ST8024 STMicroelectronics, ST8024 Datasheet - Page 14

• Manufacturer Part Number: ST8024
• Description: SMARTCARD INTERFACE
• Manufacturer: STMicroelectronics

ST8024
Figure 6: Activation sequence at t
3
ACTIVE MODE
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When the activation sequence is completed, the ST8024 will be in its active mode. Data are exchanged
between the card and the microcontroller via the I/O lines.
The ST8024 is designed for cards without V
(the voltage required to program or erase the internal
PP
non-volatile memory).
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.7):
1. RST goes LOW (t
).
10
2. CLK is held LOW (t
= t
+ 0.5 x T) where T is 64 times the period of the internal oscillator
12
10
(approximately 25 µs).
3. I/O, AUX1 and AUX2 are pulled LOW (t
= t
+ T).
13
10
4. V
starts to fall towards zero (t
= t
+ 1.5 x T).
CC
14
10
5. The deactivation sequence is complete at t
, when V
reaches its inactive state.
de
CC
6. V
falls to zero (t
= t
+ 5T) and all card contacts become low-impedance to GND; I/OUC, AUX1UC
UP
15
10
and AUX2UC remain at V
(pulled-up via a 11 kΩ resistor).
DD
7. The internal oscillator returns to its lower frequency.
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