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Original question:

TLC2274: TLC2274 ESD issue

ESDS314: ESD Grounding for Floating DC powered remote Sensor Node

Neet
Intellectual 582 points
Part Number: ESDS314

Hello TI Community,

I'm seeking advice on establishing an effective ESD protection strategy for a specific setup and would appreciate your insights. Here are the key details:

Project Overview

  • System Configuration: A floating 2-layer PCB based sensor node system designed to collect data from different locations within 2m radius of the power supply.
  • Power Supply: 5V DC  & 1A output (Power & Return only), utilizing an AC to DC linear transformer. This setup powers a group of 4 sensor nodes.
  • Communication: Data communication via RS485.
  • Ground: No direct connection to Earth or Chassis Ground - floating ground which is connected to the Power Supply Return cable.
  • PCB Design: Features a solid, uninterrupted bottom layer ground plane connected to the power supply return, leading back to the transformer.
  • Main Concern: Uncertainty regarding the appropriate connection point for the TVS Diode's Ground pin in a system without chassis or earth ground.

Questions:

  1. Where should the TVS Diode's Ground pin be connected in a floating system like ours?
  2. Are there any additional precautions or modifications we should consider to mitigate the high inductance of the return cable connected to the PCB's ground plane?

Your guidance and recommendations on these issues would be greatly appreciated.

Thank you.

  • 0
    TI__Expert 5290 points

    Hi Neet,

    If possible, connecting the TVS Diode's GND pin to the ground plane would be the best scenario for placing the device.

    I am not quite sure any specific modifications to the design to specifically mitigate the high inductance.

    If you have any other specific ESD/TVS questions, please feel free to ask away!

    Best Regards,

    Josh Prushing 

  • 0 in reply to Josh Prushing
    Intellectual 582 points

    Hello Josh,

    Thanks for the update, do you know of any similar reference design by TI Engineers that I can refer to?

    At the end of the day, our's is a sensor node network for data acquisition system for monitoring machine parameters.

    & I am sure this type of floating configuration might be fairly common use case.

  • 0 in reply to Neet
    TI__Expert 5290 points

    Hi Neet,

    I'm not sure of any of these off the top of my head, but I will keep an eye out and reply if I come across any.

    Best Regards,

    Josh Prushing