The **AT83C26-RKTUL** is a high-performance smart card reader interface IC manufactured by Microchip (formerly Atmel). It is specifically designed to manage the communication and power supply requirements between a microcontroller and a smart card (ISO 7816). --- ## 1. Key Specifications and Features The device acts as an interface level shifter and power manager. Below are the primary technical specifications: | Feature | Specification | | :--- | :--- | | **Supply Voltage (Vcc)** | 2.7V to 5.5V | | **Smart Card Voltages** | 1.8V, 3V, 5V (Class A, B, and C) | | **Interface** | Two-wire serial interface (I2C Compatible) | | **Package Type** | VQFN-28 (Lead-free/ROHS) | | **Operating Temp** | -40°C to +85°C | | **Clock Frequency** | Up to 20 MHz | --- ## 2. Main Functional Components The AT83C26 integrates several critical electronic sections into a single chip: ### A. Voltage Regulator (LDO) It features a built-in Low Dropout Regulator that converts the system voltage to the specific voltage required by the smart card (1.8V, 3V, or 5V). This eliminates the need for external DC-DC converters. ### B. Level Shifters Since the host microcontroller might operate at 3.3V while the smart card operates at 5V, the AT83C26 handles the bidirectional level shifting for data lines (I/O), Reset (RST), and Clock (CLK). ### C. ESD Protection & Safety * **ESD Protection:** Built-in protection exceeding 6kV on card-side pins. * **Short Circuit Protection:** Protects the system if the card pins are shorted. * **Thermal Protection:** Shuts down the device if it overheats. ### D. Card Detection Logic It includes a dedicated input to monitor the "Card Presence" switch. It can generate an interrupt to the host controller when a card is inserted or removed. --- ## 3. Pinout Overview (VQFN-28) | Pin Category | Pins | Description | | :--- | :--- | :--- | | **Host Interface** | SDA, SCL, INT | I2C communication and Interrupt signal to MCU. | | **Card Interface** | C-I/O, C-RST, C-CLK, C-VCC | Direct connections to the Smart Card contacts. | | **Power** | VCC, GND | Main power supply pins. | | **Detection** | PRES, PRES_N | Contacts for the mechanical card presence switch. | --- ## 4. Typical Applications The AT83C26-RKTUL is commonly found in electronic devices that require secure identity or payment processing: * **POS Terminals:** Credit and debit card readers. * **Set-top Boxes:** For conditional access cards (Pay-TV). * **Identification:** ID card readers for government or corporate security. * **Computer Peripherals:** USB smart card readers.