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TMUXHS221: EOS tolerance

Part Number: TMUXHS221
Other Parts Discussed in Thread: STRIKE

Hello,

I can see in the datasheet the absolute max Vio is 5.5V for a continuous voltage.  In my application I will be using the mux as a 2:1 off of a USB C connector.

The block diagram would follow this sequence:

USB C Connector->ESD Protection->Over Voltage Protection Switch->Post Switch Clamp->TMUXHS221->AM64xx

In the event of short to VBUS, the OVP switch will kick in, but it still depends on the Post Switch Clamp.  For approximately 60nS, the TMUXHS221 would see 7V, before the clamp activates fully.

Can the TMUXHS221 handle 60nS at 7V in a short to VBUS scenario?

Thank you,

Joe

  • TMUXHS221 may not work with 7v.

    We have OVP mux TS5USBC410.

    Best

    Brian

  • Thanks Brian.  I did see this part as an option.  Perhaps this question can be extended more generally.  Any ESD or over voltage event is going to briefly exceed the clamping voltage of the protection device.  The TMUXHS221 is marketed as a solution for USB 2.0 signals.  Assuming I connect the device like this and place only some ESD diodes at D+/D-, the TMUXHS221 will have to endure some over voltage. 

    Above, you said the TMUX may not work.  Is that because the 60nS too long compared to an ESD strike or another reason?

    Thank you,

    Joe

    This is the performance in a ESD/EOS diode designed for USB.

  • I said the TMUX may not work since There are no ESD protection or OVP protection.without external protection.

    Best

    Brian

  • Hi Brian, I see in the datasheet this spec which indicates some level of ESD protection in addition to the external components I mentioned in the initial post.

    Does TI have any specifications for how long the device can remain above its absolute max input?

    Thank you,
    Joe

  • Joe:

       the one you mentioned is some basic ESD protection, What I mentioned is IEC 61000-4-2 , which should pass 8kv.

    Regards

    Brian

  • The ESD protection I'm using is 30kV, but the real question is whether this mux can handle a D+/D- Short to VBUS (28V) scenario before a post switch clamp (not ESD protection) kicks in (see sequence of components in first post).  As mentioned, the secondary voltage clamp permits 7 volts for 90 nS prior to the over voltage protection cutting off the offending signal.  Thanks, Joe

  • OVP device will open the switch when seeing over voltage  to protect the device behind it. OVP pulse can be 100ns to dc

    for ESD protection device , When an ESD pulse is introduced into the system, it is necessary to ensure that ESD protection diodes conduct to prevent the ESD pulse from reaching the DUP. From the connector, the ESD protection diodes and the DUP can be seen as being connected in parallel. It is therefore important to ensure that ESD protection diodes have low impedance so that most of the ESD energy is shunted through the ESD protection diodes.

    ESD pulse normally <100ns.

    Best

    Brian

  • For dc like 28V, you need OVP protection device.

    Best

    Brian

  • Thank you Brian