Power adapter and lithium battery power supply switching circuit

Abstract

The utility model discloses a power adapter and lithium battery power supply switching circuit, and the circuit comprises a power adapter power supply module which is used for supplying power to an electric appliance; the lithium battery power supply module is used for supplying power to the electric appliance when the power adapter power supply module is powered off; and the switching module is used for switching to the lithium battery power supply module to supply power to the electric appliance when the power adapter power supply module is powered off, and can timely switch the lithium battery to supply power to the electric appliance when the mains supply is suddenly powered off.

Description

Technical Field

[0001] The utility model belongs to the technical field of voice broadcasting, and in particular relates to a power adapter and a lithium battery power supply switching circuit. Background Art

[0002] There are many small appliances on the market today, which generally support power supply from power adapters and lithium batteries. During the use of small appliances, users often connect the power adapter to the mains for a long time to power the small appliances. However, when the mains power is suddenly cut off, the lithium battery can easily damage the circuit board or the lithium battery may not be able to supply power in time, causing the small appliance to shut down.

[0003] Therefore, how to promptly switch to lithium batteries to power electrical appliances when the mains power is suddenly cut off is a technical problem to be solved by those skilled in the art. Utility Model Content

[0004] The purpose of this utility model is to solve the technical problem in the prior art that when the mains power is suddenly cut off, the lithium battery cannot be switched to power supply in time. To this end, the utility model provides a power adapter and a lithium battery power supply switching circuit, which includes:

[0005] Power adapter power supply module, used to power electrical appliances;

[0006] A lithium battery power supply module is used to power the appliance when the power adapter power supply module is powered off;

[0007] The switching module is used to switch to the lithium battery power supply module to power the appliance when the power adapter power supply module is powered off.

[0008] Furthermore, the power adapter power supply module includes:

[0009] The anode of the diode D1 is respectively connected to the 25V power supply terminal of the adapter, one end of the resistor R1, and the source of the MOS transistor Q1. The other end of the resistor R1 is respectively connected to one end of the resistor R2, the gate of the MOS transistor Q1, and the third pin of the optocoupler U1. The other end of the resistor R2 is grounded. The drain of the MOS transistor Q1 is connected to one end of the fuse F1. The other end of the fuse F1 is respectively connected to the anode of the diode D2 and one end of the resistor R9. The other end of the resistor R9 is connected to the anode of the diode D4. The cathode of the diode D4 is grounded. The cathode of the diode D2 outputs a 24V load voltage to power the electrical appliance.

[0010] Furthermore, the 4th pin of the optocoupler U1 is connected to the 25V power supply end of the adapter, the 1st pin of the optocoupler U1 is connected to one end of the resistor R5, the other end of the resistor R5 is connected to the 3.3V power supply, the 2nd pin of the optocoupler U1 is connected to the resistor R6, and the other end of the resistor R6 is grounded.

[0011] Furthermore, the lithium battery power supply module includes:

[0012] The lithium battery power supply end is respectively connected to the source of the MOS tube Q2 and one end of the resistor R3. The other end of the resistor R3 is respectively connected to one end of the resistor R4, the gate of the MOS tube Q2, and the third pin of the optocoupler U2. The gate of the MOS tube Q2 is connected to one end of the fuse F2. The other end of the fuse is respectively used to connect the positive electrode of the diode D3 and the other end of the resistor R10. The cathode of the diode D3 outputs a 24V load voltage to power the electrical appliance. One end of the resistor R10 is connected to the positive electrode of the diode D5, and the negative electrode of the diode D5 is grounded.

[0013] Furthermore, the 4th pin of the optocoupler U2 is connected to the power supply end of the lithium battery, the 1st pin of the optocoupler U2 is connected to one end of the resistor R7, the other end of the resistor R7 is connected to the 3.3V power supply, the 2nd pin of the optocoupler U2 is connected to one end of the resistor R8, and the other end of the resistor R8 is grounded.

[0014] Furthermore, the switching module specifically includes the diode D1 , the resistor R3 and the resistor R4 , and the other end of the resistor R3 and one end of the resistor R4 are also connected to the cathode of the diode D1 .

[0015] Furthermore, the diode D1 , the diode D2 and the diode D3 are Schottky diodes for preventing backflow of current.

[0016] Furthermore, the MOS transistor Q1 and the MOS transistor Q2 are both P-channel diodes, and the diode D4 and the diode D5 are light emitting diodes.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] The utility model provides a power adapter and lithium battery power switching circuit. Compared with the existing technology, the circuit includes: a power adapter power supply module, which is used to power the electrical appliance; a lithium battery power supply module, which is used to power the electrical appliance when the power adapter power supply module is powered off; and a switching module, which is used to switch to the lithium battery power supply module to power the electrical appliance when the power adapter power supply module is powered off. The circuit can promptly switch to the lithium battery to power the electrical appliance when the mains power is suddenly cut off. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of this specification, the following is a brief introduction to the drawings required for use in the embodiments. The drawings described below are only some embodiments recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1 Shown is a schematic diagram of the structure of a power adapter and a lithium battery power switching circuit provided in an embodiment of this specification. DETAILED DESCRIPTION

[0021] To help those skilled in the art better understand the technical solutions in this specification, the following will provide a clear and complete description of the technical solutions in the embodiments of this specification, in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of this specification, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments in this specification without creative work should fall within the scope of protection of this specification.

[0022] like Figure 1 The following is a schematic diagram of the structure of the power adapter and lithium battery power switching circuit provided in the embodiments of this specification. Although this specification provides the structures shown in the following embodiments or figures, the structures described may include more or fewer structures after partial merging based on routine or no creative effort. These structures are not limited to the structures shown in the embodiments or figures of this specification. When the structures described are applied in actual devices or terminal products, they can be executed sequentially or in parallel according to the embodiments or module structures.

[0023] The power adapter and lithium battery power supply switching circuit provided in the embodiments of this specification can be applied to various electrical appliances with lithium batteries and power adapters. The specific connection structure is as follows: Figure 1 As shown, this circuit includes:

[0024] Power adapter power supply module, used to power electrical appliances;

[0025] A lithium battery power supply module is used to power the appliance when the power adapter power supply module is powered off;

[0026] The switching module is used to switch to the lithium battery power supply module to power the appliance when the power adapter power supply module is powered off.

[0027] Specifically, the power adapter power supply module includes:

[0028] The anode of the diode D1 is respectively connected to the 25V power supply terminal of the adapter, one end of the resistor R1, and the source of the MOS transistor Q1. The other end of the resistor R1 is respectively connected to one end of the resistor R2, the gate of the MOS transistor Q1, and the third pin of the optocoupler U1. The other end of the resistor R2 is grounded. The drain of the MOS transistor Q1 is connected to one end of the fuse F1. The other end of the fuse F1 is respectively connected to the anode of the diode D2 and one end of the resistor R9. The other end of the resistor R9 is connected to the anode of the diode D4. The cathode of the diode D4 is grounded. The cathode of the diode D2 outputs a 24V load voltage to power the electrical appliance.

[0029] The lithium battery power supply module includes:

[0030] The lithium battery power supply end is respectively connected to the source of the MOS tube Q2 and one end of the resistor R3. The other end of the resistor R3 is respectively connected to one end of the resistor R4, the gate of the MOS tube Q2, and the third pin of the optocoupler U2. The gate of the MOS tube Q2 is connected to one end of the fuse F2. The other end of the fuse is respectively used to connect the positive electrode of the diode D3 and the other end of the resistor R10. The cathode of the diode D3 outputs a 24V load voltage to power the electrical appliance. One end of the resistor R10 is connected to the positive electrode of the diode D5, and the negative electrode of the diode D5 is grounded.

[0031] The switching module specifically includes the diode D1 , the resistor R3 and the resistor R4 , and the other end of the resistor R3 and one end of the resistor R4 are both connected to the cathode of the diode D1 .

[0032] Specifically, when the power adapter and the backup lithium battery pack are connected to the circuit simultaneously: the gate voltage (pin 1) of MOS transistor Q1, after being divided by resistors R1 and R2, equals 25V / 2. The voltage difference between the gate voltage (pin 1) of MOS transistor Q1 and the source voltage (pin 2) of MOS transistor Q1 is greater than the conduction threshold voltage of MOS transistor Q1, and MOS transistor Q1 is turned on. The power adapter's supply current flows through the source of MOS transistor Q1 (pin 2), the drain of MOS transistor Q1 (pin 3), the resettable fuse F1, and the current backflow prevention Schottky diode D2, and then outputs a load voltage of 24V. LED D4 illuminates (green), indicating the power adapter's power supply circuit is on. At this point, the gate voltage (pin 1) of MOS transistor Q2, divided by resistors R3 and R4, equals VBAT / 2. However, the power adapter's input voltage of 25V remains approximately 25V after the voltage drop across the current-backflow protection Schottky diode D1. This pulls up the gate voltage (pin 1) of MOS transistor Q2 to approximately 25V. The voltage difference between the gate voltage (pin 1) and the source voltage (pin 2) of MOS transistor Q2 is less than the conduction threshold voltage of MOS transistor Q2, turning MOS transistor Q2 off. The backup lithium battery pack's supply current does not flow through the source (pin 2) of MOS transistor Q2, but instead flows through the drain (pin 3) of MOS transistor Q2, resettable fuse F2, and current-backflow protection Schottky diode D3. LED D5 does not illuminate (yellow), indicating the backup lithium battery pack's power supply circuit is off.

[0033] When the mains power fails and only the backup lithium battery pack is connected to the circuit, the gate voltage of MOS transistor Q1 equals 0V after being divided by resistors R1 and R2. Because of the presence of Schottky diode D1, the source voltage of MOS transistor Q1 also equals 0V. Therefore, the voltage difference between the gate voltage and the source voltage of MOS transistor Q1 is less than the conduction threshold voltage of MOS transistor Q1, and MOS transistor Q1 is turned off. The power adapter's supply current does not flow through the source of MOS transistor Q1, through the drain of MOS transistor Q1, the resettable fuse F1, and the Schottky diode D1. LED D4 is off (green), indicating that the power adapter's power supply circuit is in the off state. At this time, the gate voltage of MOS transistor Q2 equals VBAT / 2 after being divided by resistors R3 and R4. The voltage difference between the gate voltage and the source voltage of MOS transistor Q2 is greater than the conduction threshold voltage of MOS transistor Q2, and MOS transistor Q2 is turned on. The backup lithium battery pack's supply current flows through the source of MOS transistor Q2, through the drain of MOS transistor Q2, through resettable fuse F2, and through Schottky diode D3, ultimately outputting a load voltage of 24V. LED D5 illuminates (yellow), indicating that the backup lithium battery pack's supply circuit is conducting.

[0034] In an embodiment of the present application, the 4th pin of the optocoupler U1 is connected to the 25V power supply end of the adapter, the 1st pin of the optocoupler U1 is connected to one end of the resistor R5, the other end of the resistor R5 is connected to the 3.3V power supply, the 2nd pin of the optocoupler U1 is connected to the resistor R6, the other end of the resistor R6 is grounded, the 4th pin of the optocoupler U2 is connected to the power supply end of the lithium battery, the 1st pin of the optocoupler U2 is connected to one end of the resistor R7, the other end of the resistor R7 is connected to the 3.3V power supply, the 2nd pin of the optocoupler U2 is connected to one end of the resistor R8, and the other end of the resistor R8 is grounded.

[0035] Specifically, when optocoupler U1's control signal ONOFF1 equals 0V, optocoupler U1's pins 4 and 3 conduct, raising the gate voltage of MOS transistor Q1 to 25V. The voltage difference between the gate voltage and the source voltage of MOS transistor Q1 is less than the on-threshold voltage of MOS transistor Q1, turning Q1 off. The power adapter's supply current does not flow through the source of MOS transistor Q1, sequentially through the drain of MOS transistor Q1, resettable fuse F1, and current backflow prevention Schottky diode D1. Light-emitting diode D4 remains off (green), indicating that the power adapter's power supply circuit is off. When optocoupler U1's control signal ONOFF1 equals 3.3V, the gate voltage of MOS transistor Q1 is unaffected.

[0036] When optocoupler U2's control signal ONOFF2 equals 0V, pins 4 and 3 of optocoupler U2 conduct, raising the gate voltage of MOS transistor Q2 to VBAT, the lithium battery power supply terminal. The voltage difference between the gate voltage and the source voltage of MOS transistor Q2 is less than the conduction threshold voltage of MOS transistor Q2, turning MOS transistor Q2 off. The backup lithium battery pack's supply current does not flow through the source of MOS transistor Q2, sequentially flowing through the drain of MOS transistor Q2, resettable fuse F2, and current backflow prevention Schottky diode D3. LED D3 is off (green), indicating that the power supply circuit of the power adapter is off. When optocoupler U2's control signal ONOFF2 equals 3.3V, the gate voltage of MOS transistor Q2 is unaffected.

[0037] The control signals ONOFF1 and ONOFF2 mentioned above are both connected to the main control chip.

[0038] It should be understood that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intervening element at the same time; when an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intervening element at the same time. In addition, the "connection" used here may include wireless connection; the wording "and / or" used includes any unit and all combinations of one or more associated listed items.

[0039] It should be understood that various parts of the present application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used to implement: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0040] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0041] In addition, the functional units in the various embodiments of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into a module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0042] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0043] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0044] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

[0045] The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention cannot be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A power adapter and lithium battery power switching circuit, characterized in that: The circuit comprises: Power adapter power supply module, used to power electrical appliances; A lithium battery power supply module is used to power the appliance when the power adapter power supply module is powered off; A switching module is used to switch to the lithium battery power supply module to power the appliance when the power adapter power supply module is powered off; Wherein, the power adapter power supply module includes: The anode of the diode D1 is respectively connected to the 25V power supply terminal of the adapter, one end of the resistor R1, and the source of the MOS transistor Q1. The other end of the resistor R1 is respectively connected to one end of the resistor R2, the gate of the MOS transistor Q1, and the third pin of the optocoupler U1. The other end of the resistor R2 is grounded. The drain of the MOS transistor Q1 is connected to one end of the fuse F1. The other end of the fuse F1 is respectively connected to the anode of the diode D2 and one end of the resistor R9. The other end of the resistor R9 is connected to the anode of the diode D4. The cathode of the diode D4 is grounded. The cathode of the diode D2 outputs a 24V load voltage to power the electrical appliance. The fourth pin of the optocoupler U1 is connected to the 25V power supply terminal of the adapter. The first pin of the optocoupler U1 is connected to one end of the resistor R5. The other end of the resistor R5 is connected to the 3.3V power supply. The second pin of the optocoupler U1 is connected to the resistor R6. The other end of the resistor R6 is grounded. Wherein, the lithium battery power supply module includes: The lithium battery power supply end is respectively connected to the source of the MOS tube Q2 and one end of the resistor R3. The other end of the resistor R3 is respectively connected to one end of the resistor R4, the gate of the MOS tube Q2, and the third pin of the optocoupler U2. The gate of the MOS tube Q2 is connected to one end of the fuse F2. The other end of the fuse is respectively used to connect the positive electrode of the diode D3 and the other end of the resistor R10. The negative electrode of the diode D3 outputs a 24V load voltage to power the electrical appliance. One end of the resistor R10 is connected to the positive electrode of the diode D5, and the negative electrode of the diode D5 is grounded. The fourth pin of the optocoupler U2 is connected to the lithium battery power supply end. The first pin of the optocoupler U2 is connected to one end of the resistor R7. The other end of the resistor R7 is connected to a 3.3V power supply. The second pin of the optocoupler U2 is connected to one end of the resistor R8, and the other end of the resistor R8 is grounded. The switching module specifically includes the diode D1 , the resistor R3 and the resistor R4 , and the other end of the resistor R3 and one end of the resistor R4 are both connected to the cathode of the diode D1 .

2. The power adapter and lithium battery power switching circuit according to claim 1, wherein: The diode D1, the diode D2 and the diode D3 are Schottky diodes for preventing backflow of current.

3. The power adapter and lithium battery power switching circuit according to claim 1, wherein: The MOS transistor Q1 and the MOS transistor Q2 are both P-channel diodes, and the diode D4 and the diode D5 are light emitting diodes.

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