By Leiditech | 20 December 2023 | 0 Comments
HDMIThe evolution of interfaces and anti-static measuresESDcountermeasure
one．HDMIInterface malfunction phenomenon
Shanghai Leiditech often receives feedback from engineersHDMIInterface malfunction phenomenon,There are several types of fault phenomena that can be summarized as follows：
l doESDCertification testing，Static electricity has not passed，Flashing appears on the screen、Twist、The situation of blurred or black screen。
l Image blur、Color distortion、The problem of image noise or sound noise。
l HDMIThe metal pins of the interface are damaged，For example, bending、fracture。
l HDMIInternal interfaceDamage caused by electronic components，Causing the entire device to fail to start or encounter other malfunctions。
two．Analyze the cause of the malfunction
HDMIInterface is a high-speed digital interface，In daily use，Electrostatic discharge from human body or other external power sources may cause damage to interfaces and connected devices。in additionHDMIThe interface is usually connected to the TV、display、Projectors and other equipment，These devices are very sensitive to electrostatic discharge。At the same time, based on the summary of the rectification case by Engineer Leiditech, there are the following reasons：
l ESDImproper diode selection， The original interface should have been selected3.3V ESDdiode，And choose5V,causeICNot receiving proper protection。
therefore，If not done wellESDprotect，The above fault conditions will occur。
To ensureHDMIStability of interfaces and connected devices、Reliability and lifespan，applyESDDiode protection devices are very necessary。It can effectively prevent damage to equipment caused by electrostatic discharge，And provide protection levels that meet standard requirements。thatESDHow to choose a diode。
three．choiceESDKey parameters for protecting diodes
Choose suitableHDMIInterfacedESDThe key parameters to consider when protecting diodes include：
1. Parasitic capacitanceCj ：
HDMI 1.0-1.2：The highest data rate can reach4.95 Gbps。
HDMI 1.3-1.4：The data rate can reach10.2 Gbps。
HDMI 2.0-2.1：The highest data rate can reach18 Gbps。
In selectingESDProtective diodebyensureTMDSWhen it comes to signal integrity of a line，Parasitic capacitance becomes one of the most important parameters。When selecting suitableHDMI ofESDWhen protecting diodes，firstConsider diodes firstjunctioncapacitance，Ensure that the capacitance of the diode meets the requirementsTMDSBudget for allowable capacitance of the line，When making a selection，To find less than0.5pF。
2. clamping voltageVc
ESD（electrostatic discharge ）The clamping voltage of a diode refers to its operating state，When subjected to electrostatic shock，The diode will begin to conduct and clamp the voltage at both ends to a relatively stable level，Known as clamp voltage。ESDThe clamping voltage of diodes is usually withinData BookThere is a detailed explanation in the middle。generally speaking，ESDThe lower the clamping voltage of the diode, the better，Because this means it can resist electrostatic discharge faster and cause less pressure on protected devices。
HDMIinterfaceESD It's a choice3.3V still5Vaccording to outputHDMIThe voltage level that the controller interface of the interface can withstand，This is very important。Shanghai Leimao You5V /3/3V DFN2510encapsulationESD:ULC0524P,ULC3304P10,and3.3V Bring it back for scanningPUSB3FR4，Refer to the following diagram for the plan。
3. IEC 61000-4-2 (ESD)
ESDhave15KV,and30KV.，Can be selected according to needs。
four．HDMI2.0Static protection scheme
Search the Shanghai Leiditech Mini Program to find the specific parameters of the above plan specifications。
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