TDA8024AT datasheet(13/29 Pages) PHILIPS

13 / 29 page

2004 July 12

Philips Semiconductors

Product speciﬁcation

IC card interface

TDA8024

8.7

Active mode

When the activation sequence is completed, the TDA8024

will be in its active mode. Data is exchanged between the

card and the microcontroller via the I/O lines. The

TDA8024 is designed for cards without VPP (the voltage

required to program or erase the internal non-volatile

memory).

8.8

Deactivation sequence

When a session is completed, the microcontroller sets the

CMDVCC line HIGH. The circuit then executes an

automatic deactivation sequence by counting the

sequencer back and finishing in the inactive mode (see

Fig.9):

1. RST goes LOW (t10).

2. CLK is held LOW (t12 =t10 + 0.5 × T) where T is 64

times the period of the internal oscillator

(approximately 25

µs).

3. I/O, AUX1 and AUX2 are pulled LOW (t13 =t10 + T).

4. VCC starts to fall towards zero (t14 =t10 + 1.5 × T).

5. The deactivation sequence is complete at tde, when

VCC reaches its inactive state.

6. VUP falls to zero (t15 =t10 + 5T) and all card contacts

become low-impedance to GND; I/OUC, AUX1UC and

AUX2UC remain at VDD (pulled-up via a 11 kΩ

resistor).

7. The internal oscillator returns to its lower frequency.

handbook, full pagewidth

RST

CMDVCC

CLK

I/O

VUP

VCC

t15

t14

t13

t12

MDB056

tde

t10

Fig.9 Deactivation sequence.

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