st8004 STMicroelectronics, st8004 Datasheet - Page 18

• Manufacturer Part Number: st8004
• Description: Smartcard Interface
• Manufacturer: STMicroelectronics

Functional description
6.9
6.10
18/26
It is recommended to:
1.
2.
3.
4.
With all these layout precautions, noise should be at an acceptable level, and jitter on C3
should be less than 100ps.
Deactivation sequence
When a session is completed, the microcontroller sets the CMDV
The circuit then executes an automatic deactivation sequence by counting the sequencer
back and ends in the inactive state (see
●
●
●
●
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Fault detection
The following fault conditions are monitored by the circuit:
Short-circuit or high current on V
Removing card during transaction
V
Overheating.
There are two different cases (
1.
2.
DD
Keep track C3 as far as possible from other tracks
Have straight connection between CGND and C5 (the 2 capacitors on C1 should be
connected to this ground track)
Avoid ground loops between CGND,PGND and GND
Decoupled V
then they should be connected in star on the main track.
RST goes LOW → (t11 = t10)
CLK is stopped LOW → (t12 = t11 +½T) where T is approximately 25 µs
I/O, AUX1 and AUX2 are output into high-impedance state → (t13 = t11 +T)(10 kΩ pull-
up resistor connected to V
V
reaches its inactive state
V
GND;
I/OUC, AUX1UC and AUX2UC remain pulled up to V
dropping
CMDV
reader, and HIGH if the card is in the reader. A supply voltage drop on V
by the supply supervisor, which generates an internal power-on reset pulse, but does
not act upon OFF. The card is not powered-up, so no short-circuit or overheating is
detected.
CMDV
a short-circuit has occurred on V
high. As soon as the fault is detected, an emergency deactivation is automatically
performed (see
may sense OFF again in order to distinguish between a hardware problem or a card
extraction. If a supply voltage drop on V
an emergency deactivation will be performed and OFF goes LOW.
CC
UP
falls to zero → (t14 = t11 +½3T); the deactivation sequence is completed when V
falls to zero → (t15 = t11 +5T) and all card contacts become low-impedance to
CC
CC
LOW: (within a card session) then, OFF falls LOW if the card is extracted, or if
HIGH: (outside a card session) then, OFF is LOW if the card is not in the
DDP
Figure 8.
and V
DD
). When the system controller sets CMDV
Figure 7.
CC
separately; if the 2 supplies are the same in the application,
CC
)
CC
)
, or if the temperature on the IC has become too
Figure 6.
DD
is detected while the card is activated, then
):
DD
via a 10 kΩ resistor.
CC
line to the HIGH state.
CC
back to HIGH, it
DD
is detected
ST8004
CC