ATMEGA16U2-MU - 16MHz AVR USB MCU 16KB Flash | Microchip
MPN: ATMEGA16U2-MU β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.59 | $2.59 |
| 10 | $2.33 | $23.30 |
| 100 | $2.15 | $215.00 |
| 500 | $1.93 | $965.00 |
| 1,000 | $1.74 | $1,740.00 |
ATMEGA16U2-MU Overview
An AVR microcontroller is a modified-Harvard-architecture 8-bit RISC processor in which flash program memory, SRAM data memory, and EEPROM are accessed through separate address spaces, allowing most instructions to execute in a single clock cycle. Within the power-management hierarchy, a USB AVR such as the ATmega16U2 combines a general-purpose MCU core with a dedicated USB device controller, replacing a separate USB-to-serial bridge chip in many designs.
Key features include 16 KB of read-while-write ISP flash, 512 B EEPROM, 512 B SRAM, 32 general-purpose working registers, two flexible timer/counters with compare modes, a 10-bit ADC, and an on-chip USB controller with 25 MHz capable PLL. The 16 MHz operation at 2.7 V to 5.5 V supply makes the device tolerant of 3.3 V and 5 V USB domains.
The core executes 133 powerful instructions, most in a single clock cycle, giving throughput close to 16 MIPS at 16 MHz. The USB interface supports full-speed 12 Mbps operation and can be used for USB-to-serial conversion or HID device emulation under firmware such as LUFA.
Typical applications include USB-to-serial interface MCUs (notably as the USB bridge on the Arduino Uno R3), HID keyboards and mice, and small embedded control nodes with USB firmware update capability.
A key design consideration is the UCAP pin: a 1 uF capacitor on the USB internal regulator output is required when operating from 3.3 V, and correct 22 ohm series termination on D+/D- improves signal integrity.
This page synthesizes distributor pricing, drop-in alternatives, pinout data, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA16U2-MU 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-MU (same form factor and footprint) β differing in Core Architecture, EEPROM, Flash Memory, Package, RoHS Status.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA32U2-MU
β Drop-Inβ In Stock
$2.74 / Unit
View Datasheet βATMEGA8U2-MU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA32U2-MUR
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA16U2-MUR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA8U2-MUR
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA16U2-MU Maximum Ratings & Electrical Characteristics
| Core Architecture | AVR 8-bit RISC |
| Maximum Clock Frequency | 16 MHz |
| Flash Memory | 16 KB (8K x 16) ISP |
| EEPROM | 512 B |
| SRAM | 512 B |
| Supply Voltage Range | 2.7 V to 5.5 V |
| Number of I/O Lines | 22 |
| USB Interface | USB 2.0 full-speed device (12 Mbps) |
| Timers/Counters | 2 x 8-bit with compare modes |
| ADC | 10-bit |
| Package | 32-VQFN (5x5 mm) |
| Mounting Type | Surface Mount |
| Data Bus Width | 8 Bit |
| Instruction Set | 133 instructions, mostly single-cycle |
| RoHS Status | Compliant (green package) |
| Lifecycle Stage | Active |
ATMEGA16U2-MU Pin Configuration
| Pin 1 | PC2 β Port C bit 2 / PCINT10 |
| Pin 2 | PD0 β Port D bit 0 (RXD) / PCINT16 |
| Pin 3 | PD1 β Port D bit 1 (TXD) / PCINT17 |
| Pin 4 | PD2 β Port D bit 2 (INT0) / PCINT18 |
| Pin 5 | PD3 β Port D bit 3 (INT1) / PCINT19 |
| Pin 6 | PD4 β Port D bit 4 (XCK) / PCINT20 |
| Pin 7 | VCC β Digital supply voltage |
| Pin 8 | GND β Ground |
| Pin 9 | PB0 β Port B bit 0 (SS) / PCINT0 |
| Pin 10 | PB1 β Port B bit 1 (SCK) / PCINT1 |
| Pin 11 | PB2 β Port B bit 2 (MOSI) / PCINT2 |
| Pin 12 | PB3 β Port B bit 3 (MISO) / PCINT3 |
| Pin 13 | PB4 β Port B bit 4 (OC2A) / PCINT4 |
| Pin 14 | PB5 β Port B bit 5 (OC1A) / PCINT5 |
| Pin 15 | PB6 β Port B bit 6 (OC1B) / PCINT6 |
| Pin 16 | PB7 β Port B bit 7 (OC0A/OC1C) / PCINT7 |
| Pin 17 | PC7 β Port C bit 7 (OC4A) / PCINT15 |
| Pin 18 | PC6 β Port C bit 6 (OC3A/OC4A) / PCINT14 |
| Pin 19 | PC5 β Port C bit 5 / PCINT13 |
| Pin 20 | PC4 β Port C bit 4 / PCINT12 |
| Pin 21 | PD7 β Port D bit 7 (INT6) / PCINT23 |
| Pin 22 | PD6 β Port D bit 6 (OC4D) / PCINT22 |
| Pin 23 | PD5 β Port D bit 5 (XCK1) / PCINT21 |
| Pin 24 | AVCC β Analog supply voltage for ADC |
| Pin 25 | XTAL2 β Crystal oscillator output |
| Pin 26 | XTAL1 β Crystal oscillator input / external clock |
| Pin 27 | UCAP β USB internal regulator output capacitor (1 uF) |
| Pin 28 | UGND β USB pad ground reference |
| Pin 29 | D- β USB negative data line |
| Pin 30 | D+ β USB positive data line |
| Pin 31 | UVCC β USB transceiver supply |
| Pin 32 | UVB β USB pad voltage reference / load switch |
Typical Applications
ATMEGA16U2-MU is suitable for 6 applications: USB-to-Serial Bridge (Arduino Uno R3), USB HID Keyboards and Mice, Industrial Control Nodes with USB Firmware Update, USB Debug and Programming Adapters, Consumer Peripheral Boards, Test and Measurement Instrument Front Panels.
USB-to-Serial Bridge (Arduino Uno R3)
The ATMEGA16U2-MU is the USB interface MCU on the Arduino Uno R3, where it converts USB traffic from the host PC into UART data for the ATmega328P main MCU. Its integrated full-speed USB 2.0 device controller and hardware UART eliminate the need for a dedicated FTDI FT232RL bridge, reducing BOM cost while keeping the interface firmware updatable via the onboard 6-pin ICSP header. The 16 KB flash is sized to hold the complete USB CDC firmware, and 16 MHz operation matches the USB PLL requirements. Because the chip is programmable, the same footprint also supports LUFA-based firmware that emulates USB HID keyboards or mice, adding capabilities a fixed-function bridge cannot provide.
Recommended
USB HID Keyboards and Mice
With its native full-speed USB 2.0 device controller, the ATMEGA16U2-MU can implement HID-class keyboards, mice, and game controllers without a separate USB interface chip. The AVR core scans keys or sensors, debounces inputs, and constructs HID reports, while the on-chip USB hardware handles enumeration and packet transfer at 12 Mbps. Firmware stacks such as LUFA or V-USB-style descriptors fit comfortably in the 16 KB flash, leaving SRAM for report buffering. The 2.7 V to 5.5 V supply range allows bus-powered designs directly from the 5 V USB rail with the internal 3.3 V regulator (UCAP capacitor) supplying the USB transceiver.
Recommended
Industrial Control Nodes with USB Firmware Update
The ATMEGA16U2-MU suits compact industrial control nodes that need local I/O plus a maintenance USB port. The 16 KB read-while-write ISP flash allows a USB bootloader to be co-resident with the application, so field technicians can update firmware from a laptop without opening the enclosure. Two 8-bit timers with compare modes drive PWM outputs for actuators, while the 10-bit ADC reads sensors. The 2.7 V to 5.5 V supply tolerance accommodates noisy industrial 5 V rails, and the 5x5 mm VQFN-32 package keeps board area small in DIN-rail and sensor-head form factors.
Recommended
USB Debug and Programming Adapters
Development-tool makers use the ATMEGA16U2-MU as the core of USB ISP programmers and debug adapters, where the USB controller enumerates as a programmer device and the AVR UART/SPI pins bit-bang or hardware-drive the target. The single-cycle RISC core provides precise SPI timing for reliable ISP programming of AVR targets, and 16 KB flash stores protocol firmware plus descriptor tables. The internal PLL supplies the 48 MHz USB clock from a low-cost 8-16 MHz crystal on XTAL1/XTAL2. Because the design is fully public in the Arduino ecosystem, second-sourcing the adapter MCU is straightforward using the ATmega32U2-MU drop-in.
Recommended
Consumer Peripheral Boards
Consumer peripherals such as smart cable adapters, LED controllers with USB configuration, and small interactive devices benefit from the ATMEGA16U2-MU's combination of USB device capability and general-purpose AVR I/O. The 22 GPIO lines drive LEDs, read buttons, and control external circuitry directly, while USB provides both power and a configuration channel. The device's low power operation and bus-powered 5 V supply simplify enclosure design with no external regulator for the USB transceiver. Production assembly is well supported since the VQFN-32 package is standard for reflow soldering, and the reel-packaged MUR variant suits high-volume pick-and-place lines.
Recommended
Test and Measurement Instrument Front Panels
In bench instruments and data loggers, the ATMEGA16U2-MU serves as the USB reporting front end, streaming measurement data from the main processing MCU to a PC as a virtual COM port. The hardware UART receives data at up to 2 Mbps from the instrument's processor, and the USB CDC firmware presents it to host software without vendor-specific drivers. The 512 B SRAM buffers burst traffic to smooth data flow, and the 10-bit ADC handles local auxiliary sensing such as panel temperature. Its active lifecycle status and multi-distributor availability protect long-term instrument production runs.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA16U2-MU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA32U2-MU | ATMEGA8U2-MU | ATMEGA16U2-MUR |
|---|---|---|---|---|
| Package | 32-VQFN (5x5 mm) | 32-VQFN (5x5 mm) - same | 32-VQFN (5x5 mm) - same | 32-VQFN (5x5 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 16 KB | 32 KB | 8 KB | 16 KB |
| Maximum Clock Frequency | 16 MHz | 16 MHz | 16 MHz | 16 MHz |
| SRAM | 512 B | 512 B | 512 B | 512 B |
| USB Interface | USB 2.0 full-speed device | USB 2.0 full-speed device | USB 2.0 full-speed device | USB 2.0 full-speed device |
| Supply Voltage | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V |
| GPIO Count | 22 | 22 | 22 | 22 |
Key Differentiators
- Balanced 16 KB flash for USB CDC + HID stacks (vs ATMEGA8U2-MU)
- Cost-optimized vs the 32U2 for 16 KB-class firmware (vs ATMEGA32U2-MU)
- Arduino ecosystem compatibility (vs ATMEGA8U2-MU)
- Trade-off: less code headroom than the 32U2 (vs ATMEGA32U2-MU)
Design Notes
Route the D+ and D- USB lines as a matched 90 ohm differential pair with length matching within a few millimeters. Add 22 ohm series resistors close to the ATmega16U2 pins as termination, following the reference design used in the Arduino Uno R3 schematic. Place a 1 uF capacitor on UCAP (pin 27) directly adjacent to the pin - this stabilizes the internal 3.3 V USB regulator and is mandatory for reliable enumeration. Connect UGND (pin 28) to a quiet ground island under the crystal and USB pads, tied to main ground at one point.
Decouple VCC (pin 7) and AVCC (pin 24) each with 100 nF ceramic capacitors placed within 2 mm of the pins, plus a bulk 4.7-10 uF capacitor near the supply entry. AVCC should be filtered through an LC or RC network if the ADC is used in noisy environments, since ADC accuracy directly depends on AVCC ripple. When the board is USB bus-powered at 5 V, the internal regulator fed via UVCC (pin 31) powers the transceiver; ensure total bus-powered current stays within the 100 mA unconfigured USB budget.
Do not substitute a fixed 3.3 V supply on D+/D- domains without checking UVCC wiring - the transceiver expects UVCC tied to the 5 V rail when the internal regulator is used. Firmware flashed for the ATmega328P will not run on the 16U2: device signatures differ, and ISP programmers will refuse without the correct target selected. Finally, remember that replacing the chip erases the Arduino USB firmware - always re-flash the USB-to-serial firmware via the onboard ICSP header after chip replacement.
The 16 MHz crystal on XTAL1/XTAL2 should use load capacitors matched to the crystal specification (typically 18-22 pF for standard AT-cut crystals) with short traces to UGND-referenced ground. Keep the crystal loop away from USB lines and switching regulators to prevent jitter on the PLL-derived 48 MHz USB clock. Excessive jitter can cause CRC errors and intermittent disconnection under Windows hosts, which are less tolerant than Linux hosts of marginal full-speed signaling.
Compliance Information
RoHS compliant green package per Microchip product page and distributor listings. REACH, halogen-free, and conflict-minerals status not stated in provided data.