I missed your other point: with a recent consumer product they had field
failures in one of two ways: destruction of power supply components, and
destruction of power ICs. In both cases we were able to recreate the
failed components with ESD discharges, and with appropriate design we
were able to greatly increase the ESD immunity.
Curt
Curt McNamara wrote:
> I don't know what your device looks like -- perhaps it is hand held?
> With USB jacks installed in PCBs we find that the shell needs to be
> tied to circuit ground. It can also be tied to chassis ground (case
> ground) if that is available. Tying the USB shell to chassis only has
> caused problems for us.
>
> The standard is fine, we have customer devices tested upwards of 20KV!
> The levels are dependent on the market and application. We have also
> had troubles with hand-held devices at 6KV. With a hand-held there is
> nowhere for the ESD energy to go after discharge, so making sure the
> discharge path creates just common mode voltages is critical. Adding
> physical protection so that direct contact is not possible helps.
>
>
> Curt
>
> in real life
> Curt McNamara P.E. // principal electrical engineer
> Logic Product Development
> 411 Washington Ave. N. Suite 400
> Minneapolis, MN 55401
> T // 612.436.5178
> F // 612.672.9489
> www.logicpd.com
>
> Bharathkumar Raju wrote:
>> Dear Memebrs,
>> I feel EN61000 - 4 - 2 is an over kill for assessing the ESD
>> immunity level of a device. An USB device with a CCD type sensor is
>> repeatedly failing in the lab testing conducted as per the standard
>> and as per sensor manufacturer's recomendations. On the other hand
>> the sensor manufacturer claims that millions of sensors are deployed
>> in the field for more than a year and absolutely no field returns on
>> ESD account. The lab results are not at all matching with field
>> results calimed by the sensor manufacturer. As a product
>> certification engineer, I am confused whether to give the go ahead to
>> my company for the mass production.
>> I look for the members advise
>> a. Do you see a reasonable match between the EN 61000 - 4 - 2 lab
>> test results and field results.
>> b. Is there any other standard that you feel better than EN 61000 - 4
>> - 2.
>>
>> Wishing you all a Happy Christmas & Prosperous New Year 2008
>>
>> Bharath
>>
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