1. © 2008 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPaper #15 1 Ted Eaton coerced by the late Bill Eklow 9/15/2010 1149.6 Cross-over issue

2. © 2008 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPaper #15 2 1149.6 test Receivers Differential?  The standard tells us 6.2.1.1 Rules a) All AC pins (see 4.1) that receive input data, whether they are single-ended or one leg of a differential pair, shall have exactly one test receiver function monitoring the mission pin signal.  BSDL tells us : List all DIFF + pins in the AIO_PIN_BEHAVIOR Infer.6 behavior on – pins using PORT_GROUPING  The ATPG tools don’t bother to care A DIFF is a DIFF is a DIFF

3. © 2008 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPaper #15 3 ATPG Does this great

4. © 2008 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPaper #15 4 1149.6 test Receivers Differential?  Board Layout rules tell us sometimes it is better to route + to –  ASIC design says ok… connect the pins as you need and we will invert + and – in functional mode and.6 is single ended so who cares.  The ATPG tools don’t bother to care “A DIFF is a DIFF is a DIFF”

5. © 2008 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPaper #15 5 ATPG Does this Great… WAIT!!!! A DIFF is NOT a DIFF

6. © 2008 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPaper #15 6