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TS3USB3000: Bias For Switch

Jeffrey Cohen
Prodigy 110 points
Part Number: TS3USB3000

Dear TI Support,

I'm looking at a design that 's using the TS3USB3000. 

On the input to the D+/D- is either LVDS (+/- 1.2V) or SERDES (+/+ 200mV). The OE line is grounded (Active) and the select line is used to select

between LVDS and SERDES. There is an LRC on each of the USB+/-  of 10UH, 10ohms and 10UF. I was told that this is needed to

bias the  TS3USB switch and to turn it on on power up. Once the capacitor charges up the LRC is not in the circuit anymore.

Does the TS3USB need to be biased? I didn't see this anywhere in the  data sheet?

Thanks,

Jeff Cohen

Dentsply Sirona Inc Long Island City NY 11101

  • 0
    TI__Intellectual 1165 points
    Hi Jeffrey,

    Please note that the recommended operating conditions for the signals on D+/-, USB+/- and MHL+/- is 0 to 3.6V. So in case your signal levels go negative you have to bias them to meet the specifications of TS3USB3000 so that the signal gets passed through without distortion.

    Powerup of the device is controlled by OE.

    Please let me know in case you have any further questions.

    Best regards
    Cevin
  • 0 in reply to Cevin
    Prodigy 110 points

    Hi Cevin,

    The part that is driving the TS3USB3000 is a NXP PTN36221A single-channel superspeed USB 3.0 redriver.

    It has an automatic low power management scheme, If there isn't a load of Zrx_DC (18-30) OHMS applied to the D+/D- lines the

    PTN36221A will turn off. There is also a delay of up to 115us from low power to on state. The idea is by placing a DC load that sinks current when the device is plugged in, the  D+/D- lines will see teh DC load which will turn on the device. Does this seem reasonable?

    Thanks,

    Jeff

  • 0 in reply to Jeffrey Cohen
    TI__Intellectual 1165 points
    Hi Jeff,

    are this two different designs you are mentioning in your first post and the last one? What is the use case for the mux in your application?

    Usually this detection is used for receiver detection (if there is a device connected). The TS3USB3000 as passive mux is transparent for this, putting a load there is not recommended, because it will change the overall termination load seen by the transmitter.

    Best regards
    Cevin