Power supply circuit and small electronic equipment

Abstract

The utility model discloses a power supply circuit and a small electronic device. The power supply circuit comprises a first ideal diode circuit, a power-off protection circuit, and a voltage stabilizing circuit connected with the first ideal diode circuit and the power-off protection circuit. The first ideal diode circuit comprises a first MOS tube and a first MOS tube controller connected with the first MOS tube, the input end of the first MOS tube is used for being connected with external power supply equipment, and the output end of the first MOS tube is connected with the voltage stabilizing circuit; the voltage stabilizing circuit is connected with a power utilization unit of the small electronic equipment so as to provide preset voltage for the power utilization unit. According to the utility model, insufficient power supply caused by voltage drop when power is supplied to the power utilization unit can be avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of power-off protection, and particularly relates to a power supply circuit and a small electronic device. Background Art

[0002] In existing small consumer electronic products, in order to improve the safety performance of the products, a power-off protection scheme is mostly designed in the products. The basic composition mode of the existing power-off protection scheme is electrolytic capacitor (supercapacitor) + diode. However, for devices powered by USB, whether the supply voltage is sufficient is a very important point. Currently, the power supply of small consumer electronic devices is generally through the USB port of an external device, and its power supply capacity is very limited. Now, the trend of the development of small consumer electronic devices is that their power consumption is constantly increasing. In the ordinary supercapacitor + diode scheme, due to the voltage drop caused by the diode, the power supply of small consumer electronic devices is often insufficient, resulting in the risk of power-off or even burning of small consumer electronic devices. For example, Patent CN204537049U discloses a protection system for preventing sudden power-off of a hard disk, including a computer and a hard disk. The computer is connected to the hard disk through a data cable; a current isolation diode and a farad capacitor are sequentially connected between the computer and the hard disk through a wire. Although it can effectively reduce the risk of accidental damage to the hard disk and data when the external hard disk is hot-plugged or the device suddenly powers off, users can rest assured to plug and unplug the hard disk at any time to exchange, transfer, and back up data. At the same time, users do not need to worry about increasing the risk of damaging the hard disk when shutting down, restarting, hibernating, or standby. It can be widely used in products such as the second hard disk rack of a notebook computer, the hard disk rack of a desktop computer, and a mobile hard disk. However, the voltage drop caused by setting the diode will make the power supply of the hard disk insufficient.

[0003] Therefore, how to provide a circuit with a power-off protection function and without insufficient power supply when powered by a USB port is an urgent problem to be solved by those skilled in the art. Summary of the Utility Model

[0004] Aiming at the defects existing in the prior art, the utility model provides a power supply circuit and a small electronic device, which can avoid the situation of insufficient power supply caused by voltage drop when supplying power to the power-consuming unit.

[0005] In a first aspect, the utility model provides a power supply circuit for a small electronic device, including: a first ideal diode circuit, a power-off protection circuit, and a voltage stabilization circuit connected to the first ideal diode circuit and the power-off protection circuit;

[0006] The first ideal diode circuit includes a first MOS transistor and a first MOS transistor controller connected to the first MOS transistor. The input end of the first MOS transistor is used to be connected to an external power supply device, and the output end is connected to the voltage stabilization circuit;

[0007] The voltage stabilizing circuit is connected to the power-consuming unit of the small electronic device to provide a predetermined voltage to the power-consuming unit.

[0008] Furthermore, the turn-on voltage of the first MOS transistor is 0.03V ± 0.01V.

[0009] Furthermore, the first MOS transistor is an NMOS transistor. The anode pin of the first MOS transistor controller is connected to the source of the first MOS transistor, the gate pin of the first MOS transistor controller is connected to the gate of the first MOS transistor, and the cathode pin of the first MOS transistor controller is connected to the drain of the first MOS transistor.

[0010] Furthermore, the power-off protection circuit includes an energy storage element and a unidirectional conduction module. The input end of the energy storage element is used to be connected to an external power supply device, and the output end of the energy storage element is connected to the voltage stabilizing circuit through the unidirectional conduction module.

[0011] Furthermore, the energy storage element is a super capacitor.

[0012] Furthermore, the power-off protection circuit further includes a charging circuit. The charging circuit includes a linear voltage regulator, a plurality of second MOS transistors, a voltage detection resistor, and a charging controller. The plurality of second MOS transistors are connected in series to form a conduction and cutoff circuit. The input end of the linear voltage regulator is used to be connected to an external power supply device, and the output end is connected to the energy storage element and the unidirectional conduction module through the conduction and cutoff circuit. The charging controller is connected to the plurality of second MOS transistors and is connected to the energy storage element through the voltage monitoring resistor.

[0013] Furthermore, the power-off protection circuit further includes a boost voltage stabilizing circuit composed of a boost converter.

[0014] Furthermore, the unidirectional conduction module includes a second ideal diode circuit. The second ideal diode circuit includes a third MOS transistor and a third MOS transistor controller connected to the third MOS transistor. The input end of the third MOS transistor is connected to the energy storage element, and the output end is connected to the voltage stabilizing circuit.

[0015] Furthermore, the voltage stabilizing circuit includes a buck converter and a plurality of output resistors connected to the switch pin of the buck converter. The feedback pin of the buck converter is connected between two adjacent output resistors. The power input pin of the buck converter is respectively connected to the first ideal diode circuit and the power-off protection circuit.

[0016] In a second aspect, the present invention further provides a small electronic device, including: an external power supply interface, the above-mentioned power supply circuit, and a power-consuming unit that are connected in sequence.

[0017] Furthermore, the external power supply interface is a USB port.

[0018] A power supply circuit and a small electronic device provided by the present invention at least include the following

[0019] Beneficial effects:

[0020] (1) Through the first ideal diode circuit, the voltage entering the voltage stabilization circuit can have a small voltage drop compared to the voltage of the input power supply circuit. Specifically, the voltage drop can be in the range of 0.01 - 0.05V. Compared with the voltage drop of a common diode between 0.2 - 0.4V, the voltage drop caused by the present utility model to the rear-end electrical appliance can be ignored, thus achieving a better power supply effect.

[0021] (2) By setting a second ideal diode circuit at the output end of the power-off protection circuit, when the power-off protection circuit is enabled, it can have a one-way conduction effect while also avoiding a large voltage drop in the voltage input from the end protection circuit to the voltage stabilization circuit. Description of the drawings

[0022] Figure 1 Schematic diagram of a power supply circuit for a small electronic device provided by the present utility model;

[0023] Figure 2 Circuit schematic diagram of the power supply circuit provided by an embodiment of the present utility model;

[0024] Figure 3 Circuit schematic diagram of the first ideal diode circuit provided by an embodiment of the present utility model;

[0025] Figure 4 Circuit schematic diagram of the charging circuit provided by an embodiment of the present utility model;

[0026] Figure 5 Circuit schematic diagram of the boost voltage stabilization circuit provided by an embodiment of the present utility model;

[0027] Figure 6 Circuit schematic diagram of the voltage stabilization circuit provided by an embodiment of the present utility model;

[0028] Figure 7 Schematic diagram of a small electronic device provided by the present utility model.

[0029] Description of the reference numerals: 1 - first ideal diode circuit, 2 - voltage stabilization circuit, 31 - energy storage element, 32 - one-way conduction module, 33 - charging circuit, 34 - boost voltage stabilization circuit. Detailed implementation manners

[0030] To better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings of the specification and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "the" and "said" used in the embodiments of the present invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. "Plural" generally includes at least two.

[0032] It should also be noted that the term "comprising", "including" or any other variation thereof is intended to cover a non-exclusive inclusion, such that a commodity or device including a series of elements includes not only those elements but also other elements not expressly listed, or also includes elements inherent to such commodity or device. Without further limitation, an element defined by the statement "including a..." does not exclude the presence of additional identical elements in the commodity or device including the said element.

[0033] The present invention innovatively adopts a scheme of supercapacitor + ideal diode (a circuit composed of a controller and a MOS tube) to replace the scheme of supercapacitor + ordinary diode to solve the problem of large power supply voltage drop. In the capacitor + diode scheme, the voltage drop of the ordinary diode is between 0.2 - 0.4V, while using an ideal diode to replace the ordinary diode, the voltage drop of the ideal diode adopted by the present invention is in the range of 0.01 - 0.05V. The voltage drop caused by adopting the scheme of supercapacitor + ideal diode has almost negligible influence on the subsequent electrical appliances. Therefore, using the supercapacitor + ideal diode of the present invention to replace the existing supercapacitor + diode scheme can effectively solve a series of problems caused by insufficient supply voltage.

[0034] Specifically, as Figure 1 and Figure 2 shown, the present invention provides a power supply circuit for a small electronic device, which may include: a first ideal diode circuit 1, a power-off protection circuit, and a voltage stabilization circuit 2 connected to the first ideal diode circuit 1 and the power-off protection circuit;

[0035] The first ideal diode circuit 1 includes a first MOS tube Q1 and a first MOS tube controller U1 connected to the first MOS tube Q1. The input end of the first MOS tube Q1 is used to connect to an external power supply device, and the output end is connected to the voltage stabilization circuit 2;

[0036] The voltage stabilizing circuit 2 is connected to the power-consuming unit of the small electronic device to provide a predetermined voltage to the power-consuming unit.

[0037] By setting the power-off protection circuit + the first ideal diode circuit 1, the problem of voltage drop during power supply can be reduced while achieving power-off protection. At the same time, by the setting method of the first MOS transistor + the first MOS transistor controller, the voltage drop across the first ideal diode circuit 1 can be reduced to within the range of 0.01 - 0.05V. Specifically, as Figure 3 shown, the first MOS transistor Q1 is an NMOS transistor, where the conduction voltage of the first MOS transistor Q1 is 0.03V ± 0.01V; the power supply pin and the ground pin of the first MOS transistor controller U1 are respectively connected with a first capacitor C1 and a second capacitor C2. Both the first capacitor C1 and the second capacitor C2 are used to connect with an external power supply device. The ground pin of the first MOS transistor controller U1 is grounded. The enable pin of the first MOS transistor controller U1 is connected to the external power supply device. The anode pin of the first MOS transistor controller U1 is connected to the source electrode of the first MOS transistor Q1. The gate pin of the first MOS transistor controller U1 is connected to the gate of the first MOS transistor Q1. The cathode pin of the first MOS transistor controller U1 is connected to the drain of the first MOS transistor Q1. The source electrode of the first MOS transistor Q1 is connected to the external power supply device. Among them, the specification parameters of the first capacitor C1 and the second capacitor C2 are both 100nF / 50V.

[0038] The power-off protection circuit includes an energy storage element 31 and a unidirectional conduction module 32. The input end of the energy storage element 31 is used to connect with an external power supply device. The output end of the energy storage element 31 is connected to the voltage stabilizing circuit 2 through the unidirectional conduction module 32. Among them, the energy storage element 31 is a super capacitor J1. The energy storage element 31 can charge and store energy during external power supply and discharge and release energy when the external power supply is disconnected, so as to achieve the effect of power-off protection.

[0039] Specifically, the power-off protection circuit further includes a charging circuit 33, as Figure 4As shown, the charging circuit 33 may include a linear voltage regulator U2, multiple second MOS transistors (Q2A, Q2B), a voltage detection resistor, and a charging controller. The multiple second MOS transistors are connected in series to form a switching circuit. The input terminal of the linear voltage regulator U2 is used to connect to an external power supply device, and the output terminal is connected to the energy storage element 31 and the unidirectional conduction module 32 through the switching circuit. The charging controller is connected to the multiple second MOS transistors and is connected to the energy storage element 31 through the voltage monitoring resistor. Among them, the charging circuit 33 includes two second MOS transistors. The second MOS transistors are PMOS transistors. The drains of the two second MOS transistors are connected. The source of one second MOS transistor (Q2A) is connected to the linear voltage regulator U2, and the source of the other second MOS transistor (Q2B) is connected to the super capacitor and the unidirectional conduction module 32 through a first resistor R1. The sources of the two second MOS transistors are both connected to the gates through a second resistor R2. The charging controller is connected to the gates of the two second MOS transistors. The charging controller is connected between the first resistor and the super capacitor J1 through a third resistor R3 and is connected to the unidirectional conduction module 32. The specification of the super capacitor is 2.7V 1.5F. To ensure no overvoltage risk during charging, after the external power supply is connected, the charging voltage is first stabilized at 2.7V by the linear voltage regulator U2. The charging controller (MCU) detects the voltage of the super capacitor through the third resistor. When the voltage is lower than 2.7V, the MCU controls the multiple second MOS transistors to control the charging of the super capacitor.

[0040] The power-off protection circuit may further include a boost voltage regulation circuit 34 composed of a boost converter. Among them, as Figure 5 shown, the switching pin of the boost converter U3 is connected to the super capacitor J1 and the charging circuit 33 through a first inductor L1, and is connected to the unidirectional conduction module 32 through a first diode D1. The ground pin of the boost converter U3 is grounded. The feedback pin of the boost converter U3 is connected to the fourth resistor R4 and then grounded. The feedback pin of the boost converter U3 is connected to the power supply pin of the boost converter U3 and the output terminal of the first diode D1 through a fifth resistor R5. The output terminal of the first diode D1 is grounded through a third capacitor C3. The enable pin of the boost converter U3 is connected to the super capacitor J1 and the charging circuit 33. The discharge voltage range of the super capacitor is 2.7 - 1.0V. The boost converter U3 sets the boost voltage to 4.2V through the fourth resistor R4 and the fifth resistor R5. The minimum input voltage of the boost converter U3 is 0.8V. When the external voltage is removed, the unidirectional conduction module 32 conducts.

[0041] As Figure 6As shown in the figure, the voltage stabilization circuit 2 includes a buck converter U4 and a plurality of output resistors connected to the switching pin of the buck converter U4. The feedback pin of the buck converter U4 is connected between two adjacent output resistors. The power input pin of the buck converter U4 is respectively connected to the first ideal diode circuit 1 and the power-off protection circuit. Among them, the sensing input pin of the buck converter U4 is connected to the power input pin through the sixth resistor R6. The connection between the power input pin of the buck converter U4 and the sixth resistor R6 is grounded through the fourth capacitor C4. The power input pin is grounded through the fifth capacitor C5. The sensing input pin of the buck converter U4 is grounded through the sixth capacitor C6. The soft start pin of the buck converter U4 is grounded through the seventh capacitor C7. The ground pin of the buck converter U4 is grounded. The switching pin of the buck converter U4 is grounded through the second inductor L2 and a plurality of output resistors R7 in sequence. There are two output resistors R7. The feedback pin of the buck converter U4 is connected between the two output resistors R7. The connection between the second inductor L2 and the output resistor R7 is used to connect to the power-consuming unit. The connection between the output resistors R7 is connected to the output end of the second inductor L2 through the eighth capacitor C8. The output end of the second inductor L2 is grounded through at least two parallel-connected ninth capacitors C9. Among them, the conversion efficiency of the buck converter U4 is 96%, the input voltage range is 2.5V - 5.5V, and the maximum output current is 5A; the output voltage of the buck converter U4 through the two output resistors is 3.3V; the input voltage of the buck converter U4 is 5 - 3.9V, and it can stably output a 3.3V voltage.

[0042] The unidirectional conduction module 32 of the present utility model can be an ordinary diode. Preferably, the unidirectional conduction module 32 can also adopt an improved circuit, specifically including a second ideal diode circuit. The second ideal diode circuit includes a third MOS transistor and a third MOS transistor controller connected to the third MOS transistor. The input end of the third MOS transistor is connected to the energy storage element 31, and the output end is connected to the voltage stabilization circuit 2. Among them, the connection manner in the second ideal diode circuit is the same as that in the first ideal diode circuit 1.

[0043] In an actual application scenario, the present utility model replaces the diode after external power supply with the first ideal diode circuit 1. The voltage drop of the first ideal diode circuit 1 directly depends on the on-state voltage drop of the first MOS transistor. The on-state voltage of the first MOS transistor is 0.03V ± 0.01V. The impact of the voltage generated when the first ideal diode circuit 1 conducts on the subsequent circuits and devices can be ignored. Specifically, when powered by external power supply, the input voltage of the external power supply is stepped down through the first ideal diode circuit 1, and the voltage drops by about 0.03V relative to the external power supply. The standard output voltage of the external power supply port (USB) is 5V ± 0.2V. After the external power supply is stepped down through the first ideal diode circuit 1, its voltage is still within the range of the external power supply voltage. It is especially suitable for situations where the voltage of some external power supply ports is relatively low, or when other electrical devices such as an expansion dock are used. After entering the voltage stabilization circuit 2 for power supply to the subsequent stage, it provides stable and ideal power supply for the subsequent devices.

[0044] When powered by the power-off protection circuit, the external power supply supplies power to the energy storage element 31 (supercapacitor) through the charging circuit 33. After the supercapacitor is fully charged, when the external power supply is disconnected, the supercapacitor starts to discharge, enters the boost voltage stabilization circuit 34, and the boosted power supply passes through the unidirectional conduction module 32 (which is an ordinary diode or a second ideal diode circuit), and then enters the voltage stabilization circuit 2 for power supply to the subsequent stage, and supplies stable power to the subsequent devices after voltage stabilization.

[0045] As Figure 7 shown, the present utility model also provides a small electronic device, including: an external power supply interface, the above-mentioned power supply circuit, and an electrical unit connected in sequence. Among them, the external power supply interface is a USB port. The small electronic device can be an expansion dock, a hard disk box, a power bank, or a wireless screen mirroring device, and the electrical unit is an integration of components corresponding to the small electronic device.

[0046] Although the preferred embodiments of the present utility model have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments as well as all changes and modifications falling within the scope of the present utility model. Obviously, those skilled in the art can make various changes and variations to the present utility model without departing from the spirit and scope of the present utility model. Thus, if these modifications and variations of the present utility model fall within the scope of the claims of the present utility model and their equivalent technologies, the present utility model also intends to include these changes and variations.

Claims

1. A power supply circuit for a small electronic device, characterized in that, Comprising: A first ideal diode circuit (1), a power-off protection circuit, and a voltage stabilizing circuit (2) connected to the first ideal diode circuit (1) and the power-off protection circuit; The first ideal diode circuit (1) includes a first MOS transistor and a first MOS transistor controller connected to the first MOS transistor. The input terminal of the first MOS transistor is used to connect to an external power supply device, and the output terminal is connected to the voltage stabilizing circuit (2); The voltage stabilizing circuit (2) is connected to the power-consuming unit of the small electronic device to provide a predetermined voltage to the power-consuming unit.

2. The power supply circuit according to claim 1, wherein The turn-on voltage of the first MOS transistor is 0.03V ± 0.01V.

3. The power supply circuit according to claim 1, wherein, The first MOS transistor is an NMOS transistor. The anode pin of the first MOS transistor controller is connected to the source of the first MOS transistor, the gate pin of the first MOS transistor controller is connected to the gate of the first MOS transistor, and the cathode pin of the first MOS transistor controller is connected to the drain of the first MOS transistor.

4. The power supply circuit according to claim 1, wherein The power-off protection circuit includes an energy storage element (31) and a unidirectional conduction module (32). The input terminal of the energy storage element (31) is used to connect to an external power supply device, and the output terminal of the energy storage element (31) is connected to the voltage stabilizing circuit (2) through the unidirectional conduction module (32).

5. The power supply circuit according to claim 4, characterized in that The energy storage element (31) is a super capacitor.

6. The power supply circuit according to claim 5, wherein, The power-off protection circuit further includes a charging circuit (33). The charging circuit (33) includes a linear voltage regulator, a plurality of second MOS transistors, a voltage detection resistor, and a charging controller. The plurality of second MOS transistors are connected in series to form a turn-on and turn-off circuit. The input terminal of the linear voltage regulator is used to connect to an external power supply device, and the output terminal is connected to the energy storage element (31) and the unidirectional conduction module (32) through the turn-on and turn-off circuit. The charging controller is connected to the plurality of second MOS transistors and is connected to the energy storage element (31) through the voltage monitoring resistor.

7. The power supply circuit according to claim 6, wherein The power-off protection circuit further includes a boost voltage stabilizing circuit (34) composed of a boost converter.

8. The power supply circuit according to any one of claims 4 to 7, characterized in that The unidirectional conduction module (32) includes a second ideal diode circuit. The second ideal diode circuit includes a third MOS transistor and a third MOS transistor controller connected to the third MOS transistor. The input terminal of the third MOS transistor is connected to the energy storage element (31), and the output terminal is connected to the voltage stabilizing circuit (2).

9. The power supply circuit according to claim 1, wherein The voltage stabilizing circuit (2) includes a buck converter and a plurality of output resistors connected to the switch pin of the buck converter. The feedback pin of the buck converter is connected between two adjacent output resistors. The power input pin of the buck converter is respectively connected to the first ideal diode circuit (1) and the power-off protection circuit.

10. A small electronic device, characterized in that, Comprising: An external power supply interface, a power supply circuit as described in any one of claims 1 to 9, and a power-consuming unit connected in sequence.

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