[SI-LIST] Re: Damaging LVDS inputs (with embedded termination) using LVPECL voltage swings?
- From: Allan Davidson <allan.davidson@xxxxxxxxxxxxxxx>
- To: sa_jr@xxxxxxxxx
- Date: Mon, 26 Aug 2002 15:28:02 -0700
Sal:
Since the receiver has embedded on-chip termination, you need to make
sure the resistor can handle the current due to the 1000mV input signal.
If the 100 ohm resistor is say 15% off on the low side, that would
result in about 11.7mA through the termination. If the embedded resistor
was optimized for an LVDS swing, it is probably not designed to handle
this much current and this could be a reliability issue. The current
density of the on-chip contacts to the resistor is likely to be the
limiting factor.
The DC specification of the receiver should indicate the maximum allowed
input voltage swing, as well as the allowable input common mode range. I
wouldn't recommend exceeding either of these specs.
Hope this helps.
Regards, Allan
Sal Aguiqaga wrote:
>
> Hello All!
>
> Is there a risk of damaging a device if an LVPECL
> voltage swing is driven into an LVDS receiver?
>
> *** (not designed to work like this, but in case of
> user error this could happen ) ***
>
> If the voltage swing is about 750 to 1000 mV with a
> offset of 2.0 Volts, will it damage the LVDS receiver?
> The LVDS receiver has an embedded 100 ohm termination
> resitor between the +/- pins. At the moment the
> connection is point to point without AC coupling.
>
> I would appreciate a response if some of you have come
> accross this one.
>
> Thank you.
>
> Sal Aguinaga Jr.
> Rolling Meadows, IL
>
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