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HD3SS215: Datasheet DDC clock / data resistor on sink / source side

Kevin Den Toom
Prodigy 450 points
Part Number: HD3SS215

Hi,

the datasheet for the HD3SS215IZQER states:

9.2.2.2 Detailed Design Procedure
The HD3SS215 is designed to operate with a 3.3 V power supply. Levels above those listed in the Absolute
Ratings table should not be used. If using a higher voltage system power supply, a voltage regulator can be used
to step down to 3.3 V. Decoupling capacitors may be used to reduce noise and improve power supply integrity.
Pull-up resistors to 5 V must be placed on the source side DDC clock and data lines according to the HDMI2.0
Standard. A weak pull down resistor should be placed on the source side HPD line. This is to ensure the source
can differentiate between when HPD is disconnected or at a high voltage level. The AUX_SEL and Dx_SEL
control pins should be set according to the application and desired muxing.

> I understand the pull-up resistors for DDC clock and data need to be placed on the source side with 3V3.

> Fig. 8 shows the pull-up resistors for DDC clock and data one the sink side with 5V.

What is the correct application?

Figure 8

  • 0
    TI__Guru 60865 points

    Hi Kevin,

    In section 7.1, it shows that the absolute rating for DDC and HPD signals is 6V. Typically, HDMI sources and sink expect DDC lines to be pulled up to 5V, where DisplayPort sources and sinks expect DDC lines to be referenced to 3.3V. The correct reference voltage will vary depending on the application.

    Regards,
    JMMN

  • 0 in reply to JMMN
    TI__Prodigy 450 points
    Hi JMMN,

    thank you for the answer. This still leaves open if pull-up resistors for DDC clock and data need to be placed on the source side or on the sink side?

    Regards,
    Kevin
  • 0 in reply to Kevin Den Toom
    TI__Guru 60865 points
    Hi Kevin,

    The placement of the DDC pullups depends on the application. If the HD3SS215 is being used with a source feeding to two sink connectors, DDC pullups would be on the source side. If the HD3SS215 is being used with a sink feeding from two source connectors, DDC pullups would be on the sink side.

    Regards,
    JMMN