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LMH1228: Preventing Damage to SDI Outputs

Takahiro Saito
Expert 5455 points
Part Number: LMH1228

Hi team,

Customer is using LMH1228 for professional video camera.

They found below articles about the preventing damage to SDI outputs. The article describes the order of connecting BNC cable and power to prevent power surge that causes SDI output damage. Do you have any perspective about this ?

Arri TECHNICAL INFORMATION [Preventing Damage to SDI Outputs] Date: February 05, 2020

https://www.arri.com/resource/blob/194752/93adc39d8bfceb069522cc126b7f1352/download-technical-information-data.pdf

 

ProVideoCoalition　[IMPORTANT: SDI Vulnerability Discovered　 Don’t fry your equipment!] 　February 23, 2020

https://www.provideocoalition.com/sdi-vulnerability-discovered

Regards,

Saito

  • 0
    TI__Guru* 93670 points

    Hi Saito-San,

    I believe what this article refers to i=c*(dv/dt) that could be dumped into the front end of the cable driver. Cable driver is AC coupled into the EQ. AC coupling cap on output of the driver in series with AC couplin cap on input of the driver reduces the overall capacitance. DC common mode voltage of the EQ - based on this article - can cause high current dumped into the cable driver due to i=c*(dv/dt)) damaging the device. In our equalizers normally we have a weak common mode voltage limiting current being dumped into the cable driver. Also, common mode voltage is low in order of 1.2V and thus we have not observed this issue on LMH1228 or other cable drivers. However, if one applies high DC voltage in order of 10V or higher multiple times it is possible to damage the device.

    Regards,, nasser