Functional description

ST8034HN, ST8034HC

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DocID024511 Rev 2

6.10

Fault detection

The fault conditions monitored by the device are:

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Card removal during transaction

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Overheating.

There are two different fault detection situations:

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Outside card session (CMDVCC pin is high): the OFF pin is low if the card is not in the

is detected by the voltage supervisor. This generates an internal power-on reset pulse

but does not act upon the OFF pin signal. The card is not powered-up and short-circuits

or overheating are not detected.



In card session (CMDVCC pin is low): when the OFF pin goes low, the fault detection

circuit triggers the automatic emergency deactivation sequence (see Figure 12).

On card insertion or removal, bouncing can occur on the card presence switch (i.e. on the

PRES signal). Therefore a debouncing feature is integrated into the ST8034 (4.5 ms

On card insertion, the OFF pin goes high after the debounce time has elapsed. When the

card is extracted, the automatic card deactivation sequence is performed on the first high to

low transition on the PRES pin. After this, the OFF pin goes low.

Figure 12. Deactivation sequence after card removal