Power supply circuit of HDMI output equipment capable of preventing backflow

Abstract

The utility model discloses an anti-backflow power supply circuit of HDMI output equipment. The anti-backflow power supply circuit comprises a power supply unit, a control unit, a first switch unit, a second switch unit and an output unit. The power supply unit is electrically connected with the first switch unit and used for outputting power supply voltage; the first switch unit is also electrically connected with the control unit and the second switch unit, and is used for preventing a power supply of an externally connected HDMI output device from flowing backward to the power supply unit. The control unit is also electrically connected with the second switch unit and is used for controlling on and off of the first switch unit and the second switch unit; and the second switch unit is also electrically connected with the output unit and is used for outputting the power supply voltage to the output unit. By arranging the first switch unit and enabling the diodes in the first switch unit and the second switch unit to be reversely connected, the problem of backward flowing of the power supply voltage caused by misconnection of external HDMI output equipment is solved, the internal resistance of the adopted MOSFET tube element is extremely small, and the stability of the HDMI power supply voltage is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of communication, in particular to a power supply circuit of an HDMI output device capable of preventing backflow. Background Art

[0002] The power control of general HDMI output devices is as follows Figure 1 , only one MOSFET element (Q1) is used to control the 5V to HDMI power output of the HDMI output device. Since the interface appearance of the HDMI input device and the HDMI output device is the same, when the HDMI output device is connected to another HDMIOUT device. When the power of the external HDMI output device is turned on and this HDMI output device is not powered, the power of the external HDMI output device will flow back into the 5V power supply circuit through the diode of the MOSFET element (Q1) of this HDMI output device, and spread to other possible involved lines, causing this device to work abnormally. Summary of the invention

[0003] When an existing HDMI output device is mistakenly connected to another HDMI output device, the power of the other HDMI output device may flow back into the circuit of the HDMI output device, causing circuit abnormality.

[0004] In view of the above problems, a power supply circuit of an HDMI output device capable of preventing backflow is proposed. By setting a first switch unit and reversely connecting the diodes in the first switch unit and the second switch unit, the problem of power supply voltage backflow caused by misconnection of an external HDMI output device is solved. The internal resistance of the MOSFET tube element used is extremely small, which improves the stability of the HDMI power supply voltage.

[0005] A power supply circuit of an HDMI output device capable of preventing backflow, comprising:

[0006] Power supply unit;

[0007] Control unit;

[0008] a first switch unit;

[0009] a second switch unit;

[0010] Output unit;

[0011] The power supply unit is electrically connected to the first switch unit and is used to output a power supply voltage;

[0012] The first switch unit is also electrically connected to the control unit and the second switch unit respectively, and is used to prevent the power of an externally connected HDMI output device from flowing back to the power supply unit;

[0013] The control unit is also electrically connected to the second switch unit, and is used to control the on and off of the first switch unit and the second switch unit;

[0014] The second switch unit is also electrically connected to the output unit, and is used to output the power supply voltage to the output unit.

[0015] In conjunction with the power supply circuit of the HDMI output device capable of preventing backflow described in the utility model, in a first possible implementation manner, the power supply circuit of the HDMI output device capable of preventing backflow further includes:

[0016] A first voltage stabilizing unit;

[0017] The first voltage stabilizing unit is electrically connected to the control unit and is used to suppress noise interference in the control signal output by the control unit.

[0018] In conjunction with the power supply circuit of the HDMI output device capable of preventing backflow described in the utility model, in a second possible implementation manner, the power supply circuit of the HDMI output device capable of preventing backflow further includes:

[0019] A second voltage stabilizing unit;

[0020] The second voltage stabilizing unit is electrically connected to the second switch unit and is used to suppress noise interference in the output power supply voltage.

[0021] In combination with the second possible implementation manner of the utility model, in a third possible implementation manner, the power supply circuit of the HDMI output device capable of preventing backflow further includes:

[0022] Filter unit;

[0023] The filtering unit is electrically connected to the second switch unit and is used to filter out clutter interference of the output power supply voltage.

[0024] In combination with the third possible implementation manner of the utility model, in a fourth possible implementation manner, the control unit includes:

[0025] Enable output terminal;

[0026] A first switching tube;

[0027] The enable output terminal is electrically connected to the first gate terminal of the first switch tube, and is used to input a control level signal to turn on / off the first switch tube;

[0028] A first source terminal of the first switch tube is grounded.

[0029] In combination with the fourth possible implementation manner of the utility model, in a fifth possible implementation manner, the first switch unit includes:

[0030] The second switch tube;

[0031] Bias resistor;

[0032] The second gate terminal of the second switch tube is electrically connected to the first drain terminal of the first switch tube;

[0033] The first end of the bias resistor is connected to the second gate terminal and the first drain terminal, and the second end of the bias resistor is electrically connected to the second drain terminal of the second switch tube;

[0034] The second source terminal of the second switch tube is electrically connected to the power supply unit.

[0035] In combination with the fifth possible implementation manner of the utility model, in a sixth possible implementation manner, the second switch unit includes:

[0036] The third switch tube;

[0037] The third gate terminal of the third switch tube is commonly connected to the first terminal of the bias resistor, the second gate terminal, and the first drain terminal;

[0038] The third drain terminal of the third switch tube is connected to the second end of the bias resistor and the second drain terminal;

[0039] The third source terminal of the third switch tube is electrically connected to the output unit, the second voltage stabilizing unit and the filtering unit.

[0040] In combination with the sixth possible implementation manner of the utility model, in a seventh possible implementation manner, the first switch tube, the second switch tube, and the third switch tube are respectively the first MOS tube, the second MOS tube, and the third MOS tube; the first gate end, the second gate end, and the third gate end are respectively the gates of the first MOS tube, the second MOS tube, and the third MOS tube; the first source end, the second source end, and the third source end are respectively the sources of the first MOS tube, the second MOS tube, and the third MOS tube; the first drain end, the second drain end, and the third drain end are respectively the drains of the first MOS tube, the second MOS tube, and the third MOS tube.

[0041] In combination with the seventh possible implementation manner of the utility model, in an eighth possible implementation manner, the first voltage stabilizing unit and the second voltage stabilizing unit include a first resistor and a second resistor respectively;

[0042] The first end of the first resistor is electrically connected to the enable output end and the first gate end;

[0043] The second end of the first resistor is grounded;

[0044] A first end of the second resistor is electrically connected to the third source terminal, and a second end of the second resistor is grounded.

[0045] In combination with the eighth possible implementation manner of the present utility model, in a ninth possible implementation manner, the filtering unit includes:

[0046] a first capacitor;

[0047] The first end of the first capacitor is electrically connected to the first end of the second resistor, the third source terminal and the output unit;

[0048] The second terminal of the first capacitor is grounded.

[0049] The power supply circuit of the HDMI output device capable of preventing backflow described in the utility model solves the problem of power supply voltage backflow caused by misconnection of an external HDMI output device by setting a first switch unit and reversely connecting the diodes in the first switch unit and the second switch unit. The internal resistance of the MOSFET tube element used is extremely small, thereby improving the stability of the HDMI power supply voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0051] Figure 1 A schematic diagram of a power supply circuit of an HDMI output device in the prior art;

[0052] Figure 2 The utility model is a schematic diagram of a power supply circuit of an HDMI output device capable of preventing backflow. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the utility model to clearly and completely describe the technical solution in the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the utility model.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0055] When an existing HDMI output device is mistakenly connected to another HDMI output device, the power of the other HDMI output device may flow back into the circuit of the HDMI output device, causing circuit abnormality.

[0056] In view of the above problems, a power supply circuit of an HDMI output device capable of preventing backflow is proposed.

[0057] A power supply circuit for an HDMI output device capable of preventing backflow, such as Figure 2 , Figure 2 The utility model is a schematic diagram of a power supply circuit of an HDMI output device capable of preventing backflow, comprising a power supply unit 100, a control unit 200, a first switch unit 300, a second switch unit 400, and an output unit 500; the power supply unit 100 is electrically connected to the first switch unit 300 for outputting a power supply voltage; the first switch unit 300 is also electrically connected to the control unit 200 and the second switch unit 400 respectively, for preventing the power supply of an externally connected HDMI output device from backflowing into the power supply unit 100; the control unit 200 is also electrically connected to the second switch unit 400 for controlling the on and off of the first switch unit 300 and the second switch unit 400; the second switch unit 400 is also electrically connected to the output unit 500 for outputting the power supply voltage to the output unit 500. By setting the first switch unit 300 and making the diodes in the first switch unit 300 and the second switch unit 400 reversely connected, the problem of power supply voltage backflow caused by misconnection of an external HDMI output device is solved, the internal resistance of the MOSFET tube element used is extremely small, and the stability of the HDMI power supply voltage is improved.

[0058] The power supply unit 100 may be a 5V power supply to supply power to the HDMI output device, and the control unit 200 outputs a level control signal to the first switch unit 300 and the second switch unit 400 to turn them on, thereby outputting a 5V voltage through the output unit 500.

[0059] The first switch unit 300 is used to prevent the external power supply voltage from flowing back when the external HDMI output device is connected by mistake. Specifically, after the connection is made by mistake, the first switch unit 300 and the second switch unit 400 are both turned off to prevent the external power supply voltage from flowing into the power supply unit 100.

[0060] The control unit 200 includes an enable output terminal and a first switch tube; the enable output terminal is electrically connected to a first gate terminal of the first switch tube for inputting a control level signal to turn on / off the first switch tube; and a first source terminal of the first switch tube is grounded.

[0061] The first switch unit 300 includes a second switch tube and a bias resistor R4; the second gate terminal of the second switch tube is electrically connected to the first drain terminal of the first switch tube; the first end of the bias resistor R4 is connected to the second gate terminal and the first drain terminal, and the second end of the bias resistor R4 is electrically connected to the second drain terminal of the second switch tube; the second source terminal of the second switch tube is electrically connected to the power supply unit 100.

[0062] The second switch unit 400 includes a third switch tube; the third gate terminal of the third switch tube is connected to the first end, the second gate terminal, and the first drain terminal of the bias resistor R4; the third drain terminal of the third switch tube is connected to the second end and the second drain terminal of the bias resistor R4; the third source terminal of the third switch tube is electrically connected to the output unit 500, the second voltage stabilizing unit 700 and the filtering unit 800.

[0063] The first switch tube, the second switch tube and the third switch tube are respectively the first MOS tube Q5, the second MOS tube Q3 and the third MOS tube Q4; the first gate terminal, the second gate terminal and the third gate terminal are respectively the gates of the first MOS tube Q5, the second MOS tube Q3 and the third MOS tube Q4; the first source terminal, the second source terminal and the third source terminal are respectively the sources of the first MOS tube Q5, the second MOS tube Q3 and the third MOS tube Q4; the first drain terminal, the second drain terminal and the third drain terminal are respectively the drains of the first MOS tube Q5, the second MOS tube Q3 and the third MOS tube Q4.

[0064] Furthermore, the power supply circuit of the HDMI output device capable of preventing backflow further includes a first voltage stabilizing unit 600 and a second voltage stabilizing unit 700; the first voltage stabilizing unit 600 is electrically connected to the control unit 200, and is used to suppress noise interference in the control signal output by the control unit 200. The second voltage stabilizing unit 700 is electrically connected to the second switch unit 400, and is used to suppress noise interference in the output power supply voltage. Specifically, the first voltage stabilizing unit 600 and the second voltage stabilizing unit 700 respectively include a first resistor R5 and a second resistor R6; the first end of the first resistor R5 is electrically connected to the enable output terminal (TXPWR5V_EN) and the first gate terminal; the second end of the first resistor R5 is grounded; the first end of the second resistor R6 is electrically connected to the third source terminal, and the second end of the second resistor R6 is grounded.

[0065] Furthermore, it also includes a filter unit 800; the filter unit 800 is electrically connected to the second switch unit 400, and is used to filter out the clutter interference of the output power supply voltage. The filter unit 800 includes a first capacitor C2; the first end of the first capacitor C2 is electrically connected to the first end of the second resistor R6, the third source terminal and the output unit 500; the second end of the first capacitor C2 is grounded.

[0066] The second MOS transistor and the third MOS transistor may be enhanced P-channel MOSFET elements Q3 and Q4 respectively, the first MOS transistor Q5 may be an enhanced N-channel MOSFET element, the output unit 500 may be an HDMI output socket CON1, and the bias resistor R4.

[0067] The overall circuit structure can be:

[0068] The power output unit 500 (5V power supply) is connected to the 3rd pin (second source terminal) of the second MOS tube Q3, the 2nd pin (second drain terminal) of the second MOS tube Q3 is connected to the 2nd pin (third drain terminal) of the third MOS tube Q4 and the 1st pin of the bias resistor R4, the 3rd pin (third source terminal) of the third MOS tube Q4 is connected to the 1st pin of the second resistor R6, the 1st pin of the first capacitor C2 and the 18th pin of the output unit 500CON1, which is the HDMIOUT output 5V power path TXPWR5V; the 1st pin of the second MOS tube Q3 is connected to the 1st pin of the third MOS tube Q4, the 3rd pin of the first MOS tube Q5 and the 2nd pin of the bias resistor R4, the enable output terminal (TXPWR5V_EN) is connected to the 1st pin of Q5 and the 1st pin of the first resistor R5, the 2nd pin of the first MOS tube Q5 and the 2nd pin of the first resistor R5 are connected to the ground.

[0069] The normal working process of this device is that the enable unit (control signal TXPWR5V_EN) outputs a high level, so that Q5 is turned on, that is, the 3rd pin of Q5 (the first drain terminal) outputs a low level, and then the 1st pin of Q3 and Q4 (the second gate terminal and the third gate terminal) are low. On the other hand, the power supply unit 100 (5V power supply) of this device makes the 2nd pins (the second drain terminal and the third drain terminal) of Q3 and Q4 high through the body diode of Q3. At this time, there is a forward voltage drop between the source gate of the P-channel MOSFET element Q3 and the source gate of Q4, Q3 and Q4 are turned on, and the device 5V outputs 5V power to the output unit 500 (HDMIOUT interface CON1) through the 3rd pin (the second source terminal), the 2nd pin (the second drain terminal) of Q3 and the 2nd pin (the third drain terminal), the 3rd pin (the third source terminal) of Q4. Since the internal resistance of MOSFET is extremely small, the power supply voltage of HDMIOUT is almost equal to the 5V power supply voltage of this device, which is very stable.

[0070] When the power supply unit 100 (5V power supply) of this HDMI output device is not turned on and CON1 is mistakenly connected to an external HDMI output device (HDMIOUT), the control signal path TXPWR5V_EN of the HDMIOUT output power supply loses power control, and the 1st pin of Q5 is connected to the ground through the resistor R5, so that the gate and source of Q5 are both low level, and Q5 is cut off. At this time, due to the connection of R4, the voltage between the gate and source of Q3 and Q4 is 0, and Q3 and Q4 will also be in the cut-off state, showing only ordinary diode characteristics. The external power supply is connected to the 3rd pin of Q4 through the TXPWR5V line, and to the 2nd pin of Q4 and the 2nd pin of Q3 through the body diode of Q4. Since the body diode of Q3 connected to the line is opposite to the body diode of Q4, the external power supply can only reach the position of Q3, and will not invade other lines of this device, and will not cause abnormalities.

[0071] The power supply circuit of an HDMI output device capable of preventing backflow is implemented in the utility model. By setting a first switch unit 300 and reversely connecting the diodes in the first switch unit 300 and the second switch unit 400, the problem of power supply voltage backflow caused by misconnection of an external HDMI output device is solved. The internal resistance of the MOSFET tube element used is extremely small, which improves the stability of the HDMI power supply voltage.

[0072] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A power supply circuit of an HDMI output device capable of preventing backflow, characterized in that: include: Power supply unit; Control unit; a first switch unit; a second switch unit; Output unit; The power supply unit is electrically connected to the first switch unit and is used to output a power supply voltage; The first switch unit is also electrically connected to the control unit and the second switch unit respectively, and is used to prevent the power of an externally connected HDMI output device from flowing back to the power supply unit; The control unit is also electrically connected to the second switch unit, and is used to control the on and off of the first switch unit and the second switch unit; The second switch unit is also electrically connected to the output unit, and is used to output the power supply voltage to the output unit.

2. The power supply circuit of the HDMI output device capable of preventing backflow according to claim 1, characterized in that: The power supply circuit of the HDMI output device capable of preventing backflow also includes: A first voltage stabilizing unit; The first voltage stabilizing unit is electrically connected to the control unit and is used to suppress noise interference in the control signal output by the control unit.

3. The power supply circuit of the HDMI output device capable of preventing backflow according to claim 2, characterized in that: The power supply circuit of the HDMI output device capable of preventing backflow also includes: A second voltage stabilizing unit; The second voltage stabilizing unit is electrically connected to the second switch unit and is used to suppress noise interference in the output power supply voltage.

4. The power supply circuit of the HDMI output device capable of preventing backflow according to claim 3, characterized in that: The power supply circuit of the HDMI output device capable of preventing backflow also includes: Filter unit; The filtering unit is electrically connected to the second switch unit and is used to filter out clutter interference of the output power supply voltage.

5. The power supply circuit of the HDMI output device capable of preventing backflow according to claim 4, characterized in that: The control unit comprises: Enable output terminal; A first switching tube; The enable output terminal is electrically connected to the first gate terminal of the first switch tube, and is used to input a control level signal to turn on / off the first switch tube; A first source terminal of the first switch tube is grounded.

6. The power supply circuit of the HDMI output device capable of preventing backflow according to claim 5, characterized in that: The first switch unit comprises: The second switch tube; Bias resistor; The second gate terminal of the second switch tube is electrically connected to the first drain terminal of the first switch tube; The first end of the bias resistor is connected to the second gate terminal and the first drain terminal, and the second end of the bias resistor is electrically connected to the second drain terminal of the second switch tube; The second source terminal of the second switch tube is electrically connected to the power supply unit.

7. The power supply circuit of the HDMI output device capable of preventing backflow according to claim 6, characterized in that: The second switch unit comprises: The third switch tube; The third gate terminal of the third switch tube is commonly connected to the first terminal of the bias resistor, the second gate terminal, and the first drain terminal; The third drain terminal of the third switch tube is connected to the second end of the bias resistor and the second drain terminal; The third source terminal of the third switch tube is electrically connected to the output unit, the second voltage stabilizing unit and the filtering unit.

8. The power supply circuit of the HDMI output device capable of preventing backflow according to claim 7, characterized in that: The first switch tube, the second switch tube, and the third switch tube are respectively the first MOS tube, the second MOS tube, and the third MOS tube; the first gate end, the second gate end, and the third gate end are respectively the gates of the first MOS tube, the second MOS tube, and the third MOS tube; the first source end, the second source end, and the third source end are respectively the sources of the first MOS tube, the second MOS tube, and the third MOS tube; the first drain end, the second drain end, and the third drain end are respectively the drains of the first MOS tube, the second MOS tube, and the third MOS tube.

9. The power supply circuit of the HDMI output device capable of preventing backflow according to claim 8, characterized in that: The first voltage stabilizing unit and the second voltage stabilizing unit include a first resistor and a second resistor respectively; The first end of the first resistor is electrically connected to the enable output end and the first gate end; The second end of the first resistor is grounded; A first end of the second resistor is electrically connected to the third source terminal, and a second end of the second resistor is grounded.

10. The power supply circuit of the HDMI output device capable of preventing backflow according to claim 9, characterized in that: The filtering unit comprises: a first capacitor; The first end of the first capacitor is electrically connected to the first end of the second resistor, the third source terminal and the output unit; The second terminal of the first capacitor is grounded.

Images