ATMEGA16U2-AU - 8-bit AVR USB MCU 16KB Flash 16MHz TQFP-32 | Microchip
MPN: ATMEGA16U2-AU β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.41 | $3.41 |
| 10 | $3.07 | $30.70 |
| 100 | $2.62 | $262.00 |
| 500 | $2.1 | $1,050.00 |
| 1,000 | $1.86 | $1,860.00 |
ATMEGA16U2-AU Overview
An 8-bit AVR microcontroller is a Harvard-architecture RISC processor from the AVR family (now owned by Microchip Technology after its acquisition of Atmel). AVR MCUs execute most instructions in a single clock cycle, sit in the broader hierarchy of microcontroller units (MCU) under embedded processors, and integrate flash program memory, SRAM, EEPROM data storage, timers, USART, SPI, TWI and general purpose I/O on a single die.
Key features of the ATMEGA16U2-AU include 16 KB of self-programmable ISP flash with read-while-write support, a built-in full-speed USB controller with device mode (no external USB transceiver required), 22 general purpose I/O lines, two flexible 8-bit and 16-bit timer/counters, and a USART with SPI-compatible mode for USB-to-serial bridging. The AVR enhanced RISC core executes powerful instructions mostly in one cycle, delivering near-1 MIPS per MHz throughput at 16 MHz.
Architecturally, the device uses 32 general purpose working registers directly connected to the ALU, allowing two independent registers to be accessed in one instruction. Hardware support includes power-on reset, brown-out detection, internal 8 MHz calibrated RC oscillator, watchdog timer, and three sleep modes (Idle, Power-down, Standby) for low-power designs.
Typical applications include USB-to-serial conversion on Arduino Uno R3 and Mega 2560 R3 boards (where it bridges USB to the ATmega328P/2560 UART), USB HID devices such as keyboards, mice and game controllers, and USB CDC virtual-COM-port adapters.
A key design consideration: at 16 MHz the flash is rated for a maximum of 4.5 V operation (2.7 V for 8 MHz), so always pair the supply voltage with clock speed, and tie the /HWB pin appropriately so the on-chip DFU bootloader is entered only when needed.
This page synthesizes distributor pricing, drop-in same-footprint alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA16U2-AU β 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 ATMEGA16U2-AU (same form factor and footprint) β differing in Mounting Type, Operating Temperature, Package, SRAM.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA32U2-AU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA8U2-AU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA16U2-AUR
β Drop-Inβ In Stock
$2.42 / Unit
View Datasheet βATMEGA16U2-AU Maximum Ratings & Electrical Characteristics
| Core Processor | AVR 8-bit RISC |
| Core Size | 8-bit |
| Speed | 16 MHz |
| Flash Memory | 16 KB (8K x 16) |
| EEPROM | 512 B |
| SRAM | 512 B |
| General Purpose I/O | 22 I/O lines |
| USB Controller | USB 2.0 full-speed device |
| UART/USART | 1 x USART |
| Timers/Counters | 2 (one 8-bit, one 16-bit) |
| Operating Voltage | 2.7 V to 5.5 V |
| Operating Temperature | -40C to +85C |
| Package | 32-TQFP (7x7 mm) |
| Mounting Type | Surface Mount |
| Oscillator Type | Internal (calibrated RC) and external |
| Programming Interface | ISP, ICSP, USB DFU bootloader |
| Peripherals | Brown-out Detect/Reset, POR, PWM, WDT, SPI, TWI |
ATMEGA16U2-AU Pin Configuration
| Pin 1 | PB0 β Port B bit 0 / SPI SS / PCINT0 |
| Pin 2 | PB1 β Port B bit 1 / SPI SCLK / PCINT1 |
| Pin 3 | PB2 β Port B bit 2 / PDI / MOSI / PCINT2 |
| Pin 4 | PB3 β Port B bit 3 / PDO / MISO / PCINT3 |
| Pin 5 | PB4 β Port B bit 4 / PCINT4 |
| Pin 6 | PB5 β Port B bit 5 / PCINT5 / OC1A |
| Pin 6 | PB6 β Port B bit 6 / PCINT6 / OC1B |
| Pin 8 | PB7 β Port B bit 7 / PCINT7 / OC0A |
| Pin 9 | /RESET β Reset input (active low) |
| Pin 10 | VCC β Digital supply voltage |
| Pin 11 | GND β Ground |
| Pin 12 | XTAL2 β Inverting oscillator amplifier output / PC7 |
| Pin 13 | XTAL1 β Inverting oscillator amplifier input / PC6 |
| Pin 14 | PD0 β Port D bit 0 / PCINT16 / OC0B |
| Pin 15 | PD1 β Port D bit 1 / PCINT17 / SDA |
| Pin 16 | PD2 β Port D bit 2 / RXD1 (USART) / INT0 / PCINT18 |
| Pin 17 | PD3 β Port D bit 3 / TXD1 (USART) / INT1 / PCINT19 |
| Pin 18 | PD4 β Port D bit 4 / INT2 / PCINT20 |
| Pin 19 | PD5 β Port D bit 5 / XCK1 / INT3 / PCINT21 |
| Pin 20 | PD6 β Port D bit 6 / INT6 / PCINT22 / RTS |
| Pin 21 | PD7 β Port D bit 7 / INT7 / PCINT23 / CTS |
| Pin 22 | PE0 β Port E bit 0 / ICP1 / CLKO / PCINT8 |
| Pin 23 | PE1 β Port E bit 1 / AIN0 / PCINT9 |
| Pin 24 | PE2 β Port E bit 2 / /HWB (hardware bootloader enable) |
| Pin 25 | PC4 β Port C bit 4 / PCINT12 |
| Pin 26 | PC2 β Port C bit 2 / PCINT10 |
| Pin 27 | AVCC β Analog supply for port pins |
| Pin 28 | UGND β USB ground reference |
| Pin 29 | D- β USB differential data negative |
| Pin 30 | D+ β USB differential data positive |
| Pin 31 | UVCC β USB pad supply voltage |
| Pin 32 | UCAP β USB internal regulator output capacitor (1 uF to GND) |
Typical Applications
ATMEGA16U2-AU is suitable for 6 applications: USB-to-Serial Bridge for Arduino Boards, USB HID Keyboards, Mice and Game Controllers, USB CDC Virtual COM Port Adapters, Industrial Control and Automation Nodes, USB-Powered Consumer Electronics and Gadgets, Test Equipment, Debuggers and Developer Tools.
USB-to-Serial Bridge for Arduino Boards
The ATMEGA16U2-AU is the factory-fitted USB bridge on the Arduino Uno R3 and Mega 2560 R3, where it enumerates as a USB CDC virtual COM port and forwards serial traffic to the main ATmega328P or ATmega2560 over USART (PD2 RXD1 / PD3 TXD1). Its hardware full-speed USB 2.0 device controller handles enumeration and packet CRC in silicon, delivering a reliable 12 Mbps link without firmware bit-banging, while the 16 KB flash hosts the CDC firmware with room for custom descriptors. Because the flash is self-programmable via the on-chip DFU bootloader (entered by pulling /HWB low at reset), makers can reflash the bridge into a USB HID keyboard or MIDI device without any external programmer. Recommended companion parts include the ATMEGA328P-AU main MCU and a 16 MHz crystal with 22 pF load capacitors for the accurate USB clock.
Recommended
USB HID Keyboards, Mice and Game Controllers
The ATMEGA16U2-AU is a strong fit for USB HID input devices because its integrated full-speed USB 2.0 device controller manages endpoint buffering, handshake packets and CRC in hardware, so the AVR core only formats report descriptors and scans the key matrix. With 16 KB of ISP flash, it hosts complete HID keyboard/mouse/joystick class firmware - the LUFA open-source library ships mature HID class drivers specifically for the 8U2/16U2/32U2 family. The 22 GPIO lines provide enough key-scanning rows and columns for compact keyboards, and 512 B SRAM comfortably holds HID report descriptors and endpoint buffers. A practical design tip: run at 16 MHz from a crystal for a stable USB clock, power from the 5 V VBUS rail through a 3.3 V or 5 V LDO, and keep the D+/D- differential pair at 90 ohm differential impedance with series 22 ohm termination resistors.
Recommended
USB CDC Virtual COM Port Adapters
Designers use the ATMEGA16U2-AU as a discrete USB-to-UART converter in embedded products that need a firmware-updatable bridge, offering an alternative to fixed-function chips like the FTDI FT232RL. Unlike fixed-function bridges, the 16U2 can run custom protocols, vendor-specific VID/PID descriptors, or add USB MSC and HID composite classes, since the firmware resides in 16 KB self-programmable flash. The USART runs at up to 2 Mbps in synchronous mode, and USB CDC class firmware achieves practical throughput suitable for debug consoles, bootloader links and sensor streaming. Its DFU bootloader enables field firmware updates over the same USB cable with dfu-programmer or Atmel FLIP, no extra connector required. Consider this part when bridge customization, firmware field updates, or BOM consolidation with an in-house AVR codebase outweigh the simplicity of a fixed USB-UART IC.
Recommended
Industrial Control and Automation Nodes
In industrial automation, the ATMEGA16U2-AU serves as a compact control node with a built-in USB service port for configuration and diagnostics. The industrial temperature range of -40C to +85C on the AU suffix suits factory-floor enclosures, while brown-out detection, power-on reset and a watchdog timer protect against brownouts from inductive loads and motor starts. Its two timer/counters generate PWM for actuator control, SPI and TWI (I2C) interfaces connect sensors and EEPROMs, and 22 GPIO lines drive relays or opto-isolated inputs. USB connectivity allows technicians to reflash firmware or pull logs from a laptop without opening the enclosure. Design with a 5 V rail filtered against switching noise, add TVS protection on the USB lines for hot-plug robustness, and use the power-down sleep mode (sub-uA class current) for low-duty-cycle monitoring nodes.
Recommended
USB-Powered Consumer Electronics and Gadgets
The ATMEGA16U2-AU fits USB-powered consumer devices - LED controllers, small displays, dongles and toys - because it draws power directly from the 5 V VBUS pin, requires no external USB transceiver, and enumerates as a standard device with vendor-customizable descriptors. The internal 8 MHz calibrated RC oscillator allows clockless BOM savings in applications tolerant of the USB timing budget, while a 16 MHz crystal is used where full-speed USB accuracy is critical. Power-down and Idle sleep modes keep standby current low for battery-backup scenarios, and the watchdog timer recovers from firmware lockups in unattended devices. With 16 KB flash and a DFU bootloader, manufacturers can ship one hardware revision and update features (LED effects, button mappings, USB classes) over the USB cable in the field, reducing warranty returns and enabling post-sale product differentiation at essentially zero hardware cost.
Recommended
Test Equipment, Debuggers and Developer Tools
Development-tool makers use the ATMEGA16U2-AU as the USB front-end in programmers, debug bridges and instrument interfaces, since its USB device controller plus USART/SPI peripherals can implement CDC, HID and vendor-specific transport classes from one 16 KB firmware image. As documented on the Microchip product page, the MPLAB SNAP programmer ecosystem connects over High-Speed USB 2.0 and uses ICSP on two device I/O pins plus reset - the same connectivity pattern the 16U2 enables in low-cost tools. The 512 B SRAM suits packet buffering for SWD/ISP bridge firmware, and the self-programmable flash lets the tool update its own USB firmware via DFU during manufacturing or in the field. For best signal quality, route D+/D- as a matched 90-ohm differential pair, place 22 ohm series resistors at the connector, and keep the 16 MHz crystal within 10 mm of the XTAL pins.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA16U2-AU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA32U2-AU | ATMEGA8U2-AU | ATMEGA16U2-AUR |
|---|---|---|---|---|
| Package | 32-TQFP (7x7 mm) | 32-TQFP (7x7 mm) - same | 32-TQFP (7x7 mm) - same | 32-TQFP (7x7 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 16 KB | 32 KB | 8 KB | 16 KB |
| SRAM | 512 B | 512 B | 512 B | 512 B |
| EEPROM | 512 B | 512 B | 512 B | 512 B |
| Max Clock Speed | 16 MHz | 16 MHz | 16 MHz | 16 MHz |
| 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 |
| GPIO Count | 22 | 22 | 22 | 22 |
| Operating Temperature | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
Key Differentiators
- Balanced memory for USB bridge firmware (vs ATMEGA8U2-AU)
- Lower cost than larger sibling (vs ATMEGA32U2-AU)
- No cross-brand pin equivalent exists (vs CH340G / CP2102 (board-level only))
Design Notes
USB full-speed signaling demands attention to D+/D- routing: keep the differential pair matched in length, routed as a 90-ohm differential impedance, no longer than about 20 cm, and away from switching nodes. Place 22-ohm series resistors close to the D+/D- pins when the trace to the connector exceeds a few centimeters. The USB clock must come from a 16 MHz crystal with a total accuracy within +/-0.25% (including load capacitance tolerance) to meet full-speed tolerance; the internal RC oscillator alone is generally not accurate enough for USB without calibration.
Power the device at 5 V (4.5 V-5.5 V) when running at 16 MHz, since the datasheet speed grade limits 8 MHz to lower voltages. Decouple VCC and AVCC each with a 100 nF ceramic capacitor placed within 3 mm of the pins, plus one 4.7 uF-10 uF bulk capacitor per supply rail. The UCAP pin requires a 1 uF capacitor to ground for the internal 3.3 V USB regulator - do not omit it or USB signaling will fail. Connect UGND to system ground at a single quiet point near the USB connector to avoid ground-loop noise in the USB receiver.
The /HWB pin (PE2) selects the DFU bootloader at reset: leave it pulled high (10 k to VCC) for normal application startup, or pull it low via a button only when bootloader entry is wanted. A floating /HWB can cause erratic entry into DFU mode instead of running application firmware. Also remember that the factory DFU bootloader occupies part of the 16 KB flash; if you erase it via ISP and need USB updates later, you must reprogram a bootloader. Set fuse bits to boot size appropriate for your bootloader, and never disable the JTAG-disable/ISP fuses without a recovery plan.
Compliance Information
RoHS compliant and lead-free per Microchip ordering information and distributor listings (AU suffix = matte tin TQFP). REACH, halogen-free and conflict minerals status not stated in provided data.
