TDA8029C2 datasheet(46/58 Pages) PHILIPS

46 / 58 page

2003 Oct 30

Philips Semiconductors

Product speciﬁcation

Low power single card reader

TDA8029

8.17

Deactivation sequence

When the session is completed, the microcontroller resets

bit START (t10). The circuit then executes an automatic

deactivation sequence shown in Fig.13:

• Card reset (pin RST falls LOW) (t11)

• Clock (pin CLK) is stopped LOW (t12)

• Pin I/O falls to 0 V (t13)

• VCC falls to 0 V with typical 0.17 V/µs slew rate (t14)

• The DC/DC converter is stopped and CLK, RST, VCC

and I/O become low impedance to GNDC (t15).

t11 =t10 + 3/64T, t12 =t11 + 1/2T, t13 =t11 +T,

t14 =t11 + 3/2T, t15 =t11 + 7/2T.

tde is the time that VCC needs for going down to less than

0.4 V.

Automatic emergency deactivation is performed in the

following cases:

• Withdrawal of the card (PRES LOW)

• Overcurrent detection on VCC (bit PRTL1 set)

• Overcurrent detection on RST (bit PRTL1 set)

• Overheating (bit PTL set)

• Supply too low (bit SUPL set)

• RESET pin active HIGH.

If the reason of the deactivation is a card take off, an

overcurrent or an overheating, then INT0_N is LOW. The

corresponding bit in the hardware status register is set. Bit

START is automatically reset.

If the reason is a supply dropout, then the deactivation

sequence occurs, and a complete reset of the chip is

performed. When the supply will be OK again, then the bit

SUPL will be set in HSR.

handbook, full pagewidth

START

VUP

VCC

I/O

CLK

RST

t10

t12

t13

tde

t14

t15

t11

FCE685

Fig.13 Deactivation sequence.

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