Subject: Dynamic Noise Immunity Spec.

From: [email-masked] (Ahmed Omer)
Date: Fri, 9 Aug 1996 18:23:29 -0500

Hello Everyone
Below is my AR from the last meeting.
...

STATEMENT OF THE ISSUE
     
Currently, IBIS specifies input logic "low/high" DC voltages for 
input and I/O model-types (i.e. Vinl and Vinh).
  
This information does not specify the required time for a signal to 
stay at Vinl or Vinh before an input is sufficiently disturbed to 
cause a level switch.  Therefore, pulse amplitude Vs pulse width data is 
needed to complete the specification.  Figure 1 shows a generic plot of 
such data.

               ^
 	PULSE  |  *                      
	       |                                
	 A     |     
	 M     |    *
 	 P     |       
 	 L     |     *     Sufficient                              
 	 I     |              Energy                              
	 T     |       *
	 U     |        *
         D     |                         
	 E     |           *                        
	       |               *                      
	(V)    |                   *                   
	       |   Insufficient         *  * * * *  <- DC value
	       |                                         
	       |                                        
	       |-----+-----+-----+-----+-----+--------->    
               0    Tr    2Tr   3Tr   4Tr   5Tr

                          PULSE WIDTH (ns)               

                      Figure 1: Receiver Noise Tolerance
                      ----------------------------------

This is also referred to as dynamic noise immunity curve. To summarize the plot:
- Pulses with widths of 5 rise times (Tr) or more, DC value will causes 
  a receiver switch.
- Pulses with widths of less than 5Tr, amplitudes of larger than DC value 
  are necessary to cause switch.
- In the region below the curve, the receiver will not switch.
- In the region above the curve, the receiver will switch.

SUGGESTED SPECIFICATION

SUGGESTION A - Combine with Vinl and Vinh
A table of at least five data points should be provided with each Vinl and 
with each Vinh.  Each point is a pair of time and voltage values in the form
(t, v) where  Tr < t < 5Tr. Suggested format is shown below.

Vinl= xx.xx; Table: (tl1, vl1) (tl2, vl2) (tl3, vl3) (tl4, vl4) (tl5, vl5)
Vinh= xx.xx; Table: (th1, vh1) (th2, vh2) (th3, vh3) (th4, vh4) (th5, vh5)

SUGGESTION B - Use separate keyword
Keyword: [Dynamic Noise Immunity]
This keyword defines a table of voltage versus time points. The table 
contains three columns:
    1- time
    2- low voltage rise (volts above Ground)      
    3- high voltage drop (Volts below Power)   

Regards, Ahmed
|---------------------------------------+------------------------------------|
|Ahmed Omer                             | Advanced Interconnect Systems Labs |
|E-MAIL: [email-masked]  | Semiconductor Products Sector      |
|      : [email-masked]       | M O T O R O L A, Inc.              |
|Phone:	 512-933-2247                   | 3501 Ed Bluestein Blvd  MDrop: F36 |
|Fax:	 512-933-5845                   | Austin, TX 78721                   |
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