STMicroelectronics ST8024CTR

Overview

ST8024CTR from STMicroelectronics is a smartcard analog interface IC designed for ISO 7816-compliant 3 V and 5 V asynchronous smart cards. It integrates a 26 MHz crystal oscillator, DC-DC converter for VCC generation, three protected half-duplex I/O lines (C4/C7/C8), thermal/short-circuit protection, and automatic activation/deactivation logic. Used in set-top box readers, banking terminals, and pay-TV conditional access systems.

For engineers reviewing the ST8024CTR datasheet, ST8024CTR pinout, ST8024CTR application, or ST8024CTR equivalent, this device delivers regulated card supply (3/5 V ±5%), programmable clock division (÷1/2/4/8), ESD-hardened card-side I/O (>6 kV), and integrated debounce for card presence detection - all in a TSSOP28 package rated for -25 to +85 °C.

Technical Context

The ST8024CTR implements a dual-supply architecture: VDDP (4–6.5 V) powers an internal step-up converter generating VCC (3/5 V ±5%), while VDD (2.7–6.5 V) supplies the logic core. Its clock subsystem includes a 26 MHz integrated crystal oscillator with synchronous frequency division via CLKDIV1/CLKDIV2 pins, supporting card clocks up to 20 MHz.

Three bidirectional buffered I/O lines (I/O, AUX1, AUX2) connect directly to card contacts C7, C4, and C8, each featuring 11 kΩ pull-ups to VCC and current limiting (±15 mA). Fault handling includes filtered overload detection (~120 mA), thermal shutdown at 150 °C, and hardware-triggered deactivation on short-circuit or card removal.

Key Specifications

Pinout & Package

TSSOP28 package (4.4 mm × 9.7 mm, 0.65 mm pitch), thermally optimized with R_thJA = 50 °K/W on multilayer board.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar smartcard interface applications.

Compared with ST8024CDR, the ST8024CTR offers superior thermal performance in space-constrained layouts; versus ST8034CTR, it trades extended temperature and efficiency for cost-sensitive consumer-grade applications where -25 to +85 °C suffices.

Availability

ST8024CTR is available at Aetrix Electronics and suitable for set-top box readers, banking terminals, and pay-TV conditional access systems requiring stable component supply across multi-year production cycles.

Supply support for ST8024CTR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in microcontrollers, power management, and analog interface solutions for industrial, automotive, and consumer markets.

The ST8024 belongs to ST's smartcard interface product line, engineered specifically to simplify ISO 7816-3 compliant reader design by integrating power, clock, protection, and signal conditioning functions into a single TSSOP28 device.

FAQ

What is the maximum allowable current draw on the VCC pin, and how does overload protection respond?

The ST8024CTR limits VCC output current to 120 mA under overload conditions. When current exceeds ~90 mA, the device initiates filtered detection and triggers automatic deactivation within microseconds, asserting the OFF pin and disabling VCC, CLK, and RST outputs. Recovery requires hardware reset via CMDVCC or software reinitialization.

Can the ST8024CTR operate with an external clock instead of the internal 26 MHz oscillator?

Yes - the ST8024CTR supports external clock injection via the XTAL1 pin while leaving XTAL2 unconnected. The internal oscillator is disabled automatically when an external signal ≥2 MHz is detected. Clock division (CLKDIV1/CLKDIV2) and synchronization logic remain fully functional with external sources.

How does the 5V/3V pin select the card supply voltage, and what happens if it's left floating?

The 5V/3V pin is a logic input: driven high selects 5 V VCC regulation; driven low selects 3 V. If left floating, internal weak pull-down forces 3 V mode. This behavior ensures safe default operation but requires explicit MCU control for 5 V card support to avoid undervoltage faults.

What is the purpose of the two PRES pins (pins 9 and 10), and how should they be connected?

Pins 9 (PRES) and 10 (PRES) provide complementary card presence sensing: one active-low, one active-high. They share internal debounce circuitry and must be wired to the same mechanical switch contact. Using both enables flexible MCU interrupt configuration without external logic inversion or polling overhead.