Fool-proof circuit, power adapter and electronic equipment

Abstract

The utility model discloses a fool-proof circuit, a power adapter and an electronic device, the fool-proof circuit comprises a voltage dividing unit, a first end of the voltage dividing unit is suitable for being connected with a power supply, and a second end of the voltage dividing unit is suitable for being connected with an enabling end of a DCDC circuit; the first end of the overvoltage protection unit is suitable for being connected with a power supply, the second end of the overvoltage protection unit is connected with the second end of the voltage dividing unit and the enabling end, the third end of the overvoltage protection unit is grounded, and the overvoltage protection unit is used for lowering the voltage at the enabling end when the voltage of the power supply is larger than a voltage threshold value. The circuit can play a role in protecting the DCDC circuit when a user does not use a corresponding power adapter, so that the product is prevented from being burnt out.

Description

Technical Field

[0001] This utility model relates to the field of power adapter technology, and in particular to a foolproof circuit, a power adapter, and an electronic device. Background Technology

[0002] In the consumer electronics field, there are usually two power supply designs: 5V and 12V. However, it often happens that users do not use the corresponding power adapter. For example, using a 12V power adapter for a 5V set-top box may cause the product to burn out. Utility Model Content

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of the present invention is to provide a foolproof circuit that protects the DC-DC circuit from damage when the user is not using the corresponding power adapter.

[0004] The second objective of this utility model is to provide a power adapter.

[0005] The third objective of this utility model is to propose an electronic device.

[0006] To address the aforementioned problems, a first aspect of this utility model proposes a foolproof circuit, comprising: a voltage divider unit, wherein a first end of the voltage divider unit is adapted to be connected to a power supply, and a second end of the voltage divider unit is adapted to be connected to the enable terminal of a DC-DC circuit; and an overvoltage protection unit, wherein a first end of the overvoltage protection unit is adapted to be connected to the power supply, a second end of the overvoltage protection unit is connected to the second end of the voltage divider unit and the enable terminal, and a third end of the overvoltage protection unit is grounded, and the overvoltage protection unit is used to pull down the voltage at the enable terminal when the voltage of the power supply is greater than a voltage threshold.

[0007] According to the foolproof circuit of this utility model embodiment, based on the design of overvoltage protection unit and voltage divider unit, when the voltage of the power supply is greater than the voltage threshold, the overvoltage protection unit pulls down the voltage at the enable terminal, thereby protecting the DC-DC circuit and preventing the product from being burned out.

[0008] In some embodiments, the overvoltage protection unit includes: a sampling subunit, a first terminal of which is adapted to be connected to the power supply, and a second terminal of which is grounded; and a switching subunit, a first terminal of which is connected to a third terminal of which is connected to the sampling subunit, a second terminal of which is connected to a second terminal of which is connected to the voltage divider unit and the enable terminal, and a third terminal of which is grounded.

[0009] In some embodiments, the switching subunit includes: a first resistor, a first end of which is connected to a third end of the sampling subunit; a transistor, the base of which is connected to a second end of the first resistor, the collector of which is connected to a second end of the voltage divider unit and the enable terminal, and the emitter of which is grounded.

[0010] In some embodiments, the sampling subunit includes: a second resistor, a first end of which is adapted to be connected to the power supply, and a second end of which is connected to the first end of the first resistor; and a third resistor, a first end of which is connected to the first end of the first resistor and the second end of the second resistor, and a second end of which is grounded.

[0011] In some embodiments, the voltage divider unit includes: a fourth resistor, the first end of which is adapted to be connected to the power supply, and the second end of which is connected to the second end of the overvoltage protection unit and the enable terminal; and a fifth resistor, the first end of which is connected to the second end of the fourth resistor, and the second end of which is grounded.

[0012] In some embodiments, the foolproof circuit further includes an energy storage unit, the first end of which is connected to the second end of the fourth resistor, the second end of the overvoltage protection unit, the enable terminal, and the first end of the fifth resistor, and the second end of the energy storage unit is grounded.

[0013] In some embodiments, the energy storage unit includes: a capacitor, the first end of which is connected to the second end of the fourth resistor, the second end of the overvoltage protection unit, the enable terminal, and the first end of the fifth resistor, and the second end of the capacitor is grounded.

[0014] A second aspect of this utility model provides a power adapter, including a DC-DC circuit; and a foolproof circuit as described in the above embodiment, wherein the foolproof circuit is connected to the enable terminal of the DC-DC circuit.

[0015] According to the power adapter of this utility model embodiment, by setting a foolproof circuit, it can protect the DC-DC circuit when the user does not use the corresponding power adapter, and prevent the product from being burned out.

[0016] A third aspect of this utility model provides an electronic device, including the power adapter described in the above embodiments.

[0017] According to the embodiments of the present invention, the electronic device, by employing a power adapter, can protect the DC-DC circuit when the user is not using the corresponding power adapter, thus preventing the product from being burned out.

[0018] In some embodiments, the electronic device is a set-top box.

[0019] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0021] Figure 1 This is a circuit topology diagram of a power adapter according to an embodiment of the present invention;

[0022] Figure 2 This is a structural block diagram of an electronic device according to an embodiment of the present invention.

[0023] Figure label:

[0024] Electronic equipment 2000;

[0025] Power adapter 1000;

[0026] 100 units of error-proof circuit; 200 units of DC-DC circuit;

[0027] Voltage divider unit 10; overvoltage protection unit 20; energy storage unit 30;

[0028] Sampling subunit 1; Switching subunit 2;

[0029] First resistor R1; second resistor R2; third resistor R3; fourth resistor R4; fifth resistor R5; transistor Q1; capacitor C1. Detailed Implementation

[0030] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The embodiments of the present invention are described in detail below.

[0031] To address the aforementioned problems, the first aspect of this utility model proposes a foolproof circuit that can protect the DC-DC circuit from damage when the user does not use the corresponding power adapter.

[0032] The following is for reference. Figure 1 The following describes a foolproof circuit 100 according to an embodiment of the present invention. The foolproof circuit 100 includes a voltage divider unit 10 and an overvoltage protection unit 20.

[0033] The voltage divider unit 10 has a first end that is adapted to be connected to a power supply, and a second end that is adapted to be connected to the enable terminal EN of the DC-DC circuit. The overvoltage protection unit 20 has a first end that is adapted to be connected to a power supply, and a second end that is connected to the second end of the voltage divider unit 10 and the enable terminal EN. The third end of the overvoltage protection unit 20 is grounded. The overvoltage protection unit 20 is used to pull down the voltage at the enable terminal EN when the voltage of the power supply is greater than the voltage threshold.

[0034] Specifically, when the power supply voltage is the normal operating voltage of the DCDC circuit (i.e., the power supply voltage is less than or equal to the voltage threshold), the voltage divider unit 10 ensures that the enable terminal EN of the DCDC circuit maintains a fixed voltage level. At this time, the enable terminal EN is at a high level, and the DCDC circuit can operate normally. When the power supply voltage is greater than the voltage threshold, the overvoltage protection unit 20 will pull down the voltage at the enable terminal EN of the DCDC circuit, causing the enable terminal to be directly grounded, thus preventing the DCDC circuit from working. This protects the DCDC circuit and prevents the product from being burned out when the user is not using the corresponding power adapter. The voltage threshold can be set according to the actual situation, for example, the voltage threshold can be set to 5V, but no specific limitation is made here.

[0035] According to the foolproof circuit 100 of this utility model embodiment, based on the design of voltage divider unit 10 and overvoltage protection unit 20, when the voltage of the power supply is greater than the voltage threshold, the overvoltage protection unit 20 pulls down the voltage at the enable terminal EN, thereby protecting the DC-DC circuit and preventing the product from being burned out.

[0036] In some embodiments, reference Figure 1 As shown, the overvoltage protection unit 20 includes a sampling subunit 1 and a switching subunit 2.

[0037] The first end of the sampling subunit 1 is suitable for connection to a power supply, and the second end of the sampling subunit 1 is grounded; the first end of the switching subunit 2 is connected to the third end of the sampling subunit, the second end of the switching subunit 2 is connected to the second end of the voltage divider unit 10 and the enable terminal EN, and the third end of the switching subunit 2 is grounded.

[0038] Specifically, sampling subunit 1 can detect the power supply voltage and control switching subunit 2 according to the power supply voltage. For example, when sampling subunit 1 detects that the power supply voltage is greater than the voltage threshold, sampling subunit 1 can control switching subunit 2 to turn on, so as to pull down the voltage at the enable terminal EN and protect the DC-DC circuit. Conversely, when sampling subunit 1 detects that the power supply voltage is less than or equal to the voltage threshold, sampling subunit 1 controls switching subunit 2 to turn off, and the overvoltage protection unit 20 does not affect the normal operation of the DC-DC circuit.

[0039] In some embodiments, reference Figure 1 As shown, the switch subunit 1 includes a first resistor R1 and a transistor Q1.

[0040] In this circuit, the first end of the first resistor R1 is connected to the third end of the sampling subunit 1; the base of the transistor Q1 is connected to the second end of the first resistor R1; the collector of the transistor Q1 is connected to the second end and the enable end EN of the voltage divider unit 10; and the emitter of the transistor Q1 is grounded.

[0041] Specifically, when sampling subunit 1 detects that the power supply voltage is greater than the voltage threshold, it provides a voltage greater than the turn-on voltage of transistor Q1, turning on Q1 and thus pulling down the voltage at the enable terminal EN, preventing the DC-DC circuit from operating. Conversely, if sampling subunit 1 detects that the power supply voltage is less than or equal to the voltage threshold, it provides a voltage less than the turn-on voltage of transistor Q1, turning off Q1, and the overvoltage protection unit does not affect the normal operation of the DC-DC circuit. Therefore, by utilizing the switching characteristics of the transistor and determining its conduction status through sampling subunit 1, the voltage at the enable terminal is controlled, resulting in a simple, low-cost, and easy-to-use circuit.

[0042] The forward voltage of transistor Q1 can be set according to actual conditions, such as 0.6V, 0.65V, 0.7V, etc., without specific limitations. The first resistor R1 is used to protect transistor Q1 by limiting the current flowing through its base, preventing excessive current from damaging the transistor.

[0043] In some embodiments, reference Figure 1 As shown, sampling subunit 2 includes a second resistor R2 and a third resistor R3.

[0044] Among them, the first end of the second resistor R2 is suitable for connecting to a power source, and the second end of the second resistor R2 is connected to the first end of the first resistor R1; the first end of the third resistor R3 is connected to the first end of the first resistor R1 and the second end of the second resistor R2, and the second end of the third resistor R3 is grounded.

[0045] Specifically, the base voltage of transistor Q1 is calculated using formula 1, where V1 is the control voltage of switch subunit 1 and VDC is the power supply voltage. Taking the resistance of the second resistor R2 as 1000Ω and the resistance of the third resistor R3 as 100Ω as an example, the conduction voltage of transistor Q1 is 0.65V. When the power supply voltage is 5V, V1 is calculated to be 0.45V using formula 1, and transistor Q1 is turned off, which does not affect the normal operation of the DC-DC circuit. When the power supply voltage is 12V, i.e., the power supply voltage is greater than the voltage threshold, V1 is calculated to be 1.09V using formula 1, and transistor Q1 is turned on. The voltage at the enable terminal EN of the DC-DC circuit is pulled low, and the DC-DC circuit does not work, thus protecting the DC-DC circuit.

[0046]

[0047] In some embodiments, reference Figure 1 As shown, the voltage divider unit 10 includes a fourth resistor R4 and a fifth resistor R5.

[0048] Among them, the first end of the fourth resistor R4 is suitable for connecting to the power supply, and the second end of the fourth resistor R4 is connected to the second end and the enable end EN of the overvoltage protection unit 20; the first end of the fifth resistor R5 is connected to the second end of the fourth resistor R4, and the second end of the fifth resistor R5 is grounded.

[0049] Specifically, when the power supply voltage is less than or equal to the voltage threshold, the voltage level at the enable terminal EN of the DC-DC circuit is determined by the voltage divider unit 10. The voltage at the enable terminal EN is calculated with reference to formula 2, where V2 is the voltage at the enable terminal, R4 is the resistance value of the fourth resistor, and R5 is the resistance value of the fifth resistor. Taking the resistance value of the fourth resistor R4 as 10000Ω and the resistance value of the fifth resistor R5 as an example, the high voltage threshold at the enable terminal EN is 1.5V. If the power supply voltage is 5V, the voltage at the enable terminal EN is calculated to be 2.5V. This voltage is greater than the high voltage threshold at the enable terminal EN, and the DC-DC circuit works normally.

[0050]

[0051] In some embodiments, reference Figure 1 As shown, the foolproof circuit 100 also includes an energy storage unit 30.

[0052] The first end of the energy storage unit 30 is connected to the second end of the fourth resistor R4, the second end of the overvoltage protection unit 20, the enable terminal EN, and the first end of the fifth resistor R5. The second end of the energy storage unit 30 is grounded.

[0053] Specifically, the energy storage unit 30 can improve timing, delay the turn-on of the DCDC circuit, and ensure that the DCDC circuit starts working after the power supply voltage stabilizes.

[0054] In some embodiments, reference Figure 1 As shown, the energy storage unit 30 includes a capacitor C1.

[0055] Among them, the first end of capacitor C1 is connected to the second end of the fourth resistor R4, the second end of the overvoltage protection unit 20, the enable terminal EN, and the first end of the fifth resistor R5, and the second end of capacitor C1 is grounded.

[0056] Specifically, in the relevant technology, the conduction time of transistor Q1 is about 100ns. By designing the delay time of capacitor C1 to be much greater than the conduction time of transistor, for example, the delay time of capacitor C1 is 1ms, the output of DC-DC circuit can be controlled. After the power supply is turned on, the foolproof circuit 100 charges capacitor C1 through the fourth resistor R4. The delay time of capacitor C1 can be calculated according to formula 3, where T is the delay time, R4 is the resistance value of the fourth resistor, and C1 is the capacitance value.

[0057]

[0058] A second aspect of this utility model provides a power adapter 1000, see reference. Figure 1 and Figure 2 As shown, the power adapter 1000 includes a DC-DC circuit 200 and a foolproof circuit 100.

[0059] The foolproof circuit 100 is connected to the enable terminal EN of the DC-DC circuit 200.

[0060] According to the power adapter 1000 of this utility model embodiment, by setting the foolproof circuit 100, it can protect the DC-DC circuit 200 when the user does not use the corresponding power adapter 1000, and prevent the product from being burned out.

[0061] A third aspect of this utility model provides an electronic device 2000, see reference. Figure 2 As shown, the electronic device 2000 includes a power adapter 1000.

[0062] According to the embodiment of the present invention, the electronic device 2000, by employing a power adapter 1000, can protect the DC-DC circuit 200 when the user is not using the corresponding power adapter 1000, thus preventing the product from being burned out.

[0063] In some embodiments, the electronic device 200 is a set-top box.

[0064] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0065] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A foolproof circuit, characterized in that, include: A voltage divider unit, wherein the first end of the voltage divider unit is adapted to be connected to a power supply, and the second end of the voltage divider unit is adapted to be connected to the enable terminal of a DC-DC circuit; An overvoltage protection unit is provided, wherein a first terminal of the overvoltage protection unit is adapted to be connected to the power supply, a second terminal of the overvoltage protection unit is connected to the second terminal of the voltage divider unit and the enable terminal, and a third terminal of the overvoltage protection unit is grounded. The overvoltage protection unit is used to pull down the voltage at the enable terminal when the voltage of the power supply is greater than a voltage threshold.

2. The foolproof circuit according to claim 1, characterized in that, The overvoltage protection unit includes: A sampling subunit, wherein a first terminal of the sampling subunit is adapted to be connected to the power supply, and a second terminal of the sampling subunit is grounded; The switching subunit has a first terminal connected to the third terminal of the sampling subunit, a second terminal connected to the second terminal of the voltage divider unit and the enable terminal, and a third terminal grounded.

3. The foolproof circuit according to claim 2, characterized in that, The switching subunit includes: A first resistor, the first end of which is connected to the third end of the sampling subunit; The transistor has its base connected to the second end of the first resistor, its collector connected to the second end of the voltage divider unit and the enable terminal, and its emitter grounded.

4. The foolproof circuit according to claim 3, characterized in that, The sampling subunit includes: A second resistor, the first end of which is adapted to be connected to the power supply, and the second end of which is connected to the first end of the first resistor; The third resistor has its first end connected to the first end of the first resistor and the second end of the second resistor, and its second end is grounded.

5. The foolproof circuit according to any one of claims 1-4, characterized in that, The voltage divider unit includes: A fourth resistor, the first end of which is adapted to be connected to the power supply, and the second end of which is connected to the second end of the overvoltage protection unit and the enable terminal; The fifth resistor has its first end connected to the second end of the fourth resistor, and its second end is grounded.

6. The foolproof circuit according to claim 5, characterized in that, The foolproof circuit also includes: An energy storage unit, wherein the first end of the energy storage unit is connected to the second end of the fourth resistor, the second end of the overvoltage protection unit, the enable terminal, and the first end of the fifth resistor, and the second end of the energy storage unit is grounded.

7. The foolproof circuit according to claim 6, characterized in that, The energy storage unit includes: The capacitor has its first terminal connected to the second terminal of the fourth resistor, the second terminal of the overvoltage protection unit, the enable terminal, and the first terminal of the fifth resistor, and its second terminal is grounded.

8. A power adapter, characterized in that, include: DCDC circuit; The foolproof circuit according to any one of claims 1-7, wherein the foolproof circuit is connected to the enable terminal of the DC-DC circuit.

9. An electronic device, characterized in that, Includes the power adapter as described in claim 8.

10. The electronic device according to claim 9, characterized in that, The electronic device is a set-top box.

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