ST8004CD Ver la hoja de datos (PDF) - STMicroelectronics

Número de pieza

componentes Descripción

fabricante

ST8004CD

SMARTCARD INTERFACE

STMicroelectronics 

Figure 6 : Emergency deactivation sequence

ST8004

Figure 7 : Definition of output transition times

FUNCTIONAL DESCRIPTION

Throughout this document it is assumed that the reader is familiar with iso7816 norm terminology

POWER SUPPLY

The supply pins for the IC are VDD and GND. VDD should be in the range of 2.7 to 6.5 V. All interface

signals with the microcontroller are referenced to VDD; therefore be sure the supply voltage of the

microcontroller is also at VDD. All card contacts remain inactive during powering up or powering down.

The sequencer is not activated until VDD reaches Vth2 +Vhys(th2) or Vth3 + Vhys(th3) when VTHSEL = GND.

When VDD falls below Vth2 or Vth3, an automatic deactivation of the contacts is performed. To generate a

5 V ±5% VCC supply to the card, an integrated voltage doubler is incorporated. This step-up converter

should be separately supplied by VDDP and PGND (from 4.5 to 6.5 V). In order to satisfy the VI(RIPPLE)(P-P)

specifications, VDDP should be from 4.75V to 5.25V. Due to large transient currents, the 2x100 nF

capacitors of the step-up converter should have an ESR of less than 100 mΩ, and be located as near as

possible to the IC. The supply voltages VDD and VDDP may be applied to the IC in any time sequence. To

get the correct deactivation of the card VDDP is allowed to turn-off only when VDD is below the

undervoltage threshold. If a voltage between 7 and 9 V is available within the application, this voltage may

11/19

Share Link: