ATMEGA8U2-AU - 16MHz 8-bit AVR USB MCU 8KB Flash TQFP-32
MPN： ATMEGA8U2-AU ✓ 啟用中ATMEGA8U2-AU 概覽
An AVR (Advanced Virtual RISC) microcontroller is a family of 8-bit RISC cores from Microchip (formerly Atmel) featuring single-cycle instruction execution, a large register file, and Harvard architecture with separate program and data buses. The ATmega family sits at the top of the AVR 8-bit hierarchy, between the ATtiny series (smaller pin counts, less memory) and the AVR XMEGA family (higher performance, 16-bit peripherals). The USB-enabled U2 sub-family adds a built-in full-speed USB transceiver and dedicated endpoint RAM, making these parts the go-to choice for HID, CDC, and vendor-class USB devices where a separate FTDI or CP210x bridge would otherwise be required.
Key features of the ATMEGA8U2-AU include hardware USB Full-Speed (12 Mbps) with on-chip transceiver and 176 bytes of dedicated endpoint RAM; 8KB Flash with read-while-write support for bootloader updates; 512B EEPROM and 512B SRAM; six PWM channels, 10-bit ADC, two USARTs (one shared with USB), SPI, and TWI (I2C) peripherals; programmable watchdog timer with internal oscillator; and full -40C to +85C industrial operating range. The TQFP-32 (7x7 mm, 0.8 mm pitch) package is hand-solderable and easy to prototype on TQFP adapter boards.
The ATmega8U2 uses a 2-stage pipelined Harvard architecture with 130 instructions, most executing in a single clock cycle at 16 MHz (16 MIPS peak). The on-chip PLL-less USB transceiver uses a 48 MHz internal PLL referenced from an external 8 MHz crystal with specific loading requirements, and the core clock can be derived from the same crystal or the internal 8 MHz RC oscillator. The boot loader section is lockable and can self-program the application Flash via USB, HID, or UART, enabling field-upgradeable firmware without an external programmer.
Typical applications include USB HID peripherals (keyboards, mice, game controllers), USB CDC virtual COM ports replacing external bridges, Arduino Uno and Mega 2560 USB interface MCU (this is the original 8U2 used on those boards before the 16U2 update), MIDI USB adapters, and industrial USB sensor nodes. The 16 MIPS performance and USB 2.0 Full-Speed compliance cover most low-bandwidth USB device classes.
When designing with the ATMEGA8U2-AU, ensure the USB D+/D- traces are 90-ohm differential and length-matched, place the 22 ohm series termination resistors close to the MCU pins, and use a crystal that meets the USB-clock accuracy spec. For bus-powered designs, the internal 3.3V regulator can supply up to 50 mA to external circuitry; for higher loads, use an external LDO.
This page synthesizes distributor pricing, drop-in same-package alternatives (notably the higher-flash ATMEGA32U2-AU), and practical design notes not found in the manufacturer datasheet alone, so engineers can pick the right U2 part number and source it without redesigning their PCB.
直接替換替代品，適用於 ATMEGA8U2-AU — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： ATMEGA8U2-AU （相同外形與佔位） — 差異在於 Package, Timers/Counters, EEPROM, RoHS Status, SRAM.
ATMEGA32U2-AU
✅ 直接替換聯絡詢價
查看資料表 →ATMEGA16U2-AU
✅ 直接替換聯絡詢價
查看資料表 →ATMEGA8U2-AUR
✅ 直接替換📋 參考替代品（不在目錄中）
AT90USB82-16AU
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
ATMEGA8U2-MUR
✅ 直接替換聯絡詢價
查看資料表 →ATMEGA8U2-AU 最大額定值與電氣特性
| Core Architecture | 8-bit AVR RISC |
| Program Memory (Flash) | 8 KB (4K x 16) |
| EEPROM | 512 B |
| SRAM | 512 B |
| Maximum CPU Speed | 16 MHz (16 MIPS) |
| Supply Voltage (Vcc) | 2.7 V to 5.5 V |
| USB Interface | USB 2.0 Full-Speed (12 Mbps), on-chip transceiver |
| General-Purpose I/O | 22 lines |
| Timers/Counters | Two 16-bit, plus watchdog |
| PWM Channels | 6 |
| ADC | 10-bit |
| Communication Peripherals | USB, USART/UART, SPI, TWI (I2C) |
| 工作溫度 | -40 C to +85 C |
| 封裝 | 32-pin TQFP (7x7 mm, 0.8 mm pitch) |
| 安裝類型 | Surface Mount |
| MSL 等級 | 3 (168 hours) |
| RoHS 狀態 | Compliant |
| Lead-Free | Yes |
ATMEGA8U2-AU 腳位配置
| 腳位 1 | PC2 — Port C bit 2 / I/O |
| 腳位 2 | USBVCC — USB transceiver supply (3.3 V internal or external) |
| 腳位 3 | UCAP — USB 3.3 V regulator output capacitor |
| 腳位 4 | VCC — Digital supply voltage |
| 腳位 5 | GND — Ground |
| 腳位 6 | AVCC — Analog supply voltage |
| 腳位 7 | PC4 — Port C bit 4 / I/O |
| 腳位 8 | PC5 — Port C bit 5 / I/O |
| 腳位 9 | PB0 — Port B bit 0 / I/O |
| 腳位 10 | PB1 — Port B bit 1 / I/O |
| 腳位 11 | PB2 — Port B bit 2 / I/O / PDI (program/debug data) |
| 腳位 12 | PB3 — Port B bit 3 / I/O / PDO (program/debug data) |
| 腳位 13 | PB4 — Port B bit 4 / I/O |
| 腳位 14 | PB5 — Port B bit 5 / I/O |
| 腳位 15 | PB6 — Port B bit 6 / I/O |
| 腳位 16 | PB7 — Port B bit 7 / I/O |
| 腳位 17 | PC1 — Port C bit 1 / I/O |
| 腳位 18 | PC0 — Port C bit 0 / I/O |
| 腳位 19 | RESET — Reset (active low, internal pull-up) |
| 腳位 20 | VCC — Digital supply voltage |
| 腳位 21 | GND — Ground |
| 腳位 22 | XTAL2 — Crystal pin 2 (8 MHz) |
| 腳位 23 | XTAL1 — Crystal pin 1 (8 MHz) or external clock |
| 腳位 24 | D- — USB data minus |
| 腳位 25 | D+ — USB data plus |
| 腳位 26 | UVCC — USB 5 V supply (Vbus sense) |
| 腳位 27 | PD0 — Port D bit 0 / I/O |
| 腳位 28 | PD1 — Port D bit 1 / I/O |
| 腳位 29 | PD2 — Port D bit 2 / I/O |
| 腳位 30 | PD3 — Port D bit 3 / I/O |
| 腳位 31 | PD4 — Port D bit 4 / I/O |
| 腳位 32 | PD5 — Port D bit 5 / I/O |
典型應用
ATMEGA8U2-AU 適用於 6 應用s: Arduino Uno / Mega USB Interface MCU, USB HID Peripherals (Keyboard / Mouse / Custom), USB CDC Virtual COM Port Adapter, USB MIDI Adapter / Music Controller, Industrial USB Sensor Node, DFU-Programmable USB Dongle.
Arduino Uno / Mega USB Interface MCU
The ATMEGA8U2-AU is the original USB 2.0 Full-Speed interface MCU used on the Arduino Uno R2/R3 and Mega 2560 R3 boards, replacing the earlier FTDI bridge. With 16 MIPS at 16 MHz and an on-chip USB transceiver, it handles USB-to-UART conversion and is reprogrammable as a HID, MIDI, or CDC device without changing the hardware. The 8 KB Flash is sufficient for the Arduino USB DFU bootloader and the CDC-ACM stack, while the 22 GPIO (with 5V tolerance) interface cleanly with the ATmega328P main processor over UART. Choose the ATMEGA32U2-AU instead if you need more Flash for a richer HID/USB stack on the same footprint.
推薦
USB HID Peripherals (Keyboard / Mouse / Custom)
The ATMEGA8U2-AU's on-chip USB 2.0 Full-Speed transceiver and 176 bytes of dedicated endpoint RAM make it ideal for low-cost USB HID peripherals such as keyboards, mice, game controllers, and custom HID input devices. The 16 MIPS core can scan key matrices at high rates and process USB HID reports with sub-millisecond latency, while the 22 GPIO are enough to drive 8x8 keypad or 22 individual switch inputs directly. The 8 KB Flash holds the LUFA HID stack or custom HID descriptors with room to spare. Compared to designs that pair a generic MCU with an external CP2102/FT232 bridge, the 8U2 saves BOM cost and PCB area while still presenting itself as a standard HID device to the host.
推薦
USB CDC Virtual COM Port Adapter
The ATMEGA8U2-AU can act as a USB 2.0 Full-Speed CDC-ACM virtual COM port without any external bridge IC, communicating with the host as a standard /dev/ttyACMx device on Linux or COMx on Windows. The 8 KB Flash comfortably fits the LUFA CDC stack or the V-USB-derived CDC firmware, and the 512 B SRAM is enough for the endpoint buffers and a small UART ring. Compared to commercial CP2102N or FT232 bridges, the 8U2 offers user-reprogrammable firmware for custom baud rates, line-discipline tweaks, and vendor-class escapes - at the cost of having to certify a USB VID/PID or use Microchip's free VID. The 22 GPIO also allow the part to act as a CDC device with extra GPIO for control lines.
推薦
USB MIDI Adapter / Music Controller
The ATMEGA8U2-AU's USB 2.0 Full-Speed and 16 MIPS performance are well matched to USB MIDI 1.0 device implementations, with the 8 KB Flash holding the LUFA MIDI stack and a 22-GPIO interface for buttons, encoders, and LEDs on a custom MIDI controller. The part's 3.3 V internal regulator can supply a small LED matrix or a few indicator LEDs without an external LDO, and the six PWM channels support dimming or RGB-LED driving. The industrial -40C to +85C operating range means the 8U2 will work in studio and stage environments equally well. For more elaborate MIDI controllers, the ATMEGA32U2-AU upgrade quadruples the Flash without changing the PCB.
推薦
Industrial USB Sensor Node
The ATMEGA8U2-AU can act as a small industrial USB sensor node, sampling a sensor over ADC or I2C/SPI and presenting the readings over USB CDC or vendor-class. The 10-bit ADC (6 channels on the TQFP-32 package) reads analog sensors directly, the TWI port interfaces to common digital sensors, and the 16 MIPS CPU runs the USB stack plus lightweight signal conditioning. The 2.7-5.5 V supply and -40C to +85C industrial operating range support 3.3 V and 5 V industrial buses. The integrated USB also enables in-field firmware upgrades over the same USB port that supplies the readings, eliminating the need for a separate bootloader connector.
推薦
DFU-Programmable USB Dongle
The ATMEGA8U2-AU supports a hardware USB DFU (Device Firmware Upgrade) bootloader that can reflash the application Flash over USB without an external ISP or JTAG programmer, making it a low-cost platform for USB software distribution keys, debug bridges, and reprogrammable test fixtures. The 8 KB Flash and 512 B SRAM fit a small USB vendor-class application plus a DFU bootloader, and the 16 MIPS allows real-time data exchange while a new firmware image is being downloaded. The industrial operating range and lead-free RoHS package suit long-life industrial products. The same TQFP-32 footprint also supports the ATMEGA32U2-AU, enabling field-upgrade to larger firmware images without PCB change.
推薦
推薦產品摘要
工程參考資料，適用於 ATMEGA8U2-AU — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | ATMEGA32U2-AU | ATMEGA16U2-AU | ATMEGA8U2-AUR | AT90USB82-16AU | ATMEGA8U2-MU |
|---|---|---|---|---|---|---|
| Package | 32-pin TQFP (7x7 mm) | 32-pin TQFP (7x7 mm) - same | 32-pin TQFP (7x7 mm) - same | 32-pin TQFP (7x7 mm) - same | 32-pin TQFP (7x7 mm) - same | 32-pin QFN (5x5 mm) - same pin count, smaller package |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash | 8 KB | 32 KB | 16 KB | 8 KB | 8 KB | 8 KB |
| SRAM | 512 B | 1 KB | 512 B | 512 B | 512 B | 512 B |
| EEPROM | 512 B | 1 KB | 512 B | 512 B | 512 B | 512 B |
| Max CPU Speed | 16 MHz / 16 MIPS | 16 MHz / 16 MIPS | 16 MHz / 16 MIPS | 16 MHz / 16 MIPS | 16 MHz / 16 MIPS | 16 MHz / 16 MIPS |
| USB Interface | Full-Speed, on-chip transceiver | Full-Speed, on-chip transceiver | Full-Speed, on-chip transceiver | Full-Speed, on-chip transceiver | Full-Speed, on-chip transceiver | Full-Speed, on-chip transceiver |
| GPIO | 22 | 22 | 22 | 22 | 22 | 22 |
| ADC | 10-bit | 10-bit | 10-bit | 10-bit | No ADC (USB-only) | 10-bit |
| Packaging Format | Tray | Tray | Tray | Tape & Reel | Tray | Tray |
主要差異化特點
- Highest-Flash in same TQFP-32 footprint with same USB register set (對比ATMEGA8U2-AU (vs ATMEGA32U2-AU))
- On-chip USB Full-Speed transceiver eliminates external bridge IC (對比ATMEGA8U2-AU (vs ATMEGA8A-AU))
- 16 MIPS single-cycle execution with predictable interrupt latency (對比ATMEGA8U2-AU (vs AT90USB82-16AU))
設計說明
Route the USB D+ and D- traces as a 90-ohm differential pair with length matching within 150 mil. Place the two 22-ohm series termination resistors within 1 inch of the MCU pins on D+ and D-. Keep the traces away from high-frequency switching nodes and provide a clean ground return directly under the differential pair. The crystal traces should be short and symmetric with the load capacitors placed adjacent to the crystal pins.
The ATMEGA8U2-AU requires an external 8 MHz crystal (not the internal RC oscillator) for USB operation because the internal 48 MHz USB PLL needs a 7.819 MHz reference per USB spec. Standard 8 MHz crystals with 20 pF load typically work but verify the part's crystal-accuracy requirement (300 ppm over USB signaling). Do not omit the UCAP 4.7 uF decoupling capacitor on pin 3, and do not connect USBVCC directly to a noisy rail; let the internal 3.3 V regulator drive it via the UCAP pin.
Estimated: at VCC=5 V, running 16 MHz CPU and active USB Full-Speed, the ATMEGA8U2-AU draws approximately 18-22 mA core current plus up to 50 mA for the internal 3.3 V regulator driving VCC-derived loads. For self-powered designs, add a Torex XC6206 or Microchip MCP1700 3.3 V LDO for external sensors and decoupling. The MCU's internal 3.3 V regulator is not designed to source more than 50 mA; exceeding this will trigger the regulator's current limit and may cause brownouts on the USB transceiver.
The USB Full-Speed edge rates are 8-12 ns and the bus can emit 1.5 GHz-bandwidth noise on the VCC rail. Decouple VCC with a 100 nF X7R as close as possible to pins 4 and 20, plus a bulk 4.7 uF X5R tantalum or ceramic on the same node. Place a ferrite bead (600-1000 ohm at 100 MHz) on the Vbus sense line if the design is bus-powered, to keep upstream USB-bus noise from the analog AVCC pin. AVCC should be tied to VCC through an LC filter (10 ohm + 100 nF) to keep ADC sampling clean.
合規資訊
RoHS and REACH compliant per Microchip product page; lead-free matte-tin plating; not AEC-Q100 qualified (industrial -40C to +85C grade only).
