Voltage detection circuit device applied to display

Abstract

The utility model relates to the power supply detection technology, discloses a voltage detection circuit device applied to a display, and solves the problem of display fault caused by overhigh input voltage when a user inserts adapters of other specifications by mistake. According to the scheme, the power supply detection circuit is arranged in front of the power supply circuit module of the display, when the adapter is inserted into the power supply port of the display, the power supply detection circuit can detect the power supply voltage output by the adapter, and if the power supply voltage is normal, the output of the adapter normally supplies power to the power supply circuit module in the display through the power supply detection circuit; if the power supply voltage is higher than the set voltage, the power supply detection circuit is closed, that is, the power supply from the adapter to the power supply circuit module is cut off, so that the power supply circuit module cannot obtain power input; and the problem of display fault caused by failure of an internal circuit of the display due to over-high input voltage is avoided. The utility model is suitable for the television display.

Description

Technical Field

[0001] The utility model relates to power supply detection technology, and particularly to a voltage detection circuit device applied to a display. Background Art

[0002] With the development of liquid crystal displays, the application of using adapters to supply power to displays is increasing, and the output specifications of adapters are also different, such as 12V, 19V, 24V, etc. When users use them, since the output terminals of the adapters are universal ports, users may accidentally insert an adapter for other purposes (such as toys, etc.) into the liquid crystal display terminal. If the voltage output by the adapter is too high, it may cause the internal circuit of the display to fail, thereby causing display failures. Content of the Utility Model

[0003] The technical problem to be solved by the utility model is: to provide a voltage detection circuit device applied to a display, which can avoid the problem of display failure caused by too high input voltage when users accidentally insert other specification adapters.

[0004] The technical solution adopted by the utility model to solve the above technical problems is:

[0005] A voltage detection circuit device applied to a display includes a power supply detection circuit. The voltage output end of the power supply detection circuit is connected to the input end of a power supply circuit module for supplying power to the display in the display. When the power supply port of the display is inserted with an adapter, the voltage input end of the power supply detection circuit is connected to the output end of the adapter;

[0006] The power supply detection circuit includes a voltage input end, a voltage output end, a first to seventh resistor, a first to third capacitor, a first zener diode, a second zener diode, a first MOS transistor, a second MOS transistor, a voltage regulator chip and an operational amplifier;

[0007] One end of the first resistor is connected to the voltage input terminal, and the other end is connected to the non-inverting input terminal of the operational amplifier. The fourth resistor and the fifth resistor form a voltage dividing circuit connected between the voltage input terminal and the ground, and the voltage dividing point is connected to the inverting input terminal of the operational amplifier; a third capacitor is connected between the non-inverting input terminal and the inverting input terminal of the operational amplifier, a first capacitor is connected between the inverting input terminal and the ground, and the positive power supply terminal and the negative power supply terminal are respectively connected to the voltage input terminal and the ground; the output terminal of the operational amplifier is connected to the voltage dividing point of the voltage dividing circuit through the second capacitor and is connected to the gate of the second MOS transistor through the seventh resistor; the source of the second MOS transistor is grounded, and the drain is connected to the gate of the first MOS transistor through the third resistor; the source of the first MOS transistor is connected to the voltage input terminal, and the drain is connected to the voltage output terminal; the sixth resistor and the first zener diode are connected in parallel between the gate and the source of the second MOS transistor; the second resistor and the second zener diode are connected in parallel between the gate and the source of the first MOS transistor; the anode of the voltage regulator chip is grounded, and the cathode and the reference terminal are connected to the non-inverting input terminal of the operational amplifier.

[0008] Further, the voltage regulator chip uses a TL431 chip.

[0009] Further, the operational amplifier uses an LM358 chip.

[0010] Further, the first MOS transistor is a PMOS transistor, and the second MOS transistor is an NMOS transistor.

[0011] The beneficial effects of the present utility model are as follows:

[0012] By setting a power supply detection circuit before the power supply circuit module of the display, when the power supply port of the display is inserted into the adapter, the power supply detection circuit can detect the power supply voltage output by the adapter. If the power supply voltage is normal, the output of the adapter supplies power to the power supply circuit module in the display through the power supply detection circuit normally. If the power supply voltage is higher than the set voltage, the power supply detection circuit is turned off, that is, the power supply from the adapter to the power supply circuit module is disconnected, so that the power supply circuit module cannot obtain power input, thereby realizing that when the user misinserts other specifications of adapters, the problem of display failure caused by the internal circuit failure of the display due to too high input voltage is avoided. Moreover, the solution of the present utility model is implemented entirely in hardware, with a simple circuit, easy implementation, and high standardization. Description of the Drawings

[0013] Figure 1 It is a schematic diagram of the power supply detection circuit structure in the embodiment of the present utility model;

[0014] Markings in the figure: Vin represents the voltage input terminal, Vo represents the voltage output terminal, R1 represents the first resistor, R2 represents the second resistor, R3 represents the third resistor, R4 represents the fourth resistor, R5 represents the fifth resistor, R6 represents the sixth resistor, R7 represents the seventh resistor, C1 represents the first capacitor, C2 represents the second capacitor, C3 represents the third capacitor, D1 represents the first voltage regulator diode, D2 represents the second voltage regulator diode, Q1 represents the first MOS transistor, Q2 represents the second MOS transistor, U1 represents the voltage regulator chip, and X1 represents the operational amplifier. Detailed implementation mode

[0015] The utility model aims to provide a voltage detection circuit device applied to a display, which can avoid the problem of display failure caused by too high input voltage when the user mis-plugs an adapter of other specifications. The technical core is: a power supply detection circuit is arranged before the power supply circuit module of the display. When the power supply port of the display is plugged into an adapter, the power supply detection circuit can detect the power supply voltage output by the adapter. If the power supply voltage is normal, the output of the adapter supplies power to the power supply circuit module in the display through the power supply detection circuit normally. If the power supply voltage is higher than the set voltage, the power supply detection circuit is turned off, that is, the power supply from the adapter to the power supply circuit module is disconnected, so that the power supply circuit module cannot obtain power input, thus realizing the problem of avoiding display failure caused by the failure of the internal circuit of the display due to too high input voltage when the user mis-plugs an adapter of other specifications.

[0016] Embodiment

[0017] This embodiment provides a voltage detection circuit device, which includes a power supply detection circuit. The voltage output terminal of the power supply detection circuit is connected to the input terminal of the power supply circuit module in the display for supplying power to the display. When the power supply port of the display is plugged into an adapter, the voltage input terminal of the power supply detection circuit is connected to the output terminal of the adapter;

[0018] See Figure 1 , the power supply detection circuit includes a voltage input terminal Vin, a voltage output terminal Vo, first to seventh resistors R1-R7, first to third capacitors C1-C3, a first voltage regulator diode D1, a second voltage regulator diode D2, a first MOS transistor Q1, a second MOS transistor Q2, a voltage regulator chip U1, and an operational amplifier X1;

[0019] One end of the first resistor R1 is connected to the voltage input terminal Vin, and the other end is connected to the non-inverting input terminal of the operational amplifier X1. The fourth resistor R4 and the fifth resistor R5 form a voltage dividing circuit connected between the voltage input terminal Vin and the ground, and the voltage dividing point is connected to the inverting input terminal of the operational amplifier X1; a third capacitor C3 is connected between the non-inverting input terminal and the inverting input terminal of the operational amplifier X1, and a first capacitor C1 is connected between the inverting input terminal and the ground. The positive power supply terminal and the negative power supply terminal are respectively connected to the voltage input terminal Vin and the ground; the output terminal of the operational amplifier X1 is connected to the voltage dividing point of the voltage dividing circuit through the second capacitor C2 and is connected to the gate of the second MOS transistor Q2 through the seventh resistor R7; the source of the second MOS transistor Q2 is grounded, and the drain is connected to the gate of the first MOS transistor Q1 through the third resistor R3; the source of the first MOS transistor Q1 is connected to the voltage input terminal Vin, and the drain is connected to the voltage output terminal Vo; the sixth resistor R6 and the first zener diode D1 are connected in parallel between the gate and the source of the second MOS transistor Q2; the second resistor R2 and the second zener diode D2 are connected in parallel between the gate and the source of the first MOS transistor; the anode of the voltage regulator chip U1 is grounded, and the cathode and the reference terminal are connected to the non-inverting input terminal of the operational amplifier X1.

[0020] In an exemplary solution, the voltage regulator chip U1 uses a TL431 chip to generate a stable 2.5V voltage; the operational amplifier X1 uses an LM358 operational amplifier IC; the first MOS transistor Q1 is a PMOS transistor and the second MOS transistor Q2 is an NMOS transistor. The first zener diode D1 and the second zener diode D2 are used for voltage clamping to protect the gate-source voltage of the corresponding MOS transistor from exceeding the device specifications.

[0021] The working principle of the above power supply detection circuit is as follows:

[0022] When the adapter is inserted into the power supply port of the display and powered on, the voltage input terminal Vin of the power supply detection circuit will obtain the output voltage of the adapter. Vin generates a stable 2.5V reference voltage at the cathode of the voltage regulator chip U1 through the current limiting of the first resistor R1 and is connected to the non-inverting input terminal of the operational amplifier X1. Vin is connected to the inverting input terminal of the operational amplifier X1 after being voltage-divided by the fourth resistor R4 and the fifth resistor R5. When the output voltage of the adapter is normal, the voltage at the inverting input terminal of the operational amplifier X1 is lower than 2.5V, the operational amplifier X1 outputs a high level, the second MOS transistor Q2 is turned on, a negative voltage is generated between the gate and the source of the first MOS transistor Q1 and exceeds the gate-source Vth voltage, the first MOS transistor Q1 is turned on, Vin is normally output to the voltage output terminal Vo, and the two voltages are approximately equal.

[0023] When the adapter voltage is higher than the set voltage, the voltage at the inverting input terminal of the operational amplifier X1 is higher than 2.5V. The operational amplifier X1 outputs a low level, the second MOS transistor Q2 is cut off, the first MOS transistor Q1 is cut off, and the voltage at the voltage output terminal Vo is equal to zero. Then the subsequent circuit cannot obtain power input, thus obtaining protection.

[0024] Among them, the first capacitor C1 and the third capacitor C3 are filter capacitors for filtering out switching noise, and the second capacitor C2 is a feedback capacitor for ensuring the normal operation of the operational amplifier X1; the sixth resistor R6 and the seventh resistor R7 are in a voltage division relationship for ensuring that the gate-source power supply of the second MOS transistor Q2 does not exceed the device specifications. The second resistor R2 and the third resistor R3 are MOS current limiting resistors and are in a voltage division relationship to ensure that the voltage across the second resistor R2 is higher than the MOS Vth voltage when the first MOS transistor Q1 is conducting.

[0025] Although the embodiments of the present invention have been described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principle and spirit of the present invention, and all are within the protection scope of the present invention.

Claims

1. A voltage detection circuit device applied to a display, characterized in that: It includes a power supply detection circuit, wherein the voltage output end of the power supply detection circuit is connected to the input end of a power supply circuit module in the display for supplying power to the display, and when the power supply port of the display is plugged into the adapter, the voltage input end of the power supply detection circuit is connected to the output end of the adapter; The power supply detection circuit comprises a voltage input terminal (Vin), a voltage output terminal (Vo), first to seventh resistors (R1-R7), first to third capacitors (C1-C3), a first voltage stabilizing diode (D1), a second voltage stabilizing diode (D2), a first MOS transistor (Q1), a second MOS transistor (Q2), a voltage stabilizing chip (U1) and an operational amplifier (X1); One end of the first resistor (R1) is connected to the voltage input terminal (Vin), and the other end is connected to the non-inverting input terminal of the operational amplifier (X1); a fourth resistor (R4) and a fifth resistor (R5) form a voltage divider circuit connected between the voltage input terminal (Vin) and ground, and the voltage divider point is connected to the inverting input terminal of the operational amplifier (X1); a third capacitor (C3) is connected between the non-inverting input terminal and the inverting input terminal of the operational amplifier (X1), a first capacitor (C1) is connected between the inverting input terminal and the ground, and a positive power supply terminal and a negative power supply terminal are connected to the voltage input terminal (Vin) and the ground respectively; The output end of the operational amplifier (X1) is connected to the voltage dividing point of the voltage dividing circuit through a second capacitor (C2), and is connected to the gate of the second MOS tube (Q2) through a seventh resistor (R7); the source of the second MOS tube (Q2) is grounded, and the drain is connected to the gate of the first MOS tube (Q1) through a third resistor (R3); the source of the first MOS tube (Q1) is connected to a voltage input end (Vin), and the drain is connected to a voltage output end (Vo); the sixth resistor (R6) and the first voltage stabilizing diode (D1) are connected in parallel between the gate and the source of the second MOS tube (Q2); A second resistor (R2) and a second voltage stabilizing diode (D2) are connected in parallel between the gate and source of the first MOS tube (Q1); the anode of the voltage stabilizing chip (U1) is grounded, and the cathode and the reference end are connected to the in-phase input end of the operational amplifier (X1).

2. A voltage detection circuit device for a display as claimed in claim 1, characterized in that: The voltage stabilizing chip (U1) adopts a TL431 chip.

3. A voltage detection circuit device for a display as claimed in claim 1, characterized in that: The operational amplifier (X1) adopts LM358 chip.

4. A voltage detection circuit device for a display according to any one of claims 1 to 3, characterized in that: The first MOS tube (Q1) is a PMOS tube, and the second MOS tube (Q2) is an NMOS tube.

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