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TMDS1204: Pull-Down 499 Ohm resistors for AC-coupled operetion

Nikita Alisov
Prodigy 160 points

Part Number: TMDS1204

Tool/software:

Hello,

Could you please clarify what are the goals of the MOSFET here:

  • +1
    TI__Mastermind 37925 points

    Hi Nikita,

    The MOSFET allows you to control whether the 499Ohm terminations are enable or disabled. This is useful when you want to support the higher HDMI2.1 data rates.

    At lower HDMI1.4 and HDMI2.0 data rates, the 499Ohm terminations should be enabled to keep the common mode voltage in compliance with the HDMI spec. The issue is that at higher data rates, the 499Ohm terminations will pose a signal integrity concern as higher speed signals are more sensitive to terminations. If you're operating at HDMI2.1 speeds, you can disable the 499Ohm pulldowns using this MOSFET to improve the signal quality.

    Best,

    Shane

  • 0 in reply to Shane Hauser
    Prodigy 160 points

    Ooo, I thought "System 3.3V" is a power rail, now it's clear, thank you!