+ Post New Thread
Results 1 to 5 of 5
  1. #1
    Newbie level 1
    Points: 17, Level: 1

    Join Date
    Mar 2019
    Posts
    1
    Helped
    0 / 0
    Points
    17
    Level
    1

    Reverse ESD Discharge control

    Hi,

    I have a design which is suffering from ESD related issues. The design runs off both a lithium battery and a 14v DC supply and uses a simple Diode O-Ring type setup to switch between the two power sources.
    It has ESD protection consisting of ESD / TVS diodes, on all external IO’s (HDMI, USB, etc etc) as well as an RC circuit were applicable. All the electronics are housed in a plastic moulded case.

    When an ESD pulse is sent from the outside to the device we have no issues. However, when the plastic case housing the electronics is energised while running off the battery, (by say rubbing it on the carpet) and the discharge runs from the case or DC input jack to a metal object we have hardware crash inside.

    Has anyone had any experience with this ¬ďreverse¬Ē ESD type of discharge ?

    Thanks for any help,
    Jeff

    •   AltAdvertisement

        
       

  2. #2
    Super Moderator
    Points: 77,915, Level: 68
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    15,796
    Helped
    3593 / 3593
    Points
    77,915
    Level
    68

    Re: Reverse ESD Discharge control

    Hi,

    ESD protection ... but still ESD problems....
    Thus I assume you did something wrong.

    We don't know what you did, unless you show us.

    Klaus
    Please donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



  3. #3
    Advanced Member level 3
    Points: 7,460, Level: 20
    Achievements:
    7 years registered

    Join Date
    Jul 2010
    Location
    Sweden
    Posts
    997
    Helped
    383 / 383
    Points
    7,460
    Level
    20

    Re: Reverse ESD Discharge control

    First make sure that you don't have any unconnected inputs.
    Next check for sensitive high-impedande nodes.

    It it difficult to give more advice without some documentation.



  4. #4
    Advanced Member level 5
    Points: 39,802, Level: 48

    Join Date
    Mar 2008
    Location
    USA
    Posts
    6,429
    Helped
    1878 / 1878
    Points
    39,802
    Level
    48

    Re: Reverse ESD Discharge control

    ESD is ESD, it can be either polarity of voltage /
    direction of current.

    A better choice of case materials might help.

    All of that clamping may (?) prevent damage-level
    ESD but it will surely not keep inputs or outputs from
    being driven to the rails and slightly beyond. A powered
    circuit could be induced to latch up, or a spurious logic
    signal interpreted causing some sort of functional
    interrupt.



  5. #5
    Advanced Member level 5
    Points: 12,693, Level: 27
    Achievements:
    7 years registered

    Join Date
    Feb 2010
    Location
    UNITED KINGDOM
    Posts
    1,985
    Helped
    619 / 619
    Points
    12,693
    Level
    27

    Re: Reverse ESD Discharge control

    Sometime you have to use plastic for the cases, plenty of electronics in un-shielded plastic cases that work and work even if there is a ESD incident...
    Layout is critical, the position of the protection is critical... But every design has its own intricacies, so for a more focued answer we need more information.



--[[ ]]--