NCN8025A ONSEMI [ON Semiconductor], NCN8025A Datasheet - Page 12

• Manufacturer Part Number: NCN8025A
• Description: Compact SMART CARD Interface IC
• Manufacturer: ONSEMI [ON Semiconductor]

POWER−DOWN
NCN8025 / NCN8025A runs a deactivation sequence by
setting High CMDVCC. The below power down sequence
is executed:
FAULT DETECTION
card, the NCN8025 / NCN8025A provides security features
to prevent failures or damages as depicted here after.
− Card extraction detection
− V
− Short−circuit or overload on CVCC
Interrupt Pin Management:
Low.
High position. INT is Low if no card is present in the card
connector (Normally open or normally closed type). INT is
High if a card is present. If a card is inserted (INT = High)
and if V
drops Low immediately. It switches High when V
When the communication session is completed the
In order to protect both the interface and the external smart
A card session is opened by toggling CMDVCC High to
Before a card session, CMDVCC is supposed to be in a
DD
under voltage detection
DD
CMDVCC
drops below the UVLO threshold then INT pin
CVCC
PRES
/INT
CMDVCC
CVCC
CRST
CCLK
CIO
Figure 8. Fault Detection and Interrupt Management
debounce
Figure 7. Deactivation Sequence
Powerdown resulting
of card extraction
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DD
12
− CRST is forced to Low
− CCLK is set Low 12 ms after CRST.
− CI/O, CAUX1 and CAUX2 are pulled Low
− Finally CVCC supply can be shut−off.
− DC/DC operation: the internal circuit continuously
− DC/DC operation: under−voltage detection on V
− Overheating
− Card pin current limitation: in the case of a short circuit
increases again over the UVLO limit (including hysteresis),
a card being still present.
goes Low when a fault is detected. In that case a deactivation
is immediately and automatically performed (see Figure 7).
When the microcontroller resets CMDVCC to High it can
sense the INT level again after having got completed the
deactivation.
During a card session, CMDVCC is Low and INT pin
senses the CVCC voltage (in the case of either over or
under voltage situation).
to ground. No feedback is provided to the external
MPU.
T
deact
debounce
Powerdown caused
by short−circuit
DDP