Re: [SI-LIST] : VMEbus transceivers

Ramzi Ammar ([email protected])
Fri, 17 Apr 1998 10:44:53 -0500

Bill, the tighter the threshold the wider the noise margin. When in the low
state, this allows you to have ground bounce up to 1.2v and still in the
low state (TTL guarantees up to 0.8V only). When in the high state, this
allows you to have a dip or a valley down to 1.6 and still in the high
state (TTL guarantees down to 2V only).

I hope this clears it up.

Ramzi Ammar

At 10:08 AM 4/17/98 -0500, Bill Dempsey wrote:
>Ramzi Ammar wrote:
>> John, Texas Instruments offer 2 devices that were designed
>> specifically for
>> VME64 bus,
>> The SN74ABTE16245 and the SN74ABTE16246. Both devices have tighter
>> threshold than the
>> normal TTL std parts, however, they are backward compatible with TTL,
>> (VILMIN=1.4V vs 0.8V-TTL and VIHMAX=1.6V vs 2V-TTL). These specs help
>> you
>> eliminate the
>> glitches due to a wider noise margin.
>> regards,
>> Ramzi Ammar
>> Texas Instruments
>Seems like a *smaller* NOISE margin.... now it's 0.2v vs TTL's 1.2v...
>Food for thought.