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TPD1E01B04: use at USB2 signal question

Part Number: TPD1E01B04
Other Parts Discussed in Thread: TPD4E05U06

Hi Team,

My customer use our TPD1E01B04 in their high speed signal.

In the datasheet typical application capture, we show that for the USB2 we suggest to use TPD4E05U06.

  1. May we know what is the main different between TPD1E01B04 and TPD4E05U06?
  2. If we use TPD1E01B04 to protect USB2 high-speed/full-speed/low-speed signal, will have any concern?
  3. How should we judge we should use what part for such different speed signal ?

Thanks! 

Kai 

  • Hi Kai,

    1. The main difference between these devices are the polarities, channel counts, and working voltage. The TPD1E01B04 is a 1-ch bi-directional diode with a working voltage of 3.6 and the TPD4E05U06 is a 4-ch unidirectional diode with a working voltage of 5.5 V. I would recommend viewing this FAQ ESD Fundamentals for further details on reverse working voltage and polarity configuration. 

    2/3. There is no concern in using the TPD1E01B04 for USB2.0. The max speed for USB2.0 will be 480Mbps and this device has a very low capacitance of 0.18pF which is more than sufficient for that signal speed. The TPD4E04U06 has a low capacitance of 0.5pF so it can also support USB2.0 signals. For further details on capacitance please see this FAQ ESD Capacitance 

    The best way to judge if a device can support a certain signal speed is by looking at the insertion loss graph in the datasheet. The general rule of thumb is to make sure the signal speed you're protecting is below the -3dB point on the insertion loss graph to minimally attenuate the signal. The TPD1E10B04's insertion loss graph is shown below, as you can see  the -3dB point is at 20GHz. 

    Regards,

    Sebastian 

  • Hi Sebastian,

    Thanks for your reply in detail, learn a lot.

    One more question : 

    Because USB2 signal D+, D- level can be 3.6v in low-speed/full-speed.

    Is this still fine to our TPD1E01B04 ? Will it have concern ?

    Thanks!

    Kai

  • Hi Kai,

    As long as the max voltage on the D+,D- lines is 3.6 V there is no issue. Even if the voltage on the line went slightly over 3.6 V the diode would only leak a few more nA of current. Once the voltage on the line reaches the breakdown voltage, which is around 6 V for this device, then the diode will start conducting larger amounts of current.  

    Regards,

    Sebastian 

  • Thanks a lot ! Sebastian