SB nº 97 : Minimum Value of t3 and t4 (Spec Change)

Specification Bulletin No. 97 First Edition February 2012 Minimum Value of t3 and t4 This Specification Bulletin changes the definition of the minimum value of t3 and t4

Effective Date

This specification bulletin is effective from November 2012 at which time any affected or new type approval testing will come into effect.

Applicability

This Specification Bulletin applies to:

• EMV Contactless Specifications for Payment Systems, Book D – EMV Contactless Communication Protocol Specification, Version 2.1 – March 2011.

Related Documents

• None

Description

Table A.2 defines the minimum value of t3 in terms of the minimum value of t4: t3 = 1.5 x t4. Knowing that there is an uncertainty associated with the measurement of the t4 timing, there is also an uncertainty associated with assignment of the minimum limit for the t3 timing. Due to the multiplication factor in the limit, the uncertainty of the t3 timing measurement is 1.5 times the uncertainty of the t4 measurement. This together with the small timing values of t3 and t4 leads to a disproportionate risk that measurements will fail good readers. To avoid the multiplication factor, this specification bulletin changes the definition of the minimum value of t3 and t4 by defining t4 in terms of t3.

Specification Change Change minimum value for t3 and t4 in Table A.2 as follows: Table A.2—RF Power and Signal Interface Topic Modulation PCD→PICC (Type A) Parameter... t3 t4... Value Min 1.5 x t4 0 0 Max 1.18 min(0.44, t3 / 1.5) Units µs µs Change minimum value for tS,3 and tS,4 in Table A.4 as follows: Table A.4—Set-up Values for EMV Contactless Level 1 Test Equipment Topic Modulation PCD→PICC (Type A) Parameter... tS,3 tS,4 Min Nom 1.5 x tS,4..0 0 Max Unit 1.25 µs min(0.52, tS,3 / 1.45) µs