Datasheet

2004 July 12 13
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 V
PP
(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 (t
10
).
2. CLK is held LOW (t
12
=t
10
+ 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 (t
13
=t
10
+ T).
4. V
CC
starts to fall towards zero (t
14
=t
10
+ 1.5 × T).
5. The deactivation sequence is complete at t
de
, when
V
CC
reaches its inactive state.
6. V
UP
falls to zero (t
15
=t
10
+ 5T) and all card contacts
become low-impedance to GND; I/OUC, AUX1UC and
AUX2UC remain at V
DD
(pulled-up via a 11 kΩ
resistor).
7. The internal oscillator returns to its lower frequency.
handbook, full pagewidth
RST
CMDVCC
CLK
I/O
V
UP
V
CC
t
15
t
14
t
13
t
12
MDB056
t
de
t
10
Fig.9 Deactivation sequence.