st8024l STMicroelectronics, st8024l Datasheet - Page 22

• Manufacturer Part Number: st8024l
• Description: Smartcard Interface
• Manufacturer: STMicroelectronics

Functional description
5.9
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V
The V
65 mA (max) at 3 V, and 45 mA (max) at 1.8 V. An internal overload detector operates at
approximately 120 mA. Current samples to the detector are internally filtered, allowing
spurious current pulses up to 200 mA with a duration in the order of µs to be drawn by the
card without causing deactivation. The average current must stay below the specified
maximum current value. For reasons of V
ESR < 350 mΩ should be tied to CGND near to pin V
same ESR should be tied to CGND near card reader contact C1.
Fault detection
The following fault conditions are monitored:
Depending on the type of card-present switch within the connector (normally closed or
normally open) and on the mechanical characteristics of the switch, bouncing may occur on
the PRES signals at card insertion or withdrawal.
There is a debounce feature in the device with an 8 ms typical duration (see
When a card is inserted, output OFF goes high only at the end of the debounce time.
When the card is extracted, an automatic deactivation sequence of the card is performed on
the first true/false transition on PRES or PRES and output OFF goes low.
CC
– Short-circuit or high current on V
– Removal of a card during a transaction
– V
– Step-up converter operating out of the specified values (V
– Overheating
– There are two different cases (see
– CMDVCC high outside a card session. Output OFF is low if a card is not in the card
– CMDVCC low within a card session. Output OFF goes low when a fault condition is
CC
V
reader, and high if a card is in the reader. A voltage drop on the V
detected by the supply supervisor, this generates an internal power-on reset pulse but
does not act upon OFF. No short-circuit or overheating is detected because the card
is not powered-up.
detected. As soon as this occurs, an emergency deactivation is performed
automatically (see
may sense the OFF level again after completing the deactivation sequence. This
distinguishes between a hardware problem or a card extraction (OFF goes high again
if a card is present).
generator
DD
UP
generator has a capacity to supply up to 80 mA (max) continuously at 5 V,
too high)
dropping
Figure
Doc ID 17709 Rev 3
9). When the system controller resets CMDVCC to high it
CC
CC
Figure
voltage accuracy, a 100 nF capacitor with an
8):
CC
, and 100 nF capacitor with the
DDP
too low or current from
DD
supply is
Figure
ST8024L
8).