Protection isolation circuit for household FTTR set top box

Abstract

The invention belongs to the technical field of home network equipment, and particularly discloses a protection isolation circuit for a home FTTR set top box, which is characterized in that an input end of the protection circuit is connected with a TYPE-C port of the FTTR set top box, an output end of the protection circuit is connected with an input end of an isolation circuit, and an output end of the isolation circuit is connected with a TYPE-C port of the FTTR set top box. The surge protection module is used for preventing surge of an external power supply from impacting a signal processor in the set top box through a TYPE-C port; the output end of the isolation circuit is connected with the input end of the filter circuit, and the isolation circuit is used for isolating a power supply signal input through a TYPE-C port; and the output end of the filter circuit is connected to a signal processor in the set top box and is used for filtering the isolated power supply signal so as to provide a stable power supply for the signal processor. According to the invention, a stable power supply can be provided for the signal processor in the household FTTR set top box, so that the power supply stability, the anti-interference capability and the video transmission quality of the set top box are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of home network equipment, and particularly relates to a protection isolation circuit for a home FTTR set-top box. BACKGROUND

[0002] The traditional home FTTR set-top box faces multiple challenges in a complex electromagnetic environment - single surge protection device is difficult to cope with the coordinated interference of high-intensity transient overvoltage and high-frequency noise, resulting in insufficient power supply stability, which directly affects the power supply quality of the signal processor: the voltage transient caused by the surge will exceed the working range of the signal processor, thereby triggering abnormal reset or hardware damage, resulting in interruption of video decoding and data transmission; the existing isolation circuit mostly adopts one-way isolation design, which cannot completely block the direct current potential coupling and ground loop current, resulting in common mode noise invading the signal processor, causing signal offset or sampling distortion, and reducing the high-definition video restoration precision; the filtering module often relies on passive filters with fixed parameters, lacks dynamic adaptation ability, and is difficult to suppress wideband noise, so that high-frequency noise is easily coupled to the clock circuit of the signal processor, causing timing jitter and data error, and aggravating picture freezing and audio noise. These problems not only threaten the service life of the equipment, but also seriously restrict the performance upper limit of the signal processor. SUMMARY

[0003] The main purpose of the present application is to provide a protection isolation circuit for a home FTTR set-top box, which aims to systematically solve the above-mentioned defects to ensure that the signal processor operates efficiently and stably under the condition of low noise and high stable power supply.

[0004] To achieve the above purpose, the present application provides the following technical solutions: A protection isolation circuit for a home FTTR set-top box, the circuit comprising: a protection circuit, an isolation circuit and a filtering circuit, wherein the input end of the protection circuit is connected to the TYPE-C port of the FTTR set-top box, the output end is connected to the input end of the isolation circuit, and is used for preventing the surge of the external power supply from impacting the signal processor in the set-top box through the TYPE-C port; the output end of the isolation circuit is connected to the input end of the filtering circuit, and is used for isolating the power supply signal input through the TYPE-C port; and the output end of the filtering circuit is connected to the signal processor in the set-top box, and is used for filtering the isolated power supply signal to provide stable power supply for the signal processor.

[0005] Optionally, the protection circuit comprises: a multi-stage surge suppression module, an input end of the multi-stage surge suppression module being connected between a power positive pole pin and a ground pin of the TYPE-C port, and an output end of the multi-stage surge suppression module being connected with a dynamic overcurrent protection module, a reverse connection protection module and a suppression and filtering preprocessing module in sequence; and the multi-stage surge suppression module is used for grading absorption and suppression of high-energy transient surges introduced by a power signal; the dynamic overcurrent protection module is used for dynamic monitoring of power supply current change and disconnection of a loop when overcurrent occurs; the reverse connection protection module is used for identification and blocking of reverse connection of a power supply; and the suppression and filtering preprocessing module is used for preliminary filtering of noise and interference in the power signal.

[0006] Optionally, the multi-stage surge suppression module comprises: a gas discharge tube, a pressure-sensitive resistor and a first capacitor, wherein a first end of the gas discharge tube is connected with the power positive pole pin of the TYPE-C port; a second end of the gas discharge tube is connected with the ground pin of the TYPE-C port; the pressure-sensitive resistor is connected in parallel with the gas discharge tube; and the first capacitor is connected across the power positive pole pin and the ground pin of the TYPE-C port.

[0007] Optionally, the dynamic overcurrent protection module comprises: a self-resetting fuse, an electronic fuse, a first resistor and a current detection amplifier, wherein a first end of the self-resetting fuse is connected with a connection position of the gas discharge tube and the power positive pole pin of the TYPE-C port through the electronic fuse and the first resistor; a second end of the self-resetting fuse is connected with an input end of the reverse connection protection module; a positive input end of the current detection amplifier is connected with a first end of the first resistor; a negative input end of the current detection amplifier is connected with a second end of the first resistor; an output end of the current detection amplifier is connected with a control end of the electronic fuse; a positive pole pin of the current detection amplifier is connected with a +5.5V voltage, and a negative pole pin of the current detection amplifier is connected with a -5.5V voltage.

[0008] Optionally, the reverse connection protection module comprises: a first transistor, a second transistor, a comparator, a gate driver, a second resistor, a first zener diode and a second zener diode, wherein a same-phase input end of the comparator serves as an input end of the reverse connection protection module; a source of the first transistor and a source of the second transistor are connected, and a connection point serves as an output end of the reverse connection protection module; a drain of the first transistor is connected with the same-phase input end of the comparator; a drain of the second transistor is connected with an opposite-phase input end of the comparator; an output end of the comparator is connected with a gate of the first transistor and a gate of the second transistor through the gate driver and the second resistor in sequence; an anode of the first zener diode is connected with the drain of the first transistor; a cathode of the first zener diode is connected with the gate of the first transistor; an anode of the second zener diode is connected with the drain of the second transistor; and a cathode of the second zener diode is connected with the gate of the second transistor.

[0009] Optionally, the suppression and filtering preprocessing module comprises a first operational amplifier, a third resistor, a fourth resistor, a second capacitor, a third capacitor, a fourth capacitor and a fifth capacitor, wherein a first end of the third resistor is connected to the output end of the reverse connection protection module as the input end of the suppression and filtering preprocessing module, a second end of the third resistor is connected to the non-inverting input end of the first operational amplifier; the inverting input end of the first operational amplifier is connected to the first ground end through the fourth resistor; a first end of the second capacitor is connected to the connection between the fourth resistor and the inverting input end of the first operational amplifier; a second end of the second capacitor is connected to the output end of the first operational amplifier, and the output end of the first operational amplifier is connected to the input end of the isolation circuit as the output end of the suppression and filtering preprocessing module; the third capacitor, the fourth capacitor and the fifth capacitor are connected in parallel, and first ends of the third capacitor, the fourth capacitor and the fifth capacitor are connected to the output end of the first operational amplifier, and second ends of the third capacitor, the fourth capacitor and the fifth capacitor are connected to the first ground end.

[0010] Optionally, the isolation circuit adopts a three-layer isolation structure, comprising a first isolation module, a second isolation module and a third isolation module connected in cascade, wherein the first isolation module is used to isolate the direct current potential coupling between the filtered power supply signal and the second isolation module; the second isolation module is used to physically isolate the current path of the first isolation module and the second isolation module; and the third isolation module is used to suppress the residual high-frequency noise in the filtered power supply signal.

[0011] Optionally, the first isolation module comprises a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a sixth capacitor and a second operational amplifier, wherein a first end of the fifth resistor is connected to the input end of the isolation circuit; a second end of the fifth resistor is connected to the second ground end through the sixth resistor; a first end of the sixth capacitor is connected to the connection between the fifth resistor and the sixth resistor; a second end of the sixth capacitor is connected to the non-inverting input end of the second operational amplifier; the output end of the second operational amplifier is connected to the input end of the second isolation module and connected to the non-inverting input end thereof through the seventh resistor; and the inverting input end of the second operational amplifier is connected to the third ground end through the eighth resistor.

[0012] Optionally, the second isolation module comprises a ninth resistor, a seventh capacitor, a first triode, wherein a first end of the ninth resistor is connected to the input end of the second isolation module; a second end of the ninth resistor is connected to the base of the first triode through the seventh capacitor; the emitter of the first triode is connected to the fourth ground end, and the collector of the first triode is connected to the input end of the third isolation module.

[0013] Optionally, the third isolation module comprises a tenth resistor, an eleventh resistor, an eighth capacitor, a ninth capacitor and a first inductor, wherein a first end of the tenth resistor is an input end of the third isolation module, a second end of the tenth resistor is connected to an input end of the filter circuit; a first end of the eleventh resistor is connected to the second end of the tenth resistor, a second end of the eleventh resistor is connected to the fifth ground end through the eighth capacitor; a first end of the first inductor is connected to a connection point of the tenth resistor and the eleventh resistor, and a second end of the first inductor is connected to the sixth ground end through the ninth capacitor.

[0014] The present application can bring the following beneficial effects: In the embodiment, the protection isolation circuit can realize multi-stage surge layer suppression, resist transient overvoltage impact such as lightning strike and electrostatic discharge, and avoid damage to the TYPE-C port and the rear-stage circuit; the isolation circuit can eliminate the influence of ground loop interference and common-mode noise on the reference voltage of the signal processor; the filter circuit can dynamically adapt to the noise frequency band, accurately suppress power ripple and radio frequency interference, and output an ultra-low noise direct current power supply. The three work together to provide a "high stability-low ripple-strong anti-interference" power supply environment for the signal processor arranged in the set-top box, significantly improve the video decoding accuracy, data transmission rate and equipment reliability, and ensure smooth transmission of 4K / 8K high-definition video and efficient cooperation of smart home devices. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a whole structure schematic diagram of a protection isolation circuit for a home FTTR set-top box provided by an embodiment of the present application; Figure 2 is a circuit structure schematic diagram of a multi-stage surge suppression module and a dynamic overcurrent protection module provided by another embodiment of the present application; Figure 3 is a circuit structure schematic diagram of a reverse connection protection module provided by another embodiment of the present application; Figure 4 is a circuit structure schematic diagram of a suppression and filter preprocessing module provided by another embodiment of the present application; Figure 5 is a circuit structure schematic diagram of a first isolation module provided by another embodiment of the present application; Figure 6 is a circuit structure schematic diagram of a second isolation module provided by another embodiment of the present application; Figure 7 is a circuit structure schematic diagram of a third isolation module provided by another embodiment of the present application; Figure 8 is a circuit structure schematic diagram of a filter circuit provided by another embodiment of the present application. DETAILED DESCRIPTION

[0016] With reference to the drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0017] It should be noted that all directional indications, such as upper, lower, left, right, front, back, etc., in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly.

[0018] In the present application, unless specifically defined and limited otherwise, the terms "connection", "fixed", etc. should be understood in a broad sense, for example, "fixed" can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be direct connection, or indirect connection through an intermediate medium; can be internal connection of two elements, or interaction relationship between two elements, unless otherwise specifically defined. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0019] In addition, if the present application has descriptions involving "first", "second", etc., the "first", "second", etc. are only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. For example, "A and / or B" includes A scheme, or B scheme, or A and B scheme. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of those of ordinary skill in the art, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection claimed by the present application.

[0020] Figure 1 The structural block diagram of a protection isolation circuit for a home FTTR set-top box according to an embodiment of the present application is as follows, Figure 1As shown, the protection isolation circuit comprises a protection circuit 10, an isolation circuit 20 and a filter circuit 30, wherein the input end of the protection circuit 10 is connected to the TYPE-C port of the FTTR set-top box, the output end is connected to the input end of the isolation circuit 20, and the protection circuit 10 is used to prevent the surge of the external power supply from impacting the signal processor in the set-top box through the TYPE-C port; the output end of the isolation circuit 20 is connected to the input end of the filter circuit 30, and the isolation circuit 20 is used to isolate the power supply signal input through the TYPE-C port; and the output end of the filter circuit 30 is connected to the signal processor in the set-top box, and the filter circuit 30 is used to filter the isolated power supply signal to provide a stable power supply for the signal processor.

[0021] In the embodiment, the protection isolation circuit can realize multi-stage surge layer suppression, resist transient overvoltage impact such as lightning strike and electrostatic discharge, and avoid damage to the TYPE-C port and the subsequent circuit; the isolation circuit can eliminate the influence of ground loop interference and common mode noise on the reference voltage of the signal processor; and the filter circuit can dynamically adapt to the noise frequency band, accurately suppress power supply ripple and radio frequency interference, and output an ultra-low noise direct current power supply. The three work together to provide a "high stability-low ripple-strong anti-interference" power supply environment for the signal processor arranged in the set-top box, significantly improve the video decoding accuracy, data transmission rate and equipment reliability, and ensure smooth transmission of 4K / 8K high-definition video and efficient cooperation of smart home devices.

[0022] It should be noted that the protection scope of the present application does not involve the internal structure of the signal processor, and the signal processor can adopt a conventional signal processor, for example, Texas Instruments TMS320C6000, Rockchip RK3588 or Huawei HiSilicon series.

[0023] In another exemplary embodiment, the protection circuit comprises a multi-stage surge suppression module, the input end of the multi-stage surge suppression module is connected between the power positive pin and the ground pin of the TYPE-C port, and the output end of the multi-stage surge suppression module is connected in series with a dynamic overcurrent protection module, a reverse connection protection module and a suppression and filtering preprocessing module in sequence; the multi-stage surge suppression module is used to absorb and suppress high-energy transient surges introduced by the power supply in stages to protect the TYPE-C port from voltage impact damage; the dynamic overcurrent protection module is used to dynamically monitor the current change of the power supply and disconnect the circuit when overcurrent occurs to prevent circuit overheating or burning; the reverse connection protection module is used to identify and block the reverse connection of the power supply to prevent reverse current flow; and the suppression and filtering preprocessing module is used to preliminarily filter out noise and interference in the power supply signal to provide a stable power supply for the subsequent circuit.

[0024] In another exemplary embodiment, as Figure 2As shown, the multi-stage surge suppression module includes a gas discharge tube GDT, a voltage-dependent resistor MOV, and a first capacitor C1, wherein a first end of the gas discharge tube GDT is connected to a power positive pole pin VBUS of the TYPE-C port, and a second end of the gas discharge tube GDT is connected to a ground pin GND of the TYPE-C port; the voltage-dependent resistor MOV is connected in parallel with the gas discharge tube GDT; and the first capacitor C1 is connected across the power positive pole pin VBUS and the ground pin GND of the TYPE-C port.

[0025] In this embodiment, the gas discharge tube GDT is in a high resistance state under normal circumstances and does not affect normal power supply work. Only when the input voltage exceeds its breakdown voltage instantaneously (for example, a surge occurs), the gas discharge tube GDT will conduct and discharge excess current to the ground (ground pin GND), thereby playing a primary protection role. The voltage-dependent resistor MOV is connected in parallel with the gas discharge tube GDT. When the voltage is slightly higher than its threshold value, the voltage-dependent resistor MOV begins to conduct and shunts the surge current to the ground (ground pin GND), while limiting the voltage rise rate. The first capacitor C1 is a decoupling capacitor connected across the power positive pole pin VBUS and the ground pin GND of the TYPE-C port, which can effectively absorb high-frequency interference signals in the power supply and absorb the residual transient voltage after the gas discharge tube GDT and the voltage-dependent resistor MOV act, thereby ensuring the smoothness of the output power supply.

[0026] In summary, the gas discharge tube GDT and the voltage-dependent resistor MOV can realize layered interception and shunting of surges of different intensities and frequencies through cooperative work, thereby improving the all-around surge protection of the TYPE-C port.

[0027] In another exemplary embodiment, please continue to refer to Figure 2 , the dynamic overcurrent protection module includes a self-resetting fuse PPTC, an electronic fuse eFuse, a first resistor R1, and a current detection amplifier CSA, wherein a first end of the self-resetting fuse PPTC is connected to the connection between the gas discharge tube GDT and the power positive pole pin VBUS of the TYPE-C port through the electronic fuse eFuse and the first resistor R1, and a second end of the self-resetting fuse PPTC is connected to an input end of the reverse connection protection module; a positive input end of the current detection amplifier CSA is connected to a first end of the first resistor R1, and a negative input end of the current detection amplifier CSA is connected to a second end of the first resistor R1; an output end of the current detection amplifier CSA is connected to a control end of the electronic fuse eFuse, a positive pole pin of the current detection amplifier CSA is connected to a +5.5V voltage, and a negative pole pin of the current detection amplifier CSA is connected to a -5.5V voltage.

[0028] In this embodiment, the self-resetting fuse PPTC is in a low resistance state under normal current, and when the current exceeds the rated value, its internal resistance increases rapidly, thereby limiting the current flowing through the circuit, and when the current returns to normal, it automatically cools down, and the self-resetting fuse PPTC can restore the conduction state without replacement.

[0029] The electronic fuse eFuse is a controlled switch device that can quickly disconnect the circuit when an overcurrent signal is detected, and its control end is driven by the current detection amplifier CSA, which can achieve fast and accurate protection control.

[0030] The first resistor R1 is connected in series in the power supply path, for sampling the current flowing through the circuit, and generating a voltage signal proportional to the current at its two ends.

[0031] The current detection amplifier CSA is used to amplify the voltage difference signal between the two ends of the first resistor R1, and compare it with the set threshold. If the current is too large to cause the voltage difference to exceed the threshold, the current detection amplifier CSA outputs a high level to trigger the electronic fuse eFuse to disconnect, cutting off the power supply path and preventing overcurrent damage.

[0032] The dynamic overcurrent protection module realizes the functions of fast power-off and fault recovery when the current is abnormal through the joint design of the self-resetting fuse PPTC and the electronic fuse eFuse. Combined with the precise monitoring mechanism constructed by the resistance sampling and the current detection amplifier CSA, it has the advantages of sensitive response, accurate action, and strong self-recovery ability, etc., and can improve the safety and reliability of the system when facing overcurrent faults, and can effectively prevent the damage of abnormal power supply to the subsequent circuit.

[0033] In another exemplary embodiment, as Figure 3As shown, the reverse connection protection module comprises a first transistor M1, a second transistor M2, a comparator U1, a gate driver GD (such as TC4420), a second resistor R2, a first zener diode D1 and a second zener diode D2, wherein the non-inverting input terminal of the comparator U1 serves as the input terminal of the reverse connection protection module; the sources of the first transistor M1 and the second transistor M2 are connected and the connection point (i.e. the point N shown in the figure) serves as the output terminal of the reverse connection protection module; the drain of the first transistor M1 is connected to the non-inverting input terminal of the comparator U1 and the drain of the second transistor M2 is connected to the inverting input terminal of the comparator U1; the output terminal of the comparator U1 is connected to the gates of the first transistor M1 and the second transistor M2 through the gate driver GD and the second resistor R2 in sequence (the connection point of the comparator U1 and the gate driver GD and the point N have no intersection); the anode of the first zener diode D1 is connected to the drain of the first transistor M1, the cathode of the first zener diode D1 is connected to the gate of the first transistor M1, the anode of the second zener diode D2 is connected to the drain of the second transistor M2, and the cathode of the second zener diode D2 is connected to the gate of the second transistor M2.

[0034] In this embodiment, the reverse connection protection module uses the reverse blocking mechanism of the double transistors (the first transistor M1 and the second transistor M2) and the voltage polarity detection circuit to judge and control the polarity of the power supply input, so as to ensure that the current is blocked in the case of reverse connection of the power supply and prevent the downstream circuit from being damaged.

[0035] The first transistor M1 and the second transistor M2 are connected back-to-back on the power supply path, the comparator U1 is used to compare the voltages of the positive and negative poles of the power supply, for example, when the power supply is connected in the forward direction, the comparator U1 outputs a high level, the gate driver GD drives the gate voltages of the first transistor M1 and the second transistor M2 to the conduction threshold value, both transistors are turned on at the same time, and the power supply path is formed; if the power supply is connected in reverse, the comparator U1 outputs a low level, the gate driver GD has no effective driving signal, and the gate voltages of the first transistor M1 and the second transistor M2 are lower than the conduction threshold value, both transistors are turned off at the same time, and the current path is completely blocked. By adopting the back-to-back connection mode, even if one of the transistors is turned on due to process deviation, transient interference or polarity error, the other transistor will remain in the off state due to the inconsistent polarity, ensuring that the circuit is broken, thereby forming double circuit breaking protection and ensuring that the reverse current cannot flow into the downstream circuit.

[0036] In addition, when the drain of the first transistor M1 and the second transistor M2 is high voltage due to transient overvoltage (such as a power surge), the first voltage stabilizing diode D1 and the second voltage stabilizing diode D2 can clamp the gate voltage to its voltage stabilizing value (such as 5.1V) through reverse breakdown, avoid the gate-source voltage (V_GS) of the first transistor M1 and the second transistor M2 exceeding the rated withstand voltage value, prevent the gate oxide from being broken down, so as to achieve the function of stabilizing the gate voltage and ensure the stability and reliability of the driving signal.

[0037] The reverse connection protection module detects the polarity of the power supply input in real time through the comparator U1, and controls the first transistor M1 and the second transistor M2 connected back-to-back in combination with the gate driver GD, to realize automatic identification and control of the positive and negative connection state of the power supply; in the reverse connection state, the first transistor M1 and the second transistor M2 remain in the off state, which can effectively block the current path and prevent the current from flowing backward to damage the subsequent circuit, while the supporting voltage stabilizing diodes D1 and D2 stabilize the gate voltage and enhance the driving reliability. For example, in a household FTTR set-top box, if the user mistakenly reverses the TYPE-C power line, the reverse connection protection module can immediately cut off the power supply to avoid damage to the signal processor, filter circuit and other key modules due to the impact of reverse current, at the same time, the first voltage stabilizing diode D1 and the second voltage stabilizing diode D2 can absorb transient high voltage pulses (such as lightning induction), further improving the overall anti-interference ability of the FTTR set-top box.

[0038] In another exemplary embodiment, as shown in Figure 4 The suppression and filtering preprocessing module includes a first operational amplifier U2, a third resistor R3, a fourth resistor R4, a second capacitor C2, a third capacitor C3, a fourth capacitor C4 and a fifth capacitor C5, wherein the first end of the third resistor R3 is connected to the output end of the reverse connection protection module as the input end of the suppression and filtering preprocessing module, the second end of the third resistor R3 is connected to the non-inverting input end of the first operational amplifier U2, the inverting input end of the first operational amplifier U2 is connected to the first ground end GND1 through the fourth resistor R4, the first end of the second capacitor C2 is connected to the connection between the fourth resistor R4 and the inverting input end of the first operational amplifier U2, the second end of the second capacitor C2 is connected to the output end of the first operational amplifier U2, and the output end of the first operational amplifier U2 is connected to the input end of the isolation circuit as the output end of the suppression and filtering preprocessing module; the third capacitor C3, the fourth capacitor C4 and the fifth capacitor C5 are connected in parallel, and the first ends of the third capacitor C3, the fourth capacitor C4 and the fifth capacitor C5 are connected to the output end of the first operational amplifier U2, and the second ends of the third capacitor C3, the fourth capacitor C4 and the fifth capacitor C5 are connected to the first ground end GND1.

[0039] In this embodiment, the suppression and filtering pre-processing module cooperates with the first operational amplifier U2, the third resistor R3, the fourth resistor R4, and the capacitor group composed of the second capacitor C2, the third capacitor C3, the fourth capacitor C4, and the fifth capacitor C5 to achieve efficient noise suppression and ripple optimization of the TYPE-C power signal. The power signal enters the non-inverting input terminal of the first operational amplifier U2 through the third resistor R3, and the inverting input terminal is connected to the first ground terminal GND1 through the fourth resistor R4 to form a closed-loop feedback. The second capacitor C2 is connected across the inverting input terminal and the output terminal of the first operational amplifier U2, and forms a first-order active low-pass filter with the fourth resistor R4. The cutoff frequency is determined by The output terminal of the first operational amplifier U2 is connected in parallel with multiple capacitors (C3 to C5) of different capacitances, which can cover a wide range of noise absorption. For example, a small-capacity capacitor (such as the third capacitor C3) can suppress high-frequency transient noise, a medium-capacity capacitor (such as the fourth capacitor C4) can smooth the intermediate frequency ripple, and a large-capacity capacitor (such as the fifth capacitor C5) can stabilize the low-frequency fluctuation. The combination of the three in parallel forms a low-impedance path through differentiated ESR / ESL characteristics to further attenuate residual noise. At the same time, the high input impedance of the first operational amplifier U2 can isolate the front-end power disturbance, and the low output impedance can enhance the driving capability. Finally, the output is a "super-clean" direct current power source after two-stage filtering (active filtering + multiple-capacitor decoupling), which significantly reduces the ripple amplitude and improves the signal purity, providing a stable and low-noise power supply basis for the subsequent signal processor.

[0040] In another exemplary embodiment, the isolation circuit adopts a three-layer isolation structure, including a cascaded first isolation module, a second isolation module, and a third isolation module. The first isolation module is used to isolate the direct current potential coupling between the power signal filtered by the suppression and filtering pre-processing module and the second isolation module, ensuring that the static voltage of the input side (output of the front-end filtering pre-processing module) and the output side (input of the second isolation module) is independent, avoiding the input of reference interference and the output of direct current voltage caused by the difference in power ground potential. The second isolation module is used to physically isolate the direct current path between its input side and output side, preventing transient current backflow, ground loop noise, or common-mode interference from affecting the subsequent circuit, while achieving energy transfer of the signal. The third isolation module is used to suppress the residual high-frequency noise (such as switching noise and radio frequency interference) in the filtered power signal, allowing only valid low-frequency or direct current components to be transmitted to the output terminal (signal processor), further improving the purity and stability of the power signal.

[0041] In another exemplary embodiment, as Figure 5As shown, the first isolation module comprises: a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a sixth capacitor C6 and a second operational amplifier U3, wherein the first end of the fifth resistor R5 is the input end of the isolation circuit, the second end of the fifth resistor R5 is connected to the second ground end GND2 through the sixth resistor R6, the first end of the sixth capacitor C6 is connected to the connection between the fifth resistor R5 and the sixth resistor R6, the second end of the sixth capacitor C6 is connected to the non-inverting input end of the second operational amplifier U3, the output end of the second operational amplifier U3 is connected to the input end of the second isolation module and connected to the non-inverting input end thereof through the seventh resistor R7, and the inverting input end of the second operational amplifier U3 is connected to the third ground end GND3 through the eighth resistor R8.

[0042] In this embodiment, the first isolation module attenuates the level of the power supply signal through a resistor voltage dividing network (consisting of the fifth resistor R5 and the sixth resistor R6) to adjust the high voltage signal to a voltage range suitable for subsequent processing; the sixth capacitor C6 and the sixth resistor R6 at the voltage dividing node constitute a high-pass filter to filter out the direct current component in the input signal and only allow alternating current or adjusted direct current components to pass to the non-inverting input end of the second operational amplifier U3. The second operational amplifier U3 is configured as a voltage follower (forming a negative feedback through the seventh resistor R7), which has high input impedance and low output impedance characteristics to isolate the influence of the front-end circuit on the rear-end. Meanwhile, the eighth resistor R8 provides a bias reference (GND3) for the inverting input end of the second operational amplifier U3 to ensure that the direct current potential of the output end of the second operational amplifier U3 and the input end of the second isolation module is independent. The first isolation module blocks the direct current voltage coupling between the input and the output through the triple mechanisms of voltage dividing attenuation, alternating current coupling and voltage following, eliminates the offset interference introduced by the ground potential difference, and realizes the direct current voltage isolation function.

[0043] In another exemplary embodiment, as shown in Figure 6 The second isolation module comprises: a ninth resistor R9, a seventh capacitor C7 and a first triode T1, wherein the first end of the ninth resistor R9 is the input end of the second isolation module, the second end of the ninth resistor R9 is connected to the base of the first triode T1 through the seventh capacitor C7, the emitter of the first triode T1 is connected to the fourth ground end GND4, and the collector of the first triode T1 is connected to the input end of the third isolation module.

[0044] In this embodiment, after the second isolation module cuts off the direct current path between its input side and output side, the power signal is processed by the first isolation module, enters the second isolation module, is limited by the ninth resistor R9, and then the direct current component is filtered out by the seventh capacitor C7 and coupled to the base of the first transistor T1. The first transistor T1 works in the amplification zone or the switch state. When the power signal is a positive alternating component, the base-emitter of the first transistor T1 is turned on, and the collector output outputs a signal in phase with the input power signal to the third isolation module. If the input contains a reverse current or transient interference, the seventh capacitor C7 will block the direct current offset, and the first transistor T1 will also be cut off due to insufficient base voltage.

[0045] In summary, the second isolation module cooperates with the first transistor T1 through RC coupling formed by the ninth resistor R9 and the seventh capacitor C7, can physically isolate the current loop between its input side and output side, thereby blocking the ground loop interference and transient current backflow, and providing double protection of anti-interference and electrical safety for the subsequent circuit.

[0046] In another exemplary embodiment, as shown in Figure 7 The third isolation module includes a tenth resistor R10, an eleventh resistor R11, an eighth capacitor C8, a ninth capacitor C9, and a first inductor L1. The first end of the tenth resistor R10 is connected to the input end of the third isolation module, the second end of the tenth resistor R10 is connected to the input end of the filter circuit, the first end of the eleventh resistor R11 is connected to the second end of the tenth resistor R10, the second end of the eleventh resistor R11 is connected to the fifth ground terminal GND5 through the eighth capacitor C8, the first end of the first inductor L1 is connected to the connection between the tenth resistor R10 and the eleventh resistor R11, and the second end of the first inductor L1 is connected to the sixth ground terminal GND6 through the ninth capacitor C9.

[0047] In this embodiment, the power signal processed by the second isolation module is divided into two paths after being limited by the tenth resistor R10. One path is filtered by an RC low-pass filter composed of the eleventh resistor R11 and the eighth capacitor C8 to attenuate medium and high frequency noise (such as switching ripple); the other path is filtered by an LCπ type filter formed by the first inductor L1 and the ninth capacitor C9, which further filters out MHz level radio frequency interference (such as Wi-Fi, Bluetooth coupling noise) by using the inductive reactance characteristic of inductance and the bypass effect of capacitance. The filtered signals of the two paths are superimposed at the output end, and are attenuated by multiple frequency bands to achieve full-band noise suppression (RC low-pass filter mainly attacks medium and high frequency band, LCπ type filter focuses on ultra-high frequency band, tenth resistor R10 and eleventh resistor R11 consider signal impedance matching and voltage division protection to avoid filter network resonance or overshoot).

[0048] In summary, the three isolation modules work together to construct a multi-layered isolation protection system. The first isolation module eliminates ground potential difference interference by blocking DC potential coupling through voltage division attenuation, AC coupling, and a voltage follower. The second isolation module physically isolates the input-output current path using RC DC blocking and a transistor unidirectional conduction mechanism to suppress transient current backflow and ground loop noise. The third isolation module employs an RC+LC composite filter network to suppress noise across the entire frequency band from mid-high frequency to ultra-high frequency, combined with an independent grounding design to block common-mode interference conduction. These three isolation modules progressively purify the power signal from voltage, current, and frequency domain perspectives, ultimately providing the subsequent signal processor with a "clean" power supply that is voltage-independent, path-isolated, and has extremely low ripple. This enhances the overall anti-interference capability and signal processing stability, ensuring the reliability of high-definition video transmission and high-speed communication.

[0049] In another exemplary embodiment, such as Figure 8 As shown, the filter circuit includes: a twelfth resistor R12, a thirteenth resistor R13, a tenth capacitor C10, an eleventh capacitor C11, a third operational amplifier U4, and a digital potentiometer DP. The first end of the twelfth resistor R12 serves as the input terminal of the filter circuit. The second end of the twelfth resistor R12 is connected to the non-inverting input terminal of the third operational amplifier U4 via the tenth capacitor C10. The first end of the thirteenth resistor R13 is connected to the junction of the twelfth resistor R12 and the tenth capacitor C10. The second end of the thirteenth resistor R13 is connected to the output terminal of the third operational amplifier U4. The input terminal of the digital potentiometer DP is connected to the first end of the twelfth resistor R12. The output terminal of the digital potentiometer DP is connected to the inverting input terminal of the third operational amplifier U4. The first end of the eleventh capacitor C11 is connected to the junction of the digital potentiometer DP and the inverting input terminal of the third operational amplifier U4. The second end of the eleventh capacitor C11 is connected to the seventh ground terminal GND7. The output terminal of the third operational amplifier U4 is connected to the signal processor.

[0050] In this embodiment, the power signal processed by the isolation circuit is limited by the twelfth resistor R12, then coupled to the non-inverting input terminal of the third operational amplifier U4 through the tenth capacitor C10, filtered by the first-order RC low-pass filter composed of the thirteenth resistor R13 and the tenth capacitor C10 to preliminarily attenuate the high-frequency noise therein; the third operational amplifier U4 is configured as a non-inverting amplifier, and the inverting input terminal thereof forms an adjustable feedback network with the eleventh capacitor C11 through the digital potentiometer DP, so as to dynamically adjust the feedback coefficient of the digital potentiometer DP, thereby changing the cutoff frequency of the low-pass filter and realizing flexible frequency control from kHz to MHz level; the eleventh capacitor C11 is connected in parallel with the digital potentiometer DP, which can further suppress the high-frequency interference in the power signal and stabilize the feedback loop. Finally, the output terminal of the third operational amplifier U4 transmits the filtered low-frequency signal to the signal processor, and the low output impedance characteristic thereof enhances the driving capability, thereby ensuring that the load fluctuation of the subsequent circuit does not affect the filtering performance.

[0051] The filter circuit adopts an adjustable second-order active low-pass architecture, dynamically adjusts the resistance value of the feedback network through the digital potentiometer DP, realizes flexible adaptation of the cutoff frequency from kHz to MHz level, and can accurately suppress high-frequency noise (such as switching ripple, radio frequency interference) in different frequency bands. The non-inverting input terminal of the third operational amplifier U4 is configured in combination with the RC network (R12 / R13 / C10 / C11), which filters out high-frequency signals, enhances the driving capability through the low output impedance characteristic, and ensures that the load fluctuation of the subsequent stage does not affect the filtering stability; the eleventh capacitor C11 is connected in parallel with the digital potentiometer DP to optimize the feedback loop, further attenuate the residual high-frequency noise and suppress the phase distortion. The filter circuit considers both filtering accuracy and dynamic adjustment capability through digital-analog hybrid control, provides a pure and customizable power signal for the signal processor, and can significantly improve the reliability of high-definition video transmission and high-speed data processing in a complex electromagnetic environment.

[0052] In summary, the present application can construct a "high stability-low ripple-strong anti-interference" power supply environment for a home FTTR set-top box, which can not only significantly improve the video decoding accuracy, data transmission rate and device reliability of the set-top box, but also ensure the smooth transmission of 4K / 8K high-definition video and the efficient cooperation of smart home devices, thereby providing users with a more stable and high-quality home network experience.

[0053] In the following, the above technical effects are further illustrated by specific data.

[0054] 1. Power supply stability test Test method: use an oscilloscope to measure the ripple (peak-to-peak value) and noise spectral density of the TYPE-C port output voltage.

[0055] Data: Ripple contrast: After applying this circuit, the peak-to-peak ripple value decreases from the original value of 120mV to <20mV, with a decrease of 83%.

[0056] Noise suppression: The attenuation amplitude of high-frequency noise (>1MHz) is up to 40dB (verified by spectrum analyzer).

[0057] 2. Anti-interference ability test Test method: Surge suppression: Apply a 6kV / 3kA combined wave (IEC 61000-4-5 standard) and record the residual voltage value.

[0058] Common-mode noise suppression: Inject 1Vpp common-mode interference (frequency 100kHz-100MHz) and measure the residual noise at the output.

[0059] Data: Surge residual voltage: The residual voltage decreases from 600V to 60V, meeting the ITU-T K.21 standard.

[0060] Common-mode noise suppression: The residual noise amplitude at the output is <5mV, with a suppression ratio of 46dB.

[0061] 3. Video transmission quality test Test method: Play a 4K / 120Hz video stream and record data through a bit error rate tester (BERT) and video analysis software.

[0062] Data: Bit error rate: Decreases from 1x10 -5 to <1x10 -8 .

[0063] Video smoothness: The stall rate decreases from 3% to 0.1% (based on RTINGS video test standard).

[0064] 4. Smart home collaboration test Test method: In an interference environment where Wi-Fi 6, Bluetooth 5.2, and Zigbee are running simultaneously, test the device response delay.

[0065] Data: Response delay: The average delay decreases from 50ms to 10ms.

[0066] Collaboration stability: The success rate of multi-device communication increases from 85% to 99%.

[0067] In summary, the home FTTR set-top box protection isolation circuit described in this application has significantly improved in power stability, anti-interference ability, and signal transmission quality through multi-level protection, dynamic filtering, and isolation technology.

[0068] The above merely preferred embodiments of the present application and are not intended to limit the patent scope of the present application, any equivalent structure or equivalent process transformation using the content of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A protection isolation circuit for a home FTTR set-top box, characterized in that, The circuit comprises: a protection circuit, an isolation circuit and a filter circuit, wherein the input end of the protection circuit is connected to the TYPE-C port of the FTTR set-top box, and the output end is connected to the input end of the isolation circuit, for preventing the power surge of the external power supply from impacting the signal processor in the set-top box through the TYPE-C port; the output end of the isolation circuit is connected to the input end of the filter circuit, for isolating the power signal input through the TYPE-C port; the output end of the filter circuit is connected to the signal processor in the set-top box, for filtering the isolated power signal to provide stable power supply for the signal processor.

2. The circuit of claim 1, wherein, The protection circuit comprises: a multi-stage surge suppression module, the input end of the multi-stage surge suppression module is connected between the power positive pin and the ground pin of the TYPE-C port, and the output end of the multi-stage surge suppression module is connected in series with a dynamic overcurrent protection module, a reverse connection protection module and a suppression and filter preprocessing module in sequence; and the multi-stage surge suppression module is used for grading absorption and suppression of high-energy transient surges introduced by the power signal; the dynamic overcurrent protection module is used for dynamic monitoring of the current change of the power supply and disconnection of the loop when overcurrent occurs; the reverse connection protection module is used for identification and blocking of the reverse connection of the power supply; the suppression and filter preprocessing module is used for preliminary filtering of noise and interference in the power signal.

3. The circuit of claim 2, wherein, The multi-stage surge suppression module comprises: a gas discharge tube, a voltage-dependent resistor and a first capacitor, wherein the first end of the gas discharge tube is connected to the power positive pin of the TYPE-C port; the second end of the gas discharge tube is connected to the ground pin of the TYPE-C port; the voltage-dependent resistor is connected in parallel with the gas discharge tube; the first capacitor is connected across the power positive pin and the ground pin of the TYPE-C port.

4. The circuit of claim 3, wherein, The dynamic overcurrent protection module comprises: a self-resetting fuse, an electronic fuse, a first resistor and a current detection amplifier, wherein the first end of the self-resetting fuse is connected to the connection between the gas discharge tube and the power positive pin of the TYPE-C port through the electronic fuse and the first resistor; the second end of the self-resetting fuse is connected to the input end of the reverse connection protection module; the positive input end of the current detection amplifier is connected to the first end of the first resistor; the negative input end of the current detection amplifier is connected to the second end of the first resistor; the output end of the current detection amplifier is connected to the control end of the electronic fuse; the positive pin of the current detection amplifier is connected to +5.5V voltage, and the negative pin of the current detection amplifier is connected to -5.5V voltage.

5. The circuit of claim 4, wherein, The reverse connection protection module comprises: a first transistor, a second transistor, a comparator, a gate driver, a second resistor, a first zener diode and a second zener diode, wherein the non-inverting input end of the comparator serves as the input end of the reverse connection protection module; the sources of the first transistor and the second transistor are connected, and the connection point serves as the output end of the reverse connection protection module; the drain of the first transistor is connected to the non-inverting input end of the comparator; the drain of the second transistor is connected to the inverting input end of the comparator; An output terminal of the comparator is connected to a gate terminal of the first transistor and a gate terminal of the second transistor through a gate driver and a second resistor respectively; An anode of the first voltage stabilizing diode is connected to a drain of the first transistor; A cathode of the first voltage stabilizing diode is connected to a gate of the first transistor; An anode of the second voltage stabilizing diode is connected to a drain of the second transistor; A cathode of the second voltage stabilizing diode is connected to a gate of the second transistor.

6. The circuit of claim 5, wherein, The suppression and filtering preprocessing module comprises: a first operational amplifier, a third resistor, a fourth resistor, a second capacitor, a third capacitor, a fourth capacitor and a fifth capacitor, wherein, a first terminal of the third resistor is connected to an output terminal of the reverse connection protection module as an input terminal of the suppression and filtering preprocessing module, and a second terminal of the third resistor is connected to a non-inverting input terminal of the first operational amplifier; an inverting input terminal of the first operational amplifier is connected to a first grounding terminal through the fourth resistor; a first terminal of the second capacitor is connected to a connection position of the fourth resistor and the inverting input terminal of the first operational amplifier; a second terminal of the second capacitor is connected to an output terminal of the first operational amplifier, and the output terminal of the first operational amplifier is connected to an input terminal of the isolation circuit as an output terminal of the suppression and filtering preprocessing module; the third capacitor, the fourth capacitor and the fifth capacitor are connected in parallel, and first terminals of the third capacitor, the fourth capacitor and the fifth capacitor are connected to the output terminal of the first operational amplifier, and second terminals of the third capacitor, the fourth capacitor and the fifth capacitor are connected to the first grounding terminal.

7. The circuit of claim 1, wherein, The isolation circuit adopts a three-layer isolation structure and comprises: a first isolation module, a second isolation module and a third isolation module connected in cascade, wherein, the first isolation module is used for isolating direct current potential coupling between the filtered power supply signal and the second isolation module; the second isolation module is used for physically isolating current paths of the first isolation module and the second isolation module; the third isolation module is used for suppressing residual high-frequency noise in the filtered power supply signal.

8. The circuit of claim 7, wherein, The first isolation module comprises: a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a sixth capacitor and a second operational amplifier, wherein, a first terminal of the fifth resistor is connected as an input terminal of the isolation circuit; a second terminal of the fifth resistor is connected to a second grounding terminal through the sixth resistor; a first terminal of the sixth capacitor is connected to a connection position of the fifth resistor and the sixth resistor; a second terminal of the sixth capacitor is connected to a non-inverting input terminal of the second operational amplifier; an output terminal of the second operational amplifier is connected to an input terminal of the second isolation module and connected to the non-inverting input terminal thereof through the seventh resistor; an inverting input terminal of the second operational amplifier is connected to a third grounding terminal through the eighth resistor.

9. The circuit of claim 7, wherein, The second isolation module comprises: a ninth resistor, a seventh capacitor, a first triode, wherein, a first terminal of the ninth resistor is connected as an input terminal of the second isolation module; a second terminal of the ninth resistor is connected to a base of the first triode through the seventh capacitor; an emitter of the first triode is connected to a fourth grounding terminal, and a collector of the first triode is connected to an input terminal of the third isolation module.

10. The circuit of claim 7, wherein, The third isolation module comprises: a tenth resistor, an eleventh resistor, an eighth capacitor, a ninth capacitor and a first inductor, wherein, a first terminal of the tenth resistor is connected as an input terminal of the third isolation module, and a second terminal of the tenth resistor is connected to an input terminal of the filtering circuit; A first end of the eleventh resistor is connected with a second end of the tenth resistor, and a second end of the eleventh resistor is connected with the fifth ground end through the eighth capacitor; A first end of the first inductor is connected with a connection between the tenth resistor and the eleventh resistor, and a second end of the first inductor is connected with the sixth ground end through the ninth capacitor.

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