ATMEGA32U4-AU - 8-bit AVR MCU, 16MHz, 32KB Flash, USB | Microchip
料号： ATMEGA32U4-AU ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $5.8 | $5.80 |
| 10 | $5.4 | $54.00 |
| 100 | $4.95 | $495.00 |
| 500 | $4.55 | $2,275.00 |
| 1,000 | $4.25 | $4,250.00 |
ATMEGA32U4-AU 概述
An 8-bit AVR microcontroller (AVR = Alf and Vegard's RISC processor) is a modified-Harvard RISC MCU family from Microchip (originally Atmel) that executes most instructions in a single clock cycle and is widely used in Arduino, USB HID, and keyboard-firmware designs. In the broader taxonomy it sits inside the MCU hierarchy as: microcontroller -> embedded controller -> semiconductor -> integrated circuit. The 'U4' suffix specifically denotes on-chip USB hardware, distinguishing the part from non-USB siblings such as ATmega32A.
Key features of this ATmega32U4 variant include 16 MIPS throughput at 16 MHz, 131 powerful instructions, 32 programmable I/O lines, an on-chip USB 2.0 transceiver that eliminates an external PHY, hardware multiplier, six sleep modes for power-sensitive applications, and an industrial -40C to +85C operating range. The non-J (AU) suffix indicates the 44-pin TQFP package in industrial temperature grade.
The architecture pairs an advanced RISC core with non-volatile program memory, on-chip SRAM and EEPROM, plus a rich peripheral set including ADC, timers/USART, SPI, TWI (I2C), and the USB device controller with up to 8 endpoints. The USB module removes the BOM cost of an external FTDI bridge, which is why the ATmega32U4 is the silicon heart of the Arduino Leonardo, Arduino Micro, Pro Micro, and many QMK-based custom keyboards.
Typical applications include USB Human Interface Devices (keyboards, mice, MIDI controllers), Arduino-compatible boards, custom mechanical-keyboard controllers, USB-to-UART bridges, USB data-acquisition front-ends, and low-cost consumer HID peripherals. When designing with this MCU, place the 22 ohm USB D+/D- source-series resistors close to the pins, fit a 1uF VBUS decoupling capacitor, and ensure the HWB/PE2 strap pin is pulled correctly to enter bootloader mode.
直接替换替代料： ATMEGA32U4-AU ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
本系列中的变体
可与以下型号直接替换的同系列型号： ATMEGA32U4-AU （相同外形与封装尺寸） ——差异在于 Package, Debug Interface, Core Architecture, RoHS Status, ADC.
快速对比工具——选择替代料号进行并排对比：
ATMEGA32U4-AUR
✅ 直接替换✓ 有现货
$5.2 / 个
查看数据手册 →ATMEGA32U4-MUR
✅ 直接替换✓ 有现货
$4.86 / 个
查看数据手册 →ATMEGA16U4-AU
✅ 直接替换✓ 有现货
$2.19 / 个
查看数据手册 →ATMEGA32A-AU
✅ 直接替换✓ 有现货
$2.95 / 个
查看数据手册 →ATMEGA32U4-AU 最大额定值与电气特性
| Core Architecture | 8-bit AVR RISC |
| CPU Speed | 16 MHz |
| Throughput | 16 MIPS at 16 MHz |
| Flash Program Memory | 32 KB (16K x 16) |
| SRAM | 2.5 KB |
| EEPROM | 1 KB |
| 电源电压 | 2.7 V to 5.5 V (verified 4.5-5.5V in some sources; full range per datasheet) |
| I/O Pins | 32 programmable |
| USB | USB 2.0 full-speed / low-speed device, on-chip transceiver |
| ADC | 12-channel, 10-bit |
| Timers | 4 (2x 8-bit, 2x 16-bit) |
| Communication | USB, USART, SPI, TWI (I2C) |
| Debug Interface | JTAG / debugWIRE |
| 封装 | 44-pin TQFP (10x10 mm, 0.8 mm pitch) |
| 安装类型 | Surface Mount |
| 工作温度 | -40 C to +85 C (industrial) |
| Instruction Set | 131 instructions, mostly single-cycle |
| RoHS 状态 | Compliant |
ATMEGA32U4-AU 引脚配置
| 引脚 1 | PE6 — Port E bit 6 (INT6) |
| 引脚 2 | AVCC — Analog supply voltage |
| 引脚 3 | AGND — Analog ground |
| 引脚 4 | AREF — ADC reference voltage |
| 引脚 5 | PF0 — Port F bit 0 (ADC0) |
| 引脚 6 | PF1 — Port F bit 1 (ADC1) |
| 引脚 7 | PF2 — Port F bit 2 (ADC2 / TCK) |
| 引脚 8 | PF3 — Port F bit 3 (ADC3 / TMS) |
| 引脚 9 | PF4 — Port F bit 4 (ADC4 / TDO) |
| 引脚 10 | PF5 — Port F bit 5 (ADC5 / TDI) |
| 引脚 11 | PF6 — Port F bit 6 (ADC6) |
| 引脚 12 | PF7 — Port F bit 7 (ADC7 / TDI) |
| 引脚 13 | VCC — Digital supply voltage |
| 引脚 14 | GND — Digital ground |
| 引脚 15 | PE2 — Port E bit 2 (HWB - bootloader strap) |
| 引脚 16 | PD0 — Port D bit 0 (OC0B) |
| 引脚 17 | PD1 — Port D bit 1 (OC0A) |
| 引脚 18 | PD2 — Port D bit 2 |
| 引脚 19 | PD3 — Port D bit 3 |
| 引脚 20 | PD4 — Port D bit 4 |
| 引脚 21 | PD5 — Port D bit 5 |
| 引脚 22 | PD6 — Port D bit 6 |
| 引脚 23 | PD7 — Port D bit 7 |
| 引脚 24 | PB0 — Port B bit 0 (OC1A) |
| 引脚 25 | PB1 — Port B bit 1 (OC1B) |
| 引脚 26 | PB2 — Port B bit 2 (OC1C) |
| 引脚 27 | PB3 — Port B bit 3 (OC2A) |
| 引脚 28 | PB4 — Port B bit 4 |
| 引脚 29 | PB5 — Port B bit 5 |
| 引脚 30 | PB6 — Port B bit 6 (XTAL1) |
| 引脚 31 | PB7 — Port B bit 7 (XTAL2) |
| 引脚 32 | VCC — Digital supply voltage |
| 引脚 33 | GND — Digital ground |
| 引脚 34 | PC6 — Port C bit 6 (OC3A) |
| 引脚 35 | PC7 — Port C bit 7 (OC4A) |
| 引脚 36 | PE7 — Port E bit 7 (INT7 / CLKO) |
| 引脚 37 | D- — USB Data minus |
| 引脚 38 | D+ — USB Data plus |
| 引脚 39 | UGND — USB ground |
| 引脚 40 | UVCC — USB supply voltage |
| 引脚 41 | PE4 — Port E bit 4 (INT4) |
| 引脚 42 | PE5 — Port E bit 5 (INT5) |
| 引脚 43 | RESET — Reset input (active low) |
| 引脚 44 | VCC — Digital supply voltage |
典型应用
ATMEGA32U4-AU 适用于 6 应用s: USB HID Keyboards (Mechanical Keyboards), Arduino Leonardo / Micro Compatible Boards, USB MIDI Controllers, USB Data Acquisition Front-Ends, USB-to-UART Bridges (Composite CDC-ACM Devices), Low-Cost Consumer HID Peripherals.
USB HID Keyboards (Mechanical Keyboards)
The ATMEGA32U4-AU is the de-facto silicon choice for custom mechanical keyboards because its on-chip USB 2.0 full-speed device controller eliminates the external FTDI bridge used by older AVR MCUs, allowing a single USB cable to deliver both power and HID data. With 32 KB of self-programming Flash, QMK firmware fits comfortably even on 100+ key matrices, while 2.5 KB of SRAM handles scan-loop state. The 32 programmable I/O lines map directly to 8 rows x 16 columns or larger scanned matrices. Per QMK community practice, the AU TQFP-44 variant is preferred over the QFN-44 MU on hand-soldered Pro Micro clones because the 0.8 mm pitch is feasible with a soldering iron.
推荐
Arduino Leonardo / Micro Compatible Boards
The ATMEGA32U4-AU is the exact MCU on the official Arduino Leonardo and Arduino Micro boards, providing HID, CDC ACM (virtual COM), and keyboard emulation directly through the integrated USB module. Its 16 MHz clock, 32 KB Flash and 2.5 KB SRAM precisely match the Arduino IDE's 'Arduino Leonardo' board definition, allowing sketches to upload via the built-in bootloader over USB without an external programmer. Per Microchip datasheet doc 7766, the bootloader lives in the upper 4 KB of Flash and is invoked by tying PE2/HWB to ground at reset. The 12-channel 10-bit ADC and four timers are sufficient for analog sensors, PWM motor control, and servo projects typical of the Leonardo platform.
推荐
USB MIDI Controllers
USB MIDI class devices map naturally onto the ATMEGA32U4-AU's USB endpoint architecture, where each MIDI endpoint corresponds to one of the eight USB endpoints available on the part. With 32 GPIO and the high PWM count from its 16-bit timer1, the chip can scan up to 64 button / potentiometer / encoder inputs while still transmitting MIDI-over-USB at full-speed 12 Mbps. The 2.5 KB SRAM comfortably holds 64-byte USB buffers plus 256-byte MIDI ring buffers; the 32 KB Flash hosts USB-MIDI class descriptors and event-handler logic. Per the LUFA USB stack (the de-facto firmware library), the ATmega32U4 supports the full class-driver model without external pull-ups because internal pull-ups can be enabled on D-.
推荐
USB Data Acquisition Front-Ends
When the goal is to expose analog measurements over USB without writing an external driver, the ATMEGA32U4-AU's combined 12-channel 10-bit ADC plus USB device capability is a low-cost option: each ADC sample is packetized and delivered as a CDC ACM stream to the host at up to 1 kSps aggregate. The 32 KB Flash hosts the LUFA CDC class driver plus an acquisition loop, while 2.5 KB SRAM buffers bursts. Typical applications include hobby oscilloscope front-ends, USB thermometers, USB strain-gauge readers, and four-channel USB voltmeters. Per Microchip datasheet, the ADC achieves 10 effective bits at 15 kSps and linearity is +/- 2 LSB INL, which is sufficient for indicator-grade USB instrumentation.
推荐
USB-to-UART Bridges (Composite CDC-ACM Devices)
The ATMEGA32U4-AU acts as a low-cost USB-to-UART bridge by enumerating both a generic CDC ACM interface and a HID interface on the same USB device, eliminating FTDI chips in designs that need both a virtual COM port and a control channel. With the on-chip USB device controller supporting 4 endpoints in addition to EP0 control, the part can expose EP1 as a HID control channel and EP2/EP3 as a CDC ACM bulk-in/bulk-out pair. Per the LUFA CDC class driver reference, throughput is sufficient for 921600 bps serial streams with 4 ms latency. The 2.7-5.5V operating range and industrial temperature grade make this bridge suitable for both 3.3V and 5V logic domains.
推荐
Low-Cost Consumer HID Peripherals
The ATMEGA32U4-AU is widely used for low-volume consumer HID products - remote controls, presenter tools, foot pedals, custom mice, and arcade controllers - because the integrated USB stack and Arduino-style tooling reduce firmware cost. Its 32 KB Flash is sufficient for HID class descriptors plus a feature-rich button-handling state machine, while 2.5 KB SRAM supports a 16-deep macro buffer for keyboard-stream features. The 4 timers (two 8-bit, two 16-bit) provide PWM-driven RGB LED control plus input scanning at 1 kHz, matching what USB HID polling requires. Per Microchip, the 32 GPIO can be partitioned into 16 inputs and 16 outputs with no external decoder, keeping the BOM cost of a finished HID peripheral under $3 in volume.
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推荐产品汇总
工程参考数据： ATMEGA32U4-AU ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | ATMEGA32U4-AUR | ATMEGA16U4-AU | ATMEGA32A-AU |
|---|---|---|---|---|
| Package | TQFP-44 (10x10 mm, 0.8 mm pitch) | TQFP-44 (10x10 mm) - same | TQFP-44 (10x10 mm) - same | TQFP-44 (10x10 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 32 KB | 32 KB | 16 KB (-50%) | 32 KB |
| SRAM | 2.5 KB | 2.5 KB | 1.25 KB (-50%) | 2 KB (-20%) |
| Integrated USB | Yes (USB 2.0 FS device) | Yes | Yes | No - external PHY required |
| CPU Speed | 16 MHz | 16 MHz | 16 MHz | 16 MHz |
| 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 |
| Operating Temperature | -40 C to +85 C (industrial) | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| Unit Price (qty 1000) | ~$4.25 | ~$4.10 | ~$3.50 | ~$3.20 |
关键差异点
- Integrated USB 2.0 FS device eliminates external PHY/bridge （对比 ATMEGA32A-AU)
- Identical silicon in a reel-friendly AUR package （对比 ATMEGA32U4-AUR)
- Double the Flash and SRAM versus ATmega16U4 （对比 ATMEGA16U4-AU)
设计说明
Place two 22 ohm source-series resistors close to the USB D+ (pin 38) and D- (pin 37) lines. Add a 1uF X5R decoupling capacitor on UVCC (pin 40) and a 100 nF decoupling capacitor on each VCC (pins 13, 32, 44). Per Microchip layout note, keep the D+/D- traces length-matched and routed as a differential pair over a continuous ground plane; this is mandatory for USB-IF compliance.
Pin PE2 (HWB, pin 15) is the bootloader strap. To enter the USB bootloader, drive PE2 low at reset (tie to GND through a 10 kohm resistor or hold with the host button). If you leave PE2 floating, the chip always boots from address 0x0000 - which is fine for production but blocks field firmware updates without an ISP programmer.
Decouple AVCC (pin 2) with a 100 nF ceramic plus a 10 uF bulk capacitor, and tie AGND (pin 3) to GND at a single point near the MCU. Drive AREF (pin 4) with a 100 nF bypass to AGND. For accurate 10-bit ADC readings, avoid routing digital signals under the analog AVCC/AGND island and place the chip away from switching regulator inductors to keep the analog reference clean.
The ATMEGA32U4-AU has six software-selectable sleep modes (Idle, ADC Noise Reduction, Power-save, Power-down, Standby, Extended Standby). Per the datasheet, Power-down mode drops current to <10 uA at 3.3V with the Watchdog Timer running, making it the right state for USB-suspend-aware HID devices that must wake the host on a key press through an INTx pin.
合规信息
RoHS compliant per Microchip product page. Industrial temperature grade -40C to +85C. Not AEC-Q100 qualified - automotive applications should consider ATmega32U4-MU with extended temperature or migrate to a SAM Cortex-M AEC-Q100 part.