Voltage detection circuit, method and device for internal lithium cell in lithium conversion dry cell

Abstract

This application discloses a voltage detection circuit, method, and apparatus for the internal lithium battery in a lithium-to-dry-cell battery. The circuit includes a controller, a charging circuit, and a current detection circuit. The controller is electrically connected to both the charging circuit and the current detection circuit. The charging circuit is electrically connected to the current detection circuit, which is connected to the positive terminal of the lithium-to-dry-cell battery's power source. The current detection circuit detects the current flowing through the battery in real time. The controller obtains the corresponding detection value from the current detection circuit and uses this value to adjust the charging voltage output by the charging circuit until the charging voltage is adjusted to be equal to or close to the actual voltage of the internal lithium battery. Based on this application, by detecting the change in current direction between the external circuit and the battery during the transition between the discharge and charging states of the lithium-to-dry-cell battery, the voltage of the internal lithium battery can be accurately determined. This is beneficial for real-time monitoring of the actual charge state of the lithium battery, predicting remaining operating time, and monitoring and managing battery health and lifespan.

Description

Technical Field

[0001] This application relates to the field of lithium battery testing technology, and in particular to a voltage detection circuit, method and apparatus for the internal lithium battery in a lithium-to-dry cell battery. Background Technology

[0002] With the increasing demand for portability in electronic devices and growing environmental awareness, rechargeable lithium batteries are gradually replacing traditional disposable dry cell batteries. Therefore, lithium-to-dry cell batteries have emerged, which convert lithium batteries into dry cell batteries for use. In this application, these are referred to as lithium-to-dry cell batteries. The terms "this type of battery" and "this type of battery" in this application specifically refer to lithium-to-dry cell batteries to distinguish them from ordinary dry cell batteries.

[0003] However, the operating voltage of ordinary dry cell batteries is 1.5V, while the nominal voltage of ordinary lithium batteries is 3.7V. This significant voltage difference prevents ordinary lithium batteries from being directly used in electronic products powered by ordinary dry cell batteries. To address this, the industry has developed conversion circuits and chips to convert the voltage of ordinary lithium batteries to the operating voltage of ordinary dry cell batteries. This voltage conversion allows ordinary lithium batteries to replace ordinary dry cell batteries in products powered by them.

[0004] However, this type of solution has a key technical flaw: the external application of lithium-to-dry-cell batteries is equivalent to that of ordinary dry-cell batteries, outputting the operating voltage range (0-1.5V) of ordinary dry-cell batteries. Voltage monitoring during use can only detect this voltage range, and cannot obtain the true voltage state of the internal lithium battery. Here, to distinguish it from ordinary lithium batteries, the lithium battery in the lithium-to-dry-cell battery is referred to as the internal lithium battery. When the lithium-to-dry-cell battery outputs 1.5V, it can only be inferred that the internal lithium battery is still usable, but the actual voltage value is unclear; when the lithium-to-dry-cell battery outputs 0V, it indicates that the internal lithium battery voltage is low. This indirect and vague voltage information about the internal lithium battery severely restricts the user's accurate judgment of the lithium-to-dry-cell battery's state, leading to the following problems: first, it is impossible to grasp the actual charge state of the internal lithium battery in real time; second, it is difficult to predict the remaining working time of the lithium-to-dry-cell battery; third, it is not conducive to the health monitoring and lifespan management of the lithium-to-dry-cell battery; and fourth, it affects the user experience and the efficiency of the lithium-to-dry-cell battery. Summary of the Invention

[0005] The main technical problem addressed by this application is to provide a voltage detection circuit, method, and apparatus for the internal lithium battery in a lithium-to-dry battery, so as to solve the problem of accurate detection of the internal lithium battery voltage.

[0006] To solve the above-mentioned technical problems, one technical solution adopted in this application is to provide a voltage detection circuit for the internal lithium battery in a lithium-to-dry battery, including: a controller, a charging circuit, and a current detection circuit; the controller is electrically connected to the charging circuit and the current detection circuit respectively, the charging circuit is electrically connected to the current detection circuit, and the current detection circuit is used to electrically connect to the positive terminal of the power supply of the lithium-to-dry battery; the current detection circuit detects the current flowing through it in real time, the controller obtains the detection value corresponding to the current detection circuit, and uses the detection value to adjust the charging voltage output by the charging circuit until the charging voltage is adjusted to be equal to or close to the actual voltage of the internal lithium battery.

[0007] In some embodiments, the charging circuit includes a controlled switch, the input terminal of which is electrically connected to a DC power supply, the output terminal of which is electrically connected to the current detection circuit, and the control terminal of which is electrically connected to the controller. The controller controls the on and off time ratios of the controlled switch to adjust the voltage output from the output terminal to the current detection circuit accordingly.

[0008] In some embodiments, the current detection circuit includes a sampling resistor, the two ends of which are respectively used to electrically connect the output terminal of the charging circuit and the output terminal of the lithium-to-dry battery; the two ends of the sampling resistor are also electrically connected to two differential voltage acquisition terminals of a differential amplifier circuit, used to acquire the voltage across the sampling resistor, and the digital signal amplified by the differential amplifier circuit and converted from analog to digital as the detection value, which is then input to the controller.

[0009] In some embodiments, the differential amplifier circuit includes a differential amplifier, which includes a positive input pin and a negative input pin, corresponding to two differential voltage acquisition terminals of the differential amplifier circuit, and is electrically connected to both ends of the sampling resistor; the differential amplifier also includes a voltage reference pin and an output pin, the voltage reference pin is electrically connected to a bias circuit, the output pin is electrically connected to the controller, and the output pin outputs a digital signal after analog-to-digital conversion to the controller.

[0010] In some embodiments, the bias circuit includes a fifth resistor, a sixth resistor, a seventh resistor, a voltage regulator, and a second capacitor. The first terminal of the fifth resistor is connected to a second DC power supply, and the second terminal is connected to the voltage reference pin of the differential amplifier. The second terminal of the fifth resistor is also electrically connected to the first terminal of the sixth resistor, the first terminal of the second capacitor, and the cathode of the voltage regulator. The anode of the voltage regulator is grounded. The reference terminal of the voltage regulator is connected to the second terminal of the sixth resistor. The second terminal of the sixth resistor is also electrically connected to the first terminal of the seventh resistor. The second terminal of the seventh resistor is grounded. The power supply pin of the differential amplifier is electrically connected to the second DC power supply.

[0011] In some embodiments, the voltage across the sampling resistor is zero, and the detected value corresponds to the analog-to-digital conversion value of the bias voltage. In this case, the output voltage of the charging circuit is equal to or close to the actual voltage of the internal lithium battery.

[0012] This application also provides a method for detecting the voltage of the internal lithium battery in a lithium-to-dry battery, comprising: sequentially connecting a detection circuit and a charging circuit to the output pin of the lithium-to-dry battery; adjusting the output voltage of the charging circuit to correspondingly acquire the detection value of the detection circuit; if the detection value is equal to a preset condition, then the current output voltage of the charging circuit is equal to the current actual voltage of the internal lithium battery.

[0013] In some embodiments, the detection circuit includes a sampling resistor connected in series between the output pin of the lithium-to-dry battery and the charging circuit. The detection value collected by the detection circuit includes the voltage difference across the sampling resistor. The preset condition is that the voltage difference is zero.

[0014] In some embodiments, regulating the output voltage of the charging circuit includes regulating the output voltage from high to low, with the current flowing through the sampling resistor flowing from the charging circuit to the output pin of the lithium-to-dry battery, and the voltage difference gradually decreasing until it becomes zero; or, regulating the output voltage of the charging circuit includes regulating the output voltage from low to high, with the current flowing through the sampling resistor flowing from the output pin of the lithium-to-dry battery to the charging circuit, and the voltage difference gradually decreasing until it becomes zero.

[0015] This application also provides an electronic device, including the aforementioned voltage detection circuit for the internal lithium battery in a lithium-to-dry cell.

[0016] The beneficial effects of this application are as follows: This application discloses a voltage detection circuit, method, and apparatus for the internal lithium battery in a lithium-to-dry battery. The circuit includes a controller, a charging circuit, and a current detection circuit. The controller is electrically connected to both the charging circuit and the current detection circuit. The charging circuit is electrically connected to the current detection circuit, which is connected to the positive terminal of the lithium-to-dry battery. The current detection circuit detects the current flowing through the battery in real time. The controller obtains the detection value corresponding to the current detection circuit and uses this detection value to adjust the charging voltage output by the charging circuit until the charging voltage is adjusted to be equal to or close to the actual voltage of the internal lithium battery. Based on this application, by detecting the change in the current direction between the external circuit and the battery when the lithium-to-dry battery transitions between the discharge and charging states, the voltage of the internal lithium battery can be accurately determined. This is beneficial for real-time monitoring of the actual charge state of the lithium battery, prediction of remaining working time, and monitoring and lifespan management of the battery's health status. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the circuit composition of an embodiment of the voltage detection circuit of the internal lithium battery in a lithium-to-dry battery according to this application. Figure 2 This is a schematic diagram of the conversion circuit in one embodiment of the voltage detection circuit of the internal lithium battery in the lithium-to-dry battery of this application; Figure 3 This is a schematic diagram of the conversion circuit in one embodiment of the voltage detection circuit of the internal lithium battery in the lithium-to-dry battery of this application; Figure 4 This is a schematic diagram of the charging circuit composition of another embodiment of the voltage detection circuit of the internal lithium battery in the lithium-to-dry battery of this application. Figure 5 This is a schematic diagram of the current detection circuit in one embodiment of the voltage detection circuit of the internal lithium battery in a lithium-to-dry battery according to this application. Figure 6 This is a schematic diagram of the current detection circuit in one embodiment of the voltage detection circuit of the internal lithium battery in a lithium-to-dry battery according to this application. Figure 7 This is a flowchart illustrating the voltage detection method for the internal lithium battery in a lithium-to-dry cell according to this application. Detailed Implementation

[0018] To facilitate understanding of this application, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0019] It should be noted that, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0020] The following is a detailed description with reference to specific examples. Figure 1 The diagram shows a schematic of an embodiment of the voltage detection circuit of the internal lithium battery in the lithium-to-dry battery of this application, including a voltage detection circuit 1 and a lithium-to-dry battery 2, as well as an internal lithium battery 21 and a conversion circuit 22 in the lithium-to-dry battery 2. The voltage detection circuit 1 includes a controller 11, a charging circuit 12, and a current detection circuit 13.

[0021] The controller 11 is electrically connected to the charging circuit 12 and the current detection circuit 13 respectively. The charging circuit 12 is electrically connected to the current detection circuit 13, and the current detection circuit 13 is electrically connected to the conversion circuit 22. The current detection circuit 13 detects the flowing current in real time. The controller 11 obtains the corresponding detection value and uses this detection value to correspondingly regulate the charging voltage output by the charging circuit 12 until the charging voltage is regulated to be equal to or close to the actual voltage of the internal lithium battery 21.

[0022] Combined with Figure 2 as shown, this is Figure 1 an embodiment of the lithium-to-dry battery 2, where the conversion circuit 22 includes a lithium battery monitoring chip U1, and the model of this chip is LC9205D. The conversion circuit 22 includes this lithium battery monitoring chip and the capacitor, resistor, and inductor components connected to the periphery of this chip. Among them, the power supply pin BAT of this chip is electrically connected to the positive electrode of the internal lithium battery BAT1, and the negative electrode is grounded. An inductor L1 is connected between the output pin OUT and the SW pin of this chip. This output pin serves as the output pin of this lithium-to-dry battery, and the corresponding voltage is 1.5V. At the same time, the output pin of this lithium-to-dry battery is also the charging input pin. Therefore, here VAP / OUT is shown to represent a multiplexed discharge (output) pin and charging (input) pin. VAP represents the charging input, and OUT represents the discharge output.

[0023] Further, the conversion circuit can use LC9205D to compare the voltage VOUT of the OUT pin and the voltage VBAT of the BAT pin to determine its working mode. When VOUT>VBAT + 100mV, LC9205D works in the charge management mode (Charge mode), and its function is to use the voltage of the OUT pin as the working power supply to linearly charge the single-cell lithium battery at the BAT end. When VOUT<VBAT, LC9205D works in the discharge management mode (Buck DC / DC mode), and its function is to convert the voltage of the single-cell lithium battery at the BAT end into the output voltage of a single-cell dry battery of 1.5V and output it from the OUT pin.

[0024] Figure 3 is Figure 1 another embodiment of the lithium-to-dry battery 2, where the chip in the conversion circuit corresponds to SM5102. The output pin VOUT of this chip is also a multiplexed pin for charging input and discharge output, and the power supply pin BAT is also used to electrically connect to the positive electrode of the internal lithium battery. And the relationship between the voltage of the output pin of this chip and the voltage of the power supply pin (i.e., the lithium battery) also conforms to Figure 2 the corresponding charge management mode and discharge management mode in the embodiment shown, which will not be elaborated here.

[0025] Further, based on Figure 2 and Figure 3 The charging and discharging characteristics of the illustrated embodiment are for Figure 1 The charging circuit 12 can dynamically change its output voltage, thereby enabling the switching detection between charging management mode and discharging management mode to find the current actual voltage of the internal lithium battery.

[0026] Therefore, in this application, voltage regulation can be achieved by continuously adjusting the voltage between the charging circuit and the output pin of the lithium-to-dry battery. The controller can control the charging circuit to output PWM waves with different duty cycles to control the output voltage; that is, the adjustment of the output voltage of the charging circuit is achieved by the controller outputting PWM waves with different duty cycles. For example, controlling the on and off of a transistor or MOSFET. Taking an NPN transistor as an example, when a PWM wave is applied to the base of the transistor, a high level turns the transistor on, and a low level turns it off. For example, , This refers to the PWM duty cycle; VCC is the input voltage of the charging circuit. For example... By changing the duty cycle of the PWM wave, the ratio of the transistor's on and off times within one cycle can be controlled, thereby controlling the output voltage. .

[0027] like Figure 4 As shown, here is Figure 1 One embodiment of the charging circuit 12 includes a transistor Q1. The base of transistor Q1 is electrically connected to a first resistor R4, and a second resistor R5 is connected between the base and emitter. The first resistor R4 is electrically connected to a controller, which can output PWM waves with different duty cycles as control signals to control the conduction or disconnection between the base and emitter of transistor Q1. The collector of transistor Q1 is also electrically connected to a first DC power supply Vcc, such as a 5V DC power supply, via a third resistor R6. Additionally, the collector is electrically connected to a diode D2, which is also electrically connected to a current sensing circuit. The use of diode D2 prevents reverse power supply from the conversion circuit to the transistor via the current sensing circuit. However, a fourth resistor R7 is connected between the cathode of the diode and the power supply ground, allowing discharge from the conversion circuit via the current sensing circuit to be received. Furthermore, a first capacitor C6 is connected between the collector of transistor Q1 and the power supply ground to rectify and filter the voltage waveform output to the current sensing circuit.

[0028] Therefore, the charging circuit includes a controlled switch, and the controlled switch can be implemented in various ways, such as... Figure 4 The transistor Q1 in the diagram can also be a MOSFET, a relay, etc. The input terminal of this controlled switch (e.g., Figure 4 The collector of transistor Q1 is used to electrically connect to a DC power supply, and the output terminal of the controlled switch (such as...) Figure 4The negative terminal of the diode is electrically connected to the current detection circuit, and the control terminal of the controlled switch (such as...) Figure 4 The base of transistor Q1 is electrically connected to the controller, and the controller controls the voltage output from the output terminal to the current detection circuit according to the ratio of the on and off time of the controlled switch.

[0029] like Figure 5 As shown, the current detection circuit 13 includes a sampling resistor 131 connected in series between the charging circuit 12 and the conversion circuit 22. The two ends of the sampling resistor are respectively used to electrically connect the output terminal of the charging circuit and the output terminal of the lithium-to-dry battery. (Combined with...) Figure 2 and Figure 4 As shown, it is in Figure 2 The OUT pin of the lithium battery monitoring chip U1 is connected to Figure 4 A sampling resistor 131 is connected in series between the negative terminals of the first diode D1. The two ends of the sampling resistor are also electrically connected to the two differential voltage acquisition terminals of the differential amplifier circuit, which are used to acquire the voltage across the sampling resistor, and the digital signal amplified by the differential amplifier circuit and converted from analog to digital as the detection value, which is then input to the controller.

[0030] The sampling resistor is a precision resistor, with high accuracy and a small resistance value, resulting in a small voltage drop. For example, using a 0.01 ohm precision resistor, assuming a maximum current of 2A (generally, charging and discharging currents are less than this), the positive and negative voltage values ​​can be calculated using the formula V=I * R: V=2*0.01=±0.02V. Therefore, a differential amplifier circuit 132 is needed to amplify the voltage difference across it so that the controller can obtain the voltage difference value. For example, amplifying it by 50 times yields 0.02*50=±1V.

[0031] As can be seen, the main purpose of this application is to find the critical point at which the direction of the current flowing through the sampling resistor 131 changes. This critical point corresponds precisely to the voltage of the output pin corresponding to the switching between the charging management mode and the discharging management mode of the conversion circuit.

[0032] Therefore, when the output voltage V1 of the charging circuit 12 is relatively large in the initial stage, although there is a voltage drop through the sampling resistor, the voltage VOUT applied to the output pin of the conversion circuit is greater than VBAT + 100mV. Thus, the conversion circuit 22 is in charging management mode, meaning it is being charged by the charging circuit. Therefore, the charging state can be determined by measuring the voltage difference across the sampling resistor.

[0033] As the output voltage V1 of the charging circuit 12 is regulated in the direction of gradual decrease, the voltage VOUT corresponding to the output pin of the conversion circuit 22 also decreases accordingly. When it decreases to a critical point, that is, when the voltage VOUT of the output pin of the conversion circuit 22 < VBAT, the conversion circuit 22 will operate in the discharge management mode. At this time, the direction of the current flowing through the sampling resistor 131 will change, and the critical state can be judged by collecting the voltage difference across the sampling resistor 131 in real time. Thus, based on the output voltage V1 of the charging circuit 12 and the voltage difference across the sampling resistor 131 at this time, the voltage VOUT of the output pin of the conversion circuit 22 can be calculated, which is the actual voltage of the internal lithium battery at present.

[0034] When the output voltage V1 of the charging circuit 12 is relatively small in the initial stage, the conversion circuit 22 is in the discharge management mode, that is, discharging to the charging circuit 12. Therefore, the output voltage V1 of the charging circuit 12 can also be regulated in the direction of gradual increase. When the voltage VOUT acting on the output pin of the conversion circuit 22 > VBAT + 100 mV, the conversion circuit 22 will switch from the discharge management mode to the charging management mode. At this time, the direction of the current flowing through the sampling resistor will change, and the critical state can be judged by collecting the voltage difference across the sampling resistor in real time. Thus, based on the output voltage V1 of the charging circuit and the voltage difference across the sampling resistor at this time, the voltage VOUT of the output pin of the conversion circuit can be calculated. Subtracting 100 mV from this voltage VOUT is the actual voltage of the internal lithium battery at present. Therefore, in this case, the voltage VOUT of the output pin of the conversion circuit is close to the actual voltage of the internal lithium battery at present, and the range of this closeness is within 100 mV, that is, less than or equal to 100 mV.

[0035] Therefore, in Figure 5 According to the positive and negative changes of the voltage difference obtained from both ends of the sampling resistor 131 and combined with Ohm's law, when the direction of the current flowing through the sampling resistor 131 changes, the actual voltage of the internal lithium battery can be identified and judged based on the output voltage V1 of the charging circuit. Among them, the differential amplifier circuit 132 amplifies the voltage difference across the sampling resistor to obtain a more accurate identification and judgment. The ADC (analog-to-digital conversion) 133 digitally samples the amplified analog voltage, converting the analog signal into a digital signal and then being received by the controller 11. In practical applications, the ADC 133 can be implemented independently, or integrated as part of the controller chip in the controller chip, or integrated as part of the differential amplifier in the differential amplifier chip.

[0036] It can be seen that in Figure 5The schematic diagram shows positive and negative values ​​for the voltage difference. In practical applications, the inconvenience caused by these variations can be overcome by setting a bias voltage in the differential amplifier. For details, please refer to... Figure 6 The following is an example of the application of the current sampling circuit in this application.

[0037] exist Figure 6 This includes a sampling resistor R8, whose two ends are electrically connected to the charging circuit and the conversion circuit, respectively, and also electrically connected to the positive input pin IN+ and the negative input pin IN- of the differential amplifier chip U2, model number INA199. Additionally, a bias circuit is electrically connected to the voltage reference pin REF of this chip to provide a bias voltage for the differential amplifier chip U2. The differential amplifier chip U2 also integrates an AD converter, which can convert the acquired analog signal into a digital signal and output it. The output pin OUT is used to output the digital signal after AD conversion to the controller.

[0038] based on Figure 6 As shown, the bias circuit includes a fifth resistor R9, a sixth resistor R10, a seventh resistor R11, a voltage regulator U3, and a second capacitor C8. The first terminal of the fifth resistor R9 is connected to the 3.3V DC voltage output from the second DC power supply. The second terminal of the fifth resistor R9 is connected to the voltage reference pin REF of the differential amplifier chip U2, serving as the bias voltage input. The second terminal of the fifth resistor R9 is also electrically connected to the first terminal of the sixth resistor R10, the first terminal of the second capacitor C8, and the cathode of the voltage regulator U3. The cathode of the voltage regulator U3 is connected to the voltage reference pin REF of the differential amplifier chip U2, and the anode of the voltage regulator U3 is grounded. The reference terminal of the voltage regulator U3 is connected to the second terminal of the sixth resistor R10. The second terminal of the sixth resistor R10 is also electrically connected to the first terminal of the seventh resistor R11, and the second terminal of the seventh resistor R11 is grounded. The power supply pin V+ of the differential amplifier chip U2 is connected to the 3.3V DC voltage output from the second DC power supply, thus determining that the maximum output voltage of the output pin OUT is 3.3V.

[0039] In this application, to shift the negative voltage corresponding to a negative current into a positive voltage range, a bias voltage V2 (e.g., 1.65V) can be applied to the differential amplifier chip U2. When the current flowing through the sampling resistor is 0, the output voltage (the voltage value after analog-to-digital conversion) of the output pin OUT of the differential amplifier chip U2 is the bias voltage V2 (e.g., 1.65V). When the current value is positive, the output voltage of this pin is Vout = V2 + I*R (I: the current to be measured, R: the sampling resistor). When the current value is reversed, the output voltage of this pin is Vout = V2 - I*R. Here, Vout is also the voltage value after analog-to-digital conversion.

[0040] Therefore, the voltage across the sampling resistor is zero, corresponding to I=0. The detection value output by the output pin OUT of the differential amplifier chip U2 corresponds to the analog-to-digital conversion value of the bias voltage V2. At this time, the output voltage of the charging circuit is equal to or close to the actual voltage of the internal lithium battery.

[0041] Preferably, the bias voltage can be set to the bias circuit power supply, i.e., half the voltage value of the second DC power supply. Taking 3.3V as the voltage value of the second DC power supply as an example, the ADC range is 3.3V. Assuming the maximum positive and negative current value is 2A (generally, the charging and discharging current value is less than this value), the obtained voltage value can be calculated based on V=I * R, which is V=2*0.01=0.02V. After being amplified 50 times by the differential amplifier chip U2, 0.02*50=1V is obtained, and the output voltage Vout of this pin is in the range of [V2-1,V2+1]. For example, when V2=1.65V, the corresponding range is [0.65V-2.65V].

[0042] Here, by properly setting the resistance values ​​of the fifth resistor R9, the sixth resistor R10, and the seventh resistor R11, the bias voltage can be accurately set.

[0043] For regulator U3, the output voltage at its cathode is Vout = Vref * (1 + R10 / R11), where Vref is the internal reference voltage of regulator U3. For the TLV431 chip, this internal reference voltage is 1.24V. Substituting Vout = 1.65V and Vref = 1.24V into the above formula, we can calculate 1 + R10 / R11 = 1.65 / 1.24 ≈ 1.3306, that is, R10 / R11 ≈ 0.3306. Assuming the current flowing through these two voltage divider resistors is 100uA, then R11 = Vref / 100uA = 12.4KΩ, and R10 = R11 * 0.3306 ≈ 4.1KΩ.

[0044] The function of the fifth resistor R9 is to provide the operating current Ika for the TLV431 and the current Iload for the differential amplifier chip U2. Therefore, R9 = (Vin - Vout) / (Ika + Iload). Given that the maximum value of Ika is 80uA and the maximum value of Iload is 5uA, the denominator should be greater than 85uA. Therefore, R9 = (3.3 - 1.65) / 0.001 = 1.65K. Correspondingly, we get: R9 = 1.65K, R10 = 4.1K, and R11 = 12.4K.

[0045] The final controller judges the current value based on the sampled value output by the ADC. If the sampled value is greater than the sampled value corresponding to 1.65V, it is regarded as the current value for forward charging. If the sampled value is less than the sampled value corresponding to 1.65V, it is regarded as the current value for reverse discharging.

[0046] In conjunction with the foregoing description, this application also includes a method for detecting the voltage of the internal lithium battery in a lithium-to-dry cell, such as... Figure 7 As shown, the steps include: S101: Connect the current detection circuit and the charging circuit sequentially to the output pin of the lithium-to-dry battery. S102: Adjust the output voltage of the charging circuit to collect the detection value of the current detection circuit accordingly; S103: If the detected value is equal to the preset condition, then the current output voltage of the charging circuit is equal to the current actual voltage of the internal lithium battery.

[0047] The current detection circuit includes a sampling resistor connected in series between the output pin of the lithium-to-dry battery and the charging circuit. The detection value collected by the detection circuit includes the voltage difference across the sampling resistor. The preset condition is that the voltage difference is zero.

[0048] Furthermore, regulating the output voltage of the charging circuit includes two regulation methods: First, regulating the output voltage of the charging circuit involves decreasing the output voltage from high to low, with the current flowing through the sampling resistor flowing from the charging circuit to the output pin of the lithium-to-dry battery, and the voltage difference gradually decreasing until it reaches zero. Second, regulating the output voltage of the charging circuit involves increasing the output voltage from low to high, with the current flowing through the sampling resistor flowing from the output pin of the lithium-to-dry battery to the charging circuit, and the voltage difference gradually decreasing until it reaches zero.

[0049] This application also provides an electronic device, such as a charger, detector, or maintenance device for lithium-to-dry-cell batteries. The electronic device includes... Figure 1 The illustrated embodiment includes the circuit, a display screen and other human-machine interface electrically connected to the circuit, and a housing on which the circuit is mounted.

[0050] Therefore, this application discloses a voltage detection circuit, method, and electronic device for the internal lithium battery in a lithium-to-dry-cell battery. The circuit includes a controller, a charging circuit, and a current detection circuit. The controller is electrically connected to both the charging circuit and the current detection circuit. The charging circuit is electrically connected to the current detection circuit, which is connected to the positive terminal of the lithium-to-dry-cell battery's power source. The current detection circuit detects the current flowing through the battery in real time. The controller obtains the corresponding detection value from the current detection circuit and uses this value to adjust the charging voltage output by the charging circuit until the charging voltage is adjusted to be equal to or close to the actual voltage of the internal lithium battery. Based on this application, by detecting the change in current direction between the external circuit and the battery during the transition between the discharge and charging states of the lithium-to-dry-cell battery, the voltage of the internal lithium battery can be accurately determined. This is beneficial for real-time monitoring of the actual charge state of the lithium battery, prediction of remaining working time, and monitoring and management of battery health and lifespan.

[0051] The above are merely embodiments of this application and do not limit the scope of this patent application. Any equivalent structural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A voltage detection circuit for the internal lithium battery in a lithium-to-dry cell, characterized in that, include: Controller, charging circuit, and current detection circuit; The controller is electrically connected to the charging circuit and the current detection circuit respectively. The charging circuit is electrically connected to the current detection circuit. The current detection circuit is used to be electrically connected to the positive terminal of the lithium-to-dry battery. The current detection circuit detects the current flowing through it in real time. The controller obtains the detection value corresponding to the current detection circuit and uses the detection value to adjust the charging voltage output by the charging circuit until the charging voltage is adjusted to be equal to or close to the actual voltage of the internal lithium battery.

2. The voltage detection circuit for the internal lithium battery in a lithium-to-dry cell according to claim 1, characterized in that, The charging circuit includes a controlled switch, the input terminal of which is electrically connected to a DC power supply, the output terminal of which is electrically connected to the current detection circuit, and the control terminal of which is electrically connected to the controller. The controller controls the on and off time ratios of the controlled switch to adjust the voltage output from the output terminal to the current detection circuit.

3. The voltage detection circuit for the internal lithium battery in a lithium-to-dry cell according to claim 1, characterized in that, The current detection circuit includes a sampling resistor, the two ends of which are electrically connected to the output terminal of the charging circuit and the output terminal of the lithium-to-dry battery, respectively. The two ends of the sampling resistor are also electrically connected to two differential voltage acquisition terminals of a differential amplifier circuit, which are used to acquire the voltage across the sampling resistor and the digital signal after being amplified by the differential amplifier circuit and converted from analog to digital as the detection value, which is then input to the controller.

4. The voltage detection circuit for the internal lithium battery in a lithium-to-dry cell according to claim 3, characterized in that, The differential amplifier circuit includes a differential amplifier, which includes a positive input pin and a negative input pin, corresponding to the two differential voltage acquisition terminals of the differential amplifier circuit, and is electrically connected to both ends of the sampling resistor respectively. The differential amplifier further includes a voltage reference pin and an output pin. The voltage reference pin is electrically connected to the bias circuit, and the output pin is electrically connected to the controller. The output pin outputs a digital signal after analog-to-digital conversion to the controller.

5. The voltage detection circuit for the internal lithium battery in a lithium-to-dry cell according to claim 4, characterized in that, The bias circuit includes a fifth resistor, a sixth resistor, a seventh resistor, a voltage regulator, and a second capacitor. The first end of the fifth resistor is connected to a second DC power supply, and the second end is connected to the voltage reference pin of the differential amplifier for inputting a bias voltage. The second end of the fifth resistor is also electrically connected to the first end of the sixth resistor, the first end of the second capacitor, and the cathode of the voltage regulator. The anode of the voltage regulator is grounded. The reference terminal of the voltage regulator is connected to the second end of the sixth resistor. The second end of the sixth resistor is also electrically connected to the first end of the seventh resistor. The second end of the seventh resistor is grounded. The power supply pin of the differential amplifier is electrically connected to the second DC power supply.

6. The voltage detection circuit for the internal lithium battery in a lithium-to-dry cell according to claim 5, characterized in that, The voltage difference across the sampling resistor is zero, and the detected value corresponds to the analog-to-digital conversion value of the bias voltage. At this time, the output voltage of the charging circuit is equal to or close to the actual voltage of the internal lithium battery.

7. A method for detecting the voltage of an internal lithium battery in a lithium-to-dry cell, characterized in that: The detection circuit and the charging circuit are connected sequentially to the output pin of the lithium-to-dry battery. Adjust the output voltage of the charging circuit to collect the corresponding detection value from the detection circuit; If the detected value equals the preset condition, then the output voltage of the current charging circuit is equal to the current actual voltage of the internal lithium battery.

8. The method for detecting the voltage of the internal lithium battery in a lithium-to-dry cell according to claim 7, characterized in that: The detection circuit includes a sampling resistor connected in series between the output pin of the lithium-to-dry battery and the charging circuit. The detection value collected by the detection circuit includes the voltage difference across the sampling resistor. The preset condition is that the voltage difference is zero.

9. The method for detecting the voltage of the internal lithium battery in a lithium-to-dry cell according to claim 8, characterized in that: Regulating the output voltage of the charging circuit includes adjusting the output voltage from high to low, with the current flowing through the sampling resistor flowing from the charging circuit to the output pin of the lithium-to-dry battery, and the voltage difference gradually decreasing until it becomes zero; or, regulating the output voltage of the charging circuit includes adjusting the output voltage from low to high, with the current flowing through the sampling resistor flowing from the output pin of the lithium-to-dry battery to the charging circuit, and the voltage difference gradually decreasing until it becomes zero.

10. An electronic device, characterized in that, Includes the voltage detection circuit for the internal lithium battery in a lithium-to-dry cell as described in any one of claims 1-6.

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