ATMEGA32U2-MU - 8-bit AVR USB MCU 16MHz 32KB | Microchip
MPN: ATMEGA32U2-MU β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.28 | $4.28 |
| 10 | $3.85 | $38.50 |
| 100 | $3.42 | $342.00 |
| 500 | $3.08 | $1,540.00 |
| 1,000 | $2.74 | $2,740.00 |
ATMEGA32U2-MU Overview
A microcontroller (MCU) is a single-chip computer integrating a processor core, memory, and programmable peripherals on one die. The ATMEGA32U2 belongs to the AVR ATmega USB family within the broader microcontroller and power-management hierarchy of embedded semiconductors, positioned for applications that need native USB device connectivity without an external USB-to-serial converter.
Key features include 131 powerful AVR RISC instructions with mostly single-cycle execution, a full-speed USB 2.0 device controller with 32 endpoint addresses and hardware flow control, 22 general-purpose I/O lines, two flexible 8-bit/16-bit timer/counters with compare modes and PWM, USART, SPI interface, programmable watchdog timer, and an internal oscillator. The USB controller supports remote wake-up and can be clocked directly from a calibrated internal RC oscillator, reducing external component count.
The advanced RISC architecture combines 32 general-purpose working registers directly connected to the ALU, allowing one instruction to execute in a single clock cycle, delivering up to 16 MIPS throughput at 16 MHz. Read-while-write ISP Flash enables in-system self-programming for firmware updates over USB, which is why this MCU is widely used as a USB bridge and bootloader device.
Typical applications include USB-to-UART bridge circuits, custom HID devices such as keyboards and game controllers, Arduino Uno R3-style USB interface controllers, and general embedded products requiring USB connectivity. The industrial temperature rating supports factory and outdoor deployments.
Design consideration: the device operates from 2.7 V to 5.5 V (4.5 V to 5.5 V for 16 MHz full-speed operation), so supply voltage and USB bus voltage (5 V) must be coordinated; decouple VCC and AVCC with 100 nF ceramics placed close to the pins.
This page synthesizes distributor pricing, drop-in family alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA32U2-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 ATMEGA32U2-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:
ATMEGA16U2-MU
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$1.74 / Unit
View Datasheet βATMEGA8U2-MU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
AT90USB162-MU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
AT90USB82-MU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA32U2-MU Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Maximum Clock Frequency | 16 MHz |
| Flash Memory | 32 KB (16K x 16) ISP, read-while-write |
| EEPROM | 1 KB |
| SRAM | 1 KB |
| USB Controller | Full-speed USB 2.0 device, 32 endpoints |
| General Purpose I/O | 22 I/O lines |
| Working Registers | 32 general-purpose registers |
| Timers/Counters | 2 (8-bit and 16-bit) with compare modes and PWM |
| Communication Interfaces | USART, SPI, USB |
| Watchdog Timer | Programmable with internal oscillator |
| Supply Voltage Range | 2.7 V to 5.5 V (16 MHz: 4.5 V to 5.5 V) |
| Operating Temperature | -40C to +85C (industrial) |
| Package | 32-VQFN (5x5 mm) with exposed pad |
| Mounting Type | Surface Mount |
| Throughput | Up to 16 MIPS at 16 MHz |
| RoHS Status | Compliant |
| Lifecycle Stage | Active |
ATMEGA32U2-MU Pin Configuration
| Pin 1 | PB0 β Port B bit 0 (SS/PCINT0) |
| Pin 2 | PB1 β Port B bit 1 (SCK/PCINT1) |
| Pin 3 | PB2 β Port B bit 2 (PDI/PCINT2) |
| Pin 4 | PB3 β Port B bit 3 (PDO/PCINT3) |
| Pin 5 | PB4 β Port B bit 4 (PCINT4) |
| Pin 6 | PB5 β Port B bit 5 (PCINT5) |
| Pin 7 | PB6 β Port B bit 6 (PCINT6) |
| Pin 8 | PB7 β Port B bit 7 (PCINT7) |
| Pin 9 | PC7 β Port C bit 7 |
| Pin 10 | RESET/PC6 β Reset input / Port C bit 6 |
| Pin 11 | PC5 β Port C bit 5 |
| Pin 12 | PC4 β Port C bit 4 |
| Pin 13 | PC2 β Port C bit 2 |
| Pin 14 | PC1 β Port C bit 1 |
| Pin 15 | PC0 β Port C bit 0 |
| Pin 16 | PD7 β Port D bit 7 (HWB) |
| Pin 17 | PD6 β Port D bit 6 (INT6) |
| Pin 18 | PD5 β Port D bit 5 (OC0B) |
| Pin 19 | PD4 β Port D bit 4 (OC1B) |
| Pin 20 | PD3 β Port D bit 3 (INT1 / USB D+) |
| Pin 21 | PD2 β Port D bit 2 (INT0 / USB D-) |
| Pin 22 | PD1 β Port D bit 1 (TXD) |
| Pin 23 | PD0 β Port D bit 0 (RXD) |
| Pin 24 | VCC β Digital supply voltage |
| Pin 25 | GND β Ground |
| Pin 26 | XTAL2 β Crystal oscillator output |
| Pin 27 | XTAL1 β Crystal oscillator input / external clock |
| Pin 28 | AREF β Analog reference for ADC |
| Pin 29 | AVCC β Analog supply voltage (ADC/USB) |
| Pin 30 | PAD (EP) β Exposed pad - connect to GND |
| Pin 31 | NC β Not connected (per datasheet) |
| Pin 32 | NC β Not connected (per datasheet) |
Typical Applications
ATMEGA32U2-MU is suitable for 6 applications: USB-to-UART Bridge, HID Keyboards, Mice and Gamepads, USB Interface Controller for Embedded Systems, Development Boards and Bootloader Targets, Custom USB Devices and Protocol Converters, Consumer Electronics with USB Charging Ports.
USB-to-UART Bridge
The ATMEGA32U2-MU is widely deployed as a USB-to-serial bridge, the role it performs on Arduino Uno R3-class boards. Its full-speed USB 2.0 device controller enumerates as a USB CDC-ACM virtual COM port, while the USART handles the UART side at standard baud rates, giving deterministic bridging with no external USB-to-serial IC. With 32 KB Flash, firmware can implement CDC descriptors, flow control, and auxiliary vendor commands simultaneously. Design-wise, the USB D-/D+ lines connect through 22 ohm series resistors, and the 16 MHz crystal meets USB clock accuracy. Unlike fixed-function bridges, firmware is fully customizable, so command framing and custom protocols can be layered on top of transparent passthrough, which matters for debug probes, ISP programmers, and industrial device consoles.
Recommended
HID Keyboards, Mice and Gamepads
For USB HID peripherals, the ATMEGA32U2-MU provides the full-speed USB device controller with 32 endpoint addresses, interrupt endpoints for low-latency key and axis reporting, and remote wake-up so the host can sleep while the device waits for input. The 22 GPIO lines support key-matrix scanning for keyboards of typical consumer size, and two timer/counters with PWM support LED backlight dimming and analog joystick sampling. The 32 KB Flash holds HID descriptors, debounce logic, and macro features with substantial headroom, and 1 KB EEPROM stores user calibration data persistently. Because the AVR core executes mostly single-cycle instructions, scan and report cycles are deterministic, which directly improves perceived input latency in gaming peripherals.
Recommended
USB Interface Controller for Embedded Systems
Industrial and instrumentation boards use the ATMEGA32U2-MU as a dedicated USB connectivity coprocessor, isolating USB protocol handling from the main application MCU. The device operates from -40C to +85C (industrial grade), tolerating factory and outdoor environments, and its 2.7 V to 5.5 V supply range simplifies integration into 5 V systems. Firmware such as LUFA implements CDC, HID, or vendor-class stacks, while SPI and USART links transfer data to the host processor. Because Flash supports read-while-write self-programming, the bridge firmware itself can be field-updated over USB without opening the enclosure. This architecture removes protocol timing pressure from the main MCU and provides a standardized debug/update port across a product family.
Recommended
Development Boards and Bootloader Targets
The ATMEGA32U2-MU is a natural bootloader target for educational and maker platforms. Its in-system self-programming capability with read-while-write Flash lets a USB DFU or HID bootloader overwrite application firmware entirely from the host, eliminating external programmers. The 32 KB Flash accommodates a compact bootloader plus a meaningful application, and the ISP interface remains available for factory programming via SPI. Board designers pair the MCU with a 16 MHz crystal and USB-B or USB-C receptacle to build low-cost self-programming boards. The device's proven use as the USB controller on Arduino-family boards means toolchain, firmware examples, and community support are mature, reducing bring-up time for new development platforms.
Recommended
Custom USB Devices and Protocol Converters
Product designers use the ATMEGA32U2-MU to build custom USB devices: sensor dongles, DMX interfaces, CAN adapters, and vendor-class data loggers. The USB controller's 32 endpoint addresses support composite devices combining HID control with bulk data endpoints, and the 1 KB SRAM buffers endpoint payloads and protocol state. Two timer/counters generate PWM outputs and capture inputs for protocol timing, while SPI connects to external ADCs, flash, or transceivers. Because the firmware is fully user-defined, proprietary enumeration strings, VID/PID, and custom descriptors are trivially set. The industrial temperature range and RoHS-compliant 32-VQFN package make it suitable for both commercial and professional equipment, with a 5x5 mm footprint fitting compact dongle PCBs.
Recommended
Consumer Electronics with USB Charging Ports
In consumer products, the ATMEGA32U2-MU handles USB enumeration, device authentication prompts, and status indication alongside the main system controller. Its 5 V supply tolerance means it can be powered directly from the USB VBUS rail, simplifying power architecture in chargers, docks, and accessories. Remote wake-up and suspend support meet USB power management requirements, and the internal watchdog timer adds robustness for unattended consumer operation. The 32-VQFN 5x5 mm package with exposed pad suits two-layer or four-layer consumer PCBs where board area is constrained, and its low external component count (crystal, a few capacitors, 22 ohm USB series resistors) keeps the bill of materials minimal for high-volume cost-sensitive designs.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA32U2-MU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA16U2-MU | ATMEGA8U2-MU | AT90USB162-MU | AT90USB82-MU |
|---|---|---|---|---|---|
| Package | 32-VQFN (5x5 mm) | 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 |
| Flash Memory | 32 KB | 16 KB | 8 KB | 16 KB | 8 KB |
| SRAM | 1 KB | 512 B | 512 B | 512 B | 512 B |
| EEPROM | 1 KB | 512 B | 512 B | 512 B | 512 B |
| Maximum Clock Frequency | 16 MHz | 16 MHz | 16 MHz | 16 MHz | 16 MHz |
| USB Controller | Full-speed USB 2.0 device, 32 endpoints | Full-speed USB 2.0 device, 32 endpoints | Full-speed USB 2.0 device, 32 endpoints | Full-speed USB 2.0 device, 32 endpoints | Full-speed USB 2.0 device, 32 endpoints |
| GPIO Count | 22 I/O lines | 22 I/O lines | 22 I/O lines | 22 I/O lines | 22 I/O lines |
| 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 | 2.7 V to 5.5 V |
| Pin-to-Pin Compatibility | Reference | Pin-to-pin compatible | Pin-to-pin compatible | Pin-to-pin compatible (family) | Pin-to-pin compatible (family) |
Key Differentiators
- Twice the Flash of the common 16U2 bridge device (vs ATMEGA16U2-MU)
- Doubled SRAM and EEPROM within the same package (vs AT90USB162-MU)
- Native USB without an external bridge IC (vs ATMEGA328P-MU)
- Honest trade-off: smaller SRAM/EEPROM than the 32U4 (vs ATMEGA32U4-MU)
Design Notes
Follow the USB hardware design in the Microchip ATmega8U2/16U2/32U2 datasheet typical application: place 22 ohm series resistors close to the MCU on the D-/D+ lines, route them as a matched differential pair with 90-ohm differential impedance, and keep the pair away from clock and switching traces. Add 100 nF decoupling capacitors on VCC and AVCC within 2 mm of the pins, and connect the exposed pad to the ground plane with a via array for low-inductance grounding.
Power the device from the 5 V USB VBUS through a low-drop point-of-load filter when bus-powered: at 16 MHz with USB active, current consumption is in the low tens of milliamps per AVR typical characteristics, so a simple ferrite bead plus bulk capacitance is usually sufficient. Remember that 3.3 V operation limits the maximum safe clock frequency; do not run 16 MHz code on a 3.3 V rail. Use the internal brown-out detector (programmed via fuse bits) to prevent corrupted Flash writes during brownout events.
Set the correct fuse configuration before first USB use: CKOUT/CKSEL fuses must select the external 16 MHz crystal for full-speed USB compliance, and the HWB (PD7) pin state at reset selects bootloader entry - keep it pulled to a defined level. Do not omit the HWB pull-down if the bootloader should not auto-enter. If migrating from ATMEGA16U2/AT90USB82, verify the firmware fits the target's smaller Flash and EEPROM before committing the substitution.
For the 32-VQFN 5x5 mm package, fan out with via-in-pad or short escapes on the fine 0.5 mm pitch pins; the exposed pad should occupy at least a 5x5 mm thermal land connected to ground through 4-9 vias. Keep the 16 MHz crystal and its load capacitors within 5 mm of XTAL1/XTAL2 with a local ground guard. Good crystal layout directly affects USB clock accuracy and enumeration reliability in noisy environments.
Compliance Information
RoHS-compliant industrial microcontroller per distributor listings; not an automotive AEC-Q100 part. REACH and conflict minerals declarations available from Microchip on request.
