UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

AR# 41083

Design Advisory for Spartan-6 IODELAY2 - IODELAY2 Data Rate and Corresponding Bit Error Rates for New Mask Revision Silicon

Description

The Spartan-6 Production Errata (EN148) details maximum data rates for the Spartan-6 FPGAIODELAY2 element in order to avoid data loss for New Mask Revision silicon. If some amount of data loss may be acceptable to a design, this answer record gives more information to assist in that analysis.

This answer record does not apply to Previous Mask Revision devices (for information onhow to identify new mask revisions, see errata EN148 or PCN XCN11012).For Previous Mask Revision devices, see (Xilinx Answer 38408). XA Automotive, XQ, Q grade, andXC Lower Power -1L devices will be released with the New Mask Revision only.

Solution

For Spartan-6 devices with the JTAG ID (Revision Code) listed under New Mask Revision in XCN11012, the IODELAY2 block can experience single data bit corruption. The MCB interfaces are not affected by the IODELAY2 errata.

Single Data Bit Corruption in IDELAY and ODELAY Modes
The IODELAY2 block can corrupt a single data bit for some IDELAY_VALUE and ODELAY_VALUE settings.

Work-arounds

IDELAY_TYPE=FIXED, VARIABLE_FROM_ZERO, VARIABLE_FROM_HALF_MAX or DIFF_PHASE_DETECTOR, or when used in ODELAY mode

Limit the data rate through the IODELAY2 to the maximum specifications in Table 2.

IDELAY_TYPE=FIXED or VARIABLE_FROM_ZERO or when used in ODELAY mode, with tap limit

When using a fixed tap value and requiring higher performance than specified in Table 2, restricting the maximum IDELAY_VALUE or ODELAY_VALUE can avoid data corruption at the higher indicated data rates. Table 3 provides a summary of these higher data rates for fixed tap values.



Work-around: Error Rates for Operation Outside of Maximum Data Rates

When using the standard VCCINT operating range (1.14 to 1.26 volts), higher data rates may be required than those given above and in EN148. The user can potentially trade off data rate against the possibility of data loss. Numbers are given in Table 4 and Table 5 below for various data rates and for the MTBF (Mean Time Before Failure) and corresponding BER (Bit Error Rate) for all speed and temperature grades. The BERs, while very low, are statistically non-zero and it is up to the designer as to whether an application can tolerate the given error rate. The numbers are given per IODELAY2 element (a master and a slave acting together in differential phase detector mode count as one IODELAY2) and should be multiplied by the number of data lines being received in the application to get an overall BER.

Table 4: MTBF and BER for I and Q Temperature Grade with New Mask Revision Silicon

MTBF (seconds)

BER

Data Rate (Mbps)

Bit Period (pS)

-3I/Q

-2I/Q

-3I/Q

-2I/Q

667

1499

Not Applicable

2.0 x 1027

Not Applicable

7.5 x 10-37

750

1333

1.0 x 1033

1.0 x 1022

1.3 x 10-42

1.3 x 10-31

800

1250

2.0 x 1028

3.0 x 1018

6.2 x 10-38

4.2 x 10-28

950

1053

1.0 x 1018

1.0 x 1011

1.0 x 10-27

1.0 x 10-20

1050

952

8.0 x 1012

8.0 x 106

1.2 x 10-22

1.2 x 10-16

1080

926

2.0 x 1011

5.0 x 105

4.6 x 10-21

1.8 x 10-15

Table 5: MTBF and BER for C Temperature Grade with New Mask Revision Silicon

MTBF (seconds)

BER

Data Rate (Mbps)

Bit Period (pS)

-3C

-2C

-3C

-2C

750

1333

Not Applicable

5.0 x 1023

Not Applicable

2.7 x 10-33

800

1250

Not Applicable

1.5 x 1020

Not Applicable

8.3 x 10-30

950

1053

5.0 x 1019

5.0 x 1012

2.1 x 10-29

2.1 x 10-22

1050

952

4.0 x 1014

4.0 x 106

2.4 x 10-24

2.4 x 10-18

1080

926

1.0 x 1013

2.5 x 107

9.3 x 10-23

3.7 x 10-17

Linked Answer Records

Master Answer Records

Answer Number Answer Title Version Found Version Resolved
34856 Design Advisory Master Answer Record for Spartan-6 FPGA N/A N/A

Associated Answer Records

AR# 41083
Date Created 04/14/2011
Last Updated 02/19/2013
Status Active
Type Design Advisory
Devices
  • Spartan-6 LX
  • Spartan-6 LXT
  • Spartan-6Q