DS8113-RNG+ datasheet(10/17 Pages) MAXIM

10 / 17 page

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) VCC 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.

Smart Card Interface

______________________________________________________________________________________

ATR

CMDVCC

RST

RSTIN

CLK

VCC

I/O

I/OIN

t0 t1

t5 = tACT

Figure 3. Activation Sequence Using RSTIN and

CMDVCC

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