A compatible dry battery and lithium battery boost-buck circuit structure and flashlight

Abstract

This invention relates to the field of lighting technology and provides a boost / buck circuit structure and flashlight compatible with dry lithium batteries. The circuit structure includes: a power interface, a battery type detection module, a continuity module, a boost module, a buck constant current module, a current sampling module, a control module, and a load interface. The advantages of this application are that the circuit can adaptively switch the power supply path according to the type of battery connected; when a lithium battery is connected, the input power does not need to pass through the boost branch, reducing additional voltage drop and power loss; when a dry battery is connected, the input power can be automatically boosted by the boost module before being delivered to the load; with the help of the current sampling module, control module, and buck constant current module, the load current can be detected and controlled in real time, achieving high efficiency, strong output capability, low component cost, and high current stability.

Description

Technical Field

[0001] This invention belongs to the field of lighting technology, and in particular relates to a step-up / step-down circuit structure compatible with dry cell batteries and lithium batteries, and a flashlight. Background Technology

[0002] Lighting equipment is widely used in outdoor activities, inspection operations, emergency lighting, industrial maintenance, and everyday portable lighting.

[0003] As application scenarios continue to expand, users are placing higher demands on the power supply flexibility of mobile lighting devices. In daily use, users typically prefer rechargeable lithium batteries to achieve higher discharge capacity and better cost-effectiveness; however, in situations where charging is unavailable or in emergencies, users prefer to be able to directly power the devices with ordinary dry cell batteries to improve their emergency applicability and ease of use.

[0004] However, there are significant differences between ordinary dry cell batteries and lithium batteries in terms of output voltage, internal resistance characteristics, and discharge capacity. When using a single, fixed driving method to integrate both dry cell batteries and lithium batteries in the same lighting device, it is often difficult to balance the driving efficiency, output power, and constant current control effect under different battery types.

[0005] In existing technologies, to ensure compatibility with dry cell battery power, a common approach is to first boost the voltage and then drive it directly, or to first boost the voltage and then buck the voltage. The former typically uses a boost circuit to raise the battery output to the operating voltage required by the load, and then uses switching devices for brightness adjustment; the latter adds a buck regulation stage after boosting the voltage to improve the constant current output effect. Other solutions directly use buck-boost chips that automatically switch between boost and buck modes based on changes in the input voltage to adapt to different battery power supply conditions.

[0006] While current mainstream solutions offer some compatibility with different batteries, they still have significant limitations in practical applications. For boost-then-direct-drive and boost-then-buck-then-voltage solutions, the current path typically passes through the boost unit. Even when using lithium batteries, it's difficult to avoid voltage drops and losses from diodes, inductors, and switching devices in the boost circuit, affecting overall efficiency and limiting high-current output. Especially in high-brightness lighting scenarios, the current handling capacity and heat generation characteristics of the boost devices further restrict the flashlight's output power. While using buck-boost chips simplifies control logic, existing chips often struggle to balance compatibility with ordinary single-cell dry cell batteries, achieving high output power, and control costs. Furthermore, component selection is limited, resulting in higher overall costs. In addition, existing driver circuits require dedicated boost chips, buck chips, operational amplifiers, and voltage regulator references to achieve constant current output from the LED. This results in a complex circuit structure with numerous components, increasing manufacturing costs and assembly difficulty, and hindering flashlight miniaturization and reliability improvements.

[0007] Therefore, it can be seen that, given the increasing demands for high efficiency, high current, low cost, and small size in portable lighting products, the existing circuit structures compatible with dry batteries and lithium batteries suffer from problems such as high dependence on dedicated power management chips and their peripheral devices, high cost, complex circuit structure, and difficulty in further miniaturization, and therefore need to be improved. Summary of the Invention

[0008] The purpose of this application is to provide a buck-boost circuit structure compatible with both dry cell batteries and lithium batteries, aiming to solve the problems of existing circuit structures, such as high dependence on dedicated power management chips and their peripheral devices, high cost, complex circuit structure, and difficulty in further miniaturization.

[0009] This application provides a buck-boost circuit structure compatible with both dry cell batteries and lithium batteries, characterized in that the circuit structure includes: Power interface, battery type detection module, continuity module, boost module, buck constant current module, current sampling module, control module, and load interface; The power interface is used to connect dry cell batteries or lithium batteries. The battery type detection module is used to detect the input voltage of the power interface and obtain the battery type detection result based on the input voltage; The first end of the power interface is connected to the power supply node via a parallel switching module and a boost module. The power supply node is connected to the first end of the load interface via the current sampling module. The second end of the load interface is connected to the second end of the power interface via the buck constant current module. When the detection result is a lithium battery, the control module controls the switching module to turn on, so that the electrical energy input from the power interface is delivered to the power supply node through the switching module branch, without passing through the boost module branch. When the test result is a dry cell battery, the control module controls the switching module to turn off, so that the electrical energy input from the power interface is boosted by the boost module and then delivered to the power supply node without passing through the switching module branch. The current sampling module is used to collect real-time current signals flowing through the load interface; The step-down constant current module is used to perform step-down constant current control on the current flowing through the load interface.

[0010] Another objective of this application is to provide a flashlight, the flashlight comprising: The lighting assembly and the buck-boost circuit structure compatible with dry cell batteries and lithium batteries as described above; the lighting assembly is connected to the load interface; The buck-boost circuit structure is used to drive the lighting component.

[0011] This application provides a buck-boost circuit structure compatible with both dry cell batteries and lithium batteries. Its key advantage lies in the collaborative operation of a battery type detection module, a switching module, a boost module, a buck constant current module, and a current sampling module. This allows the circuit to adaptively switch power supply paths based on the type of battery connected. When a lithium battery is connected, the input power is directly delivered to the load side via the switching module branch, avoiding the additional voltage drop and power loss caused by the boost branch, thus improving conversion efficiency and high-current output capability in lithium battery power supply scenarios. When a dry cell battery is connected, the input power is boosted by the boost module before being delivered to the load side, solving the problem of insufficient voltage from a single dry cell battery to drive the load. Simultaneously, the closed-loop regulation formed by the current sampling module, control module, and buck constant current module enables real-time detection and constant current control of the load current. This allows the same circuit to achieve high efficiency, strong output capability, low component cost, and good current stability while being compatible with both dry cell and lithium battery power supply methods. Attached Figure Description

[0012] Figure 1 A module connection block diagram of a buck-boost circuit structure compatible with dry cell batteries and lithium batteries provided in this application embodiment; Figure 2 A circuit diagram of a buck-boost circuit structure compatible with dry cell batteries and lithium batteries is provided for embodiments of this application. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0014] It is understood that the terms "first," "second," etc., used in this application may be used herein to describe various elements, but unless otherwise specified, these elements are not limited by these terms. These terms are only used to distinguish one unit or module from another. For example, without departing from the scope of this application, a first terminal may be referred to as a second terminal, and similarly, a second module may be referred to as a first module. It is understood that, because a power interface has positive and negative terminals, the positive terminal may be named the first terminal and the negative terminal the second terminal; alternatively, the negative terminal may be named the first terminal and the positive terminal the second terminal.

[0015] Figure 1 A module connection block diagram of a buck-boost circuit structure compatible with dry cell batteries and lithium batteries provided in this application embodiment is shown below. Figure 1 As shown, the circuit structure includes at least: Power interface, battery type detection module, continuity module, boost module, buck constant current module, current sampling module, control module, and load interface; The power interface is used to connect dry cell batteries or lithium batteries. The battery type detection module is used to detect the input voltage of the power interface and obtain the battery type detection result based on the input voltage; The first end of the power interface is connected to the power supply node via a parallel switching module and a boost module. The power supply node is connected to the first end of the load interface via the current sampling module. The second end of the load interface is connected to the second end of the power interface via the buck constant current module. When the detection result is a lithium battery, the control module controls the switching module to turn on, so that the electrical energy input from the power interface is delivered to the power supply node through the switching module branch, without passing through the boost module branch. When the test result is a dry cell battery, the control module controls the switching module to turn off, so that the electrical energy input from the power interface is boosted by the boost module and then delivered to the power supply node without passing through the switching module branch. The current sampling module is used to collect real-time current signals flowing through the load interface; The step-down constant current module is used to perform step-down constant current control on the current flowing through the load interface.

[0016] Those skilled in the art will know that asynchronous boost circuits include diodes and inductors. Diodes cause a voltage drop of 0.3V to 0.5V, and the voltage drop increases with the current. However, since the LED voltage is only 3.7~3.5V, the voltage drop can reach 10~20%. Inductors typically introduce resistance of tens of milliohms, and for every 1A increase in current, the voltage drop increases by tens of millivolts, further reducing voltage and efficiency. Currently, mainstream synchronous boost chips compatible with dry-cell batteries can only handle around 3A of current, such as the TPS61021, but cost over two yuan, limiting current handling when using lithium batteries and increasing cost. Dry-cell batteries are for emergency use, while lithium batteries are the primary application, where performance is more critical. This solution introduces a low-cost switching transistor for path switching, avoiding the voltage drop of inductors and diodes, and is cost-effective. For example, the GTMQ1833A PMOS transistor used in this application costs only 0.27 yuan and has an internal resistance of only a few milliohms. The NMOS used for level control of the PMOS can be a very low-cost signal NMOS. Therefore, a lower-cost, more configurable MCU (Microcontroller Unit) buck-boost constant current output circuit is achieved. This application can directly use an MCU as the control module, replacing the high-cost DC-DC converter chip. It can use low-resistance MOSFETs to achieve a stronger current output capability than most buck converter chips. The output capability of highly integrated buck power management chips depends on the performance of the internally integrated MOSFETs, and high-power buck converter chips are relatively expensive due to their small shipment volume, which prevents economies of scale. This application simplifies the circuit structure, reduces the number of components, and utilizes a current-sensing amplifier for high-side sampling, allowing the use of more cost-effective buck switching NMOS at the low end, eliminating the need for complex high-side drive circuitry. Currently, circuits using both boost and buck converter chips also require an MCU controller, so this application has a significant cost advantage.

[0017] Those skilled in the art will recognize that in existing technologies, the current flows through the boost circuit first, regardless of whether a dry cell battery or a lithium battery is used. Synchronous boost chips supporting dry cell batteries are expensive and have limited current handling capacity. Asynchronous boost circuits, due to the large voltage drop caused by diodes, affect efficiency when using lithium batteries, and their power output is limited to approximately 5-10W. For buck-boost solutions, there are no commercially available chips supporting ordinary single dry cell batteries; they are mostly used with CR123A or two ordinary 1.5V dry cell batteries. Buck-boost chips are even more expensive, have limited current handling capacity, and their power output is also limited to approximately 5-10W. In existing technologies, to achieve constant current, a buck chip, a boost chip, and an operational amplifier are often introduced, increasing costs. Additionally, a voltage regulator chip is needed before the MCU controller to provide a stable voltage reference, further increasing costs.

[0018] In this embodiment, an MCU can be used to directly control the switching transistor instead of a buck converter chip, reducing costs while allowing for greater freedom in achieving lower internal resistance and higher efficiency, thus increasing operating current. It also requires fewer components, offers higher reliability, and allows for a smaller size. Furthermore, it allows for higher power outputs, such as power control for a 20W load.

[0019] In this embodiment, the current sampling module is primarily used to acquire the actual state of the load current, forming a basis for closed-loop control. Connected to the load path, it collects the current information flowing through the LED load and outputs the corresponding sampling signal to the control module. The control module determines whether the current output current has reached the target value based on the sampling signal, and further adjusts the duty cycle of the buck constant current module, and, if necessary, adjusts the working state of the boost module. The core functions of the current sampling module include: providing current feedback signals to the control module; and providing a basis for control decisions during constant current control, brightness adjustment, and mode switching. For example, by sampling the current information on the resistor, amplifying it, and sending it to the MCU, the MCU can adjust the PWM control according to the feedback result to achieve constant current output. The buck constant current module can regulate the current flowing through the load in the subsequent drive path, enabling the load to obtain a stable target current output. It can be located on the load return path, with one end connected to the load and the other end connected to the loop ground, receiving control signals output by the control module. This module can control the average current in the load branch through switching adjustment, allowing the LED to maintain a relatively stable brightness and working state under different battery power supply conditions. Therefore, the functions of the buck constant current module include, but are not limited to: receiving power from the direct power supply path or the boost output path of the preceding stage; regulating the load current; and achieving constant current drive with the cooperation of the current sampling module feedback signal. In this application, whether it is a direct buck after buck in lithium battery mode or a boost and then buck in dry battery mode, the module is ultimately responsible for the precise control of the LED current. When the input power supply is a dry battery, the boost module can first boost the lower input voltage to a voltage level sufficient to drive the load, providing the necessary voltage margin for the subsequent constant current regulation. It is located in the forward power supply path, connected to the path switching module at the front end and connected to the load forward power supply path at the rear end. In dry battery mode, the input voltage is usually insufficient to directly drive the LED, so the boost module needs to boost the input power before sending the boosted energy to the subsequent stage; while in lithium battery mode, due to the higher input voltage and power supply capacity, the path switching module will establish a direct path bypassing the boost module, at which point the boost module no longer plays the role of the main power supply. The core functions of the boost module include, but are not limited to: boosting voltage under low input conditions; providing sufficient input voltage for the subsequent buck constant current module; and acting as the main power supply stage in dry battery mode. The buck constant current module can directly acquire a real-time current signal to perform buck-constant current control on the current flowing through the load interface, or it can indirectly perform buck-constant current control on the current flowing through the load interface based on a real-time current signal via a control module. Preferably, the indirect control method via a control module reduces the number of circuit components, simplifies the structure, and lowers costs.

[0020] As an embodiment of this application, and as an example, the battery type determination method can be as follows: upon power-up, the battery voltage is detected; if it is higher than 3.35V, it is treated as a lithium battery; otherwise, it is treated as a dry cell battery. A PMOS transistor is used for path switching. In the dry cell battery scenario, a boost-then-buck circuit is switched on: the PMOS is turned off to prevent the boosted voltage from flowing back into the dry cell battery; in the lithium battery scenario, a direct buck circuit is switched on: the PMOS is turned on, as its internal resistance is very low when it is conducting, and the boost circuit is turned off. The control module reads the signal from the current sensing amplifier as feedback to adjust the duty cycle of the output PWM to achieve constant current.

[0021] In a preferred embodiment, the current sampling module is connected to the control module and is used to send the real-time current signal to the control module; The control module is connected to the step-down constant current module and is used to control the working state of the step-down constant current module based on the real-time current signal, generate a constant current control signal, and input the constant current control signal to the step-down constant current module to step down and constant current the current flowing through the load interface to a preset current value.

[0022] In this embodiment, the current sampling module, control module, and buck constant current module constitute a constant current control. Specifically, the current sampling module samples the actual operating current in the load branch in real time and feeds back the sampled real-time current signal to the control module. The control module generates a corresponding constant current control signal based on the deviation between the real-time current signal and the target current value, and outputs the constant current control signal to the buck constant current module to adjust the conduction state, conduction duration, or duty cycle of the switching devices in the buck constant current module, thereby dynamically adjusting the output current flowing through the load interface. Through the above control method, the current flowing through the load can be stably controlled near a preset current value even when the input battery voltage fluctuates, the load state changes, or the power supply mode switches, ensuring the stability of the output brightness of the lighting load.

[0023] In a preferred embodiment, the switching module includes a switching PMOS and a logic control switching device; The first terminal of the switching PMOS is connected to the first end of the power interface, and the second terminal of the switching PMOS is connected to the power supply node. The control terminal of the logic control switching device is connected to the control module, and the output terminal is connected to the control terminal of the switching PMOS. It is used to change the conduction state of the switching PMOS under the control of the control module to connect or disconnect the on / off module branch.

[0024] The switching module is used to switch the main power supply path between lithium battery operating mode and dry cell battery operating mode. A switching PMOS is located on the positive power supply path, with its first terminal connected to the first end of the power interface and its second terminal connected to the positive power supply path on the load side. A logic control switch is used to respond to the control signal output by the control module, changing the potential state of the switching PMOS control terminal to control the switching PMOS to turn on or off. When the control module determines that the currently connected battery is a lithium battery based on the battery type detection result, it controls the logic control switch to turn on the switching PMOS, establishing a direct power supply path from the first end of the power interface through the switching module branch to the first end of the load interface, allowing the input power to be directly delivered to the subsequent load branch without passing through the boost module branch. When the control module determines that the currently connected battery is a dry cell battery, it controls the logic control switch to turn off the switching PMOS, cutting off the direct power supply path, causing the input power to be delivered to the load interface via the boost module branch. This structural design reduces additional losses during voltage boosting in lithium battery scenarios and retains the necessary voltage boosting capability in dry cell battery scenarios.

[0025] In a preferred embodiment, the boost module includes a boost inductor, a boost freewheeling diode, a boost switching device, an input filter capacitor, and an output filter capacitor; The input filter capacitor is connected between the first end of the power interface and the second end of the power interface; One end of the boost inductor is connected to the first end of the power interface, and the other end of the boost inductor is connected to the boost switch node; The first terminal of the boost switching device is connected to the boost switching node, the second terminal is connected to the second end of the power interface, and the control terminal is connected to the control module. The first terminal of the boost freewheeling diode is connected to the boost switching node, and the second terminal is connected to the power supply node; The output filter capacitor is connected between the power supply node and the second end of the power interface; The power supply node is connected to the first end of the load interface via the current sampling module, so as to deliver the boosted electrical energy to the load interface when the switching module is turned off.

[0026] In this embodiment, the boost module is used to boost the input voltage in dry battery power mode to meet the voltage requirements of the load. The input filter capacitor filters the original voltage input from the power interface, suppressing input-side ripple and noise; the boost inductor stores and releases energy during the periodic on / off cycles of the boost switching device; the boost switching device switches periodically under the control of the control module, causing the boost switching node to form a corresponding switching waveform; the boost freewheeling diode directs the energy released by the boost inductor to the power supply node during the off-cycle of the boost switching device; the output filter capacitor filters and smooths the boost output at the power supply node to form a relatively stable boost voltage output. When the switching module is off, the electrical energy input from the power interface reaches the power supply node via the boost module branch, and is then delivered to the load interface via the subsequent load power supply path, providing sufficient driving voltage to the lighting load even when the dry battery voltage is low.

[0027] In a preferred embodiment, the current sampling module includes a current sampling resistor and a current detection amplifier; The current sampling resistor is connected in series between the power supply node and the first end of the load interface; The input terminals of the current sensing amplifier are connected to both ends of the current sampling resistor, and the output terminal is connected to the control module. It is used to detect and amplify the current signal flowing through the current sampling resistor and then feed it back to the control module.

[0028] In this embodiment, the current sampling module uses a combination of a sampling resistor and a current sensing amplifier to detect the load current. The current sampling resistor is connected in series in the main power supply path of the load, so that the operating current flowing through the load interface flows synchronously through the current sampling resistor, forming a voltage signal corresponding to the actual current magnitude across the sampling resistor. The current sensing amplifier is connected across the current sampling resistor to detect, amplify, and process the voltage signal before outputting it to the control module. The control module determines the real-time current magnitude flowing through the load based on the received amplified current signal and uses this as the basis for subsequently adjusting the operating state of the buck constant current module. Through this method, high-sensitivity detection and feedback of the output current can be achieved without significantly increasing power loss.

[0029] In a preferred embodiment, when the detection result is a dry cell battery, the control module controls the buck constant current module to first perform constant current adjustment based on the real-time current signal; when the control duty cycle of the buck constant current module reaches the preset upper limit and the current flowing through the load interface still does not reach the preset current value, the control module is controlled to start working to increase the voltage delivered to the power supply node.

[0030] In dry battery mode, the control module preferentially adjusts the load current first through a buck constant current module. If, as load demand increases or battery voltage decreases, the buck constant current module's duty cycle reaches its preset upper limit while the output current still fails to reach the target value, it indicates that the current input voltage is insufficient to maintain the required constant current output. In this case, the control module activates the boost module, boosting the input power before it is delivered to the power supply node, thereby increasing the available voltage of the subsequent stage and ensuring that the output current at the load interface continues to reach the preset current value. By first implementing buck constant current and then activating boost as needed, the control method can balance output stability and system efficiency.

[0031] In a preferred embodiment, the step-down constant current module includes a third switching transistor, an energy storage inductor, a freewheeling diode, and a filter capacitor; The second end of the load interface is connected to one end of the energy storage inductor, and the other end of the energy storage inductor is connected to the switching node; The first terminal of the third switching transistor is connected to the switching node, the second terminal is connected to the second end of the power interface, and the control terminal is connected to the control module. The freewheeling diode is connected between the switching node and the first end of the load interface; The filter capacitor is connected between the first end of the load interface and the second end of the load interface; The control module controls the conduction state of the third switching transistor to reduce the voltage and maintain a constant current for the current flowing through the load interface.

[0032] In this embodiment, the step-down constant current module is used to further regulate the current in the load branch based on the on / off or boost power supply of the preceding stage, so as to keep the current flowing through the lighting load stable. The energy storage inductor is used to store and release energy during the periodic on and off of the third switch; the third switch performs switching action under the constant current control signal output by the control module to adjust the working state at the switching node; the freewheeling diode provides a freewheeling path for the energy storage inductor to release energy during the off-state of the third switch; the filter capacitor smooths the voltage and current fluctuations across the load to further improve output stability. The control module dynamically adjusts the on-state of the third switch or controls the duty cycle based on the real-time current signal fed back by the current sampling module, regulating the energy storage and release process of the energy storage inductor, ultimately achieving step-down constant current control of the current flowing through the load interface.

[0033] In a preferred embodiment, the battery type detection module includes a voltage detection branch, which is connected between the first end of the power interface and the second end of the power interface, and the output end is connected to the control module. The control module is used to compare the input voltage detected by the voltage detection branch with a preset threshold to obtain the detection result of the battery type; When the input voltage is higher than the preset threshold, it is determined to be a lithium battery, and the on / off module is controlled to be turned on. When the input voltage is not higher than the preset threshold, it is determined to be a dry cell battery, and the on / off module is controlled to turn off.

[0034] In this embodiment, the battery type detection module distinguishes the type of battery currently connected by detecting the voltage value at the power interface input terminal. The voltage detection branch can use a voltage divider sampling method to convert the input voltage at both ends of the power interface into a detection signal suitable for sampling and recognition by the control module, and output the detection signal to the control module. The control module compares the detected input voltage with a preset threshold. When the input voltage is detected to be higher than the preset threshold, it determines that the currently connected battery is a lithium battery and controls the switching module to turn on to establish a direct power supply path for the lithium battery; when the input voltage is detected to be lower than the preset threshold, it determines that the currently connected battery is a dry cell battery and controls the switching module to turn off, so that the input power is supplied to the load through the boost module branch.

[0035] In a preferred embodiment, the circuit structure further includes: an auxiliary power supply module; The auxiliary power supply module is connected between the power interface and the control module, and is used to convert the voltage input by the power interface into a power supply voltage suitable for the operation of the control module; The auxiliary power supply module includes a voltage conversion chip, a second inductor, and a second filter capacitor; One end of the second inductor is connected to the first end of the power interface, and the other end is connected to the switching terminal of the voltage conversion chip; The ground terminal of the voltage conversion chip is connected to the second terminal of the power interface, and the output terminal is connected to the power supply pin of the control module. The second filter capacitor is connected between the output terminal of the voltage conversion chip and the second terminal of the power interface.

[0036] In this embodiment, the auxiliary power supply module provides an independent and stable operating voltage for the control module, ensuring its normal operation under different battery input conditions. The raw voltage input from the power interface is first fed to a voltage conversion chip, where a second inductor completes the voltage conversion process, resulting in a suitable power supply voltage for the control module at the output. A second filter capacitor is connected between the output of the voltage conversion chip and the second terminal of the power interface to filter and smooth the output voltage, reducing ripple and transient fluctuations, and providing a relatively stable power supply for the control module. By setting up the auxiliary power supply module, the control module can be prevented from being directly affected by main power path switching, input voltage fluctuations, or low battery voltage.

[0037] In a preferred embodiment, such as Figure 2 The diagram shows a step-up / step-down circuit structure compatible with both dry cell and lithium batteries. The entire circuit uses battery B1 as the input power source, with the positive terminal of B1 connected to the positive input bus and the negative terminal grounded. The positive input bus is connected to the voltage detection branch, the on / off module branch, and the step-up module branch. In the on / off module, the first terminal of a PMOS transistor is connected to the positive input bus, and the second terminal is connected to the power supply node. The output of the step-up module is also connected to the power supply node. The power supply node is connected to the positive terminal of an LED via a current sampling module. The negative terminal of the LED is connected to ground via a step-down constant current module. The current sampling module includes a current sampling resistor connected in series between the power supply node and the positive terminal of the LED, and a current detection amplifier connected across the current sampling resistor. The output of the current detection amplifier is connected to the ADC sampling pin of the MCU microcontroller. The buck constant current module includes a buck switching device, an energy storage inductor, a freewheeling diode, and a filter capacitor. The PWM output pin of the MCU microcontroller is connected to the control terminal of the buck switching device and the control terminal of the logic control switching device, which are used to control the buck constant current module and the on / off module respectively.

[0038] After the circuit is powered on, the MCU microcontroller reads the battery voltage through the voltage detection branch. If the voltage is higher than a preset threshold, it is determined to be a lithium battery. The control logic controls the switching device to turn on the on / off module, allowing the input power to be delivered to the power supply node via the on / off module branch and then to the positive terminal of the LED bead via the current sampling module. If the voltage is not higher than the preset threshold, it is determined to be a dry cell battery. The control logic controls the switching device to turn off the on / off module and simultaneously controls the boost module to operate, allowing the input power to be boosted before being delivered to the power supply node and then to the positive terminal of the LED bead via the current sampling module. The MCU microcontroller adjusts the control signal of the buck constant current module based on the real-time current signal fed back from the current detection amplifier to achieve constant current drive for the LED bead.

[0039] In a preferred embodiment, a flashlight is provided, the flashlight comprising: The lighting assembly and the buck-boost circuit structure compatible with dry cell batteries and lithium batteries as described above; the lighting assembly is connected to the load interface; The buck-boost circuit structure is used to drive the lighting component.

[0040] In this embodiment, the flashlight integrates the aforementioned buck-boost circuit structure, compatible with both dry cell and lithium batteries, into a portable lighting product. The lighting component is connected to the load interface as a load, and the buck-boost circuit structure automatically switches its operating mode according to the type of battery connected to the flashlight. When a lithium battery is connected, the buck-boost circuit structure establishes a direct power supply path, enabling efficient delivery of input power to the lighting component, and works in conjunction with a buck constant current module to stably control the operating current of the lighting component. When a dry cell battery is connected, the buck-boost circuit structure activates the boost module, increasing the lower input voltage before delivering it to the lighting component, again working in conjunction with a buck constant current module to achieve stable drive. Thus, the flashlight is compatible with different types of batteries and maintains relatively stable lighting output under different power supply conditions, improving the product's flexibility, adaptability, and practical value.

[0041] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A buck-boost circuit structure compatible with both dry cell batteries and lithium batteries, characterized in that, The circuit structure includes: Power interface, battery type detection module, continuity module, boost module, buck constant current module, current sampling module, control module, and load interface; The power interface is used to connect dry cell batteries or lithium batteries. The battery type detection module is used to detect the input voltage of the power interface and obtain the detection result of the battery type based on the input voltage; The first end of the power interface is connected to the power supply node via a parallel switching module and a boost module. The power supply node is connected to the first end of the load interface via the current sampling module. The second end of the load interface is connected to the second end of the power interface via the buck constant current module. When the detection result is a lithium battery, the control module controls the switching module to turn on, so that the electrical energy input from the power interface is delivered to the power supply node through the switching module branch, without passing through the boost module branch. When the test result is a dry cell battery, the control module controls the switching module to turn off, so that the electrical energy input from the power interface is boosted by the boost module and then delivered to the power supply node without passing through the switching module branch. The current sampling module is used to collect real-time current signals flowing through the load interface; The step-down constant current module is used to perform step-down constant current control on the current flowing through the load interface.

2. The buck-boost circuit structure compatible with both dry cell batteries and lithium batteries according to claim 1, characterized in that, The current sampling module is connected to the control module and is used to send the real-time current signal to the control module; The control module is connected to the step-down constant current module and is used to control the working state of the step-down constant current module based on the real-time current signal, generate a constant current control signal, and input the constant current control signal to the step-down constant current module to step down and constant current the current flowing through the load interface to a preset current value.

3. The step-up / step-down circuit structure compatible with dry cell batteries and lithium batteries according to claim 1, characterized in that, The switching module includes a switching PMOS and a logic control switching device; The first terminal of the switching PMOS is connected to the first end of the power interface, and the second terminal of the switching PMOS is connected to the power supply node. The control terminal of the logic control switching device is connected to the control module, and the output terminal is connected to the control terminal of the switching PMOS. It is used to change the conduction state of the switching PMOS under the control of the control module to connect or disconnect the on / off module branch.

4. The step-up / step-down circuit structure compatible with both dry cell batteries and lithium batteries according to claim 1, characterized in that, The boost module includes a boost inductor, a boost freewheeling diode, a boost switching device, an input filter capacitor, and an output filter capacitor; The input filter capacitor is connected between the first end of the power interface and the second end of the power interface; One end of the boost inductor is connected to the first end of the power interface, and the other end of the boost inductor is connected to the boost switch node; The first terminal of the boost switching device is connected to the boost switching node, the second terminal is connected to the second end of the power interface, and the control terminal is connected to the control module. The first terminal of the boost freewheeling diode is connected to the boost switching node, and the second terminal is connected to the power supply node; The output filter capacitor is connected between the power supply node and the second end of the power interface; The power supply node is connected to the first end of the load interface via the current sampling module, so as to deliver the boosted electrical energy to the load interface when the switching module is turned off.

5. The step-up / step-down circuit structure compatible with dry cell batteries and lithium batteries according to claim 1, characterized in that, The current sampling module includes a current sampling resistor and a current detection amplifier; The current sampling resistor is connected in series between the power supply node and the first end of the load interface; The input terminals of the current sensing amplifier are connected to both ends of the current sampling resistor, and the output terminal is connected to the control module. It is used to detect and amplify the current signal flowing through the current sampling resistor and then feed it back to the control module.

6. The buck-boost circuit structure compatible with dry cell batteries and lithium batteries according to claim 2, characterized in that, When the test result is a dry cell battery, the control module controls the buck constant current module to perform constant current adjustment based on the real-time current signal; when the control duty cycle of the buck constant current module reaches the preset upper limit and the current flowing through the load interface still does not reach the preset current value, the boost module is controlled to start working to increase the voltage delivered to the power supply node.

7. The buck-boost circuit structure compatible with dry cell batteries and lithium batteries according to claim 1, characterized in that, The step-down constant current module includes a third switching transistor, an energy storage inductor, a freewheeling diode, and a filter capacitor; The second end of the load interface is connected to one end of the energy storage inductor, and the other end of the energy storage inductor is connected to the switching node; The first terminal of the third switching transistor is connected to the switching node, the second terminal is connected to the second end of the power interface, and the control terminal is connected to the control module. The freewheeling diode is connected between the switching node and the first end of the load interface; The filter capacitor is connected between the first end of the load interface and the second end of the load interface; The control module controls the conduction state of the third switching transistor to reduce the voltage and maintain a constant current for the current flowing through the load interface.

8. The step-up / step-down circuit structure compatible with dry cell batteries and lithium batteries according to claim 1, characterized in that, The battery type detection module includes a voltage detection branch, which is connected between the first end of the power interface and the second end of the power interface, and the output end is connected to the control module. The control module is used to compare the input voltage detected by the voltage detection branch with a preset threshold to obtain the detection result of the battery type; When the input voltage is higher than the preset threshold, it is determined to be a lithium battery, and the on / off module is controlled to be turned on. When the input voltage is not higher than the preset threshold, it is determined to be a dry cell battery, and the on / off module is controlled to turn off.

9. The step-up / step-down circuit structure compatible with dry cell batteries and lithium batteries according to claim 1, characterized in that, The circuit structure also includes: an auxiliary power supply module; The auxiliary power supply module is connected between the power interface and the control module, and is used to convert the voltage input by the power interface into a power supply voltage suitable for the operation of the control module; The auxiliary power supply module includes a voltage conversion chip, a second inductor, and a second filter capacitor; One end of the second inductor is connected to the first end of the power interface, and the other end is connected to the switching terminal of the voltage conversion chip; The ground terminal of the voltage conversion chip is connected to the second terminal of the power interface, and the output terminal is connected to the power supply pin of the control module. The second filter capacitor is connected between the output terminal of the voltage conversion chip and the second terminal of the power interface.

10. A flashlight, characterized in that, The flashlight includes: The lighting assembly and the buck-boost circuit structure compatible with dry cell batteries and lithium batteries as described in any one of claims 1 to 9; the lighting assembly is connected to the load interface; The buck-boost circuit structure is used to drive the lighting component.

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