AN2646 datasheet(13/43 Pages) STMICROELECTRONICS

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AN2646 - Application note

ISO 7816-3 – electronic signal and transmission protocol

13/43

For external clock cards:

initial etu = 372/fi s

work etu = (1/D)*(F/fs) s

The minimum value of fs must be 1 MHz.

The maximum value of fs is given in Table 4.

I and P define the active state on VPP.

●

Maximum programming current: Ipp = 1 mA

●

Programming voltage : Vpp = P.V

N is an extra guardtime requested by the card. Before receiving the next character, the card

requires a delay of at least (12+N) etu from the leading edge of the previous character. No

extra guardtime is used to send characters from the card to the interface device.

The default values of these parameters are:

F = 372; D = 1; I = 50; P = 5; N = 0

Integer values represent the number of global interface bytes

The global interface bytes, TA1, TB1, TC1, TB2 contain integer values FI,DI, II, PI1, N and

PI2 which either directly contain or are used to compute the values of the parameters F, D, I,

P, N presented above.

TA1 codes FI over the most significant half byte (b8 to b5) and DI over the least significant

half byte (b4 to b1).

TB1 codes II over bits b7 and b6, and PI1 over the 5 least significant bits b5 to b1. The most

significant bit b8 has a value of 0.

Note:

The interface device may ignore bit b8 of TB1.

TC1 codes N over the eight bits (b8 to b1).

TB2 codes PI2 over the eight bits (b8 to b1).

RFU : Reserved for Future Use

Table 4.

Clock rate conversion factor F

Values

0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111

372

558

774

1116 1488 1860 RFU RFU

512

768

1024 1536 2048 RFU RFU

Freq

max

7.5

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