HDMI does not support hot swap? Will it burn out the power amplifier TV?
First, the principle of HDMI support hot swap
Most of today's flat-panel TVs are equipped with an HDMI interface. HDMI Chinese is called High Definition Multimedia Interface. It is a high-speed fully digital image and sound transmission interface, which means only one line is needed. It is capable of transmitting both high-definition video signals and audio signals at the same time, and is uncompressed. In line with the current and future high-definition video and audio transmission needs, it has been more and more widely supported. Currently, devices including TVs, computers, tablets and even mobile phones have corresponding HDMI interfaces.
But more and more, it means that the possibility of problems has increased. On the one hand, from time to time, there will be an incident about HDMI hot plugging and burning the interface chip. On the other hand, many users have been hot plugging the HDMI interface. There are no problems in dozens or even hundreds of times. Come on, can the HDMI interface be hot swappable?
HDMI theory supports hot swap?
HDMI has evolved by about 10 versions, and HDMI 1.4a was released in 2010. The latest version is HDMI2.0. Maybe you don't believe that HDMI has been designed to be hot swappable since its inception. In other words, the HDMI interface supports hot swapping regardless of which version. (Another statement is that the 1.2 version starts to support, but the number of devices before the 1.2 version is not much on the market?)
Principle of hot plugging
On the 19th pin of the HDMI female, place a half-pin, called the Hot Plug Detect. When the HDMI is unplugged, the hot-swappable monitor pin is disconnected first, then HDMI. After the circuit detects the disconnection, it notifies the input and output device to stop working and plays the role of hot plugging. According to the length of the interface pin, the principle of hot plugging is achieved, which is similar to the hot plugging of USB. There are four gold fingers inside the USB interface. The longer two are the power supply. When plugging and unplugging, the power is preferentially guaranteed, and then the data is exchanged to ensure that the hot plug does not damage the device data.
Is there a difference in the interface?
The current HDMI interface has four types, A type (standard) width 13.9mm, generally suitable for HDTV, TV, set-top box, Blu-ray DVD and other equipment; C-type (Mini) width 10.42mm, generally suitable for MP4; camera, tablet, etc. Digital products; D-type (Micro) width 6.4mm, generally suitable for smart phones, tablets; in addition, there is a B-type interface, but only as a standard, not applied in any product. The three interfaces A, C, and D all have a hot-swappable monitoring pin, so they are all hot-swappable.
Second, the real reason for HDMI hot swap damage
Still some netizens broke down?
Although HDMI is theoretically hot-swappable, in life we ​​will still hear some interfaces and even electrical damage caused by hot-swappable HDMI cables. Moreover, some manufacturers clearly stated in the product description that the HDMI cable must be plugged and unplugged when the product power is off. Are these contradictions to the above-mentioned "theoretical support" hot swap?
The theory belongs to the theory. Actually, it depends on the specific use environment. The bad and the bad are not absolute, but the probability of high and low. In general, hot swap HDMI is more likely to cause interface chip damage if there are two cases.
1. Poor wire quality:
The HDMI line in the market can be described as a mixed bag, with varying quality, ranging from a few yuan to a few hundred dollars. Some consumers think that the connection line is a small thing, not too much consideration of quality, so only focus on price. The insulation of poor quality wires may not be done well enough, and short circuits are also possible. If the joint is not plated, it will easily rust and cause physical damage to the interface. In addition, the conductivity and anti-interference ability of the wire will be relatively low.
2. Hazards caused by static electricity:
Static electricity can be said to be the stealth killer of all electrical appliances. Since HDMI is a very high-speed digital signal, the anti-static protection circuit used in designing the transmitting and receiving chips can only withstand 5-8 kV electrostatic voltage, but in actual life, if the environment is dry, there is also an electrostatic voltage. Conditions, it is possible to generate tens of volts of electrostatic voltage is common, in the design of the source and display, generally sacrifice some capacitor margin and configure the ESD protection circuit. However, some machines do not have an ESD protection circuit in order to save costs, and it is possible to burn the chip when an electrostatic HDMI cable is inserted.
On the other hand, our power outlets may be 2 pins and have no ground wire. For some families, even the three-phase socket, the ground wire is not grounded. When a user installs an LCD TV and a projector, there is no additional grounding wire, which makes it easier to form static electricity.
Summary: In fact, many hot-plug operations caused by burnout interface accidents are not necessarily HDMI interfaces. It is well known that USB is hot-swappable, but we will still hear that a certain computer has a USB flash drive and burned the motherboard. It is probably a problem with the USB flash drive. In addition, events that are burned off by the VGA interface also occur. Therefore, in order to ensure the normal use of electrical appliances, in addition to understanding the characteristics of the product itself, the specific situation of the specific analysis, if you do not worry, then shut down the plug, but can not guarantee 100% security, but also look Wire.
The last thing I want to say is that the author just burned the computer graphics card, AV amplifier, and projector because of accidentally hitting the HDMI cable. The loss was heavy. Of course, some people said that they were always hot-swapped and there was no burning machine. The situation, but don't think that the gunshot on the battlefield is loud. If you don't fall down, you can say that the guns are not dead. You should be careful to act as soon as possible. Try to shut down the power and plug in the HDMI cable again. Otherwise, if you have an accident, you will regret it later.
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