High-Speed Data Equipment ESD Protection
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High-Speed Data Equipment ESD Protection

Views: 0     Author: Site Editor     Publish Time: 2023-10-25      Origin: Site


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With the development trend of high intensification and ultra-high data rate of electronic products, when functionality is continuously realized and improved, its maximum stability and reliability will inevitably be considered. Multi-function, high speed and stability, reliability and security are a contradiction. Discuss the electrostatic protection devices currently used on high-speed data interface lines!





FireWire ---Formerly known as IEEE 1394, is a high-performance serial bus


Display I/O---Bus


SATA II ---Stands for Serial ATA



HDMI--- High-definition multimedia interface (1.966GBd / 2.7GBd / 3.0GBd / 3.4GBd)


static protection ESD diode concept


            Unidirectional diode characteristic curve


                     Rdiff: Differential series resistance

                     VBR:  Breakdown voltage (IBR = 1mA typical)

                     VRwm: maximum reverse working voltage

                     VCL: Clamping voltage

                     VFC: Forward clamping voltage

                     IPP: Peak current (8/20µS typical)




three different protection modes for signal lines



(a) Unidirectionality

Single ESD suppression diode


(b) Low capacitance unidirectional

Combined capacitance reducing ESD suppression diode


(c) bidirectionality

Two back-to-back ESD suppression bidirectional diodes


PCB design requirements


  • There should be no residual ends in signal lines.

  • Do not reduce the effective area of ground copper platinum in order to save costs.

  • In order to shorten the length of the signal line, use as many vias as possible for the ground line.

  • Install the protective TVS tube, install the device copper platinum position on the signal line as much as possible, and keep the TVS as close as possible to the input terminal.


Simple signal line protection design example:




Case: Single HDMI TMDS channel




As can be seen from the above figure, the 100Ohm differential high-speed transmission line can be regarded as basically unchanged with the addition of protection devices and without the protection device!


TDR measurement rise time requirements


The maximum rise time of TDR measurement specified by the HDMI 1.3a standard is 200 ps. Relevant institutions have measured the TDR with the addition of ESDLC5V0D9U. The results are as follows:


* As can be seen from the above figure, after inputting 1 pulse, the rise time of the protection device is increased to 180ps (rising to 90% and falling to 10%). Since the TDR measurement of the impedance allowed by the HDMI specification is an upper limit of 200 ps The ratio is 25%, that is, 250ps, which meets the HDMI 1.3a standard requirements, so there is no need to compensate for the influence of ESDLC5V0D9U from the layout when designing the PCB.



PCB design compensation discussion


When there are requirements for ultra-low capacitance or ultra-high frequency on the transmission line, such as: 3.0GBd and 4.0GBd of the HDMI 1.3a standard (referring to 1 HDMI TMDS connection for 3 channels), then we can perform very Perfect compensation.



Note: Z1 can calculate the wire impedance value based on the conductor conductivity.

Cd refers to the capacitance of the protection device.

L length is usually calculated as a compensation length of 2~3mm.




(The above design ideas are compiled by our Yinte R&D team after testing. We will conduct further research and exploration. For more details, pay attention to our company's official release)

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