ST8034C datasheet(31/39 Pages) STMICROELECTRONICS

31 / 39 page

Functional description

ST8034T, ST8034AT, ST8034P, ST8034C

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DocID024587 Rev 4

If the CMDVCC pin is high for more than 15 ms but less than 30 ms

(15 ms < tW_VCC < 30 ms), the CMDVCC pin must be set low for t1 (200 s < t1 < 700 s)

and then high for t2 (200 s < t2 < 15 ms) before going low:

Figure 18. Card activation to VCC = 3 V, tW_VCC >15 ms

If the CMDVCC pin is high for more than 30 ms (card inactive), and if the card needs to be

activated at 3 V, the sequence shown in Figure 18 applies: the CMDVCC pin must be set

low for t1 (200 s < t1 < 700 s) and then high for t2 (200 s < t2 < 15 ms) before going low.

6.10.2

Card supply (VCC) selection by tristate VCC_SEL pin (ST8034P only)

For the ST8034P device, a 1.8 V card supply feature was added and all the 5 V, 3 V or 1.8 V

card supply (VCC) levels are pin-selectable by the single VCC_SEL input pin which works in

a tristate mode, see Table 14. To define a logic level in the case of the “left-floating” state, an

internal resistor divider (285 + 285 k

) between VDD(INTF) and GND is implemented on this

pin. The VCC voltage value should not be increased in active mode, as this could cause an

overcurrent condition and deactivation due to an attempt to step change the voltage on the

CVCC capacitor.

6.11

Chip select (ST8034C only)

The chip select (CS) input is active high, meaning normal operation when the CS input is in

logic high state. When the CS pin goes low, the status of the ST8034C device is frozen

(i.e. the status of control inputs RSTIN and CMDVCC is latched) and the I/OUC pin on the

microcontroller interface goes into a high impedance mode (with pull-up resistor to

VDD(INTF)), not transferring any data to or from the card. The OFF output pin also goes into

a high impedance mode. This allows the microcontroller interface pins to be shared among

multiple smartcard interfaces connected in parallel. The status and all the ST8034C device

functions (including the card) are maintained for immediate use when the CS goes high

again. For this reason CLKIN clock input is not affected by the chip select, the clock is

provided to the ST8034C device and to the card even when the CS is low.

Table 14. ST8034P VCC selection

VCC_SEL pin level

VCC output (card supply) voltage [V]

High

Low

Floating

1.8

ST8034C Datasheet(PDF) 31 Page - STMicroelectronics