Power management circuit with backup battery voltage input control function

Abstract

The present invention provides a power management circuit with a function of controlling the voltage input of a backup battery, comprising a main battery, a backup battery, a reference voltage module, and a voltage management module. The main battery outputs a first voltage, the backup battery outputs a second voltage, and the reference voltage module outputs a reference voltage. The voltage management module receives the first voltage, the second voltage, and the reference voltage, outputs an operating voltage to a load, and a voltage divider converts the first voltage into a third voltage. When both the first voltage and the second voltage are invalid voltages, the operating voltage exhibits a high-impedance state. When the first voltage is a valid voltage and the second voltage is an invalid voltage, the operating voltage is the first voltage. When the second voltage is a valid voltage and the first voltage is an invalid voltage, the operating voltage is the second voltage. When both the first voltage and the second voltage are valid voltages, if the third voltage is greater than the reference voltage, the operating voltage is the first voltage. If the third voltage is less than the reference voltage, the operating voltage is the second voltage.

Description

[0001] This application is a divisional application of the patent application with patent application number "202111171501.2", application date "October 8, 2021" and name "Power Management Circuit". Technical Field

[0002] The present invention relates to the field of circuits, and in particular to a power management circuit. Background Art

[0003] Currently, existing power management circuits can switch between the main battery and backup battery. However, the main battery must have a presence detection signal, which the motherboard typically performs by checking the battery compartment lid. When the battery compartment lid is in place, the circuit is powered by the main battery. When the battery compartment lid is removed, the lid transmits an absence detection signal to the motherboard. While the main battery is still in the compartment, the software-controlled circuit switches power to the backup battery. The user first removes the main battery and replaces it with a new one, then closes the battery compartment lid. The battery compartment lid transmits a presence detection signal to the motherboard, causing the software-controlled circuit to switch back to the main battery.

[0004] The existing power management circuit needs to provide an additional detection signal to the motherboard, and the existing power management circuit needs to control the switching of power supply between the main battery and the backup battery through software algorithms, which has the technical problem that the existing power management circuit is relatively complex.

[0005] Therefore, it is necessary to provide a power management circuit with the function of controlling the backup battery voltage input to solve the above technical problems. Summary of the Invention

[0006] The present invention provides a power management circuit with a function of controlling the voltage input of a backup battery, which effectively solves the relatively complex technical problems of existing power management circuits.

[0007] The present invention provides a power management circuit for managing the power supply of a load, comprising:

[0008] a main battery, configured to output a first voltage;

[0009] A backup battery, used for outputting a second voltage;

[0010] A reference voltage module, used for outputting a reference voltage;

[0011] A voltage management module, comprising a voltage dividing unit, wherein the first voltage is converted into a third voltage by the voltage dividing unit, and the voltage management module comprises the TPS2121 chip described in the voltage management module;

[0012] The TPS2121 chip includes an IN1 pin, an IN2 pin, a CP2 pin, a PR1 pin, and an OUT pin; the IN1 pin is connected to the main battery for receiving the first voltage, the IN2 pin is connected to the backup battery for receiving the second voltage, the CP2 pin is connected to the reference voltage module for receiving the reference voltage, the PR1 pin is connected to one end of the voltage divider unit for receiving the third voltage, and the other end of the voltage divider unit is connected to the main battery; the OUT pin is used to output the operating voltage;

[0013] The power management circuit further includes a first control module, a second control module, and a key signal output module. The first control module outputs the first control signal, and based on the first control signal, the voltage management module determines whether to receive the first voltage. The power management circuit further includes a second control module, the second control module outputs the second control signal, and based on the second control signal, the voltage management module determines whether to receive the second voltage.

[0014] The power management circuit includes a voltage path management module, the voltage path management module including a first input terminal and a first output terminal, the first input terminal being connected to a charging power source, the first output terminal being connected to the main battery, and being used to protect the main battery during charging; the voltage path management module including a second input terminal and a second output terminal, the second input terminal being connected to the output terminal of the voltage management module, and the second output terminal being connected to the load, and being used to stabilize the operating voltage and manage the path between the operating voltage and the output voltage of the charging power source;

[0015] The reference voltage module outputs a reference voltage signal. The power management circuit further includes a charging power supply, which outputs a charging voltage signal. The power management circuit further includes a key signal output module, which outputs a key signal, and the key signal is valid at a low level.

[0016] Based on the first control module receiving the reference voltage signal, the first control module receiving the charging voltage signal, or the first control module receiving the key signal, the first control module outputs a first control signal to the voltage management module, and the voltage management module receives the first voltage;

[0017] The voltage path management module includes an enable terminal, the enable terminal outputs an enable signal, and the enable signal is valid at a low level;

[0018] Based on the second control module not receiving the reference voltage signal and the charging voltage signal, and the second control module receiving the key signal, the second control module outputs a second control signal to the voltage management module, and the voltage management module receives the second voltage;

[0019] or based on the second control module receiving the reference voltage signal and the second control module not receiving the enable signal, the second control module outputs a second control signal to the voltage management module, and the voltage management module receives the second voltage;

[0020] The TPS2121 chip further includes an OV1 pin and an OV2 pin, the key signal output module includes a power button, the first control module and the second control module each include a seventh MOS transistor, the first control module includes a first MOS transistor, and the second control module includes a second MOS transistor, a fifth MOS transistor, and a sixth MOS transistor;

[0021] The OV1 pin is connected to the main battery and the drain of the first MOS transistor, the source of the first MOS transistor is grounded, the gate of the first MOS transistor receives the reference signal, the charging voltage signal, and the key signal respectively, the gate of the first MOS transistor is also connected to the power supply and the drain of the seventh MOS transistor, the gate of the seventh MOS transistor is connected to the power button, and the source of the seventh MOS transistor is grounded;

[0022] The OV2 pin is connected to the drain of the second MOS transistor and the backup battery, the source of the second MOS transistor is grounded, the gate of the second MOS transistor is connected to the power supply and the drain of the fifth MOS transistor, the gate of the fifth MOS transistor receives the reference voltage signal, and the source of the fifth MOS transistor is grounded; the gate of the second MOS transistor also receives the enable signal; the gate of the second MOS transistor is also connected to the power supply and the drain of the sixth MOS transistor, the gate of the sixth MOS transistor receives the charging voltage signal, and the source of the sixth MOS transistor is grounded; the gate of the second MOS transistor receives the key signal, and the drain of the seventh MOS transistor is connected to the power supply and the gate of the second MOS transistor, the gate of the seventh MOS transistor is connected to the power button, and the source of the seventh MOS transistor is grounded;

[0023] The voltage path management module includes an ETA6956Q4Y chip, which includes a VAC pin, a VBUS pin, a BAT pin, and a SYS pin. The VAC pin and the VBUS pin are both connected to the charging power supply, and the BAT pin is connected to the main battery; the BAT pin is also connected to the OUT pin, and the SYS pin is connected to the load; the OUT pin is connected to the BAT pin, the VAC pin and the VBUS pin are both connected to the charging power supply, the BAT pin is also connected to the main battery, and the SYS pin is connected to the load;

[0024] The voltage path management module includes a main battery charging control unit, which is connected between the voltage path management module and the main battery and is used to control the charging power supply to charge the main battery; the second control module includes a conduction signal output unit, which is connected to the main battery charging control unit and outputs a conduction signal based on the second control module not outputting the second control signal and the conduction signal output unit receiving the reference voltage signal or the charging voltage signal. The conduction signal is used to control the on / off of the main battery charging control unit circuit in conjunction with the charging voltage signal or the reference voltage signal;

[0025] The main battery charging control unit includes a third MOS transistor and a fourth MOS transistor connected in parallel, the source of the third MOS transistor and the source of the fourth MOS transistor are both connected to the BAT pin, the drain of the third MOS transistor and the drain of the fourth MOS transistor are both connected to the main battery, the gate of the third MOS transistor receives the charging voltage signal and the reference voltage signal respectively, and the gate of the fourth MOS transistor receives the charging voltage signal and the reference voltage signal respectively;

[0026] The conduction signal output unit includes an eighth MOS transistor, the gate of the eighth MOS transistor is connected to the gate of the second MOS transistor, the source of the eighth MOS transistor is grounded, and the drain of the eighth MOS transistor outputs the conduction signal to the gates of the third MOS transistor and the fourth MOS transistor;

[0027] When both the first voltage and the second voltage are invalid voltages, the operating voltage is in a high-impedance state; when the first voltage is a valid voltage and the second voltage is an invalid voltage, the operating voltage is the first voltage; and when the second voltage is a valid voltage and the first voltage is an invalid voltage, the operating voltage is the second voltage.

[0028] When the first voltage and the second voltage are both effective voltages, based on the third voltage being greater than the reference voltage, the operating voltage is the first voltage; and based on the third voltage being less than the reference voltage, the operating voltage is the second voltage;

[0029] The voltage management module includes a voltage adjustment unit, and the TPS2121 chip also includes an ST pin. One end of the voltage adjustment unit is connected to the voltage divider unit, and the other end of the voltage adjustment unit is connected to the ST pin. When the third voltage is less than the reference voltage, the first voltage is switched to the second voltage, and the ST pin is used to control the voltage adjustment unit to pull down the third voltage, thereby preventing the circuit from oscillating. When the third voltage is greater than the reference voltage, the second voltage is switched to the first voltage, and the ST pin is used to control the voltage adjustment unit to pull up the third voltage, thereby preventing the circuit from oscillating.

[0030] In the power management circuit of the present invention, the power management circuit includes:

[0031] a main battery, configured to output a first voltage;

[0032] A backup battery, used for outputting a second voltage;

[0033] A reference voltage module, used for outputting a reference voltage;

[0034] a voltage management module, receiving a first voltage, a second voltage, and a reference voltage, and outputting an operating voltage to the load; the voltage management module includes a voltage dividing unit, and the first voltage is converted into a third voltage by the voltage dividing unit;

[0035] When both the first voltage and the second voltage are the invalid voltages, the operating voltage is in a high-impedance state; when the first voltage is the valid voltage and the second voltage is the invalid voltage, the operating voltage is the first voltage; and when the second voltage is the valid voltage and the first voltage is the invalid voltage, the operating voltage is the second voltage.

[0036] When the first voltage and the second voltage are both the effective voltages, if the third voltage is greater than the reference voltage, the operating voltage is the first voltage; if the third voltage is less than the reference voltage, the operating voltage is the second voltage.

[0037] In the power management circuit of the present invention, the power management circuit includes a first control module, the first control module outputs a first control signal, the voltage management module receives the first control signal, and based on the first control signal, the voltage management module determines whether to receive the first voltage;

[0038] The power management circuit includes a second control module, the second control module outputs a second control signal, the voltage management module receives the second control signal, and determines whether the voltage management module receives the second voltage based on the second control signal.

[0039] In the power management circuit of the present invention, the power management circuit includes a voltage path management module, the voltage path management module includes a first input end and a first output end, the first input end is connected to a charging power source, and the first output end is connected to the main battery, for protecting the main battery during charging;

[0040] The voltage path management module includes a second input end and a second output end, the second input end is connected to the output end of the voltage management module, and the second output end is connected to the load, and is used to stabilize the operating voltage and manage the path between the operating voltage and the output voltage of the charging power supply.

[0041] In the power management circuit of the present invention, the reference voltage module outputs a reference voltage signal, the power management circuit further includes a charging power supply, the charging power supply outputs a charging voltage signal, and the power management circuit further includes a key signal output module, the key signal output module outputs a key signal, and the key signal is valid at a low level;

[0042] Based on the first control module receiving the reference voltage signal, the first control module receiving the charging voltage signal, or the first control module receiving the key signal, the first control module outputs a first control signal to the voltage management module, and the voltage management module receives the first voltage;

[0043] The voltage path management module includes an enable terminal, the enable terminal outputs an enable signal, and the enable signal is valid at a low level;

[0044] Based on the second control module not receiving the reference voltage signal, the second control module not receiving the charging voltage signal, and the second control module not receiving the key signal, the second control module outputs a second control signal to the voltage management module, and the voltage management module receives the second voltage;

[0045] Alternatively, based on the second control module receiving the reference voltage signal and the second control module not receiving the enable signal, the second control module outputs a second control signal to the voltage management module, and the voltage management module receives the second voltage.

[0046] In the power management circuit of the present invention, the voltage management module includes a TPS2121 chip, and the TPS2121 chip includes an IN1 pin, an IN2 pin, a CP2 pin, a PR1 pin, and an OUT pin. The IN1 pin is connected to the main battery and is used to input the first voltage. The IN2 pin is connected to the backup battery and is used to input the second voltage.

[0047] The CP2 pin is connected to the reference voltage module, and the CP2 pin is used to input the reference voltage. The PR1 pin is connected to one end of the voltage divider unit, and the other end of the voltage divider unit is connected to the main battery. The PR1 pin is used to input the third voltage. The OUT pin is connected to the load, and the OUT pin is used to output the operating voltage.

[0048] In the power management circuit of the present invention, the TPS2121 chip further includes an OV1 pin and an OV2 pin, the key signal output module includes a power button, the first control module and the second control module both include a seventh MOS transistor, the first control module includes a first MOS transistor, the drain of the first MOS transistor is respectively connected to the main battery and the OV1 pin, the source of the first MOS transistor is grounded, the gate of the first MOS transistor respectively receives the charging voltage signal, the reference voltage signal, and the key signal, the gate of the first MOS transistor is connected to a power supply and the drain of the seventh MOS transistor, the gate of the seventh MOS transistor is connected to the power button, and the source of the seventh MOS transistor is grounded;

[0049] The second control module includes a second MOS transistor, a fifth MOS transistor, and a sixth MOS transistor. The drain of the second MOS transistor is respectively connected to the backup battery and the OV2 pin, the source of the second MOS transistor is grounded, the gate of the second MOS transistor is connected to the power supply and the drain of the fifth MOS transistor, the gate of the fifth MOS transistor receives the reference signal, and the source of the fifth MOS transistor is grounded; the gate of the second MOS transistor also receives the enable signal; the gate of the second MOS transistor is also connected to the power supply and the drain of the sixth MOS transistor, the gate of the sixth MOS transistor receives the charging signal, and the source of the sixth MOS transistor is grounded; the gate of the second MOS transistor also receives the key signal, the drain of the seventh MOS transistor is connected to the gate of the second MOS transistor and the power supply, the gate of the seventh MOS transistor is connected to the power button, and the source of the seventh MOS transistor is grounded.

[0050] In the power management circuit of the present invention, the voltage path management module includes an ETA6956Q4Y chip, and the ETA6956Q4Y chip includes the VAC pin, the VBUS pin, the BAT pin, and the SYS pin. The VAC pin and the VBUS pin are both connected to the charging power supply, and the BAT pin is connected to the main battery; the BAT pin is also connected to the OUT pin, and the SYS pin is connected to the load;

[0051] In the power management circuit of the present invention, the voltage path management module includes a main battery charging control unit, which is connected between the voltage path management module and the main battery and is used to control the charging power supply to charge the main battery; the second control module includes a conduction signal output unit, which is connected to the main battery charging control unit and outputs the conduction signal based on the second control module not outputting the second control signal and the conduction signal output unit receiving the reference voltage signal or the charging voltage signal. The conduction signal is used to control the on / off of the main battery charging control unit circuit in conjunction with the charging voltage signal or the reference voltage signal;

[0052] The main battery charging control unit includes a third MOS transistor and a fourth MOS transistor connected in parallel, wherein the source of the third MOS transistor and the source of the fourth MOS transistor are both connected to the BAT pin, and the drain of the third MOS transistor and the drain of the fourth MOS transistor are both connected to the main battery; the gate of the third MOS transistor receives the charging voltage signal and the reference voltage signal respectively; the gate of the fourth MOS transistor receives the charging voltage signal and the reference voltage signal respectively;

[0053] The conduction signal output unit includes an eighth MOS transistor, the gate of the eighth MOS transistor is connected to the gate of the second MOS transistor, the source of the eighth MOS transistor is grounded, and the drain of the eighth MOS transistor outputs the conduction signal to the gates of the third MOS transistor and the fourth MOS transistor.

[0054] In the power management circuit described in the present invention, the voltage management module includes a voltage adjustment unit, and the TPS2121 chip also includes an ST pin. One end of the voltage adjustment unit is connected to the voltage divider unit, and the other end of the voltage adjustment unit is connected to the ST pin. When the third voltage is less than the reference voltage, the first voltage is switched to the second voltage, and the ST pin is used to control the voltage adjustment unit to pull down the third voltage, thereby preventing the circuit from oscillating. When the third voltage is greater than the reference voltage, the second voltage is switched to the first voltage, and the ST pin is used to control the voltage adjustment unit to pull up the third voltage, thereby preventing the circuit from oscillating.

[0055] Compared to the prior art, the present invention has the following advantages: The present invention provides a power management circuit, comprising a main battery, a backup battery, a reference voltage module, and a voltage management module. The voltage management module receives a first voltage, a second voltage, and a reference voltage, and outputs an operating voltage to a load. The voltage management module receives the first voltage, the second voltage, and the reference voltage, and outputs the operating voltage to the load. The voltage management module includes a voltage divider unit, which converts the first voltage into a third voltage.

[0056] When both the first and second voltages are invalid, the operating voltage output by the voltage management module assumes a high-impedance state. When the first voltage is valid and the second voltage is invalid, the operating voltage output by the voltage management module is the first voltage. When the second voltage is valid and the first voltage is invalid, the operating voltage is the second voltage. When both the first and second voltages are valid, the operating voltage output by the voltage management module is the first voltage, based on the third voltage being greater than the reference voltage. When both the first and second voltages are valid, the operating voltage output by the voltage management module is the second voltage, based on the third voltage being less than the reference voltage. Therefore, the voltage management circuit can switch the voltage outputs of the main battery and backup battery. This voltage management circuit does not require detection of a battery compartment lid presence detection signal. Assuming both the first and second voltages are valid, the voltage management circuit directly uses the third voltage as a detection signal to switch the power supply. The power switching process is performed solely by hardware circuitry, eliminating the need for software-based judgment and control. This results in a relatively simple circuit structure for the power management circuit, effectively resolving the technical issues associated with the complexity of existing power management circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 FIG. 1 is a block diagram of a power management circuit according to an embodiment of the present invention.

[0058] Figure 2 FIG. 1 is a circuit diagram of an embodiment of a power management circuit of the present invention.

[0059] Figure 3 FIG. 4 is a circuit diagram of a voltage path management module of a power management circuit of the present invention.

[0060] Figure 4 This is a circuit diagram of the backup battery charging management module of the power management circuit of the present invention.

[0061] In the figure, 10, power management circuit; 11, main battery; 12, backup battery; 13, reference voltage module; 14, voltage management module; 141, voltage divider unit; 142, voltage adjustment unit; 15, first control module; 16, second control module; 161, conduction signal output unit; 17, key signal output module; 171, power button; 18, voltage path management module; 181, main battery charging control unit; 19, backup battery charging management module; 20, charging power supply; 21, power supply. DETAILED DESCRIPTION

[0062] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0063] Directional terms mentioned in the present invention, such as "up", "down", "front", "back", "left", "right", "inside", "outside", "side", "top" and "bottom", are only used with reference to the directions of the drawings. The directional terms used are used to illustrate and understand the present invention, and are not used to limit the present invention.

[0064] The terms "first" and "second" in the present invention are used for descriptive purposes only and should not be understood as indicating or implying relative importance, and should not be used as a limitation on the order of precedence.

[0065] Please refer to Figures 1 to 4 , Figure 1 is a block diagram of an embodiment of a power management circuit of the present invention; Figure 2 is a circuit diagram of an embodiment of a power management circuit of the present invention; Figure 3 A circuit diagram of a voltage path management module of an embodiment of a power management circuit of the present invention; Figure 4 FIG. 1 is a circuit diagram of an embodiment of a backup battery charging management module of a power management circuit of the present invention.

[0066] In the figures, structurally similar elements are denoted by the same reference numerals.

[0067] Please refer to Figure 1The present invention provides a power management circuit 10. This power management circuit 10 includes a main battery 11, a backup battery 12, a reference voltage module 13, a voltage management module 14, a first control module 15, a second control module 16, and a voltage path management module 18. The main battery 11 is configured to output a first voltage, the backup battery 12 is configured to output a second voltage, and the reference voltage module 13 outputs a reference voltage. This power management circuit 10 is applied to a handheld device.

[0068] Please refer to Figures 1 to 2 The voltage management module 14 receives the first voltage, the second voltage, and the reference voltage. The output terminal of the voltage management module 14 outputs the operating voltage to the load. The voltage management module 14 includes a voltage divider 141 connected to the main battery 11. The voltage divider 141 includes a first resistor R1903, a second resistor R1904, and a third resistor R1905. The first resistor R1903, the second voltage R1904, and the third voltage R1905 are connected in parallel. The first voltage is converted to the third voltage by the voltage divider 141.

[0069] Please refer to Figures 1 to 2 When both the first voltage and the second voltage are invalid voltages, the operating voltage outputted by the output terminal of the voltage management module 14 is in a high-impedance state. When the first voltage is a valid voltage and the second voltage is an invalid voltage, the operating voltage outputted by the output terminal of the voltage management module 14 is the first voltage. When the second voltage is a valid voltage and the first voltage is an invalid voltage, the operating voltage outputted by the output terminal of the voltage management module 14 is the second voltage.

[0070] Please refer to Figures 1 to 2 When both the first and second voltages are valid voltages, the operating voltage outputted by the output terminal of the voltage management module 14 is the first voltage, based on the third voltage being greater than the reference voltage. When both the first and second voltages are valid voltages, the operating voltage outputted by the output terminal of the voltage management module 14 is the second voltage, based on the third voltage being less than the reference voltage. Therefore, the voltage management circuit 10 can switch between the voltages outputted by the main battery 11 and the backup battery 12, with a switching time of only 5μs, achieving essentially seamless switching. When the power management circuit 10 is operating normally and the main battery 11 is hot-swapped, the power management circuit 10 can switch to power supplied by the backup battery 12, making handheld devices equipped with this power management circuit 10 more user-friendly. The ETA6956Q4Y chip can detect a first voltage between 2.6V and 6V as a valid voltage, and a second voltage between 2.6V and 6V as a valid voltage.

[0071] Please refer to Figures 1 to 2The voltage management module 14 includes a voltage adjustment unit 142, which includes a fourth resistor R1994 and a fifth resistor R1995 connected in series. The resistance of the fourth resistor R1994 and the fifth resistor R1995 are both 470kΩ. The TPS2121 chip also includes an ST pin. One end of the voltage adjustment unit 142 is connected to the voltage divider unit 141, and the other end of the voltage adjustment unit 142 is connected to the ST pin. When the third voltage is less than the reference voltage, the first voltage switches to the second voltage, and the voltage adjustment unit 142 pulls down the third voltage. When the third voltage is greater than the reference voltage, the second voltage switches to the first voltage, and the voltage adjustment unit 142 pulls up the third voltage. Furthermore, when the first voltage is less than 3V, the third voltage is less than the reference voltage of 1.8V, the first voltage switches to the second voltage, and the voltage adjustment unit 142 pulls down the third voltage, making it difficult for the third voltage to fluctuate above the reference voltage of 1.8V. When the first voltage is greater than 3.42V, the third voltage is greater than the reference voltage of 1.8V, and the second voltage switches to the first voltage. The voltage adjustment unit 142 pulls up the third voltage, making it difficult for the third voltage to fluctuate below the reference voltage of 1.8V. Therefore, the first voltage has a hysteresis of 0.42V. The configuration of the voltage adjustment unit 142 can prevent the first voltage from repeatedly switching between the second voltage and the first voltage.

[0072] Please refer to Figures 1 to 2 The voltage management module 14 includes a TPS2121 chip, which includes an IN1 pin, an IN2 pin, a CP2 pin, a PR1 pin, and an OUT pin. The IN1 pin is connected to the main battery 11 and is used to input a first voltage. The IN2 pin is connected to the backup battery 12 and is used to input a second voltage. The IN2 pin is connected in parallel with the twenty-eighth capacitor C1909. The CP2 pin is connected to the reference voltage module 13 and is used to input a reference voltage. The PR1 pin is connected to one end of the voltage divider unit 141, and the other end of the voltage divider unit 142 is connected to the main battery 11. The PR1 pin is used to input a third voltage. The OUT pin is connected to a load and is used to output an operating voltage.

[0073] Please refer to Figures 1 to 2The TPS2121 chip includes an OUT1 pin, an ILIM pin, and an SS pin. The voltage management module 14 includes a sixth resistor R1912 and a first capacitor C1910. The sixth resistor R1912 has a resistance of 10 kΩ, and the first capacitor C1910 has a capacitive reactance of 100 nF. One end of the sixth resistor R1912 is connected to the ILIM pin, and the other end of the sixth resistor R1912 is grounded. One end of the first capacitor C1910 is connected to the SS pin, and the other end of the first capacitor C1910 is grounded. The voltage management module 14 includes a second capacitor C1901, a third capacitor C1902, a fourth capacitor C1903, a fifth capacitor C1904, and a sixth capacitor C1905. The second capacitor C1901, the third capacitor C1902, the fourth capacitor C1903, the fifth capacitor C1904, and the sixth capacitor C1905 have a capacitive reactance of 22 μF and a maximum withstand voltage of 10 V. The second capacitor C1901, the third capacitor C1902, the fourth capacitor C1903, the fifth capacitor C1904, and the sixth capacitor C1905 are all connected in parallel to the OUT pin.

[0074] Please refer to Figures 1 to 2 The voltage management module 14 includes a seventh capacitor C1948, an eighth capacitor C1958, a ninth capacitor C1932, a tenth capacitor C1957, an eleventh capacitor C1931, a twelfth capacitor C1956, a thirteenth capacitor C1930, a fourteenth capacitor C1955, a fifteenth capacitor C1929, a sixteenth capacitor C1954, a seventeenth capacitor C1928, an eighteenth capacitor C1953, a nineteenth capacitor C1927, a twentieth capacitor C1952, a twenty-first capacitor C1926, a twenty-second capacitor C1951, a twenty-third capacitor C1925, a twenty-fourth capacitor C1950, a twenty-fifth capacitor C1924, and a twenty-sixth capacitor C1949. The seventh capacitor C1948, the eighth capacitor C1958, the ninth capacitor C1932, the tenth capacitor C1957, the eleventh capacitor C1931, the twelfth capacitor C1956, the thirteenth capacitor C1930, the fourteenth capacitor C1955, the fifteenth capacitor C1929, the sixteenth capacitor C1954, the seventeenth capacitor C1928, the eighteenth capacitor C1953, the nineteenth capacitor C1927, the twentieth capacitor C1952, the twenty-first capacitor C1926, the twenty-second capacitor C1951, the twenty-third capacitor C1925, the twenty-fourth capacitor C1950, the twenty-fifth capacitor C1924, and the twenty-sixth capacitor C1949 are all connected in parallel to the OUT pin.

[0075] Please refer to Figures 1 to 2The power management circuit 10 includes a first control module 15, which outputs a first control signal. The voltage management module 14 receives the first control signal and determines whether the voltage management module 14 receives a first voltage based on the high and low levels of the first control signal. The power management circuit 10 includes a second control module 16, which outputs a second control signal. The voltage management module 14 receives the second control signal and determines whether the voltage management module 14 receives a second voltage based on the high and low levels of the second control signal. The power management circuit 10 also includes a key signal output module 17, which is connected to the first control module 15 and the second control module 16. The key signal output module 17 is used to output a key signal, and the key signal is valid at a low level.

[0076] Please refer to Figures 1 to 2 The TPS2121 chip also includes OV1 and OV2 pins, and the key signal output module 17 includes a power button 171 and a ninth diode D1910. Both the first control module 15 and the second control module 16 include a seventh MOS transistor. The first control module 15 includes a first MOS transistor Q1904, the drain of which is connected to the main battery 11 and the OV1 pin, respectively. Based on whether the reference voltage module 13 outputs a reference voltage, the reference voltage module 13 outputs a reference voltage signal. Based on whether the charging power supply 20 outputs a charging voltage, the charging power supply 20 outputs a charging voltage signal. Based on whether the power button 171 is grounded, the key signal output module 17 outputs a high or low level key signal. The source of the first MOS transistor Q1904 is grounded, and the gate of the first MOS transistor Q1904 is connected to the charging power supply 20 and the reference voltage module 13, respectively. The gate of the first MOS transistor Q1904 receives the charging voltage signal, the reference voltage signal, and the key signal, respectively. The gate of the first MOS transistor Q1904 is also connected to a power source and the drain of the seventh MOS transistor Q1907. The power source 21 can be the main battery 11, the backup battery 12, or the charging power source 20. The gate of the seventh MOS transistor Q1907 is connected to the power button 171, and the source of the seventh MOS transistor Q1907 is grounded. The anode of the ninth diode D1910 is connected to the gate of the seventh MOS transistor Q1907, and the cathode of the ninth diode D1910 is connected to the power button 171.

[0077] Please refer to Figures 1 to 2The first control module 15 also includes a seventh resistor R1920, an eighth resistor R1969, and a twenty-seventh capacitor C1983. The capacitive reactance of the twenty-seventh capacitor C1983 is 100 pF. One end of the seventh resistor R1920 is connected to the gate of the first MOS transistor Q1904, and the other end of the seventh resistor R1920 is connected to the eighth resistor R1969. The twenty-seventh capacitor C1983 is connected in parallel with the eighth resistor R1969, and one end of the eighth resistor R1969 is grounded. The first control module 15 includes a first diode D1928, a second diode D1927, and a third diode D1926. The anode of the first diode D1928 is connected to the reference voltage module 13, and the cathode of the first diode D1928 is connected to the gate of the first MOS transistor Q1904. The anode of the second diode D1927 is connected to the charging power source 20, and the cathode of the second diode D1927 is connected to the gate of the first MOS transistor. The anode of the third diode D1926 is connected to the drain of the seventh MOS transistor, and the cathode of the third diode D1926 is connected to the gate of the first MOS transistor. The first control module 15 also includes a ninth resistor R1906, a tenth resistor R1913, and an eleventh resistor R1914. One end of the ninth resistor R1906 is connected, and the other end of the ninth resistor R1906 is connected to the tenth resistor R1913. The tenth resistor R1913 is connected to the drain of the first MOS transistor Q1904. One end of the eleventh resistor R1914 is connected to the OV1 pin, and the other end of the eleventh resistor R1914 is grounded.

[0078] Please refer to Figures 1 to 2The second control module 16 includes a second MOS transistor Q1905, a fifth MOS transistor Q1908, and a sixth MOS transistor Q1919. The drain of the second MOS transistor Q1905 is connected to the backup battery 12 and the OV2 pin, respectively. The source of the second MOS transistor Q1905 is grounded, and the gate of the second MOS transistor Q1905 is connected to the power supply 21 and the drain of the fifth MOS transistor Q1908. The gate of the fifth MOS transistor Q1908 is connected to the reference voltage module 13, and the gate of the fifth MOS transistor Q1908 receives a reference voltage signal. The source of the fifth MOS transistor is grounded, and the gate of the second MOS transistor Q1905 also receives an enable signal. The gate of the second MOS transistor Q1905 is also connected to the power supply 21 and the drain of the sixth MOS transistor Q1919. The gate of the sixth MOS transistor Q1919 is connected to the charging power supply 20, and the gate of the sixth MOS transistor Q1919 receives a charging voltage signal. The source of the sixth MOS transistor Q1919 is grounded. The gate of the second MOS transistor Q1905 receives a key signal. The gate of the second MOS transistor Q1905 is also connected to a power source and the drain of the seventh MOS transistor Q1907. The power source 21 can be the main battery 11, the backup battery 12, or the charging power source 20. The gate of the seventh MOS transistor Q1907 is connected to the power button 171, and the source of the seventh MOS transistor Q1907 is grounded. A twenty-third resistor R1926 is connected between the drain of the seventh MOS transistor Q1907 and the power source 21. A forty-fifth resistor R1929 is connected between the gate of the seventh MOS transistor Q1907 and the power source 21.

[0079] Please refer to Figures 1 to 2The second control module 16 further includes a fourth diode D1922, a fifth diode D1908, a sixth diode D1909, a twelfth resistor R1910, a thirteenth resistor R1916, a fourteenth resistor R1911, a fifteenth resistor R1919, a sixteenth resistor R1965, a seventeenth resistor R1924, and a twenty-ninth capacitor C1935. The anode of the fourth diode D1922 is connected to the drain of the fifth MOS transistor Q1908, and the cathode of the fourth diode D1922 is connected to the gate of the second MOS transistor. The fifth diode D1908 is connected to the seventeenth resistor R1924. The anode of the sixth diode D1909 is connected to the drain of the seventh MOS transistor Q1907, and the cathode of the sixth diode D1909 is connected to the anode of the fourth diode D1922. A twelfth resistor R1910 is connected between the IN2 pin and the OV2 pin. A thirteenth resistor R1916 is connected between the OV2 pin and the drain of the second MOS transistor Q1905. One end of a fourteenth resistor R1911 is connected to the OV2 pin, and the other end of the fourteenth resistor R1911 is grounded. One end of a fifteenth resistor R1919 is connected to the gate of the second MOS transistor Q1905, and the other end of the fifteenth resistor R1919 is connected to the seventeenth resistor R1924. One end of a sixteenth resistor R1965 is connected between the fifteenth resistor R1919 and the seventeenth resistor R1924, and the other end of the sixteenth resistor R1965 is grounded. A twenty-ninth capacitor C1935 is connected in parallel with the sixteenth resistor R1965.

[0080] Please refer to Figures 1 to 2The second control module 16 further includes an eighteenth resistor R1922, a nineteenth resistor R1925, a twentieth resistor R1970, a twenty-first resistor R1964, a twenty-second resistor R1955, a twenty-third resistor R1955, a twenty-fourth resistor R1930, a thirtieth capacitor C1932, and a thirty-first capacitor C1934. One end of the eighteenth resistor R1922 is connected to the reference voltage module 13, and the other end of the eighteenth resistor R1922 is connected to the nineteenth resistor R1925. The nineteenth resistor R1925 is connected to the fifth diode D1908. One end of the twentieth resistor R1970 is connected to the gate of the sixth MOS transistor Q1919, and the other end of the twentieth resistor R1970 is connected to the charging power source 20. One end of the twenty-first resistor R1964 is connected to the gate of the sixth MOS transistor, and the other end of the twenty-first resistor R1964 is grounded. One end of the 22nd resistor R1955 is connected to the gate of the fifth MOS transistor Q1908, and the other end of the 22nd resistor R1955 is connected to the reference voltage module 13. One end of the 30th capacitor C1932 is connected to the gate of the fifth transistor Q1908 and the anode of the first diode D1928, and the other end of the 30th capacitor C1932 is grounded. One end of the 24th resistor R1930 is connected to the drain of the fifth MOS transistor Q1908, and the other end of the 24th resistor R1930 is grounded. A 31st capacitor C1934 is connected in parallel with the 24th resistor R1930.

[0081] Please refer to Figure 1 and Figure 3 The power management circuit 10 includes a voltage path management module 18. The voltage path management module 18 includes a first input terminal and a first output terminal. The first input terminal is connected to the charging power source 12, and the first output terminal is connected to the main battery 11. When the main battery 11 is charging, the voltage path management module 18 can protect the main battery to prevent large currents from damaging the main battery. The voltage path management module 18 includes a second input terminal and a second output terminal. The second input terminal is connected to the output terminal of the voltage management module 14, and the second output terminal is connected to the load. The voltage path management module 18 can also stabilize the operating voltage. Because the operating voltage is output to the load through the voltage path management module 18, and the voltage output by the charging power source 20 is output to the main battery 11 through the voltage path management module 18, the voltage path management module 18 can manage the path between the operating voltage and the output voltage of the charging power source 20.

[0082] Please refer to Figure 1 and Figure 3The voltage path management module 14 includes an ETA6956Q4Y chip. The ETA6956Q4Y chip includes a VAC pin, a VBUS pin, a BAT pin, and a SYS pin. The VAC pin and VBUS pin are all connected to the charging power supply 20, and the BAT pin is connected to the main battery. The BAT pin is also connected to the OUT pin, and the SYS pin is connected to the load. The ETA6956Q4Y chip also includes a PMID pin, an NCE pin, a PSEL pin, an NQON pin, a SW pin, a NINT pin, and an NPG pin. The voltage path management module 18 also includes a 30th resistor R610, a 31st resistor R611, a 32nd resistor R612, a 33rd resistor R613, a 34th resistor R614, a 35th resistor R615, a 33rd capacitor C607, and a 34th capacitor C608. The 33rd capacitor C607 is connected in parallel with the VAC pin, one end of the 34th capacitor C608 is connected to the PMID pin, and the other end of the 34th capacitor C608 is grounded. The NINT pin and the NPG pin are both connected to the reference voltage module 13. The 30th resistor R610 is connected between the NINT pin and the reference voltage module 13, and the 31st resistor R611 is connected between the NPG pin and the reference voltage module 13. The NCE pin is connected to the 19th resistor R1925. The NCE pin is the enable terminal of the voltage path management module 14. Based on whether the voltage path management module 14 receives the charging voltage, the NCE pin outputs an enable signal, and the enable signal is valid low. The NQON pin is connected to one end of the 35th resistor R615, and the other end of the 35th resistor R615 is connected to the power button 171. The PSEL pin is connected to one end of the 33rd resistor R613, and the other end of the 33rd resistor R613 is connected to the reference voltage module 13. The 34th resistor R614 is connected in parallel with the PSEL pin.

[0083] Please refer to Figure 1 and Figure 3The ETA6956Q4Y chip also includes a BST pin, a SW pin, a STAT pin, a VLDO pin, a TS pin, an NC pin, and a GND pin. The voltage path management module 18 also includes a 36th resistor R620, a 37th resistor R621, a 35th capacitor C609, a 36th capacitor C612, a 37th capacitor C614, a 38th capacitor C615, a 39th capacitor C610, a 40th capacitor C611, and an inductor L601. The 35th capacitor C609 is connected in series between the BST pin and the SW pin, and the SW pin is connected to the SYS pin. The inductor L601 is connected in series with the SW pin, and the 36th capacitor C612, the 37th capacitor C614, and the 38th capacitor C615 are all connected in parallel with the SW pin. The 40th capacitor C611 is connected in parallel with the BAT pin, one end of the 39th capacitor C610 is connected to the VLDO pin, and the other end of the 39th capacitor C610 is grounded. One end of the 37th resistor R621 is connected to the TS pin, the other end of the 37th resistor R621 is grounded, and the 36th resistor R620 is connected between the VLDO pin and the TS pin. The STAT pin and the NC pin are both floating, and the GND pin is grounded.

[0084] Please refer to Figures 1 to 3 The voltage path management module 18 includes a main battery charging control unit 181, which is connected between the voltage path management module 18 and the main battery 11. The main battery charging control unit 181 can control the charging power supply 20 to charge the main battery 11. The second control module 16 includes a conduction signal output unit 161, which is connected to the main battery charging control unit 181. If the second control module does not output the second control signal and the conduction signal output unit 161 receives a reference voltage signal or a charging voltage signal, the conduction signal output unit 161 outputs a conduction signal. The conduction signal can be used to control the main battery charging control unit 181 circuit in conjunction with the charging voltage signal or the reference voltage signal.

[0085] Please refer to Figures 1 to 2The main battery charging control unit 181 includes a third MOS transistor Q1901 and a fourth MOS transistor Q1902 connected in parallel. The source of the third MOS transistor Q1901 and the source of the fourth MOS transistor Q1902 are both connected to the BAT pin. The drain of the third MOS transistor Q1901 and the drain of the fourth MOS transistor Q1902 are both connected to the main battery. The gate of the third MOS transistor Q1901 is connected to the charging power supply 20 and the reference voltage module 13, respectively, and the gate of the third MOS transistor Q1901 receives the charging voltage signal and the reference voltage signal, respectively. The gate of the fourth MOS transistor Q1902 is connected to the charging power supply 20 and the reference voltage module 13, respectively, and the gate of the fourth MOS transistor Q1902 receives the charging voltage signal and the reference voltage signal, respectively. The conduction signal output unit 161 includes an eighth MOS transistor Q1906. The gate of the eighth MOS transistor Q1906 is connected to the gate of the second MOS transistor, the source of the eighth MOS transistor Q1906 is grounded, and the drain of the eighth MOS transistor Q1906 is connected to the gates of the third MOS transistor Q1901 and the fourth MOS transistor Q1902. The drain of the eighth MOS transistor Q1906 outputs a conduction signal to the gates of the third MOS transistor Q1901 and the fourth MOS transistor Q1902. The main battery charging control unit 181 includes a tenth MOS transistor Q1911 and an eleventh MOS transistor Q1912. The gates of the tenth MOS transistor Q1911 and the eleventh MOS transistor Q1912 are both connected to the gate of the third MOS transistor Q1901, and the drains of the tenth MOS transistor Q1911 and the fourth MOS transistor Q1912 are both connected to the BAT pin. The source of the tenth MOS transistor Q1911 is connected to the source of the third MOS transistor Q1901, and the source of the eleventh MOS transistor Q1912 is connected to the source of the fourth MOS transistor Q1902. The main battery charging control unit 181 also includes a twenty-sixth resistor R1901 and a thirty-second capacitor C1937. The twenty-sixth resistor R1901 is connected between the source and gate of the eleventh MOS transistor Q1912, and the twenty-seventh capacitor C1937 is connected between the source and gate of the tenth MOS transistor Q1911.

[0086] Please refer to Figures 1 to 2The voltage path management module 18 includes a ninth MOS transistor Q1903, a twenty-seventh resistor R1967, a thirty-second capacitor C1936, a twenty-eighth resistor R1902, a twenty-ninth resistor R1999, a seventh diode D1924, and an eighth diode D1925. The drain of the ninth MOS transistor Q1903 is connected to the gate of the fourth MOS transistor. The source of the ninth MOS transistor Q1903 is grounded. The drain of the ninth MOS transistor Q1903 is connected to the reference voltage module 13, the conduction signal output unit 161, and the charging power source 12, respectively. The twenty-seventh resistor R1967 and the thirty-second capacitor C1936 are connected between the source and gate of the ninth MOS transistor Q1903. The anode of the seventh diode D1924 is connected to the reference voltage module 13, and the cathode of the seventh diode D1924 is connected to the gate of the ninth MOS transistor Q1903. The anode of the eighth diode D1925 is connected to the charging power source 20, and the cathode of the eighth diode D1925 is connected to the gate of the ninth MOS transistor Q1903. The twenty-eighth resistor R1902 is connected between the gate of the ninth MOS transistor Q1903 and the cathode of the seventh diode D1924. The twenty-ninth resistor R1999 is connected between the anode of the eighth diode D1925 and the charging power source 20.

[0087] Please refer to Figure 1 and Figure 4The power management circuit 10 also includes a backup battery charging management module 19. One end of the backup battery charging management module 19 is connected to the charging power source 20, and the other end of the backup battery charging management module 19 is connected to the backup battery 12. The backup battery charging management module 19 can be used to protect the backup battery 12. When the backup battery 12 is charging, the backup battery charging management module 19 can protect the backup battery 12 to prevent damage to the backup battery 12 due to large current. The backup battery charging management module 19 includes a BQ24040 chip, which includes an IN pin, an ISET pin, a VSS pin, a PRETERM pin, a PG pin, an OUT pin, a TS pin, a CHG pin, an ISET2 pin, an NC pin, and a GND pin. The IN pin is connected to the charging power source 20, and the OUT pin is connected to the backup battery 12. The backup battery charging management module 19 also includes a Zener diode V1912, a 41st capacitor C1918, a 42nd capacitor C1919, a 38th resistor R1934, a 39th resistor R1938, a 40th resistor R1939, and a 41st resistor R1941. The 41st capacitor C1918 and the 42nd capacitor C1919 are connected in parallel to the IN pin. One end of the 38th resistor R1934 is connected to the ISET pin, and the other end of the 38th resistor R1934 is grounded. One end of the 39th resistor R1938 is connected to the PRETERM pin, the other end of the 39th resistor R1938 is grounded, and the VSS pin is grounded. The PG pin is connected to the 40th resistor R1939. One end of the 41st resistor R1941 is connected to the 40th resistor R1939, and the other end of the 41st resistor R1941 is grounded.

[0088] Please refer to Figure 1 and Figure 4 The backup battery charging management module 19 further includes a forty-third capacitor C1920, a forty-fourth capacitor C1921, a forty-second resistor R1935, a forty-third resistor R1936, and a forty-fourth resistor R1940. The forty-third capacitor C1920 and the forty-fourth capacitor C1921 are both connected in parallel to the OUT pin. One end of the forty-second resistor R1935 is connected to the TS pin, and the other end of the forty-second resistor R1935 is grounded. One end of the forty-third resistor R1936 is connected to the CHG pin, and the other end of the forty-third resistor R1936 is connected to the forty-fourth resistor R1940. The forty-fourth resistor R1940 is also grounded. The ISET2 pin and the GND pin are both grounded, and the NC pin is left floating.

[0089] The operating principle of the power management circuit 10 of the present invention is as follows: When the power management circuit 10 is operating normally, the main battery 11 outputs a first voltage. This first voltage is converted to a third voltage by the voltage divider 141. The reference voltage module 13 outputs the reference voltage, and the voltage management module 14 inputs the third voltage and the reference voltage. When the circuit is operating normally, based on the reference voltage output by the reference voltage module 14, the reference voltage module outputs a reference voltage signal, which is received by the first control module 15. The anode of the first diode D1928 receives the reference voltage signal, causing the first diode D1928 to conduct. The gate of the first MOS transistor Q1904 receives the reference voltage signal, causing the first MOS transistor Q1904 to conduct, and the first control module 15 outputs a first control signal. The voltage management module 14 receives the first control signal, and therefore inputs the first voltage.

[0090] Alternatively, when the charging power supply 20 is charging the main battery 11 or the backup battery 12, the charging power supply 20 outputs a charging voltage. Based on the charging voltage output by the charging power supply 20, the charging power supply outputs a charging voltage signal. The first control module 15 receives the charging voltage signal, and the anode of the second diode D1927 receives the charging voltage signal. The gate of the first MOS transistor Q1904 receives the charging voltage signal, thereby turning on the first MOS transistor Q1904 and causing the first control module 15 to output a first control signal. The voltage management module receives the first control signal, and the voltage management module 14 inputs the first voltage.

[0091] Alternatively, when the user presses the power button 171, the key signal input module 17 outputs a key signal based on the grounding of the power button 171, and the first control module 15 receives the key signal. Because the power button 171 is grounded, the ninth diode D1910 receives a low-level key signal and is not conducting. Because the gate of the seventh MOS transistor Q1907 is connected to the power button 171 via the ninth diode D1910, the gate of the seventh MOS transistor Q1907 receives a low-level key signal and is not conducting. Because the drain of the seventh MOS transistor Q1907 is connected to the power supply, the drain of the seventh MOS transistor Q1907 outputs a high-level power supply signal. The anode of the third diode D1926 receives the high-level power supply signal, and the third diode D1926 conducts. Consequently, the gate of the first MOS transistor Q1904 receives a high-level power supply signal, turning on the first MOS transistor Q1904 and causing the first control module 15 to output the first control signal. The voltage management module 14 receives the first control signal, thereby inputting the first voltage into the voltage management module 14. Specifically, when the power management circuit 10 is operating normally, the charging power supply 20 is charging the main battery 11 or the backup battery 12, or the first control module receives a key signal, the first control module 15 outputs a low-level first control signal, and the first voltage input from the main battery 11 is input to the TPS2121 chip. Otherwise, the first control module 15 outputs a high-level first control signal, and the first voltage output from the main battery 11 is difficult to input to the TPS2121 chip.

[0092] When the power management circuit 10 is operating normally, the backup battery 12 outputs a second voltage. When the charging power source 20 is not charging the main battery 11 through the voltage path management module 18, the NCE pin does not output an enable signal, and the enable signal is active low. Therefore, the signal output by the NCE pin is high. The NCE pin of the ETA6956Q4Y chip outputs a high-level signal to the second control module 16. Since the anode of the fifth diode D1908 is connected to the NCE pin via R1925, the anode of the fifth diode D1908 receives the high-level signal, turning on the fifth diode D1908. The gate of the second MOS transistor Q1905 receives the high-level signal, turning on the second MOS transistor Q1905. The NCE pin of the ETA6956Q4Y chip does not output an enable signal, and the power management circuit 10 is operating normally. Therefore, based on the reference voltage output by the reference voltage module 13, the reference voltage module 13 outputs a reference voltage signal, and the second control module 14 receives the reference voltage signal. The second control module 16 outputs a second control signal based on the second control module receiving the reference voltage signal and the second control module not receiving the enable signal. The voltage management module 14 receives the second control signal, so that the voltage management module 14 inputs a second voltage.

[0093] Alternatively, when the power management circuit 10 stops operating, because the reference voltage module 13 does not output a reference voltage, the reference voltage module 13 does not output a reference voltage signal. Consequently, the gate of the fifth MOS transistor Q1908 does not receive the reference voltage signal, and the fifth MOS transistor Q1908 does not conduct. Because the drain of the fifth MOS transistor Q1908 is connected to the power supply, the drain of the fifth MOS transistor Q1908 receives a high-level power supply signal, the anode of the fourth diode D1922 conducts, and the second MOS transistor Q1905 conducts. Furthermore, when the charging power supply 20 is not charging the main battery 11 or the backup battery 12, because the charging power supply 20 does not output a charging voltage, the charging power supply 20 does not output a charging voltage signal, and the second control module 16 does not receive the charging voltage signal. Because the gate of the sixth MOS transistor Q1919 does not receive the charging voltage signal through the twentieth resistor R1970, the gate of the sixth MOS transistor Q1919 does not receive the charging voltage signal, and the sixth MOS transistor Q1919 does not conduct. Because the drain of the sixth MOS transistor Q1919 is connected to the power supply, the drain of the sixth MOS transistor Q1919 receives a high-level power signal, the anode of the fourth diode D1922 is turned on, and the second MOS transistor Q1905 is turned on.

[0094] When the user presses the power button 171, the key signal input module 17 outputs a key signal based on the grounding of the power button 171, and the first control module 15 receives the key signal. Because the power button 171 is grounded, the ninth diode D1910 receives a low-level key signal and is not conducting. Because the gate of the seventh MOS transistor Q1907 is connected to the power button 171 via the ninth diode D1910, the gate of the seventh MOS transistor Q1907 receives a low-level key signal and is not conducting. Because the drain of the seventh MOS transistor Q1907 is connected to the power supply, the drain of the seventh MOS transistor Q1907 outputs a high-level power signal, and the anode of the fourth diode D1922 receives the high-level power signal. Therefore, the fourth diode D1922 is conducting, and the second MOS transistor Q1905 is conducting. Because the second control module does not receive the reference voltage signal, the charging voltage signal, and the key signal, the fourth diode D1922 is conductive, the second MOS transistor Q1905 is conductive, and the second control module 16 outputs a low-level second control signal. The voltage management module 14 receives the second control signal and, based on the low-level second control signal, inputs the second voltage. Specifically, if the charging power source is not charging the main battery 11 through the voltage path management module 18 and the power management circuit 10 is operating normally, or if the power management circuit 10 is stopped and the charging power source 20 is not charging the main battery 11 or the backup battery 12, and the user presses the power button 171, the second control module 16 outputs a low-level second control signal, and the second voltage is input to the TPS2121 chip. Otherwise, the second control module 16 outputs a high-level second control signal, making it difficult for the TPS2121 chip to input the second voltage output from the backup battery 12.

[0095] After inputting the first and second voltages, the voltage management module 14 can output an operating voltage to the load. When both the first and second voltages are inactive, the operating voltage is in a high-impedance state. When the first voltage is active and the second voltage is inactive, the operating voltage is the first voltage. When the second voltage is inactive and the second voltage is active, the operating voltage is the second voltage. When both the first and second voltages are active, and the third voltage is greater than the reference voltage, the operating voltage output by the voltage management module 14 is the first voltage; and when the third voltage is less than the reference voltage, the operating voltage output by the voltage management module 14 is the second voltage.

[0096] When the charging power source 20 charges the main battery 11 or the backup battery 12, based on the charging voltage output by the charging power source 20 and the charging voltage signal, the anode of the seventh diode D1924 receives the charging voltage signal, causing the seventh diode D1924 to conduct. Furthermore, when the second control module 16 does not output the second control signal, the second MOS transistor Q1905 is turned off. Because the gate of the eighth MOS transistor Q1906 is connected to the gate of the second MOS transistor Q1905, the eighth MOS transistor Q1906 is turned off. The drain of the eighth MOS transistor Q1906 is connected to the charging power source 20. Based on the charging voltage output by the charging power source 20 and the charging voltage signal output by the charging power source 20, the drain of the eighth MOS transistor Q1906 receives the charging voltage signal. The drain of the eighth MOS transistor Q1906 receives the charging voltage signal, thereby causing the conduction signal output unit 161 to output a conduction signal to the main battery charging control unit 181. At this time, based on the charging voltage signal and the conduction signal, the ninth MOS transistor Q1903 is turned on, and the drain of the ninth MOS transistor Q1903 outputs a low-level signal. The third MOS transistor Q1901, the fourth MOS transistor Q1902, the tenth MOS transistor Q1911, and the eleventh MOS transistor Q1912 are all PMOS transistors. The gates of the third MOS transistor Q1901, the fourth MOS transistor Q1902, the tenth MOS transistor Q1911, and the eleventh MOS transistor Q1912 all receive the low-level signal output by the drain of Q1903. Therefore, the third MOS transistor Q1901, the fourth MOS transistor Q1902, the tenth MOS transistor Q1911, and the eleventh MOS transistor Q1912 of the main battery charging control unit 181 are all turned on. Because the TPS2121 chip has a backflow prevention feature, the charging power supply 20 can charge the main battery 11 through the ETA6956Q4Y chip and the main battery charging control unit 181.

[0097] When the power management circuit 10 is operating normally, the reference voltage module 13 outputs a reference voltage signal, and the anode of the seventh diode D1924 outputs the reference voltage signal. Furthermore, when the second control module 16 does not output the second control signal, the second MOS transistor Q1905 is in an off state. Because the gate of the eighth MOS transistor Q1906 is connected to the gate of the second MOS transistor Q1905, the eighth MOS transistor Q1906 is in an off state. Because the drain of the eighth MOS transistor Q1906 is connected to the reference voltage module, the reference voltage module 13 outputs a reference voltage signal. The drain of the eighth MOS transistor Q1906 receives the reference voltage signal. The drain of the eighth MOS transistor Q1906 outputs a low-level signal, and the on-signal output unit 161 outputs a low-level signal to the main battery charging control unit 181. At this point, based on the reference voltage signal and the on-signal, the ninth MOS transistor Q1903 is turned on, and its drain outputs a low-level signal. The third MOS transistor Q1901, the fourth MOS transistor Q1902, the tenth MOS transistor Q1911, and the eleventh MOS transistor Q1912 are all PMOS transistors. The gates of the third MOS transistor Q1901, the fourth MOS transistor Q1902, the tenth MOS transistor Q1911, and the eleventh MOS transistor Q1912 all receive the low-level signal output by the drain of Q1903. Therefore, the third MOS transistor Q1901, the fourth MOS transistor Q1902, the tenth MOS transistor Q1911, and the eleventh MOS transistor Q1912 of the main battery charging control unit 181 are all turned on. Because the TPS2121 chip has backflow prevention characteristics, the charging power supply 20 can charge the main battery 11 through the ETA6956Q4Y chip and the main battery charging control unit 181. That is, if the second control module 16 does not output the second control signal and the charging power supply 20 is charging the main battery 11 or the backup battery 12, or if the second control module 16 does not output the second control signal and the power management circuit 10 is operating normally, the main battery charging control unit 181 is in the on state, and the charging power supply 20 can charge the main battery 11 through the ETA6956Q4Y chip and the main battery charging control unit 181. Otherwise, the main battery charging control unit 181 is in the off state, and the charging power supply 20 cannot charge the main battery 11 through the main battery charging control unit 181.

[0098] The present invention provides a power management circuit. The power management circuit 10 includes a main battery 11, a backup battery 12, a reference voltage module 13, and a voltage management module 14. The main battery 11 outputs a first voltage, the backup battery 12 outputs a second voltage, and the reference voltage module 13 outputs a reference voltage. The voltage management module 14 receives the first voltage, the second voltage, and the reference voltage, and outputs an operating voltage to a load. The voltage management module 14 includes a voltage divider 141, which converts the first voltage into a third voltage.

[0099] When both the first and second voltages are invalid, the operating voltage output by the voltage management module 14 assumes a high-impedance state. When the first voltage is valid and the second voltage is invalid, the operating voltage output by the voltage management module 14 is the first voltage. When the second voltage is valid and the first voltage is invalid, the operating voltage is the second voltage. When both the first and second voltages are valid, and the third voltage is greater than the reference voltage, the operating voltage output by the voltage management module 14 is the first voltage. When both the first and second voltages are valid, and the third voltage is less than the reference voltage, the operating voltage output by the voltage management module 14 is the second voltage. Therefore, the voltage management circuit 10 can switch the voltage outputs of the main battery 11 and the backup battery 12. This voltage management circuit 10 does not need to detect a battery compartment lid presence detection signal. Assuming both the first and second voltages are valid, the voltage management circuit 10 directly uses the third voltage as a detection signal to switch the power supply. The power switching process is performed solely by hardware circuitry, without the need for software judgment and control. Consequently, the circuit structure of this power management circuit 10 is relatively simple, effectively resolving the technical issues associated with the complexity of existing power management circuits.

[0100] In summary, although the present invention has been disclosed above with reference to preferred embodiments, the above preferred embodiments are not intended to limit the present invention. A person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A power management circuit with a function of controlling the voltage input of a backup battery, characterized in that: The power management circuit includes: a main battery, configured to output a first voltage; A backup battery, used for outputting a second voltage; A reference voltage module, used for outputting a reference voltage; a voltage management module, receiving a first voltage, a second voltage, and a reference voltage, and outputting an operating voltage to a load; the voltage management module includes a voltage dividing unit, and the first voltage is converted into a third voltage by the voltage dividing unit; When both the first voltage and the second voltage are invalid voltages, the operating voltage is in a high-impedance state; when the first voltage is a valid voltage and the second voltage is the invalid voltage, the operating voltage is the first voltage; and when the second voltage is the valid voltage and the first voltage is the invalid voltage, the operating voltage is the second voltage. When the first voltage and the second voltage are both the effective voltages, if the third voltage is greater than the reference voltage, the operating voltage is the first voltage; if the third voltage is less than the reference voltage, the operating voltage is the second voltage; The power management circuit includes a second control module, the second control module outputs a second control signal, the voltage management module receives the second control signal, and determines whether the voltage management module receives the second voltage based on the second control signal; The power management circuit includes a voltage path management module, the voltage path management module includes a first input terminal and a first output terminal, the first input terminal is connected to a charging power source, and the first output terminal is connected to the main battery, for protecting the main battery during charging; The voltage path management module includes a second input terminal and a second output terminal, the second input terminal is connected to the output terminal of the voltage management module, and the second output terminal is connected to the load, and is used to stabilize the operating voltage and manage the path between the operating voltage and the output voltage of the charging power supply; The reference voltage module outputs a reference voltage signal. The power management circuit further includes a charging power supply, which outputs a charging voltage signal. The power management circuit further includes a key signal output module, which outputs a key signal, and the key signal is valid at a low level. The voltage path management module includes an enable terminal. When the charging power source charges the main battery through the voltage path management module, the enable terminal outputs an enable signal, and the enable signal is valid at a low level. Based on the second control module not receiving the reference voltage signal and the second control module not receiving the charging voltage signal and the second control module receiving the key signal, the second control module outputs the second control signal to the voltage management module, and the voltage management module receives the second voltage; Alternatively, based on the second control module receiving the reference voltage signal and the second control module not receiving the enable signal, the second control module outputs the second control signal to the voltage management module, and the voltage management module receives the second voltage.

2. The power management circuit with the function of controlling the backup battery voltage input according to claim 1, characterized in that: The power management circuit includes a first control module, which outputs a first control signal. The voltage management module receives the first control signal and determines whether to receive the first voltage based on the first control signal.

3. The power management circuit with the function of controlling the backup battery voltage input according to claim 2, characterized in that: Based on the first control module receiving the reference voltage signal or the first control module receiving the charging voltage signal or the first control module receiving the key signal, the first control module outputs the first control signal to the voltage management module, and the voltage management module receives the first voltage.

4. The power management circuit with the function of controlling the backup battery voltage input according to claim 3, characterized in that: The voltage management module includes a TPS2121 chip, the TPS2121 chip includes an IN1 pin, an IN2 pin, a CP2 pin, a PR1 pin, and an OUT pin, the IN1 pin is connected to the main battery, the IN1 pin is used to input the first voltage, the IN2 pin is connected to the backup battery, and the IN2 pin is used to input the second voltage; The CP2 pin is connected to the reference voltage module, and the CP2 pin is used to input the reference voltage. The PR1 pin is connected to one end of the voltage divider unit, and the other end of the voltage divider unit is connected to the main battery. The PR1 pin is used to input the third voltage. The OUT pin is connected to the load, and the OUT pin is used to output the operating voltage.

5. The power management circuit with the function of controlling the backup battery voltage input according to claim 4, characterized in that: The TPS2121 chip further includes an OV1 pin and an OV2 pin, the key signal output module includes a power button, the first control module and the second control module both include a seventh MOS transistor, the first control module includes a first MOS transistor, the drain of the first MOS transistor is respectively connected to the main battery and the OV1 pin, the source of the first MOS transistor is grounded, the gate of the first MOS transistor receives the charging voltage signal, the reference voltage signal, and the key signal respectively, the gate of the first MOS transistor is connected to a power supply and the drain of the seventh MOS transistor, the gate of the seventh MOS transistor is connected to the power button, and the source of the seventh MOS transistor is grounded; The second control module includes a second MOS transistor, a fifth MOS transistor, and a sixth MOS transistor. The drain of the second MOS transistor is respectively connected to the backup battery and the OV2 pin, the source of the second MOS transistor is grounded, the gate of the second MOS transistor is connected to the power supply and the drain of the fifth MOS transistor, the gate of the fifth MOS transistor receives the reference voltage signal, and the source of the fifth MOS transistor is grounded; the gate of the second MOS transistor also receives the enable signal; the gate of the second MOS transistor is also connected to the power supply and the drain of the sixth MOS transistor, the gate of the sixth MOS transistor receives the charging voltage signal, and the source of the sixth MOS transistor is grounded; the gate of the second MOS transistor also receives the key signal, the drain of the seventh MOS transistor is connected to the gate of the second MOS transistor and the power supply, the gate of the seventh MOS transistor is connected to the power button, and the source of the seventh MOS transistor is grounded.

6. The power management circuit with the function of controlling the backup battery voltage input according to claim 5, characterized in that: The voltage path management module includes an ETA6956Q4Y chip, which includes a VAC pin, a VBUS pin, a BAT pin, and a SYS pin. The VAC pin and the VBUS pin are both connected to the charging power supply, and the BAT pin is connected to the main battery; the BAT pin is also connected to the OUT pin, and the SYS pin is connected to the load.

7. The power management circuit with the function of controlling the backup battery voltage input according to claim 6, characterized in that: The voltage path management module includes a main battery charging control unit, which is connected between the voltage path management module and the main battery and is used to control the charging power supply to charge the main battery; the second control module includes a conduction signal output unit, which is connected to the main battery charging control unit and outputs a conduction signal based on the second control module not outputting the second control signal and the conduction signal output unit receiving the reference voltage signal or the charging voltage signal. The conduction signal is used to control the on / off of the main battery charging control unit circuit in conjunction with the charging voltage signal or the reference voltage signal; The main battery charging control unit includes a third MOS transistor and a fourth MOS transistor connected in parallel, wherein the source of the third MOS transistor and the source of the fourth MOS transistor are both connected to the BAT pin, and the drain of the third MOS transistor and the drain of the fourth MOS transistor are both connected to the main battery; the gate of the third MOS transistor receives the charging voltage signal and the reference voltage signal respectively; the gate of the fourth MOS transistor is connected to the charging voltage signal and the reference voltage signal respectively; The conduction signal output unit includes an eighth MOS transistor, a gate of the eighth MOS transistor is connected to the gate of the second MOS transistor, a source of the eighth MOS transistor is grounded, and a drain of the eighth MOS transistor outputs a conduction signal to the gates of the third MOS transistor and the fourth MOS transistor.

8. The power management circuit with the function of controlling the backup battery voltage input according to claim 4, characterized in that: The voltage management module includes a voltage adjustment unit, and the TPS2121 chip also includes an ST pin. One end of the voltage adjustment unit is connected to the voltage divider unit, and the other end of the voltage adjustment unit is connected to the ST pin. When the third voltage is less than the reference voltage, the first voltage is switched to the second voltage, and the voltage adjustment unit is controlled to lower the third voltage through the ST pin. When the third voltage is greater than the reference voltage, the second voltage is switched to the first voltage, and the voltage adjustment unit is controlled to increase the third voltage through the ST pin.

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