August 13, 2010 PCN Number: 1013A PCN Change Level: Minor Subject: RTAX-S/SL and Axcelerator Enhanced Minimum Delay (EMD) This PCN serves to replace PCN 1013, sent on July 29th 2010. Dear Customer, We have recently discovered that a corner case use of enhanced minimum delay analysis may result in an inaccuracy in Actel’s Libero® Integrated Design Environment (IDE) static timing analysis tool, called SmartTime, for RTAX-S/SL and Axcelerator® devices. The corner case is described below along with suggested corrective actions. Enhanced Minimum Delay (EMD) is a delay calculation methodology introduced in Actel’s static timing analysis tool to compute lower bound delays on gates and nets. This is necessary for a conservative hold check (minimum delay analysis) during which the tightest timing margin (slack) is computed. This PCN should be considered only if ALL of the following conditions apply. These are the conditions where the enhanced minimum delay analysis in SmartTime prior to Libero IDE v9.0 SP2 may be inaccurate: i. The clock skew is larger than half the period. ii. There are paths between positive and negative edge flops (or negative edge and positive edge flops). iii. Minimum delay analysis is performed under WCC (worst case conditions). Under these conditions, customers must upgrade to Libero IDE v9.0 SP2, which will ensure that the tightest timing margin will be used when analyzing the corner case described above. Please refer to Appendix A and Appendix B below for further details and a workaround for pre Libero IDE v9.0 SP2 users. Please note that the opposite edge clocking scheme is typically used to eliminate risks of hold violations. Therefore, it is uncommon to see this along with a large skew. Most designs do not meet all the conditions mentioned above and thus this PCN does not apply to them. If you have any additional questions, please do not hesitate to contact Actel’s ITAR Technical support at http://www.actel.com/mycases or [email protected]. Yours Sincerely, Actel Corporation Actel Corporation 2061 Stierlin Court, Mountain View, CA 94043 Phone: 650.318.4200 Fax 650.318.4600 Part No. 54400089-1 Appendix A – Example The following is an example illustrating the inaccuracy: Data Delay Source Register Clock Insertion Delay Sink Register Clock Insertion Delay Figure 1. Sample Design In this example, the hold time check will be the following: • Arrival time is equal to the clock insertion delay to the source register plus data path delay. • Required time is the clock constraint plus the clock insertion delay of the sink register plus hold time of the sink register. • Clock constraint is the delay difference between the launching clock edge (of the source register) and the capturing clock edge (of the sink register) for the data from the previous cycle. For a 50% duty cycle clock, it is = T/2 if T is the clock period. • Slack is equal to the arrival time minus the required time. Table 1 shows the results for different operating conditions in an implementation of this design on a RTAX250S/SL with STD speed grade and military operating conditions, where the required clock period is set to 100 MHz (delays are in ns). Operating Conditions Best Worst Worst EMD Y Y N Table 1. Analysis Results Sink Clock Clock Arrival Insertion Constraint 1.458 1.652 –5.000 2.689 2.849 –5.000 4.713 5.038 –5.000 Hold Required Slack 0 0 0 –3.348 –2.151 0.038 4.806 4.840 4.675 Because the clock constraint is fixed (does not change with operating conditions), higher slack results when higher delays are used. The worst slack results when there is no EMD (bottom row). Therefore, EMD needs to be turned off to obtain the worst slack. Actel Corporation 2061 Stierlin Court, Mountain View, CA 94043 Phone: 650.318.4200 Fax 650.318.4600 2 Appendix B – Workaround Using Older Versions of Libero IDE Software (pre v9.0 SP2) Actel recommends that customers perform timing analysis at all four corners: • Minimum delay, best case • Minimum delay, worst case • Maximum delay, best case • Maximum delay, worst case Using the Enhanced Minimum Delay tool is recommended for all of these with the exception of minimum delays, worst case. For this case, Actel recommends disabling the Enhanced Minimum Delay tool and performing timing analysis using SmartTime without the Enhanced Minimum Delay feature. To turn off EMD, use the following steps: 1 Open Designer without opening the ADB design file. 2 Set the EMD def variable (see variable list below for different products) to value 0 in Designer by selecting Options > Variable Console and clicking Set Value. Variable List: RTAX4000D: RTAX2000D: RTAX4000S/SL: RTAX2000S/SL: RTAX1000S/SL: RTAX250S/SL: AX2000: AX1000: AX500: AX250: AX125: EMD_70800d EMD_70400d EMD_70800rts EMD_70400rts EMD_70200rts EMD_70050rts EMD_70400 EMD_70200 EMD_70100 EMD_70050 EMD_70025 Actel Corporation 2061 Stierlin Court, Mountain View, CA 94043 Phone: 650.318.4200 Fax 650.318.4600 3 Figure 2. Variables Console in Designer 3 Open the ADB design file and open SmartTime to confirm that EMD is turned off by checking the Analysis View Summary. Note that every time Designer is closed, the variable will be set back to no default value and the same procedure must be repeated to turn off EMD. To re-enable EMD customers, do the following: 1 If the Designer window is currently open, close the design in Designer but keep the Designer window open 2 If the Designer window is currently not open, open the Designer window without opening the design. 3 Set the same variable to a value of 1. 4 Reopen the design and reopen SmartTime. Note that the variable needs to be set in Designer before the design is opened for it to be effective. To verify whether EMD is being used, check the summary in the GUI or the header of any report to see if "Using Enhanced Min Delay" is mentioned. Actel Corporation 2061 Stierlin Court, Mountain View, CA 94043 Phone: 650.318.4200 Fax 650.318.4600 4 Appendix C – Affected Devices The following is a list of affected devices. AX1000-1BG729 AX1000-1BG729I AX1000-1BG729M AX1000-1BGG729 AX1000-1BGG729I AX1000-1BGG729M AX1000-1CGS624M AX1000-1CQ352M AX1000-1FG484 AX1000-1FG484I AX1000-1FG484M AX1000-1FG676 AX1000-1FG676I AX1000-1FG676M AX1000-1FG896 AX1000-1FG896I AX1000-1FG896M AX1000-1FGG484 AX1000-1FGG484I AX1000-1FGG484M AX1000-1FGG676 AX1000-1FGG676I AX1000-1FGG676M AX1000-1FGG896 AX125-1CS180 AX125-1CS180I AX125-1CSG180 AX125-1CSG180I AX125-1FG256 AX125-1FG256I AX125-1FG324 AX125-1FG324I Actel Corporation 2061 Stierlin Court, Mountain View, CA 94043 Phone: 650.318.4200 Fax 650.318.4600 Table 2. Affected Devices AX1000 AX1000-1FGG896I AX1000-1FGG896M AX1000-1LG624M AX1000-2BG729 AX1000-2BG729I AX1000-2BGG729 AX1000-2BGG729I AX1000-2FG484 AX1000-2FG484I AX1000-2FG676 AX1000-2FG676I AX1000-2FG896 AX1000-2FG896I AX1000-2FGG484 AX1000-2FGG484I AX1000-2FGG676 AX1000-2FGG676I AX1000-2FGG896 AX1000-2FGG896I AX1000-BG729 AX1000-BG729I AX1000-BG729M AX1000-BGG729 AX1000-BGG729I AX1000-BGG729M AX1000-CGS624M AX1000-CQ352M AX1000-FG484 AX1000-FG484I AX1000-FG484M AX1000-FG676 AX1000-FG676I AX1000-FG676M AX1000-FG896 AX1000-FG896I AX1000-FG896M AX1000-FGG484 AX1000-FGG484I AX1000-FGG484M AX1000-FGG676 AX1000-FGG676I AX1000-FGG676M AX1000-FGG896 AX1000-FGG896I AX1000-FGG896M AX1000-LG624M AX125 AX125-2CS180 AX125-2CS180I AX125-2CSG180 AX125-2CSG180I AX125-2FG256 AX125-2FG256I AX125-2FG324 AX125-2FG324I AX125-CS180 AX125-CS180I AX125-CSG180 AX125-CSG180I AX125-FG256 AX125-FG256I AX125-FG324 AX125-FG324I 5 Table 2. Affected Devices (continued) AX125-2FGG256 AX125-2FGG256I AX125-2FGG324 AX125-2FGG324I AX2000 AX2000-1CGS624M AX2000-1FGG896M AX2000-1CQ256M AX2000-1LG624M AX2000-1CQ352M AX2000-2FG1152 AX2000-1FG1152 AX2000-2FG1152I AX2000-1FG1152I AX2000-2FG896 AX2000-1FG1152M AX2000-2FG896I AX2000-1FG896 AX2000-2FGG1152 AX2000-1FG896I AX2000-2FGG1152I AX2000-1FG896M AX2000-2FGG896 AX2000-1FGG1152 AX2000-2FGG896I AX2000-1FGG1152I AX2000-CGS624M AX2000-1FGG1152M AX2000-CQ256M AX2000-1FGG896 AX2000-CQ352M AX2000-1FGG896I AX250 AX250-1CQ208M AX250-1PQG208I AX250-1CQ352M AX250-1PQG208M AX250-1FG256 AX250-2FG256 AX250-1FG256I AX250-2FG256I AX250-1FG256M AX250-2FG484 AX250-1FG484 AX250-2FG484I AX250-1FG484I AX250-2FGG256 AX250-1FG484M AX250-2FGG256I AX250-1FGG256 AX250-2FGG484 AX250-1FGG256I AX250-2FGG484I AX250-1FGG256M AX250-2PQ208 AX250-1FGG484 AX250-2PQ208I AX250-1FGG484I AX250-2PQG208 AX250-1FGG484M AX250-2PQG208I AX250-1PQ208 AX250-CQ208M AX250-1PQ208I AX250-CQ352M AX125-1FGG256 AX125-1FGG256I AX125-1FGG324 AX125-1FGG324I Actel Corporation 2061 Stierlin Court, Mountain View, CA 94043 Phone: 650.318.4200 Fax 650.318.4600 AX125-FGG256 AX125-FGG256I AX125-FGG324 AX125-FGG324I AX2000-FG1152 AX2000-FG1152I AX2000-FG1152M AX2000-FG896 AX2000-FG896I AX2000-FG896M AX2000-FGG1152 AX2000-FGG1152I AX2000-FGG1152M AX2000-FGG896 AX2000-FGG896I AX2000-FGG896M AX2000-LG624M AX250-FG256I AX250-FG256M AX250-FG484 AX250-FG484I AX250-FG484M AX250-FGG256 AX250-FGG256I AX250-FGG256M AX250-FGG484 AX250-FGG484I AX250-FGG484M AX250-PQ208 AX250-PQ208I AX250-PQ208M AX250-PQG208 AX250-PQG208I 6 AX250-1PQ208M AX250-1PQG208 Table 2. Affected Devices (continued) AX250-FG256 AX250-PQG208M AX500 AX500-1PQG208I AX500-1PQG208M AX500-2FG484 AX500-2FG484I AX500-2FG676 AX500-2FG676I AX500-2FGG484 AX500-2FGG484I AX500-2FGG676 AX500-2FGG676I AX500-2PQ208 AX500-2PQ208I AX500-2PQG208 AX500-2PQG208I AX500-CQ208M AX500-CQ352M AX500-FG484 AX500-FG484I AX500-FG484M AX500-FG676 AX500-FG676I AX500-FG676M AX500-FGG484 AX500-FGG484I AX500-FGG484M AX500-FGG676 AX500-FGG676I AX500-FGG676M AX500-PQ208 AX500-PQ208I AX500-PQ208M AX500-PQG208 AX500-PQG208I AX500-PQG208M RTAX1000S 5962-0422008QXC 5962-0422008QYC RTAX1000S-1CG624PROTO RTAX1000S-1CGS624B RTAX1000S-1CGS624E RTAX1000S-1CGS624EV RTAX1000S-1CQ352B RTAX1000S-1CQ352E RTAX1000S-1CQ352EV RTAX1000S-1CQ352PROTO RTAX1000S-1LG624B RTAX1000S-1LG624E RTAX1000S-1LG624EV RTAX1000S-1LG624PROTO RTAX1000SL-1CGS624B RTAX1000SL-1CGS624E RTAX1000SL-1CGS624EV RTAX1000SL-1CQ352B RTAX1000SL-1CQ352E RTAX1000SL-1CQ352EV RTAX1000SL-1LG624B RTAX1000SL-1LG624E RTAX1000SL-1LG624EV RTAX1000SL-CGS624B RTAX1000SL-CGS624E RTAX1000SL-CGS624EV RTAX1000SL-CQ352B RTAX1000SL-CQ352E AX500-1CQ208M AX500-1CQ352M AX500-1FG484 AX500-1FG484I AX500-1FG484M AX500-1FG676 AX500-1FG676I AX500-1FG676M AX500-1FGG484 AX500-1FGG484I AX500-1FGG484M AX500-1FGG676 AX500-1FGG676I AX500-1FGG676M AX500-1PQ208 AX500-1PQ208I AX500-1PQ208M AX500-1PQG208 5962-0422001QUA 5962-0422001QXC 5962-0422001QYC 5962-0422002QUA 5962-0422002QXC 5962-0422002QYC 5962-0422003QUA 5962-0422003QXC 5962-0422003QYC 5962-0422004QUA 5962-0422004QXC 5962-0422004QYC 5962-0422005QUA 5962-0422005QXC Actel Corporation 2061 Stierlin Court, Mountain View, CA 94043 Phone: 650.318.4200 Fax 650.318.4600 7 5962-0422005QYC 5962-0422006QUA 5962-0422006QXC 5962-0422006QYC 5962-0422007QUA 5962-0422007QXC 5962-0422007QYC 5962-0422008QUA 5962-0422101QMC 5962-0422101QNA 5962-0422101QTA 5962-0422101QUC 5962-0422101QXC 5962-0422101QYC 5962-0422102QMC 5962-0422102QNA 5962-0422102QTA 5962-0422102QUC 5962-0422102QXC 5962-0422102QYC 5962-0422103QMC 5962-0422103QNA 5962-0422103QTA 5962-0422103QUC 5962-0422103QXC 5962-0422103QYC 5962-0422104QMC 5962-0422104QNA 5962-0422104QTA 5962-0422104QUC 5962-0422104QXC 5962-0422104QYC 5962-0422105QMC 5962-0422105QNA 5962-0422105QTA Table 2. Affected Devices (continued) RTAX1000S-CG624PROTO RTAX1000SL-CQ352EV RTAX1000S-CGS624B RTAX1000S-LG624B RTAX1000S-CGS624E RTAX1000S-LG624E RTAX1000S-CGS624EV RTAX1000S-LG624EV RTAX1000S-CQ352B RTAX1000S-LG624PROTO RTAX1000S-CQ352E RTAX1000SL-LG624B RTAX1000S-CQ352EV RTAX1000SL-LG624E RTAX1000S-CQ352PROTO RTAX1000SL-LG624EV RTAX2000S 5962-0422108QTA RTAX2000SL-1CG1152B 5962-0422108QUC RTAX2000SL-1CG1152E 5962-0422108QXC RTAX2000SL-1CG1152EV 5962-0422108QYC RTAX2000SL-1CGS624B RTAX2000S-1CG1152B RTAX2000SL-1CGS624E RTAX2000S-1CG1152E RTAX2000SL-1CGS624EV RTAX2000S-1CG1152EV RTAX2000SL-1CQ256B RTAX2000S-1CG1152PROTO RTAX2000SL-1CQ256E RTAX2000S-1CG624PROTO RTAX2000SL-1CQ256EV RTAX2000S-1CGS624B RTAX2000SL-1CQ352B RTAX2000S-1CGS624E RTAX2000SL-1CQ352E RTAX2000S-1CGS624EV RTAX2000SL-1CQ352EV RTAX2000S-1CQ256B RTAX2000SL-1LG1152B RTAX2000S-1CQ256E RTAX2000SL-1LG1152E RTAX2000S-1CQ256EV RTAX2000SL-1LG1152EV RTAX2000S-1CQ256PROTO RTAX2000SL-1LG624B RTAX2000S-1CQ352B RTAX2000SL-1LG624E RTAX2000S-1CQ352E RTAX2000SL-1LG624EV RTAX2000S-1CQ352EV RTAX2000SL-CG1152B RTAX2000S-1CQ352PROTO RTAX2000SL-CG1152E RTAX2000S-1LG1152B RTAX2000SL-CG1152EV RTAX2000S-1LG1152E RTAX2000SL-CGS624B RTAX2000S-1LG1152EV RTAX2000SL-CGS624E RTAX2000S-1LG1152PROTO RTAX2000SL-CGS624EV RTAX2000S-1LG624B RTAX2000SL-CQ256B RTAX2000S-1LG624E RTAX2000SL-CQ256E RTAX2000S-1LG624EV RTAX2000SL-CQ256EV Actel Corporation 2061 Stierlin Court, Mountain View, CA 94043 Phone: 650.318.4200 Fax 650.318.4600 8 5962-0422105QUC 5962-0422105QXC 5962-0422105QYC 5962-0422106QMC 5962-0422106QNA 5962-0422106QTA 5962-0422106QUC 5962-0422106QXC 5962-0422106QYC 5962-0422107QMC 5962-0422107QNA 5962-0422107QTA 5962-0422107QUC 5962-0422107QXC 5962-0422107QYC 5962-0422108QMC 5962-0422108QNA 5962-0421901QUA 5962-0421901QXC 5962-0421901QYC 5962-0421901QZC 5962-0421902QUA 5962-0421902QXC 5962-0421902QYC 5962-0421902QZC 5962-0421903QUA 5962-0421903QXC 5962-0421903QYC 5962-0421903QZC 5962-0421904QUA 5962-0421904QXC 5962-0421904QYC 5962-0421904QZC 5962-0421905QUA 5962-0421905QXC Table 2. Affected Devices (continued) RTAX2000S-1LG624PROTO RTAX2000SL-CQ352B RTAX2000S-CG1152B RTAX2000SL-CQ352E RTAX2000S-CG1152E RTAX2000SL-CQ352EV RTAX2000S-CG1152EV RTAX2000S-LG1152B RTAX2000S-CG1152PROTO RTAX2000S-LG1152E RTAX2000S-CG624PROTO RTAX2000S-LG1152EV RTAX2000S-CGS624B RTAX2000S-LG1152PROTO RTAX2000S-CGS624E RTAX2000S-LG624B RTAX2000S-CGS624EV RTAX2000S-LG624E RTAX2000S-CQ256B RTAX2000S-LG624EV RTAX2000S-CQ256E RTAX2000S-LG624PROTO RTAX2000S-CQ256EV RTAX2000SL-LG1152B RTAX2000S-CQ256PROTO RTAX2000SL-LG1152E RTAX2000S-CQ352B RTAX2000SL-LG1152EV RTAX2000S-CQ352E RTAX2000SL-LG624B RTAX2000S-CQ352EV RTAX2000SL-LG624E RTAX2000S-CQ352PROTO RTAX2000SL-LG624EV RTAX250S 5962-0421908QYC RTAX250S-CQ352PROTO 5962-0421908QZC RTAX250SL-1CG624B RTAX250S-1CG624B RTAX250SL-1CG624E RTAX250S-1CG624E RTAX250SL-1CG624EV RTAX250S-1CG624EV RTAX250SL-1CQ208B RTAX250S-1CG624PROTO RTAX250SL-1CQ208E RTAX250S-1CQ208B RTAX250SL-1CQ208EV RTAX250S-1CQ208E RTAX250SL-1CQ352B RTAX250S-1CQ208EV RTAX250SL-1CQ352E RTAX250S-1CQ208PROTO RTAX250SL-1CQ352EV RTAX250S-1CQ352B RTAX250SL-1LG624B RTAX250S-1CQ352E RTAX250SL-1LG624E RTAX250S-1CQ352EV RTAX250SL-1LG624EV RTAX250S-1CQ352PROTO RTAX250SL-CG624B RTAX250S-1LG624B RTAX250SL-CG624E RTAX250S-1LG624E RTAX250SL-CG624EV RTAX250S-1LG624EV RTAX250SL-CQ208B RTAX250S-1LG624PROTO RTAX250SL-CQ208E Actel Corporation 2061 Stierlin Court, Mountain View, CA 94043 Phone: 650.318.4200 Fax 650.318.4600 9 5962-0421905QYC 5962-0421905QZC 5962-0421906QUA 5962-0421906QXC 5962-0421906QYC 5962-0421906QZC 5962-0421907QUA 5962-0421907QXC 5962-0421907QYC 5962-0421907QZC 5962-0421908QUA 5962-0421908QXC Table 2. Affected Devices (continued) RTAX250S-CG624B RTAX250SL-CQ208EV RTAX250S-CG624E RTAX250SL-CQ352B RTAX250S-CG624EV RTAX250SL-CQ352E RTAX250S-CG624PROTO RTAX250SL-CQ352EV RTAX250S-CQ208B RTAX250S-LG624B RTAX250S-CQ208E RTAX250S-LG624E RTAX250S-CQ208EV RTAX250S-LG624EV RTAX250S-CQ208PROTO RTAX250S-LG624PROTO RTAX250S-CQ352B RTAX250SL-LG624B RTAX250S-CQ352E RTAX250SL-LG624E RTAX250S-CQ352EV RTAX250SL-LG624EV RTAX4000S-1CG1272B RTAX4000S-1CG1272E RTAX4000S-1CG1272EV RTAX4000S-1CG1272PROTO RTAX4000S-1CQ352B RTAX4000S-1CQ352E RTAX4000S-1CQ352EV RTAX4000S-1CQ352PROTO RTAX4000S-1LG1272B RTAX4000S-1LG1272E RTAX4000S-1LG1272EV RTAX4000S-1LG1272PROTO RTAX4000S-CG1272B RTAX4000S-CG1272E Actel Corporation 2061 Stierlin Court, Mountain View, CA 94043 Phone: 650.318.4200 Fax 650.318.4600 RTAX4000S RTAX4000S-CG1272EV RTAX4000S-CG1272PROTO RTAX4000S-CQ352B RTAX4000S-CQ352E RTAX4000S-CQ352EV RTAX4000S-CQ352PROTO RTAX4000SL-1CG1272B RTAX4000SL-1CG1272E RTAX4000SL-1CG1272EV RTAX4000SL-1CQ352B RTAX4000SL-1CQ352E RTAX4000SL-1CQ352EV RTAX4000SL-1LG1272B RTAX4000SL-1LG1272E RTAX4000SL-1LG1272EV RTAX4000SL-CG1272B RTAX4000SL-CG1272E RTAX4000SL-CG1272EV RTAX4000SL-CQ352B RTAX4000SL-CQ352E RTAX4000SL-CQ352EV RTAX4000S-LG1272B RTAX4000S-LG1272E RTAX4000S-LG1272EV RTAX4000S-LG1272PROTO RTAX4000SL-LG1272B RTAX4000SL-LG1272E RTAX4000SL-LG1272EV 10