A conversion circuit for converting a lithium battery to a dry battery

Abstract

The present invention provides a conversion circuit for converting a lithium battery into a dry battery, which includes a cell voltage sampling module, a load current sampling module, an output voltage feedback module, and a power management module; two input ends of the power management module are respectively connected to a reference voltage and a feedback voltage, the output end of the cell voltage sampling module is connected to the reference voltage, the output end of the output voltage feedback module is connected to the feedback voltage, the output end of the load current sampling module is connected to one of the reference voltage and the feedback voltage, and the load current sampling module is used to output an internal resistance compensation current proportional to the load current. The conversion circuit of the present invention can achieve that the output voltage decreases as the battery voltage decreases and decreases as the load current increases, and the output curve can completely fit the voltage characteristics of the dry battery.

Description

Technical Field

[0001] The present invention belongs to the field of batteries, and particularly relates to a conversion circuit for converting a lithium battery into a dry battery. Background Art

[0002] Traditional alkaline batteries, also known as dry batteries, have a wide range of applications, with good discharge curves and higher energy densities. However, their disadvantages are also very obvious. Alkaline batteries are disposable batteries that cause serious environmental pollution after use; in addition, when placed for a long time, chemical raw materials may leak due to factors such as moisture and oxidation, resulting in damage to electronic products. Lithium batteries are lightweight, chemically stable, can be repeatedly charged and discharged in cycles, and can also be combined with components to achieve diversified electronic applications such as power reminder and charging reminder.

[0003] Dry batteries have a high energy density and are widely used, providing more stable power supply and longer service life. Therefore, it is necessary to simulate dry batteries. However, the existing lithium battery to dry battery structures all have a stepped output voltage, unable to truly fit the dry battery discharge curve and unable to achieve a linear change of the output voltage with respect to the battery voltage and load current. There are also conversion circuits that introduce the MCU architecture, which have a large circuit area and complex structure, and are not conducive to system integration. Summary of the Invention

[0004] The purpose of the present invention is to provide a conversion circuit for converting a lithium battery into a dry battery, so that the discharge curve of the output voltage can fit the voltage characteristics of the dry battery.

[0005] To achieve the above purpose, the present invention provides a conversion circuit for converting a lithium battery into a dry battery, including a discharge module connected to the battery cell of the lithium battery. The discharge module includes a battery cell voltage sampling module, a load current sampling module, an output voltage feedback module, and a power management module. Two input ends of the power management module are respectively connected to a reference voltage and a feedback voltage. The output end of the battery cell voltage sampling module is connected to the reference voltage. The output end of the output voltage feedback module is connected to the feedback voltage. The output end of the load current sampling module is connected to one of the reference voltage and the feedback voltage. The load current sampling module is used to output an internal resistance compensation current proportional to the load current.

[0006] The battery cell voltage sampling module includes a resistor voltage division structure with an input end connected to the battery cell voltage; and / or, the output voltage feedback module includes a second resistor voltage division structure with an input end connected to the output voltage of the discharge module.

[0007] The load current sampling module includes a current sampling amplifier and a current sampling switch tube connected to the output end of the current sampling amplifier.

[0008] The output terminal of the load current sampling module is connected to the reference voltage; the non-inverting voltage input terminal of the current sampling amplifier is connected to both the sampling current and the compensation resistor, and the other end of the compensation resistor is grounded to obtain the voltage drop of the sampling current across the compensation resistor, where the sampling current is obtained by sampling the load current; the inverting voltage input terminal of the current sampling amplifier is connected to one end of the fourth resistor and the low-voltage side of the current sampling switch tube, the other end of the fourth resistor is grounded, the gate of the current sampling switch tube is connected to the input terminal of the current sampling amplifier, and the high-voltage side of the current sampling switch tube is connected to the reference voltage.

[0009] The output terminal of the load current sampling module is connected to the feedback voltage; the inverting voltage input terminal of the current sampling amplifier is connected to both the sampling current and the compensation resistor, and the other end of the compensation resistor is connected to the cell voltage of the lithium battery, so that the inverting voltage input terminal obtains the cell voltage of the lithium battery minus the voltage drop of the sampling current across the compensation resistor, where the sampling current is obtained by sampling the load current; the non-inverting voltage input terminal of the current sampling amplifier is connected to one end of the fourth resistor and the high-voltage side of the current sampling switch tube, the other end of the fourth resistor is connected to the cell voltage of the lithium battery, the gate of the current sampling switch tube is connected to the input terminal of the current sampling amplifier, and the low-voltage side of the current sampling switch tube is connected to the feedback voltage.

[0010] The compensation resistor is external or internal.

[0011] The power management module adopts a traditional buck step-down structure, which includes an error amplifier, a drive module, a group of parallel buck circuit switch tubes, and a filter circuit connected in sequence.

[0012] One of the reference voltage and the feedback voltage is connected to a current regulation module, and the current regulation module is used to provide a fixed regulation current.

[0013] The reference voltage is connected to a reference voltage clamping module, and the reference voltage clamping module is used to clamp the reference voltage within the range of the threshold voltage.

[0014] The conversion circuit for converting a lithium battery to a dry battery further includes a charging module connected to the cell of the lithium battery, and the charging module is used to charge the cell of the lithium battery.

[0015] In the discharge module of the conversion circuit for converting a lithium battery to a dry battery according to the present invention, a cell voltage sampling module is provided to make the output voltage decrease as the battery voltage decreases, and a load current sampling module is provided to provide an internal resistance compensation current, so that the output voltage decreases as the load current increases. Therefore, the discharge curve of the output voltage can fully fit the voltage characteristics of a dry battery. Description of the Drawings

[0016] Figure 1 The system block diagram of the conversion circuit for converting a lithium battery into a dry battery according to the present invention.

[0017] Figure 2 The system block diagram of the discharge module of the conversion circuit for converting a lithium battery into a dry battery according to the first embodiment of the present invention.

[0018] Figure 3 The circuit diagram of the discharge module of the conversion circuit for converting a lithium battery into a dry battery according to the first embodiment of the present invention.

[0019] Figure 4 The system block diagram of the discharge module of the conversion circuit for converting a lithium battery into a dry battery according to the second embodiment of the present invention.

[0020] Figure 5 The circuit diagram of the discharge module of the conversion circuit for converting a lithium battery into a dry battery according to the second embodiment of the present invention.

[0021] Figure 6 The system block diagram of the discharge module of the conversion circuit for converting a lithium battery into a dry battery according to the third embodiment of the present invention.

[0022] Figure 7 The circuit diagram of the discharge module of the conversion circuit for converting a lithium battery into a dry battery according to the third embodiment of the present invention.

[0023] Figure 8A and Figure 8B The curve comparison diagram of the discharge test results of AA batteries and AAA batteries and the fitting results of the conversion circuit for converting a lithium battery into a dry battery according to the present invention. Detailed implementation manners

[0024] The following further describes the present invention in conjunction with specific embodiments. It should be understood that the following embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.

[0025] Figure 1 The system block diagram of the conversion circuit for converting a lithium battery into a dry battery according to the present invention. As Figure 1 shown, the conversion circuit for converting a lithium battery into a dry battery according to the present invention is reusable. Therefore, the conversion circuit for converting a lithium battery into a dry battery includes a charging module 10 connected to the battery cell of the lithium battery and a discharge module 20. The input end of the charging module 10 is connected to an external power supply to charge the battery cell of the lithium battery through the charging module 10, thereby realizing the repeated use of the lithium battery.

[0026] The output end of the discharge module 20 is connected to a load, and the output voltage of the discharge module 20 The discharge curve is the same as that of a dry battery. Thus, the discharge module 20 can achieve that the output voltage of the discharge module 20 changes linearly following the cell voltage and load current of the lithium battery, and can achieve the same output voltage range as that of a dry battery.

[0027] As Figure 2 and Figure 3 shown is the discharge module of the conversion circuit for converting a lithium battery to a dry battery according to the first embodiment of the present invention. As Figure 2 shown, the discharge module 20 includes a reference voltage clamping module 21, a cell voltage sampling module 22, a load current sampling module 23, a current regulation module 24, an output voltage feedback module 25, and a power management module 26. Among them, the output ends of the reference voltage clamping module 21, the cell voltage sampling module 22, the load current sampling module 23, and the current regulation module 24 are all connected to the reference voltage ; the output end of the output voltage feedback module 25 is connected to the feedback voltage . The two input ends of the power management module 26 are respectively connected to the reference voltage and the feedback voltage , and its output end is connected to the output voltage output by the power management module 26, and is used to make the feedback voltage equal to the reference voltage , so that the output voltage of the discharge module 20 is consistent with the output voltage of a dry battery, realizing the conversion of a lithium battery to a dry battery.

[0028] As Figure 3 shown, the feedback voltage is generated by dividing the output voltage of the discharge module 20 through resistor voltage division. In this embodiment, the output voltage feedback module 25 includes a sixth resistor and a seventh resistor connected in series as a second resistor voltage division structure, and the input end of the second resistor voltage division structure is connected to the output voltage of the discharge module 20. The connection point of the sixth resistor and the seventh resistor is used as the output end to provide the feedback voltage , and the other end of the seventh resistor (i.e., the high-voltage side of the output voltage feedback network) is used as the input end of the output voltage feedback module 25 to connect to the output voltage , and the other end of the sixth resistor is grounded.

[0029] Therefore, the feedback voltage is:

[0030] ,

[0031] Among them, is the output voltage, is the resistance value of the sixth resistor, is the resistance value of the seventh resistor.

[0032] The power management module 26 adopts a traditional buck step-down structure, which includes an error amplifier 261, a driving module 262, a group of parallel buck circuit switching tubes 263, and a filtering circuit 264 connected in sequence. The buck circuit switching tubes 263 include a first PMOS tube and a first NMOS tube. The drains of the first PMOS tube and the first NMOS tube are both connected to the filtering circuit 264. The source of the first PMOS tube is connected to the cell voltage of the lithium battery The source of the first NMOS tube is grounded. The error amplifier 261, the driving module 262, and the buck circuit switching tubes 263 are arranged on the chip. The filtering circuit 264 is arranged outside the chip and includes an inductor with one end connected to the buck circuit switching tubes 263 and a grounding capacitor connected to the other end of the inductor. The connection point of the inductor and the grounding capacitor is the output end of the power management module 26 for connecting a load to provide an output voltage and load current .

[0033] The cell voltage sampling module 22 includes a resistor voltage dividing structure with an input end connected to the cell voltage . The resistor voltage dividing structure includes a first resistor and a second resistor connected in series. The high-voltage side of the resistor voltage dividing structure is connected to the cell voltage of the lithium battery , and the low-voltage side is grounded. The connection point of the first resistor and the second resistor is the output end of the resistor voltage dividing structure and is connected to the reference voltage . Thus, the reference voltage realizes the sampling of the cell voltage through the resistor voltage dividing structure.

[0034] Therefore, the reference voltage is generated by the resistor voltage division of the resistor voltage dividing structure. Without considering other modules, the output voltage of the discharge module 20 passes through the resistor voltage division to generate an initial reference voltage as:

[0035] ,

[0036] Among them, is the cell voltage of the lithium battery, is the second resistor.

[0037] The load current sampling module 23 includes a current sampling amplifier 231 and a current sampling switch transistor N2 connected to the output end of the current sampling amplifier. The positive voltage input end of the current sampling amplifier is simultaneously connected to the sampling current and a compensation resistor . The other end of the compensation resistor is grounded to obtain the voltage drop of the sampling current across the compensation resistor . The sampling current is obtained by sampling the load current . The inverting voltage input end of the current sampling amplifier is connected to one end of a fourth resistor and the low-voltage side of the current sampling switch transistor N2. The other end of the fourth resistor is grounded. The gate of the current sampling switch transistor N2 is connected to the input end of the current sampling amplifier 231, and the high-voltage side of the current sampling switch transistor N2 is connected to the reference voltage . In this embodiment, the current sampling switch transistor is an NMOS transistor. Thus, the voltage drop of the internal resistance compensation current output by the load current sampling module across the fourth resistor is on the inverting voltage input end of the current sampling amplifier.

[0038] The sampling current is obtained by sampling the load current through a load current sampling circuit. There are also many circuit implementation methods for the load current sampling circuit, which will not be elaborated here. In this embodiment, the sampling ratio of the load current sampling circuit is 1 / N. Then the sampling current is:

[0039] ,

[0040] where 1 / N is the sampling ratio of the load current sampling circuit, is the load current.

[0041] The internal resistance compensation current output by the load current sampling module is:

[0042] ,

[0043] where is the sampling current, is the compensation resistor, is the fourth resistor, 1 / N is the sampling ratio of the load current sampling circuit, is the load current.

[0044] That is to say, the load current sampling module 23 is used to output an internal resistance compensation current proportional to the load current .

[0045] Among them, the compensation resistor can be external (i.e., set outside the chip) or internal; by using the external compensation resistor , different load current compensation coefficients can be easily achieved. The compensation resistor , the fourth resistor , and the value of the sampling ratio 1 / N are adjustable, and the design is very flexible. The design adjustment is based on the numerical simulation obtained finally. Thus, the load current sampling module 23 can sample the load current and simulate the voltage change caused by the internal resistance of the battery cell through the compensation resistor to achieve the compensation of the internal resistance of the battery cell.

[0046] The current adjustment module 24 is used to provide a fixed adjustment current , and the adjustment current is used to adjust the range of the output voltage.

[0047] The adjustment current is an additionally introduced deviation amount used to adjust the reference voltage to achieve the same output voltage range as that of the dry battery.

[0048] In this embodiment, the adjustment current is generated by the voltage generated by the adjustment current flowing through the fifth resistor . The adjustment current is:

[0049] ,

[0050] Among them, is the voltage generated by the adjustment current, is the fifth resistor. Among them, the voltage generated by the adjustment current is a fixed voltage value. The design of the two values of the voltage V0 generated by the adjustment current and the fifth resistor is also very flexible, as long as the final obtained formula can fit, there is no rigid requirement.

[0051] The reference voltage clamping module 21 is used to clamp the reference voltage within the range of the threshold voltage, so as to ensure that the range of the output voltage is consistent with the dry battery voltage and ensure that the output voltage will not be too high or too low.

[0052] The reference voltage clamping module 21 has various implementation manners, as long as it satisfies clamping the reference voltage within the range of the threshold voltage so that the corresponding output voltage is consistent with the dry battery. For example, in this embodiment, the reference voltage clamping module 21 adopts one of the basic circuit structures, including a clamping circuit amplifier. The positive input terminal of the clamping circuit amplifier is connected to the threshold voltage, and the negative input terminal and the output terminal are both connected to the reference voltage to achieve overvoltage protection.

[0053] In this embodiment, the reference voltage should be clamped between and .

[0054] In summary, the reference voltage satisfies the following formula:

[0055] ,

[0056] where is the regulating current, is the cell voltage of the lithium battery, is the reference voltage, is the second resistor, is the first resistor, is the internal resistance compensation current output by the load current sampling module.

[0057] Therefore, the reference voltage is:

[0058] ,

[0059] The power management module 26 can make the feedback voltage equal to the reference voltage through loop regulation. Therefore, the feedback voltage satisfies .

[0060] The output voltage is:

[0061] ,

[0062] which can be simplified to:

[0063] ,

[0064] where , , , and the values of these three numbers can be obtained by curve fitting.

[0065] It can be clearly seen from the output formula that the output voltage It decreases linearly with the decrease of the cell voltage and also decreases linearly with the increase of the load current, fully fitting the discharge characteristics of dry batteries.

[0066] As Figure 4 and Figure 5 shown are the system block diagram and circuit diagram of the discharge module of the conversion circuit for converting a lithium battery to a dry battery according to the second embodiment of the present invention.

[0067] As Figure 4 shown, the discharge module 20 includes a reference voltage clamping module 21', a cell voltage sampling module 22', a current regulation module 24', a load current sampling module 23', an output voltage feedback module 25', and a power management module 26'. Among them, the output terminals of the reference voltage clamping module 21', the cell voltage sampling module 22', and the current regulation module 24' are all connected to the reference voltage ; the output terminals of the load current sampling module 23' and the output voltage feedback module 25' are all connected to the feedback voltage .

[0068] The two input terminals of the power management module 26' are respectively connected to the reference voltage and the feedback voltage , and its output terminal is connected to the output voltage output by the power management module 26', for making the feedback voltage equal to the reference voltage , so that the output voltage of the discharge module 20 is consistent with the output voltage of the dry battery, realizing the conversion of a lithium battery to a dry battery.

[0069] As Figure 5 shown, the specific structures of the reference voltage clamping module 21', the cell voltage sampling module 22', the current regulation module 24', and the output voltage feedback module 25' and the connection manners of their input terminals and output terminals are the same as those of the reference voltage clamping module 21, the cell voltage sampling module 22, the current regulation module 24, and the output voltage feedback module 25 in the first embodiment of the present invention.

[0070] Thus, the reference voltage of the buck circuit consists of two parts. The first is to sample the cell voltage through a resistor voltage division structure; the second part is to regulate the current to adjust the magnitude of the reference voltage to meet the output voltage range conforming to the output voltage of the dry battery.

[0071] As Figure 5 shown, the difference between the discharge module of the conversion circuit for converting a lithium battery to a dry battery according to the second embodiment of the present invention and the first embodiment is only that the output terminal of the load current sampling module 23' is connected to the feedback voltage Connected; and the load current sampling module 23' includes a current sampling amplifier and a current sampling switch tube connected to the output end of the current sampling amplifier. The reverse voltage input end of the current sampling amplifier is simultaneously connected to the sampling current and the compensation resistor Connected, the compensation resistor The other end of is connected to the cell voltage of the lithium battery Connected, so that the reverse voltage input end obtains the cell voltage of the lithium battery Minus the sampling current The voltage drop on the compensation resistor The sampling current Is obtained by sampling the load current The positive-phase voltage input end of the current sampling amplifier is connected to one end of the fourth resistor And the high-voltage side of the current sampling switch tube. The other end of the fourth resistor Is connected to the cell voltage of the lithium battery The gate of the current sampling switch tube is connected to the input end of the current sampling amplifier. The low-voltage side of the current sampling switch tube is connected to the feedback voltage , in this embodiment, the current sampling switch tube is a PMOS tube. Thus, the reverse voltage input end of the current sampling amplifier is the internal resistance compensation current output by the load current sampling module The voltage drop on the fourth resistor .

[0072] The feedback voltage Consists of two parts. One part is the output voltage Obtained by resistor voltage division, and the other part is obtained by the load current sampling module 23' sampling the load current.

[0073] The reference voltage Is generated by resistor voltage division. Without considering other modules, the initial reference voltage Generated by resistor voltage division from the output voltage of the discharge module 20 Is:

[0074] .

[0075] In this embodiment, the regulating current Is generated by generating a voltage Through the regulating current flowing through the fifth resistor. The regulating current Is:

[0076] ,

[0077] Among them, Is the voltage generated by the regulating current, is the fifth resistor. The regulating current generates a voltage is a fixed voltage value. The design of the regulating current generating the two values of voltage V0 and the fifth resistor is also very flexible, as long as the final obtained formula can fit, there are no rigid requirements.

[0078] In summary, the reference voltage satisfies the following formula:

[0079] ,

[0080] wherein, is the regulating current, is the core voltage of the lithium battery, is the reference voltage, is the second resistor, is the first resistor.

[0081] Therefore, the reference voltage is:

[0082] ,

[0083] When only considering resistor voltage division, the initial feedback voltage generated by resistor voltage division is:

[0084] ,

[0085] wherein, is the output voltage, is the resistance value of the sixth resistor, is the resistance value of the seventh resistor.

[0086] The load current sampling module can sample the load current with a sampling ratio of 1 / N, then the sampling current is:

[0087] ,

[0088] where 1 / N is the sampling ratio of the load current sampling circuit, is the load current.

[0089] The internal resistance compensation current output by the load current sampling module is:

[0090] ,

[0091] wherein, is the sampling current, is the compensation resistor, is the fourth resistor, 1 / N is the sampling ratio of the load current sampling circuit, is the load current. Among them, the compensation resistor can be external or internal; by using an external compensation resistor , different load current compensation coefficients can be conveniently achieved.

[0092] In summary, the feedback voltage satisfies the following formula:

[0093] ,

[0094] The feedback voltage is:

[0095] .

[0096] The power management module 26 can make the feedback voltage equal to the reference voltage through loop regulation. Therefore, the feedback voltage satisfies .

[0097] The output voltage is:

[0098] ,

[0099] can be simplified to:

[0100] ,

[0101] Among them, , , , and the values of these three numbers can be obtained through curve fitting.

[0102] It can be clearly seen from the output formula that the output voltage of the discharge module 20 decreases linearly with the decrease of the cell voltage and decreases linearly with the increase of the load current, which completely fits the discharge characteristics of dry batteries.

[0103] As Figure 6 and Figure 7 show, the system block diagram and circuit diagram of the discharge module of the lithium battery to dry battery conversion circuit according to the third embodiment of the present invention are shown.

[0104] As Figure 6 shows, the discharge module 20 includes a reference voltage clamping module 21", a cell voltage sampling module 22", a load current sampling module 23", a current regulation module 24", an output voltage feedback module 25", and a power management module 26". Among them, the output terminals of the reference voltage clamping module 21" and the cell voltage sampling module 22" are both connected to the reference voltage ; the output terminals of the load current sampling module 23", the current regulation module 24", and the output voltage feedback module 25" are all connected to the feedback voltage Connection

[0105] The two input terminals of the power management module 26” are respectively connected to the reference voltage and the feedback voltage and its output terminal is connected to the output voltage output by the power management module 26” for making the feedback voltage equal to the reference voltage so that the output voltage of the discharge module 20 is consistent with the output voltage of the dry battery, realizing the conversion of the lithium battery to the dry battery.

[0106] Thus, the reference voltage realizes the sampling of the cell voltage through the resistor voltage division structure. The feedback voltage consists of three parts. The output voltage passes through resistor voltage division, load current sampling and are all the same. The only difference is that the current regulation module 24” is connected to the feedback voltage Figure 5 so that the feedback voltage additionally increases the regulation current to adjust the magnitude of the reference voltage to meet the output voltage range in line with the dry battery output voltage. For adjusting the reference voltage size to meet the output voltage range in line with the dry battery output voltage.

[0107] The reference voltage is generated by resistor voltage division. The reference voltage is:

[0108] .

[0109] When only considering resistor voltage division, the initial feedback voltage generated by resistor voltage division is:

[0110] ,

[0111] wherein, is the output voltage, is the resistance value of the sixth resistor, is the resistance value of the seventh resistor.

[0112] The load current sampling module can sample the load current with a sampling ratio of 1 / N. Then the sampling current is:

[0113] ,

[0114] wherein, 1 / N is the sampling ratio of the load current sampling circuit, is the load current.

[0115] The internal resistance compensation current output by the load current sampling module is:

[0116] ,

[0117] wherein, is the sampled current, is the compensation resistor, is the fourth resistor, 1 / N is the sampling ratio of the load current sampling circuit, is the load current. Among them, the compensation resistor can be external or internal; by using the external compensation resistor , different load current compensation coefficients can be easily achieved.

[0118] In this embodiment, the regulating current generates a voltage by flowing through the fifth resistor to generate the regulating current is:

[0119] ,

[0120] wherein, is the voltage generated by the regulating current, is the fifth resistor. Among them, the voltage V0 generated by the regulating current is a fixed voltage value, and the design of the two values of the voltage V0 generated by the regulating current and the fifth resistor is also very flexible, as long as the final obtained formula can be fitted, there is no rigid requirement.

[0121] In summary, the feedback voltage satisfies the following formula:

[0122] ,

[0123] The feedback voltage is:

[0124] ,

[0125] The power management module 26 can make the feedback voltage equal to the reference voltage through loop regulation. Therefore, the feedback voltage satisfies .

[0126] The output voltage is:

[0127] ,

[0128] can be simplified to:

[0129] ,

[0130] wherein, , , , the values of these three numerical values can be obtained by curve fitting.

[0131] It can be clearly seen from the output formula that the output voltage of the discharge module 20 decreases linearly with the decrease of the cell voltage and decreases linearly with the increase of the load current, completely fitting the discharge characteristics of dry batteries.

[0132] Since all the above structures will output a very low voltage when the voltage is low and the load current is large, and cannot be used as a battery; or output a relatively high voltage when the cell voltage is high and the load current is small, resulting in damage to the subsequent electronic components, while the output voltage range of dry batteries is 0.6V - 1.58V, the reference voltage clamping module described above can solve this problem. The reference voltage clamping module is used to clamp the reference voltage within the range of the threshold voltage, so as to ensure that the output voltage range is consistent with the dry battery voltage and ensure that the output voltage will not be too high or too low. The reference voltage clamping module has various implementation methods, as long as it satisfies clamping the reference voltage within the range of the threshold voltage so that the corresponding output voltage is consistent with the dry battery.

[0133] In Figure 3 , the reference voltage should be clamped between and . In Figure 5 , the reference voltage should be clamped between and . In Figure 7 , the reference voltage should be clamped between and .

[0134] Figure 8A and Figure 8B are curve fittings implemented according to the present invention. The abscissa is the battery discharge time, and the ordinate is the dry battery voltage or the output voltage of the lithium-to-dry structure designed in this patent. From Figure 8A and Figure 8B , it can be seen that whether it is a No. 5 dry battery (AA) or a No. 7 dry battery (AAA), the present invention can completely fit their discharge curves. Among them,

[0135] such as Figure 8A and Figure 8BAs shown, the discharge characteristics of No. 5 batteries under the conditions of 240 mA, 480 mA, and 1.2 A, and the discharge characteristics of No. 7 batteries under the conditions of 75 mA, 150 mA, 350 mA, and 750 mA are shown. The conversion circuit of lithium battery to dry battery of the present invention can realize the output of the lithium battery core with the voltage characteristics of dry battery. The conversion circuit of lithium battery to dry battery of the present invention sets a cell voltage sampling module in the discharge module to realize that the output voltage decreases as the battery voltage decreases, and sets a load current sampling module to provide an internal resistance compensation current to realize that the output voltage decreases as the load current increases. Therefore, the discharge curve of the output voltage can completely fit the voltage characteristics of dry battery.

[0136] The above-mentioned are only the preferred embodiments of the present invention, and are not used to limit the scope of the present invention. Various changes can be made to the above embodiments of the present invention. All simple, equivalent changes and modifications made according to the claims and the content of the specification of the present invention application fall within the scope of the claims of the present invention patent. Those not described in detail in the present invention are all conventional technical contents.

Claims

1. A conversion circuit for converting a lithium battery to a dry battery, characterized in that, It includes a discharge module connected to the battery cells of a lithium battery. The discharge module includes a cell voltage sampling module, a load current sampling module, an output voltage feedback module, and a power management module. Two input terminals of the power management module are respectively connected to a reference voltage and a feedback voltage. The output terminal of the cell voltage sampling module is connected to the reference voltage. The output terminal of the output voltage feedback module is connected to the feedback voltage. The load current sampling module is used to output an internal resistance compensation current proportional to the load current. The cell voltage sampling module includes a resistor voltage division structure with its input terminal connected to the cell voltage. The output voltage feedback module includes a sixth resistor and a seventh resistor connected in series as a second resistor voltage division structure. The input terminal of the second resistor voltage division structure is connected to the output voltage of the discharge module. The connection point of the sixth resistor and the seventh resistor serves as the output terminal for providing the feedback voltage. The other end of the seventh resistor serves as the input terminal of the output voltage feedback module to connect to the output voltage. The other end of the sixth resistor is grounded. The load current sampling module includes a current sampling amplifier and a current sampling switch tube connected to the output terminal of the current sampling amplifier. The output terminal of the load current sampling module is connected to the reference voltage. The positive voltage input terminal of the current sampling amplifier is simultaneously connected to the sampling current and a compensation resistor. The other end of the compensation resistor is grounded to obtain the voltage drop of the sampling current across the compensation resistor. The sampling current is obtained by sampling the load current. The negative voltage input terminal of the current sampling amplifier is connected to one end of a fourth resistor and the low-voltage side of the current sampling switch tube. The other end of the fourth resistor is grounded. The gate of the current sampling switch tube is connected to the input terminal of the current sampling amplifier. The high-voltage side of the current sampling switch tube is connected to the reference voltage. The reference voltage is connected to a reference voltage clamping module, which is used to clamp the reference voltage within the range of the threshold voltage, thereby ensuring that the range of the output voltage is consistent with the dry battery voltage. The power management module achieves the equality of the feedback voltage and the reference voltage through loop regulation. The feedback voltage is: , where is the output voltage, is the resistance value of the sixth resistor; The reference voltage is clamped between and ; The cell voltage sampling module, the load current sampling module, the output voltage feedback module, and the reference voltage clamping module are all located on-chip. The power management module adopts a traditional buck step-down structure, which includes an error amplifier, a drive module, a group of parallel buck circuit switch tubes, and a filter circuit connected in sequence. The error amplifier, the drive module, and the buck circuit switch tubes are arranged on-chip, and the filter circuit is arranged off-chip.

2. The conversion circuit for converting a lithium battery into a dry battery according to claim 1, characterized in that, The compensation resistor is external or internal.

3. The conversion circuit for converting a lithium battery to a dry battery according to claim 1, wherein One of the reference voltage and the feedback voltage is connected to a current regulation module, which is used to provide a fixed regulation current.

4. The conversion circuit for converting a lithium battery to a dry battery according to claim 1, characterized in that, It also includes a charging module connected to the battery cells of the lithium battery, and the charging module is used to charge the battery cells of the lithium battery.

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