• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 34 subscribers
  • Views 809 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TCA4311A: Hot Swap Buffer Required for I/O

Sharvy Mayan
Intellectual 680 points

Part Number: TCA4311A

Hi,

One of our project, we have a host PCB & some Add-on PCB's. In the initial customer requirement, there was no requirement of live plugging on ADD-on PCB's. Now the customer has changed the specification to add the live plugging option of ADD-on PCB. We tried the live plugging with an existing Host & add-on PCB. In some cases, we found that the controller is damaged. Can you suggest  us a solution to avoid this from your experience . I/O Hot swap buffers are enough for this?

Case Scenario:

  1. The add-on connector in the host PCB is connected direct I/O pins from the controller. Voltage tolerance is about 3.3V. 
  2. There are 4 I/O pins( input & output ) ,1 x UART TX & 1 xUART RX signals.
  3. Add-on PCB controller I/O  tolerance is 3.3V itself.
  4. 12V also connected to the Host add-on connector for powering the ADDAD_on PCB. Inside the ADDAD_on PCB, there are DC-DC regulator to get the 3.3V for add-on controller.

Can you suggest us a best solution to avoid issues related to live plugging, since our host controller is damaging in random plugging s.

BR
Sharvy

  • 0
    TI__Guru* 78271 points

    Hey Sharvy,

    TCA4311A is a device meant to support hot insertion in the sense that it will not disrupt communication when it is inserted because the two sides (in and out) are high impedance until it sees an idle condition, then it will connect out and in together. The idea here is to keep I2C signal integrity good during insertion, not protect a device from damage.What you are talking about seems to be the latter here.

    Have you recorded the active plug in event on an o-scope? I've worked on a support case where something similar happened (one of our I/O expanders would get damaged), we ended up finding out that the damage was caused by overshoots (device was spec'd to handle ~6V or 7V maximum) where the plug in event caused spikes of up to 15V to be seen on the I/O pins.

    If this is the same thing you are seeing then a hot swap buffer may not be what you need because TCA4311A can only handle up to 7V maximum. If you are seeing this kind of behavior, I think the best approach would be to find a TVS diodes to place on your TX/RX lines to suppress the voltage spikes to a level that is tolerable to your mcu.

    Thanks,

    -Bobby