DS8113_10 Datasheet, PDF (10/17 Pages) Maxim Integrated Products – Smart Card Interface

Smart Card Interface
If the card is in the reader (if PRES is active), the host
microcontroller can begin an activation sequence (start
a card session) by pulling CMDVCC low. The following
events form an activation sequence (Figure 3):
1) CMDVCC is pulled low.
2) The internal oscillator changes to high frequency (t₀).
3) The voltage generator is started (between t₀ and t₁).
4) V_CC rises from 0 to 5V, 3V, or 1.8V with a con-
trolled slope (t₂ = t₁ + 1.5 × T). T is 64 times the
internal oscillator period (approximately 25µs).
5) I/O, AUX1, and AUX2 are enabled (t₃ = t₁ + 4T)
(they were previously pulled low).
6) The CLK signal is applied to the C3 contact (t₄).
7) RST is enabled (t₅ = t₁ + 7T).
To apply the clock to the card interface:
1) Set RSTIN high.
2) Set CMDVCC low.
3) Set RSTIN low between t₃ and t₅; CLK will now start.
4) RST stays low until t₅, then RST becomes the copy
of RSTIN.
5) RSTIN has no further effect on CLK after t₅.
If the applied clock is not needed, set CMDVCC low
with RSTIN low. In this case, CLK starts at t₃ (minimum
200ns after the transition on I/O, see Figure 4); after t₅,
RSTIN can be set high to obtain an answer to request
(ATR) from an inserted smart card. Do not perform acti-
vation with RSTIN held permanently high.
Active Mode
When the activation sequence is completed, the
DS8113 card interface is in active mode. The host
microcontroller and the smart card exchange data on
the I/O lines.
CMDVCC
VCC
I/O
ATR
CLK
RSTIN
RST
I/OIN
t₀ t₁
t₂
t₃
t₄
Figure 3. Activation Sequence Using RSTIN and CMDVCC
t₅ = t_ACT
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