AT43USB326-AC

Overview

The AT43USB326 is an 8-bit microcontroller based on the AVR RISC architecture, featuring a 16 KB masked ROM program memory and 512 bytes of data SRAM. It integrates a USB hub with one attached function and two external ports, alongside a USB keyboard controller with three programmable endpoints. The device operates at 5V with an internal 3.3V supply, utilizing a 6 MHz oscillator and on-chip PLL to generate a 12 MHz system clock. Key peripherals include a single 8-bit timer/counter, watchdog timer, and support for an 18x8 keyboard matrix via dedicated I/O ports.

Feature Summary

• AVR 8-bit RISC core with 83 ns instruction cycle time and up to 12 MIPS throughput
• Integrated USB Hub (3 ports) and USB Keyboard Function with 3 programmable endpoints
• 16 KB Program Memory (Masked ROM) and 512 Bytes Data SRAM
• Support for 18x8 Keyboard Matrix with pull-up resistors and 4 LED driver outputs

Applications

• Multimedia USB keyboards
• USB hub devices with embedded functions
• Programmable keyboard controllers

Procurement Notes

Verify the specific ordering suffix against official Microchip documentation to confirm package type and temperature range. Ensure compatibility with existing firmware, as the program memory is mask-programmed ROM. Confirm that the 48-lead LQFP package fits the target PCB footprint and thermal requirements.

Selection Notes

Select this component when a combined USB hub and keyboard controller is required in a single chip. It is suitable for applications needing an 18-key matrix interface and direct LED driving capabilities. Consider the 5V operation and internal 3.3V generation if external voltage regulation is undesirable. Note that the absence of EEPROM and UART limits general-purpose I/O flexibility compared to standard AVR models.

Part Context

This device belongs to the AT43USB series of USB microcontrollers from Microchip Technology (formerly Atmel). It is derived from the AVR megaAVR family but is specialized with integrated USB hardware. Unlike general-purpose AVRs, it lacks UART, SPI, and EEPROM, focusing instead on USB connectivity and keyboard scanning logic.

Replacement Considerations

Direct pin-to-pin replacements are limited due to the specialized USB hub and keyboard controller integration. Verify functional equivalence of the USB stack and keyboard matrix handling if substituting with other AVR-based USB controllers. Check for availability of equivalent mask-ROM programming services.