By LEIDITECH | 29 July 2024 | 0 Comments
satisfyGMSLScheme for electrostatic protection requirements
What isGMSL？What is it used for？What are its advantages？designGMSLWhat is the difficulty of anti-static？
With these questions in mind, let's first understand what isGMSL。
one．Overview GMSL
GMSL（Gigabit Multimedia Serial Link）Namely, gigabit multimedia serial link，yes Maxim A high-speed serial interface launched by the company，Suitable for audio、Transmission of video and control signals。
Communication media supports coaxial cables and shielded twisted pair cables，Use 50ΩCoaxial cable or 100ΩShielded twisted pair cable（STP）Hour，Up to 15 meters in length。Its core technology is a serializer/Deconstructor technology（SerDes），Firstly, the parallel data is transferred to a serial data stream through a serializer，Then transmit through higher frequencies，Afterwards, the received serial data stream is converted into a parallel data stream through a deserializer。
GMSL The significance lies in solving the audio problem、The problem of high-speed transmission of video and control signals。Prior to this，Large amounts of data transmission typically use parallel buses to increase bandwidth，But having too many wiring harnesses will increase costs、Weight and EMI electromagnetic interference 。When the amount of data reaches a certain level，The disadvantages of parallel buses are evident，If it is difficult to synchronize with the clock、Differences in wiring length lead to synchronization difficulties、Interference between signal lines, etc，This is the technical bottleneck of parallel buses。And the serial bus does not have interference between signal lines and the same timing problem，Just increase the frequency，And generally used in industryDifferential signaltransmission，Can better ensure signal accuracy，So currently facing high data stream transmission，Serial bus is widely adopted。
two． GMSL Application occasions
GMSL Common application scenarios include the following aspects：
1. Automotive electronics field：Used for in car cameras、High speed data transmission between devices such as display screens，To support advanced driving assistance systems（ADAS）And in car infotainment system。
2. industrial automation ：In factory automation equipment，Connect various sensors、Camera and control unit，Realize high-speed、Reliable data communication。
3. Security monitoring system：Equipment used to connect surveillance cameras and monitoring centers，Ensure stable transmission of high-definition video signals。
4. Medical equipment：For example, in medical imaging equipment，Realize fast transmission and processing of image data。
thereforeGMSLApplications are right beside us，These application scenarios all rely on the high speed it can provide、Low latency and anti-interference data transmission capability。
three．GMSL Has the following characteristics and advantages
- High speed rate：Currently, based on GMSL The communication protocol of the architecture can achieve up to a single channel 6Gbps（GMSL2） Rate of。
- remote：When using specific cables, the transmission distance is 15 meters。
- Strong anti-interference ability：The serial transmission method and differential signal transmission give it strong anti-interference ability。
GMSL Technology has gone through a long period of development。first generation GMSL from 2003 Starting from the year，Maximum Support 3Gbps Transmission rate of，Transferable 1080p/30fps（1 million-3 Megapixel）Video streaming data for；2017 Appearing after the year GMSL2 Generation technology，Increase transmission bandwidth to 6Gbps，Can easily transmit 4K/30fps（8 Megapixel）Video streaming data for。
four．GMSL-POCdesign
GMSL-POC It is a technology that is widely used nowadays，POC It refers to coaxial cable power supply（Power Over Coaxial），That is to say, in coaxial cables, besides transmission GMSL Serial data external，Simultaneously transmitting power supply。
stay GMSL Used in the system POC Technology has some advantages，For example, reducing the number of cables、Simplify system wiring, etc。POC circuit designThe principle is to form a broadband filter through multiple inductors，Enable at low frequencies DC DC power supply passed smoothly，Having sufficient impedance at high frequencies to suppress forward channel data（Data signals collected by cameras）And reverse channel（control signal）Data passed through，Prevent signal leakage to the DC power supply terminal。Simultaneously using capacitors to isolate DC signals，Coupling high-speed signals，To ensure smooth passage of high-speed signals within the required bandwidth range。
in application，To ensure GMSL POC Normal operation of the system，Reasonable configuration of relevant resistors is required、Inductors and other components，And according to the specific voltage situation（as 5V or 12V POC）Make adjustments。meanwhile，Pay attention to protecting the system from overvoltage and overcurrent conditions。
GMSL-POCThe system design diagram is as follows：
five． aboutGMSLElectrostatic protection
1. Why do we need to add electrostatic protection devices
We know about electrostatic discharge（ESD）It is an accumulation of charges，Static electricity may causeGMSL Various issues with related equipment，For example, functional failure、data error、Even permanent damage, etc。In some application scenarios that require high reliability，Like automotive electronic systems，Even tiny electrostatic pulses can interfere or disrupt the transmission of data，Affects the normal operation of the entire system。say concretely，GMSL Commonly used in videos、Transmission of audio and control signals，These signals are sensitive to interference。Static electricity may be introduced into the system through various channels，For example, human contact、Friction between devices、Accumulation of static electricity in the environment, etc。
To ensure GMSL Stable and reliable operation of the system，It is necessary to take electrostatic protection measures。These protective measures typically include the use of static electricity protection deviceschipsuch asESDdiode，As shown in the figure aboveD1，D2，D3，D4。Some chips have internal componentsESDprotect，such asMAX96705It has±8kV Contact discharge ESD Protection and±15kV Air gap discharge protection，But this level of protection did not meet your requirements，So we need to add an external one，The list at the end of the article lists several Shanghai Leimao models with strong anti-static capabilitiesESD二极管，The anti-static ability is higher than that inside the chip。With the externalESDThe protection of diodes enhances the system's ability to resist electrostatic interference，Ensure that in the presence of a certain electrostatic environment，GMSL The device is still functioning properly，Reliable data transmission。
2. ESD The placement position of the diode
According to general principlesESDThe diode should be placed at the interface of the connector，But forGMSL-POCsystemESDPlace the diode close to itSerializer/DeserializerMore suitable at the chip pins，Why？
For those withPOCofGMSLsystem ,IfPOC The power supply voltage is 12V , ESDThe breakdown voltage of the diode must be high voltage 12V ，POCOnly then can it work properly，Otherwise, once powered onESDThe diode is in a breakdown state，POCUnable to supply power normally。But if the selected diode breakdown voltage is higher than 12V , When it is below 12VAfter the introduction of static electricity，Serializer/DeserializerChip pins are easily damaged，Unable to provide good protection，Therefore, theESDDiodes placed inSerializer/DeserializerThe chip pins are more suitable。IfGMSLNot usedPOC , You can choose toESDPlace the diode at the interface。
We select based onSerializer/DeserializerPin level，Choose the right oneESDDiode for protection。
3. Several models launched by Shanghai LeimaoGMSL Electrostatic protection diode
If you want to learn more about these modelsESDdiode，Please contact Shanghai Leimao sales personnel orEMCLittle brother。
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