Lithium battery discharge management circuit

Abstract

The utility model discloses a lithium battery discharge management circuit, and relates to the technical field of lithium batteries. Comprising a key switch SW1, a current limiting resistor R72, a protection diode D21, an MOS tube Q25, a triode Q26, an MCU chip U11 and a voltage stabilizing chip U12. When a user presses the SW1 once, the SW1 is short-circuited, and even if a finger loosens the switch of the SW1, the Q25 is still in a conducting state, so that the battery is ensured to continuously supply power to the outside, self-locking maintenance can be completed without depending on manual continuous pressing, and the convenience and the stability of operation are improved.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery technology, specifically a lithium battery discharge management circuit. Background Technology

[0002] Currently, lithium batteries are widely used as the main power supply unit in portable devices, power tools, and energy storage systems. Their discharge management circuits typically need to be able to manually control the battery power supply and disconnection when the battery is idle or when the load demand changes, in order to effectively manage battery energy and extend battery life. However, existing lithium battery discharge control circuits generally have the following problems:

[0003] 1. Most circuits lack an effective self-holding mechanism for battery-powered startup, requiring users to continuously press the switch to maintain power supply, resulting in inconvenient operation and poor stability.

[0004] 2. The battery voltage monitoring structure is usually normally closed and has no independent control path. It is easy to cause unnecessary consumption of battery power when it is in a powered state for a long time, and it cannot achieve accurate and low-power real-time voltage detection.

[0005] 3. During system idle or power-off standby, the existing design fails to effectively disconnect the detection and indication circuits, which can easily generate static leakage current, affecting the battery's energy storage stability and the overall energy-saving performance, making it difficult to meet the requirements of high reliability and long lifespan applications. Utility Model Content

[0006] The purpose of this application is to provide a technical solution to address the problems mentioned in the background section.

[0007] To achieve the above objectives, this application provides the following technical solution:

[0008] A lithium battery discharge management circuit includes a push-button switch SW1, a current-limiting resistor R72, a protection diode D21, a MOSFET Q25, a transistor Q26, an MCU chip U11, and a voltage regulator chip U12. One end of the push-button switch SW1 is connected to the common node of the current-limiting resistor R72 and the protection diode D21, and the other end is connected to ground.

[0009] One end of the current-limiting resistor R72 is connected to the output terminal of the voltage regulator chip U12, and the other end is connected to the positive terminal of the push-button switch SW1 and the protection diode D21;

[0010] The positive terminal of the protection diode D21 is connected to the common node of the push-button switch SW1 and the current-limiting resistor R72, and the negative terminal is connected to ground;

[0011] The source of the MOSFET Q25 is connected to the positive terminal of the battery, the drain is connected to the input terminal of the voltage regulator chip U12, the gate is connected to the common node of the push button switch SW1 and the current limiting resistor R72, and is also connected to the collector of the transistor Q26. The emitter of the transistor Q26 is connected to ground.

[0012] The power supply terminal of the MCU chip U11 is connected to the output terminal of the voltage regulator chip U12, and one of its IO pins is connected to the base of the transistor Q26.

[0013] Preferably, it also includes a transistor Q30 and a MOSFET Q20. The base of the transistor Q30 is connected to one of the I / O pins of the MCU chip U11, the collector is connected to the MOSFET Q20, and the emitter is connected to ground.

[0014] The source of the MOSFET Q20 is connected to the positive terminal of the battery, the drain is connected to the input terminal of the MCU chip U11, and the gate is connected to the transistor Q30.

[0015] Preferably, it also includes MOSFET Q23, MOSFET Q24, transistor Q31, and sampling resistor R58. The base of transistor Q31 is connected to one of the IO pins of the MCU chip U11, the collector is connected to the gate of MOSFET Q23, and the emitter is connected to ground.

[0016] The source of the MOSFET Q23 is connected to the positive terminal of the battery, and the drain is connected to the gate of the MOSFET Q24.

[0017] The drain of the MOS transistor Q24 is connected to the positive terminal of the battery, and the source is connected to one end of the sampling resistor R58. The other end of the sampling resistor R58 is connected to ground.

[0018] Preferably, the MOSFETs Q25, Q20, and Q23 are all P-channel MOSFETs.

[0019] Preferably, transistors Q26, Q30, and Q31 are all NPN transistors.

[0020] Preferably, the MOS transistor Q24 is an N-channel MOS transistor.

[0021] Preferably, the voltage regulator chip U12 is a linear voltage regulator.

[0022] In summary, the technical effects and advantages of this utility model are as follows:

[0023] 1. In this utility model, when the user prepares to start the battery power supply (i.e., the battery actively discharges to an external load), the user first operates the button switch SW1 by pressing it once. This shorts SW1, pulling the 5V1-B voltage to ground potential through the series current-limiting resistor R72 and the protection diode D21, forming a low-level signal. At this time, because the gate of Q25 (HL2301AP-MOS) is pulled low, Q25 conducts, thereby allowing the battery positive voltage B+ to be directly output to the U12 voltage regulator chip through the drain and source of Q25. U12 then regulates the battery voltage... The voltage is stably stepped down to the standard 5V1 voltage, while simultaneously supplying power to the MCUU11 (AD18F08) to initiate its power-on startup. Upon power-on, the MCU immediately recognizes the battery self-discharge startup state and, through program control, sends a high-level 5V signal to the base of Q26, turning on Q26 and continuously pulling the gate voltage of Q25 low (forming a self-holding latch). Even after the finger releases the SW1 switch, Q25 remains on, thus ensuring continuous power supply from the battery. This self-locking mechanism can be maintained without relying on continuous manual pressing, improving the convenience and stability of operation.

[0024] 2. The MCU's internal control logic further outputs a high-level signal to the base of Q30, causing Q30 to conduct. This conducts through Q20 (also an HL2301AP-MOS), thereby closing the battery voltage detection circuit and feeding back the battery voltage information to the MCU for real-time monitoring of the battery's charge status, thus achieving accurate and low-power real-time voltage detection.

[0025] 3. When the user wishes to terminate battery power to protect battery life or prevent power loss, simply press SW1 three times in succession. The MCU's internal logic recognizes the shutdown instruction and immediately stops sending high-level signals to the bases of Q26, Q30, and Q31. After Q26 is turned off, the gate voltage of Q25 is pulled up to a high level through the pull-up resistor R1A, causing Q25 to turn off, cutting off the battery power supply path. The MCU itself also loses power and enters a power-off state. At the same time, all loops are disconnected, including voltage detection, discharge control, and the LED display system. The battery is completely isolated from the load, avoiding static leakage current consumption, thereby maximizing the battery's energy storage capacity during sleep, improving battery life, and effectively saving energy. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1This is a schematic diagram of the lithium battery discharge management circuit of this utility model. Detailed Implementation

[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0029] Please see Figure 1 A lithium battery discharge management circuit includes a push-button switch SW1, a current-limiting resistor R72, a protection diode D21, a MOSFET Q25, a transistor Q26, an MCU chip U11, and a voltage regulator chip U12. One end of the push-button switch SW1 is connected to the common node of the current-limiting resistor R72 and the protection diode D21, and the other end is connected to ground. One end of the current-limiting resistor R72 is connected to the output terminal of the voltage regulator chip U12, and the other end is connected to the push-button switch SW1 and the positive terminal of the protection diode D21. The positive terminal of the protection diode D21... The common node connecting the push-button switch SW1 and the current-limiting resistor R72 is connected, with the negative terminal connected to ground; the source of the MOSFET Q25 is connected to the positive terminal of the battery, the drain is connected to the input terminal of the voltage regulator chip U12, the gate is connected to the common node connecting the push-button switch SW1 and the current-limiting resistor R72, and is also connected to the collector of the transistor Q26, with the emitter of the transistor Q26 connected to ground; the power supply terminal of the MCU chip U11 is connected to the output terminal of the voltage regulator chip U12, and one of its IO pins is connected to the base of the transistor Q26. In this circuit, when the user prepares to start the battery power supply (i.e., the battery actively discharges to an external load), they first operate the push-button switch SW1 by pressing it once. This shorts SW1, pulling the 5V1-B voltage to ground through the series current-limiting resistor R72 and the protection diode D21, forming a low-level signal. At this time, because the gate of Q25 (HL2301AP-MOS) is pulled low, Q25 conducts, allowing the battery positive voltage B+ to be directly output to the U12 voltage regulator chip via the drain and source of Q25. 12. The battery voltage is stably stepped down to the standard 5V1 voltage, and power is supplied to MCUU11 (AD18F08) to start it up. After the MCU is powered on, it immediately recognizes the battery self-discharge start-up state. Therefore, it sends a high-level 5V signal to the base of Q26 through program control. Q26 turns on and continuously pulls the gate voltage of Q25 low (forming a self-holding latch). Even if the finger releases the SW1 switch, Q25 will still remain on, thus ensuring that the battery continues to supply power to the outside without relying on continuous manual pressing to complete the self-locking maintenance.

[0030] Preferably, the system further includes a transistor Q30 and a MOSFET Q20. The base of transistor Q30 is connected to one of the I / O pins of the MCU chip U11, the collector is connected to the MOSFET Q20, and the emitter is connected to ground. The source of MOSFET Q20 is connected to the positive terminal of the battery, the drain is connected to the input terminal of the MCU chip U11, and the gate is connected to transistor Q30. Subsequently, the internal control logic of the MCU outputs a high-level signal to the base of Q30, turning on Q30. This, in turn, turns on Q20 (also an HL2301AP-MOS), thereby closing the battery voltage detection loop and feeding back the battery voltage information to the MCU for real-time monitoring of the battery's state of charge.

[0031] Preferably, the device further includes MOSFET Q23, MOSFET Q24, transistor Q31, and sampling resistor R58. The base of transistor Q31 is connected to one of the I / O pins of the MCU chip U11, the collector is connected to the gate of MOSFET Q23, and the emitter is connected to ground. The source of MOSFET Q23 is connected to the positive terminal of the battery, and the drain is connected to the gate of Q24. The drain of MOSFET Q24 is connected to the positive terminal of the battery, the source is connected to one end of the sampling resistor R58, and the other end of the sampling resistor R58 is connected to ground. In addition, to detect the battery output current, the MCU outputs a high level to the base of Q31, turning on Q31, which in turn turns on Q23 (HL2301AP-MOS), which in turn drives Q24 (high-power N-MOS), allowing a large current to flow from B+ to the load side. This current flows through the sampling resistor R58, creating a small voltage drop across it. This voltage drop is sampled by pin 6 (PA6) of the MCU U11, thus accurately identifying the current discharge current. During the entire discharge period, the MCU controls four LEDs (LED2-LED5) to light up via ports PA0-PA3, based on the current magnitude. Different numbers of LEDs lit indicate battery capacity or load current levels; for example, one lit LED represents 25% capacity, and four lit LEDs represent the full capacity. A lit indicator shows 100% capacity, allowing users to intuitively understand the discharge status. When users wish to terminate battery power to protect battery life or prevent power loss, they simply need to manually press SW1 three times consecutively. The MCU's internal logic recognizes the shutdown instruction and immediately stops sending high-level signals to the bases of Q26, Q30, and Q31. After Q26 is turned off, the gate voltage of Q25 is pulled up to a high level through the pull-up resistor R1A, causing Q25 to turn off, cutting off the battery power supply path. The MCU itself also loses power and enters a power-off state, simultaneously disconnecting all loops, including voltage detection, discharge control, and the LED display system. The battery is completely isolated from the load, avoiding static leakage current consumption, thereby maximizing the battery's energy storage capacity during dormancy, improving battery life, and effectively saving energy.

[0032] Preferably, MOSFETs Q25, Q20, and Q23 are all P-channel MOSFETs. When the source of a P-channel MOSFET is connected to a high potential (such as the positive terminal of a battery), it conducts when the gate potential is lower than the source potential (forming a negative Vgs), allowing current to flow from the source to the drain. This makes it suitable for power switch control on the high-potential side. It is also simple to drive (simply pull down the gate potential) when a high-potential power supply needs to be quickly switched on or off, and it has a low on-state voltage drop and high reliability in switching mode, making it suitable for power supply startup, voltage detection, and intermediate control paths on the positive terminal side of lithium batteries.

[0033] Preferably, transistors Q26, Q30, and Q31 are all NPN transistors. NPN transistors conduct when a forward voltage is applied to their base (approximately 0.6-0.7V higher than the emitter voltage), and can control a large collector current to flow to the emitter with a small current, serving as a level converter, switch control, and signal isolation device. Their characteristics make them very suitable as a driver stage for pulling the gate low of MOSFETs in this circuit, enabling the MCU to control a large current switching state with a small current logic signal, while also providing good anti-interference capabilities to ensure stable and reliable system operation.

[0034] Preferably, the MOSFET Q24 is an N-channel MOSFET. An N-channel MOSFET conducts when the source is connected to a low potential (e.g., ground) and the gate voltage is higher than a certain threshold (positive Vgs), allowing current to flow from the drain to the source. It has low on-resistance and excellent high current carrying capacity, making it very suitable for applications requiring high-current load control. In this circuit, Q24 serves as the main switch for discharging the battery with a large current to the load, achieving low voltage drop and high-efficiency energy transfer. It also facilitates accurate detection of the discharge current via a sampling resistor R58 connected in series with the source.

[0035] Preferably, the voltage regulator chip U12 is a linear regulator. A linear regulator continuously adjusts the voltage difference between the input and output through internal regulating elements (such as transistors) to maintain a stable output voltage. It features low output noise, fast response, and simple structure. In this circuit, U12 stably steps down the higher voltage from the battery to a standard 5V1 voltage, providing a stable power supply to the MCU and its control circuit. This ensures that the MCU can correctly recognize buttons, control switches, and detect voltage and current. Furthermore, its internal low ripple characteristics enhance the overall system stability and anti-interference performance.

[0036] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A lithium battery discharge management circuit, characterized in that: The device includes a push-button switch SW1, a current-limiting resistor R72, a protection diode D21, a MOSFET Q25, a transistor Q26, an MCU chip U11, and a voltage regulator chip U12. One end of the push-button switch SW1 is connected to the common node of the current-limiting resistor R72 and the protection diode D21, and the other end is connected to ground. One end of the current-limiting resistor R72 is connected to the output terminal of the voltage regulator chip U12, and the other end is connected to the positive terminal of the push-button switch SW1 and the protection diode D21; The positive terminal of the protection diode D21 is connected to the common node of the push-button switch SW1 and the current-limiting resistor R72, and the negative terminal is connected to ground; The source of the MOSFET Q25 is connected to the positive terminal of the battery, the drain is connected to the input terminal of the voltage regulator chip U12, the gate is connected to the common node of the push button switch SW1 and the current limiting resistor R72, and is also connected to the collector of the transistor Q26. The emitter of the transistor Q26 is connected to ground. The power supply terminal of the MCU chip U11 is connected to the output terminal of the voltage regulator chip U12, and one of its IO pins is connected to the base of the transistor Q26.

2. The lithium battery discharge management circuit according to claim 1, characterized in that: It also includes transistor Q30 and MOSFET Q20. The base of transistor Q30 is connected to one of the IO pins of the MCU chip U11, the collector is connected to the MOSFET Q20, and the emitter is connected to ground. The source of the MOSFET Q20 is connected to the positive terminal of the battery, the drain is connected to the input terminal of the MCU chip U11, and the gate is connected to the transistor Q30.

3. The lithium battery discharge management circuit according to claim 2, characterized in that: It also includes MOSFET Q23, MOSFET Q24, transistor Q31, and sampling resistor R58. The base of transistor Q31 is connected to one of the IO pins of the MCU chip U11, the collector is connected to the gate of MOSFET Q23, and the emitter is connected to ground. The source of the MOSFET Q23 is connected to the positive terminal of the battery, and the drain is connected to the gate of the MOSFET Q24. The drain of the MOS transistor Q24 is connected to the positive terminal of the battery, and the source is connected to one end of the sampling resistor R58. The other end of the sampling resistor R58 is connected to ground.

4. The lithium battery discharge management circuit according to claim 3, characterized in that: The MOSFETs Q25, Q20, and Q23 are all P-channel MOSFETs.

5. The lithium battery discharge management circuit according to claim 3, characterized in that: Transistor Q26, transistor Q30, and transistor Q31 are all NPN type transistors.

6. The lithium battery discharge management circuit according to claim 3, characterized in that: The MOSFET Q24 is an N-channel MOSFET.

7. The lithium battery discharge management circuit according to claim 1, characterized in that: The voltage regulator chip U12 is a linear voltage regulator.

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