Does the ADV7619 provide backdrive protection on the RXA_5V and RXB_5V lines on Pins 122 and 126?
Yes,ESD protection and backdrive protection are important on each and every external signal line.
Please refer HDMI port protection attachment.
Just to enhance what Poornima stated. Each of those pins are ESD rated for 200V CDM which is good enough for assembly however the real world is much harsher so external ESB protection should be included such as diode bridges. Check our reference schematics to see how we did it.
The reference schematic for the ADV7619/ADV7511 does not show any specific protection for that signal.
You are correct, this older design is missing the series 100 Ohm for RX_DDC_5V into the chip.
For the reference board I would do the following (as I have done this on newer boards)
1) DDC-5V input - 100 Ohm resistor right up on the ADV7619 pin. RXA_5V pin is an input only. 100 Ohm will extend it's protection range. Can't use the RCLAMP0504 since DDC_5V is spec'd to ~6V max which would trip the protection.
2) DDC_SDA/SCL - use RCLAMP0504 or similar bridge diode
3) For TMDS lines use RCLAMP0524 or similar
1) DDC_5V is supplied by the board so you have full control over it
2) DDC_SDA/SCL - same as RX side
3) TMDS line - same as RX side
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