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BQ24190: D+/D- pair detection creates stubs in layout

Valentin Badea
Prodigy 10 points
Part Number: BQ24190


Hi,

As is stated also in this TI post, the concern is real regarding signal integrity when it comes to the D+/D- pair. USB data lines are a transmission lines (240 MHz) and every stubs that is created will influence the quality of signal and affects the eye diagram. 

I need to connect the USB pair to the BQ24190 chip, but in the same time the same track needs to go to the CPU. I am concerned about the signal integrity in this scenario.

I attached how i think about the layout.  How will influence BQ24190 pins capacitance the USB signal. Do you have some extra information about this or how should i manage this scenario?

  • 0
    TI__Genius 10240 points
    Valentin,

    The the D+D- is used to detect the USB port after the adaptor is plugged in. Once the detection is done, the bq24190 D+ and D- are in high impedance. If you have concern about the parasitic capacitance, you can add resistors (200ohm or below) on bq24190's D+/ D- lines and then connect to other devices' D+ /D-.

    Regards,

    Eric