TDA8024T datasheet(11/29 Pages) PHILIPS

11 / 29 page

2004 July 12

Philips Semiconductors

Product speciﬁcation

IC card interface

TDA8024

8.5

Inactive mode

After a Power-on reset, the circuit enters the inactive

mode. A minimum number of circuits are active while

waiting for the microcontroller to start a session:

• All card contacts are inactive (approximately 200 Ω to

GND)

• Pins I/OUC, AUX1UC and AUX2UC are in the

high-impedance state (11 k

Ω pull-up resistor to VDD)

• Voltage generators are stopped

• XTAL oscillator is running

• Voltage supervisor is active

• The internal oscillator is running at its low frequency.

8.6

Activation sequence

After power-on and after the internal pulse width delay, the

system microcontroller can check the presence of a card

using the signals OFF and CMDVCC as shown in Table 2.

Table 2

Card presence indication

If the card is in the reader (this is the case if PRES or

PRES is active), the system microcontroller can start a

card session by pulling CMDVCC LOW. The following

sequence then occurs (see Fig.6):

1. CMDVCC is pulled LOW and the internal oscillator

changes to its high frequency (t0).

2. The voltage doubler is started (between t0 and t1).

3. VCC rises from 0 to 5 V (or 3 V) with a controlled slope

(t2 =t1 + 1.5 × T) where T is 64 times the period of the

internal oscillator (approximately 25

µs).

4. I/O, AUX1 and AUX2 are enabled (t3 =t1 + 4T) (these

were pulled LOW until this moment).

5. CLK is applied to the C3 contact of the card reader (t4).

6. RST is enabled (t5 =t1 + 7T).

The clock may be applied to the card using the following

sequence:

1. Set RSTIN HIGH.

2. Set CMDVCC LOW.

3. Reset RSTIN LOW between t3 and t5; CLK will start at

this moment.

4. RST remains LOW until t5, when RST is enabled to be

the copy of RSTIN.

5. After t5, RSTIN has no further affect on CLK; this

allows a precise count of CLK pulses before toggling

RST.

If the applied clock is not needed, then CMDVCC may be

set LOW with RSTIN LOW. In this case, CLK will start at t3

(minimum 200 ns after the transition on I/O), and after t5,

RSTIN may be set HIGH in order to obtain an Answer To

Request (ATR) from the card.

Activation should not be performed with RSTIN held

permanently HIGH.

(2)

(1)

t (ns)

(V)

(mA)

FCE661

Fig.6

I/O, AUX1 and AUX2 output voltage and

current as functions of time during a

LOW-to-HIGH transition.

(1) Current.

(2) Voltage.

OFF

CMDVCC

INDICATION

HIGH

card present

LOW

HIGH

card not present

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