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TDA4VM: J784S4X : DSI Impedance clarification

Amit Teke
Prodigy 70 points

Part Number: TDA4VM

We found two types of 100E impedance in PROC141E2_FAB.pdf drawing. Why we are using separate trace width & spacing for DSI interface line?


Ref File - 

  • 0
    TI__Guru 57635 points

    The requirement for DSI traces is 100-ohm differential and 50-ohm single ended.  This is different from simply 100-ohm differential (example is DisplayPort).  As signals transition to different layers (for example internal vs external), its possible the trace width needs to be adjusted to maintain the same impedances.

  • 0
    Prodigy 40 points

    Different layer have different reference ground, and thickness for each layer is different. So the impedance for the same trace width and spacing is different for different layer. You can not just copy and paste what TI EVM is doing, your trace width and spacing has to be calculated by you based on your PCB stack up.