[SI-LIST] Re: Dead Ethernet Controller chip suspecting due to high ESD
- From: piyush bhatt <piyush.nithmr@xxxxxxxxx>
- To: gcemobile gcemobile <gcemobile@xxxxxxxxx>
- Date: Thu, 11 Aug 2011 20:52:36 +0530
Hi GCE
PoE and PoE + have negotiation method to find out if the receiver is
PoE enabled.
PoE source first send about 25V with high source impedance and check
if receiver present " signature impedance' of 27K ohm. If that is
presented by receiver,PoE source turns on full 48Volts power supply
for powering the device.
regards
Piyush
On Thu, Aug 11, 2011 at 7:39 PM, gcemobile gcemobile
<gcemobile@xxxxxxxxx> wrote:
> Hi,
> I've 2 scopes with LAN issue caused by dead Ethernet Controller chip. All
> this while, the LAN is working fine through USB-LAN adapter until one day I
> plug the LAN cable directly to the office network port. Since then, the LAN
> is not function anymore.
> The Ethernet Controller chip (*HBM ESD +/-5kV*) is protected by a Railclamp
> chip. The Railclamp datasheet mentions "ESD protection for high-speed data
> lines to IEC 61000-4-2: (ESD) ą15kV (air), *ą8kV (contact)*".
>
> 1. From the Ethernet Controller HBM ESD spec of +/-5kV, any voltage more
> than 5V could kill the chip. In this case, the Railclamp doesn't protect the
> Ethernet Controller since it clamps at +/-8kV, right? If I understand the
> spec correctly, Railclamp will not clamp a 6kV and this kills the Ethernet
> Controller?
> 2. I read about PoE/PoE+ and understand huge voltage (~54V) exist. How
> possible is the PoE/PoE+ kills the Ethernet Controller chip?
>
> Appreciate your advice & comments. Thanks.
>
> -GCE
>
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