App note: Improving USB system reliability with transient suppressors

Posted on Saturday, July 21st, 2012 in app notes by DP

Adding transient suppressors to USB devices [PDF!] can help prevent damage from static discharge. This is important because USB devices are handled without protection, carried in pockets, tossed in bags, etc.

Because frequent human interaction with the USB system occurs as a result of its attractive hot-plugging ability, there is the possibility for large ESD strikes and damage to crucial system elements. The ESD protection included on the existing hardware is typically in the 2-kV to 4-kV range for the human body model (HBD) and 200-V to 300-V for the machine model (MM). The ESD voltage levels found in a normal USB operating environment can exceed these levels.

This entry was posted on Saturday, July 21st, 2012 at 9:00 pm and is filed under app notes. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.

5 Responses to “App note: Improving USB system reliability with transient suppressors”

  1. Squonk says:

    Yes transient suppressor is a good idea, and not only for USB… All externally reachable connectors should also be protected this way!

    I used the cheaper PRTR5V0U2X on my USBug LPC1343 Development Board.

    For an even more compact design, you can also use the EClamp2522P, with integrated 22 ohm series resistors and 1k5 pull-up.

    Noise suppression/protection for EMC is also a mandatory step for professional products!

  2. bearmos says:

    it’s probably worth-whlle mentioning that this app note (appears) to be aimed at USB 1.1. Depending on the capacitance of the TVS you put on the lines, they can slow things down enough to cause issues with higher speed USB standards.

  3. It’s a bit limited what TI shows there. They don’t have common mode chokes in their product line so they don’t talk about them. But in noisy environments they really do help.

    This application note is better because it shows several methods of protection:

Leave a Reply

Notify me of followup comments via e-mail. You can also subscribe without commenting.

Recent Comments

  • Drone: So these go for around $330 USD and NO published calibration procedure online or otherwise? Given what's inside - I don't think I'll be considering...
  • Pekka Akselin: This is ridiculous!? :-) We are back at 256(!) byte EPROMs that needed multiple, a handful, of voltages to run! :-(
  • KH: Let's try a back-of-envelope calc balancing energies. From MCP1700 datasheet, there are graphs for a 200mA load step. Estimate the energy shortfall as 12uJ. Say...
  • Daniel: It's been a week and my comment is still awaiting moderation. Apparently the CIA doesn't want their involvement known?
  • KH: Agree, so okay, I guess he must have learned from somewhere. 100nF and 1000uF is so far apart, that was jarring; it's more magic incantation...