Magnetic components are used in the set-top box power circuit. These components are mainly switching power supplies * mode inductors, and switching transformers. The Sanxian Electronics Kunshan plant mainly produces magnetic originals. For example, the common mode filter inductors are mainly EE, UT, UU, etc. The transformers mainly include EE, EI, EFD, ER, PQ. Magnetic components are used in the set-top box power circuit. These components are mainly switching power supplies * mode inductors, and switching transformers. The Sanxian Electronics Kunshan plant mainly produces magnetic originals. For example, the common mode filter inductors are mainly EE, UT, UU, etc. The transformers mainly include EE, EI, EFD, ER, PQ, etc., and can also be customized according to customer requirements. Designed by yourself or opened for mold production. These two components are ideal for use in set-top box switching power supplies. Filter inductor The common mode inductor is also called a common mode choke coil, and is used for filtering electromagnetic interference signals of various common modes of the switching power supply. The common mode inductor acts as an EMI filter to suppress electromagnetic wave radiation generated by high speed signal lines. High-frequency circuits, digital circuits, and analog circuits are mixed on the main board in the set-top box power supply, and they generate a large amount of high-frequency electromagnetic waves that interfere with each other. EMI will also be emitted through the motherboard wiring or external wiring, causing electromagnetic radiation pollution, which not only affects the normal operation of other electronic equipment, but also harmful to the human body. The common mode inductor is essentially a bidirectional filter: on the one hand, it is necessary to filter out common mode electromagnetic interference on the signal line, on the other hand, it is necessary to suppress itself from emitting electromagnetic interference and avoid affecting the normal operation of other electronic devices in the same electromagnetic environment. . The core of the common mode inductor has a high initial magnetic permeability, and has a large impedance and insertion loss under a magnetic field, and has an excellent suppression effect on interference. The common mode inductor is wound on the same core with the same number of turns and phase (wound reverse). Thus, when a normal current in the circuit flows through the common mode inductor, the current generates a reverse magnetic field in the in-phase wound inductor and cancels each other. At this time, the normal signal current is mainly affected by the coil resistance when there is a common mode. When the current flows through the coil, due to the same direction of the common mode current, the same magnetic field is generated in the coil to increase the inductive reactance of the coil, so that the coil exhibits high impedance and generates a strong damping effect, thereby attenuating the total Mode current for filtering purposes. Power transformer in the set top box The switching power supply transformer in the set-top box is regarded as the heart of the set-top box power supply. The main functions are power transmission, voltage conversion and insulation isolation. The power of the transformer is generally around 30W. The working principle is based on the principle of electromagnetic induction, which emphasizes the large power transmission and emphasizes the high insulation isolation voltage. The conditions of use of the transformer include two aspects: reliability and electromagnetic compatibility. In the past, only attention was paid to reliability. Now, due to the increased awareness of environmental protection, it is necessary to pay attention to electromagnetic compatibility. Shielding is a good way to prevent electromagnetic interference and increase the electromagnetic compatibility of high-frequency power transformers. In order to prevent the electromagnetic interference of the high-frequency power transformer, the corresponding measures should be taken in designing the core structure and designing the winding structure, for example, adding shielding copper foil to the winding of the transformer or adding a shield cover outside the transformer. There are two ways to transfer power to a switching transformer. The first type of transmission is the voltage applied to the primary winding, which produces a change in the magnetic flux in the core, causing the secondary winding to induce a voltage, thereby transferring electrical power from the primary side to the secondary side. In the power transmission process, the magnetic core is divided into two working modes: magnetic flux single direction change and bidirectional change. The second type is the inductor power transmission mode. The electric energy input from the original winding causes the magnetic core to be excited and becomes magnetic energy storage. Then, the demagnetization causes the secondary winding to induce a voltage and turn it into electric energy to be released to the load. The transmission power is determined by the energy storage of the inductor core, which in turn is determined by the inductance of the primary winding. The inductance is related to the magnetic permeability of the magnetic core, the magnetic permeability is high, the inductance is large, and the energy storage is large, and is not directly related to the magnetic flux density. The voltage conversion is done by the turns ratio of the primary and secondary windings. Regardless of the power transfer method, the voltage conversion ratio of the primary side and the secondary side is equal to the turns ratio of the primary winding and the secondary winding. However, the number of winding turns is related to the leakage inductance of the high frequency power transformer. The leakage inductance is proportional to the square of the turns of the original winding. Because the leakage inductance value is large, the stored energy is also large, and suddenly released during the power switch process, a spike voltage is generated, and the voltage peak of the switching device is increased, which is disadvantageous to the insulation of the switch tube, and also causes additional loss and electromagnetic interference. In order to reduce leakage inductance during factory manufacturing, designers should pay attention to the following control methods: 1 Reduce the number of turns of the winding, select high magnetic material with high saturation magnetic induction and low loss; 2 reduce the thickness of the winding and increase the height of the winding; 3 to minimize the insulation thickness between the windings; 4 The primary and secondary windings are layered and cross-wound; 5 The primary and secondary windings should be double-wired and wound The SCSI interface is a general interface, which can connect the host adapter and eight SCSI peripheral controllers on the SCSI bus. The peripheral devices can include disk, tape, CD-ROM, rewritable optical disk drive, printer, scanner and communication equipment, etc.
â— when the SCSI interface is connected to an external device, its connecting cable can be as long as 6m.
Small computer system interface (SCSI) is an independent processor standard used for system level interface between computer and intelligent devices (hard disk, floppy drive, optical drive, printer, scanner, etc.). SCSI is an intelligent universal interface standard Plastic SCSI Section ShenZhen Antenk Electronics Co,Ltd , https://www.antenk.com
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â— SCSI is a multi task interface with bus arbitration function. Multiple peripherals attached to a SCSI bus can work at the same time. Devices on the SCSI share the bus equally.
â— the SCSI interface can transmit data synchronously or asynchronously, the synchronous transmission rate can reach 10MB / s, and the asynchronous transmission rate can reach 1.5mb/s.
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