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RE: Clause 45: MDIO Electrical Specifications

Hi Nafea,
Even if the spec states 1.5 V HSTL, you do system vendors a big
favor if you design I/O's so they can operate with 1.5-1.8 V.
Many vendors "claim" HSTL and actually power I/Os
at 1.8V. Smart if you ask me.

-----Original Message-----
From: Nafea Bishara [mailto:nafea@xxxxxxxxxxxxx]
Sent: Tuesday, February 27, 2001 2:07 PM
To: Rabinovich, Rick
Cc: stds-802-3-hssg@xxxxxxxx
Subject: Re: Clause 45: MDIO Electrical Specifications

Hi Rick 

it is assumed that most systems will have a 1.5V supply because of the HSTL
drivers ( XGMII  or other HSTL interfaces like SRAMs and SPI-4 buses) 

in any case, any design done today will be in 0.18u geometry or smaller,
thus, u sure will have a 1.8V or lower supply on board 

"Rabinovich, Rick" wrote: 


To All, 

Table 45-41 indicates a maximum VIH = 1.5V. Why is it so restrictive? 

I suggest that the inputs should be resilient to LVTTL levels (3.3V
Nominal), otherwise system manufacturers will be forced to provide
additional voltages and logic to support a 2-wire management bus. 


Rick Rabinovich 
Hardware Group Lead Engineer 
System Architect 
Spirent Communications 
26750 Agoura Road 
Calabasas, CA 91302 
Phone: 818-676-2476 
Fax    : 818-880-9293 
Email: rick.rabinovich@xxxxxxxxxxxxxx 


                (o o) 

_/_/_/_/            Nafea Bishara 
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