AN1978 STMicroelectronics, AN1978 Datasheet - Page 2

• Manufacturer Part Number: AN1978
• Description: ST8004: SMART CARD INTERFACE
• Manufacturer: STMicroelectronics

AN1978 - APPLICATION NOTE
2. SEQUENCER
Core of the ST8004 is the sequencer (shown in figure 1) that must coordinate the enable signals for the
activation and deactivation sequence and check for possible fault conditions. This because the smart
card is basically a microcontroller and needs to be activated/deactivated by a correct sequence as
required by the ISO/IEC7816 standard.
Figure 2 and figure 3 show respectively the ST8004 activation and deactivation sequences.
Figure 2: Activation sequence
As shown in figure 2, when the PRES condition is true (PRES = low or PRES = high) and CMDVCC goes
low, the activation sequence starts; the first block to be enabled is the step-up converter (V
), while the
UP
last enabled signal is the RST that allows the start of the card software.
Figure 3 shows the deactivation sequence when the CMDVCC goes high. During the deactivation the I/O
outputs are deactivated at the time t13 being forced into a three-state condition, following the Vcc slope
(see CH 1 in figure 3).
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