An Update on 1149 6 Maintenance Work Bill
An Update on 1149. 6 Maintenance Work Bill Eklow, Cisco Systems, Inc.
Background • 1149. 6 Approved in March, 2003 • Extension to 1149. 1 for “Advanced Digital Networks” – Targets AC-Coupled AND Differential Nets • Initially used by telecom companies, use is spreading with high speed serdes • Now due for 5 year tuneup
Background: Effect of Signal Decay ? Vref Update-DR TX RX Capture-DR
Background: 1149. 1 Analog model X • Reduced Fault Coverage • Limited Diagnostic Capability Pass SA 1
IEEE 1149. 6 Solution Architecture
Output Boundary Structures • TAP logic to create AC Test Signal Based on Fig. 51, IEEE 1149. 6 Std.
Analog Test Receiver
Hysteresis Preload Race Condition
Observations from the first 5 years • • • Luck – group hit technology inflection point Test receiver design difficult Timing was not/is not an issue People got it on AC-coupling, not differential Use is picking up due to AC-coupling on more “commercial” protocols • Issues with “DC-coupled” nets
Conclusion • Standard performed well over first 5 yrs. Only minor changes required. • Design practices/requirements need to be better explained • Use of dot 6 for DC coupled nets is a hard sell. • Major contribution of next revision will be Initialize
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