ST8024 Analog interface for asynchronous
3V and 5V smart cards

ST8024 Product Page The ST8024 is a complete, cost effective anaIog interface for asynchronous 3V and 5V smart cards. It is used as a level adapter between the card and the microcontroller. Since very few external components are required to perform all supply, protection and control functions, the system cost is greatly reduced while the reliability is improved.

Smart card readers for set-top boxes; IC card readers for banking;

Identification; Electronic payment.

Designed to be compatible with the NDS conditional access systems;
3 or 5V supply for the IC;
Step-up converter for Vcc generation;
3 specifically protected half duplex bi-directional buffered I/O lines;
Automatic activation and deactivation sequences;
Thermal and short-circuit protection on all card contacts;
26MHz integrated crystal oscillator;
Clock generation for the card up to 20MHz with synchronous frequency changes;
Supply supervisor for spike-killing during power-on and off and power-on reset;
Threshold fixed internally or externally by a resistor bridge;
Enhanced ESD protection on card side;
Built-in debounce on card presence contact;
ISO7816-3 compatible;
SO-28 and TSSOP28 packages.

The supply voltage (VDD) should be in the range of 2.7 to 6.5V. Integrated in the ST8024 is a DC/DC converter powered by VDDP. This supply voltage provides the VCC for 5 or 3V cards.
The DC/DC converter works as a voltage doubler or follower according to the respective values of VCC and VDDP. A voltage supervisor block maintains the IC in the inactive mode during powering-up or powering-down of VDD.

ST8024 block diagram

Functional Description

After power-on reset, the microcontroller checks the presence of the card. If present, the microcontroller may start a card session. When the activation sequence is complete, the ST8024 will be in the active state. Data is exchanged between the card and the microcontroller via the I/O lines. As a session is finished the circuit carries out an automatic deactivation sequence and ends in the inactive state. The ST8024 is designed to monitor potentially dangerous fault conditions: over temperature, short circuit or a card extraction, then as soon as the fault is detected, an emergency deactivation is automatically performed.

Ordering Codes

P/N	Temp. range	Package
ST8024CD	0 to 70°C	SO-28
ST8024CDR	0 to 70°C	SO-28
ST8024CTR	0 to 70°C	TSSOP28