2003 Nov 06

13

Philips Semiconductors

Product specification

Dual IC card interface

TDA8020HL

Deactivation sequence

When the session is completed, the microcontroller resets bit START/STOP to logic 0 (t10). The circuit then executes an

automatic deactivation sequence (see Fig.5):

1. Card reset (RST falls LOW) (t11)

2. Clock is stopped (t12)

3. I/O falls to 0 V (t13)

to CGND (t15)

6. The internal oscillator changes to its low frequency if both cards are inactive (t15).

t11 = t10 + T/64; t12 = t11 + T/2; t13 = t11 + T; t14 = t11 + 3T/2; t15 = t11 + 7T/2.

VUP

VCC

I/O

CLK

RST

handbook, full pagewidth

START/STOP

t0 t1

t2

t3

t4

t5

FCE837

ATR

Fig.4 Activation sequence.