How to prevent electronic products from being attacked by static electricity and electromagnetic interference
We often have some experience in life. Some electronic products are good when we bought, and they have suddenly disappeared inexplicably for a while. Most of these problems are static electricity that breaks down and burns the functional chips in your electronic products, causing the function chips to fail. Therefore, how to protect electronic products from static electricity has always been an important issue for designers. This problem has become more serious in recent years, because in the past ten years, electronic products have been miniaturized from the 0.5 micron process to the current 45 nanometer process, which has reduced the chip's component size by more than 100 times. The thickness of the gate of the transistor is also continuously reduced, so that the electrostatic protection capability of the semiconductor component is continuously degraded, and the product is easily broken by sudden electrostatic damage. Every time we intentionally or unintentionally come into contact with electronic products, it is easy to cause the electrostatic discharge carried on us to cause damage to these electronic products. Unfortunately, static electricity is a natural phenomenon caused by friction. There is no simple way to make it not happen, so we can only do the necessary protection design for the electronic system.
Insufficient electronic systems often experience crashes, or parts of the system that are not functioning properly after electrostatic attacks. Some may be short-lived and then return to normal. These may be caused by static electricity, while electronic systems with complete protection may Completely immune to electrostatic attacks. Electrostatic events that occur in the environment range from 3KV to 35KV. Therefore, the electrostatic test specifications of electronic systems need to be determined according to the design conditions of their products and the environment in which they are used. For smart phones, for example, the test specifications should be from 12KV. Because the coating material of the mobile phone itself can normally resist the electrostatic energy below 12KV into the electronic system of the mobile phone, the electrostatic event of more than 12KV often occurs in the environment, so only the test specification is pulled above 12KV to confirm the design of the mobile phone in the use environment. It can be used safely without interference from static electricity. There are many ways to protect against static electricity. The easiest and most economical is to add protective parts such as TVS chips where necessary. The TVS chip has a fast response speed and the clamping voltage is low enough to approach the normal operating voltage of the electronic system, which provides good protection. Especially now the core chip of mobile phone or computer works at 1V-1.8V, and only TVS chip can provide the necessary protection.
In the case of smart phones, electrostatic attacks often occur in the following places:
USB terminal: When the USB is plugged and unplugged, it is an electrostatic attack. In particular, USB ON THE GO has a chance to attack when it is used.
Touch screen: Every time you touch the touch screen, it is an electrostatic attack. It is also an electrostatic attack when the cheeks are easily accessible to the touch screen when talking on the phone.
Headphone terminal: When the earphone is plugged and unplugged, it is an electrostatic attack.
Keyboard: The phone keyboard is also a place that is vulnerable to static electricity.
Antenna: The antenna of the mobile phone itself is more vulnerable to external charges.
Mobile phone charging terminal: Every time the mobile phone charging cable is connected, it is an electrostatic attack.
Sim/Flash card: The phone is also an opportunity for electrostatic attacks when plugging in the Sim/Flash card.
Because the space of smart phones is very small, almost every module block will be attacked by static electricity.
Another type of EMI that causes electronic products to be injured is the high complexity of the system. All hardware is concentrated in a very small space. Electromagnetic interference often causes system signal failure/signal decoding