ATMEGA8U2-MUR - 8KB Flash 16MHz AVR USB MCU | Microchip
MPN: ATMEGA8U2-MUR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.85 | $2.85 |
| 10 | $2.61 | $26.10 |
| 100 | $2.32 | $232.00 |
| 500 | $2.12 | $1,060.00 |
| 1,000 | $1.94 | $1,940.00 |
ATMEGA8U2-MUR Overview
A microcontroller (MCU) is a single integrated circuit that combines a processor core, memory, and programmable peripherals into one chip, forming the lowest tier of the embedded systems hierarchy: MCU -> embedded processor -> microprocessor-based system. The ATmega8U2 belongs to the AVR 8-bit RISC family, originally developed by Atmel and now manufactured by Microchip Technology following the 2016 acquisition.
Key features include an Advanced RISC architecture with 125 powerful instructions, most executed in a single clock cycle; an on-chip USB controller supporting full-speed 12 Mbps operation; SPI, USART, and USB connectivity options; two flexible timer/counters with compare modes and PWM; and a programmable watchdog timer. The read-while-write Flash capability allows in-system self-programming for field firmware updates.
The AVR core executes from an 8KB (4K x 16) Flash array while the built-in USB bootloader enables firmware loading without an external programmer in many designs. Operation spans the industrial temperature range, and the VQFN exposed-pad package provides good thermal and electrical performance for space-constrained designs.
Typical applications include USB-to-serial bridge conversion (the ATmega8U2 famously serves as the USB interface chip on Arduino UNO boards), USB HID devices such as keyboards and game controllers, embedded industrial control, and consumer peripherals requiring a low-cost USB-capable MCU.
Design consideration: the 8KB Flash and 512B SRAM impose tight budget constraints; use the USB bootloader judiciously and monitor RAM usage for USB endpoint buffers to avoid stack overflow in firmware.
This page synthesizes distributor pricing, drop-in alternatives, pinout guidance, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA8U2-MUR — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with ATMEGA8U2-MUR (same form factor and footprint) — differing in Timers/Counters, Package, RoHS Status, Connectivity, Core Architecture.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA16U2-MU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.74 / Unit
View Datasheet →ATMEGA32U2-MU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.74 / Unit
View Datasheet →ATMEGA8U2-MU
✅ Drop-In📋 Reference alternative (not in catalog)
ATMEGA8A-MUR
✅ Drop-In✓ In Stock
$0.7 / Unit
View Datasheet →ATMEGA8U2-MUR Maximum Ratings & Electrical Characteristics
| Core Processor | AVR |
| Core Size | 8-bit |
| Maximum Clock Frequency | 16 MHz |
| Program Memory Size | 8 KB (4K x 16) FLASH |
| EEPROM Size | 512 B |
| SRAM Size | 512 B |
| Connectivity | SPI, UART/USART, USB |
| Number of I/O | 22 |
| USB Controller | Full-speed USB 2.0 device |
| Timers/Counters | 2 (with compare modes and PWM) |
| Watchdog Timer | Yes (programmable) |
| Data Bus Width | 8 bit |
| Package | 32-VFQFN (5x5 mm) Exposed Pad |
| Mounting Type | Surface Mount |
| Packaging | Tape & Reel (TR) |
| RoHS Status | Compliant |
ATMEGA8U2-MUR 32-vfqfn (5x5 mm) exposed pad Pin Configuration Guide
Pin configuration for ATMEGA8U2-MUR (32-vfqfn (5x5 mm) exposed pad package). This digital IC includes GPIO, communication interfaces (UART, SPI, I2C), and power pins. Refer to the manufacturer datasheet for alternate pin functions and configuration options. Essential for embedded system design and PCB layout.
No detailed pinout data available for ATMEGA8U2-MUR.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA8U2-MUR is suitable for 6 applications: USB-to-Serial Bridge, USB HID Devices, Embedded Industrial Control, Consumer Peripherals, USB Firmware Update Bridges, Battery-Powered Portable Devices.
USB-to-Serial Bridge
The ATMEGA8U2-MUR is the classic USB-to-UART bridge: its integrated full-speed USB 2.0 device controller (12 Mbps) enumerates as a virtual COM port while its USART connects to the target MCU, exactly as deployed on the Arduino UNO. The 8KB Flash hosts the USB-serial firmware with headroom for customization, and the 16 MHz clock meets USB full-speed timing requirements without an external high-frequency oscillator solution. Because the chip supports DFU re-flashing over USB, end products can update bridge firmware in the field without opening the enclosure. Designers should allocate SRAM carefully, since only 512 bytes are available for endpoint buffers and application state.
Recommended
USB HID Devices
Keyboards, mice, game controllers, and custom HID panels benefit from the ATMEGA8U2-MUR native USB device controller, which eliminates the need for a separate USB interface chip. The AVR core at 16 MHz scans matrices and processes debounce logic with single-cycle instructions, while 22 GPIO lines cover typical key-matrix sizes. The 512B EEPROM stores calibration data and device serial numbers, and the VQFN-32 exposed-pad package suits compact handheld enclosures. HID reports are lightweight, so the 512B SRAM budget is generally adequate; the on-chip DFU bootloader allows end-user firmware customization, a feature popular in enthusiast input devices.
Recommended
Embedded Industrial Control
In industrial automation nodes, the ATMEGA8U2-MUR provides SPI and USART connectivity for sensor and actuator buses, two timer/counters with PWM for motor or heater control, and a programmable watchdog for fault recovery. The AVR RISC core executes 125 instructions mostly in one clock cycle, giving deterministic timing at 16 MHz for control loops. Its industrial-grade qualification and RoHS-compliant VQFN-32 package support automated PCB assembly in control panels. The USB controller can double as a local configuration and diagnostics port, letting technicians connect a laptop without adding a dedicated interface IC, reducing BOM cost in low-to-medium channel-count control boards.
Recommended
Consumer Peripherals
Cost-sensitive consumer products - toys, dongles, LED controllers, and accessories - use the ATMEGA8U2-MUR for direct USB attachment at a low unit price (approximately $2.85 at qty 1 as of 2026-09-19). The 8KB Flash accommodates firmware plus a USB stack, while read-while-write Flash enables in-system self-programming for factory firmware updates via the USB port alone, removing programming headers from the bill of materials. Tape & Reel packaging supports high-volume pick-and-place, and heavy distributor stock (over 44,000 pieces reported) protects against allocation. Power is drawn from the 5V VBUS with minimal external components, simplifying single-sided cost-optimized layouts.
Recommended
USB Firmware Update Bridges
Systems whose main processor lacks USB can add field-update capability with the ATMEGA8U2-MUR acting as a DFU bootloader front-end: the host pushes firmware over USB, and the AVR forwards it via SPI or USART to the target device. The 8KB Flash holds the update agent, and the built-in hardware USB controller guarantees protocol timing without software bit-banging. The watchdog timer guards against failed update sessions, and EEPROM stores version metadata. Because the AVR family programming model is well documented with MPLAB SNAP ICSP support, initial bring-up is straightforward, making this a common pattern in modems, lighting controllers, and motor drives.
Recommended
Battery-Powered Portable Devices
The AVR ATmega family's low-power architecture - including idle, power-down, and power-save sleep modes inherited across the ATmega8x series - makes the ATMEGA8U2-MUR usable in battery-powered portable accessories that occasionally connect over USB. Designers keep the core in power-down between USB sessions and wake on VBUS or interrupt, extending battery life substantially. The 16 MHz internal options and crystal-less USB clocking flexibility reduce component count in compact layouts. Note that the 512B SRAM limits concurrent USB buffering and application logic; firmware should use static allocation and avoid deep call stacks to maintain reliability in constrained memory conditions.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA8U2-MUR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA8U2-MU | ATMEGA16U2-MU | ATMEGA32U2-MU | ATMEGA8A-MUR |
|---|---|---|---|---|---|
| Package | 32-VFQFN (5x5 mm) Exposed Pad | 32-VQFN (5x5 mm) - same | 32-VQFN (5x5 mm) - same | 32-VQFN (5x5 mm) - same | 32-VQFN (5x5 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Core / Speed | AVR 8-bit, 16 MHz | AVR 8-bit, 16 MHz | AVR 8-bit, 16 MHz | AVR 8-bit, 16 MHz | AVR 8-bit, 16 MHz |
| Flash Memory | 8 KB (4K x 16) | 8 KB | 16 KB | 32 KB | 8 KB |
| SRAM | 512 B | 512 B | 512 B | 1 KB | 1 KB |
| USB Controller | Full-speed USB 2.0 device | Full-speed USB 2.0 device | Full-speed USB 2.0 device | Full-speed USB 2.0 device | None |
| Lifecycle Status | Active | Active | Active | Active | Active |
Key Differentiators
- Integrated full-speed USB controller (vs ATMEGA8A-MUR)
- Lowest-cost entry to the USB AVR family (vs ATMEGA16U2-MU)
- Same-footprint Flash scalability (vs ATMEGA32U2-MU)
Design Notes
Estimated: USB bus-powered designs draw VBUS at up to 100 mA for low-power enumeration; budget the ATMEGA8U2 core current plus LED and external loads under this ceiling and declare configuration appropriately in the USB descriptors. Decouple VCC with 0.1 uF per power pin plus a bulk 4.7-10 uF capacitor near the device. Verify that inrush at hot-plug stays within USB limits, adding a soft-start resistor or ferrite bead on the VBUS tap if needed.
Route the USB D+/D- pair as a matched-length differential pair with 90-ohm differential impedance where the stack-up permits, and keep the traces as short as possible from the VQFN-32 pads to the connector. Place 22-ohm series resistors (if your design uses them per reference designs) close to the MCU. The exposed pad should be soldered to a ground-plane via array for thermal dissipation and EMI control; do not leave the thermal pad as an artistic void in the stencil.
Only 512 bytes of SRAM are available - the most frequent ATmega8U2 failure mode is stack-overheap collision once USB endpoint buffers are allocated. Use static allocation, compile-time checks (linker map review), and avoid printf-style libraries. Also verify the HWB pin state at reset: grounding HWB through a jumper or resistor selects the bootloader, and floating it can cause inconsistent boot behavior in production units.
Keep the 16 MHz crystal within 10 mm of XTAL1/XTAL2 with ground guarding, and load capacitors sized per the crystal datasheet (typically estimated 18-22 pF for standard 16 MHz crystals - confirm with crystal CL spec). Clock radiating into the USB pair causes CRC errors and enumeration failures; separate the crystal island from D+/D- routing and reference both to a continuous ground plane without splits underneath.
Compliance Information
RoHS compliance indicated in distributor listings (Heisener/Win Source). REACH, halogen-free, and conflict-minerals status must be confirmed via the official Microchip environmental documentation.
