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TDA2x layout guide for bus impedance control

Daniel Liao
Prodigy 10 points

Dear Sir,

Could you clarify the informtion about signal impedance control  ?

I checked TDA2x ABC-SR2.0_DM_1 , that indicated HDMI differential trace must be routed 100 ohm & single-end 60 ohm.

But I checked the EVM board file ( 516581_H.brd) with allegro PCB editor , the constraint manager show HDMI belong to "145-OHM_PH" Net-Class.

This setting confused me.

Please help to confirm all need to control impedance buses and suggested impedance for routing.

Thank you.

Ex: 

DDR3: single-end : ?ohm / differential : ? ohm

HDMI: single-end : ?ohm / differential : ? ohm

USB: single-end : ?ohm / differential : ? ohm

Ethernet: single-end : ?ohm / differential : ? ohm 

Others ?

  • 0
    TI__Intellectual 2330 points
    Hi Daniel,

    Below is a quote from the following link:
    processors.wiki.ti.com/.../AM572x_Schematic_Checklist

    "EVM vs Datasheet

    In case of any discrepancy between the TI EVMs and the device datasheet, always follow the datasheet. Despite the designer's best efforts, the EVMs may contain errors which may still function but are not completely aligned with the datasheet specification. Therefore the EVM designs should not be considered as reference designs to be blindly reused. "

    Although it is for AM572x the same should apply also to TDA2x devices. IMO, you should follow the guidelines in the Data Manual (datasheet).

    BR,
    Dobrin