ATXMEGA128A4U-AUR - 8/16-bit AVR XMEGA MCU, 128KB Flash, 44-TQFP | Microchip
MPN: ATXMEGA128A4U-AUR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.16 | $8.16 |
| 10 | $7.51 | $75.10 |
| 100 | $6.78 | $678.00 |
| 500 | $6.12 | $3,060.00 |
| 1,000 | $5.45 | $5,450.00 |
ATXMEGA128A4U-AUR Overview
An AVR XMEGA microcontroller is a high-performance 8/16-bit RISC MCU family from Microchip (originally Atmel) targeting low-power embedded designs that need more peripherals than classic ATmega parts but still rely on the AVR core rather than ARM Cortex-M. Within the broader taxonomy it sits as an MCU -> microcontroller -> embedded controller -> semiconductor. The "XMEGA" name signals an upgraded peripheral set including hardware crypto, DES, AES, and 12-bit ADC/DAC blocks, plus the unified event system for inter-peripheral signalling without CPU intervention.
Key differentiating specifications include the 128 KB Flash (64K x 16 organization), 8 KB SRAM, 2 KB EEPROM, 12-bit ADC and DAC peripherals, full-speed USB 2.0 with device and host capability, and an operating voltage range of 1.6 V to 3.6 V. The device supports both 1.8 V and 2.5 V/3.3 V operation, allowing direct attachment to Li-ion, NiMH, or 3.3 V regulated rails without level shifters. An external bus interface provides address/data expansion for external memories or graphics controllers.
Architecturally, the ATXMEGA128A4U-AUR uses the Atmel AVR enhanced RISC core with 32 working registers directly connected to the ALU, achieving single-cycle execution. The integrated DMA controller can move data between peripherals and memory without CPU involvement, freeing the core for application code. The 8-channel event system routes peripheral events (timer overflows, ADC conversions, I/O edges) to other peripherals, enabling deterministic hardware-software co-design. The USB 2.0 full-speed transceiver is on-die, requiring only an external pull-up resistor and bypass capacitors.
Typical applications include USB HID devices, USB mass storage controllers, industrial sensor hubs with USB diagnostics, low-power data loggers, motor control front ends, and battery-powered handheld instruments. The combination of low active current, deep sleep modes down to sub-microamp, and integrated USB makes it particularly attractive for USB-powered sensor peripherals. Designers also use the A4U family in consumer audio accessories where 12-bit DAC and PWM drive suit headphone or intercom front ends.
When designing with this part, budget for the 44-pin TQFP footprint and ensure the USB D+/D- traces are 90 ohm differential-matched. Boot loader and PDI programming share the same pins, so reserve access for in-system programming via the Atmel-ICE or AVR Dragon. The integrated 32 kHz internal RC oscillator can replace an external crystal in space-constrained designs but trades accuracy for BOM savings.
This page synthesizes distributor pricing, USB-enabled drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for ATXMEGA128A4U-AUR — 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 ATXMEGA128A4U-AUR (same form factor and footprint) — differing in Core Architecture, Program Memory (Flash), ADC, EEPROM, SRAM.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATXMEGA128A4U-AU
✅ Drop-In📋 Reference alternative (not in catalog)
ATXMEGA64A4U-AUR
✅ Drop-In📋 Reference alternative (not in catalog)
ATXMEGA128A4U-CU
✅ Drop-In📋 Reference alternative (not in catalog)
ATXMEGA128A3U-AUR
✅ Drop-In📋 Reference alternative (not in catalog)
ATXMEGA32A4U-AU
✅ Drop-In📋 Reference alternative (not in catalog)
ATXMEGA128A4U-AUR Maximum Ratings & Electrical Characteristics
| Core Architecture | AVR XMEGA 8/16-bit RISC |
| Family | ATxmega A4U |
| Program Memory (Flash) | 128 KB (64K x 16) |
| Boot Code Section | 4 KB |
| SRAM | 8 KB |
| EEPROM | 2 KB (2048 bytes) |
| Maximum CPU Speed | 32 MHz |
| Throughput | 32 MIPS |
| Operating Voltage | 1.6 V to 3.6 V |
| ADC Resolution | 12-bit |
| DAC Resolution | 12-bit |
| USB Interface | USB 2.0 Full-Speed Device/Host |
| DMA Channels | 4 |
| Event System Channels | 8 |
| External Bus Interface | Yes |
| Package | 44-pin TQFP (10x10 mm) |
| Operating Temperature | -40C to +85C (Industrial) |
| Mounting Type | Surface Mount |
| MSL Level | 3 (168 hours) |
| RoHS Status | Compliant |
ATXMEGA128A4U-AUR Pin Configuration
| Pin 1 | VCC — Power supply (1.6 V to 3.6 V) |
| Pin 2 | PA0 — GPIO / ADC0 positive input |
| Pin 3 | PA1 — GPIO / ADC0 negative input |
| Pin 4 | PA2 — GPIO / ADC1 positive input |
| Pin 5 | PA3 — GPIO / ADC1 negative input |
| Pin 6 | PA4 — GPIO / ADC2 positive input |
| Pin 7 | PA5 — GPIO / ADC2 negative input |
| Pin 8 | PA6 — GPIO / ADC3 positive input |
| Pin 9 | PA7 — GPIO / ADC3 negative input |
| Pin 10 | GND — Ground |
| Pin 11 | PB0 — GPIO / ADC4 positive input |
| Pin 12 | PB1 — GPIO / ADC4 negative input |
| Pin 13 | PB2 — GPIO / ADC5 positive input |
| Pin 14 | PB3 — GPIO / ADC5 negative input |
| Pin 15 | VCC — Power supply |
| Pin 16 | GND — Ground |
| Pin 17 | PC0 — GPIO / SCL (TWI) |
| Pin 18 | PC1 — GPIO / SDA (TWI) |
| Pin 19 | PC2 — GPIO / USART0 RXD |
| Pin 20 | PC3 — GPIO / USART0 TXD |
| Pin 21 | PC4 — GPIO / USART0 XCK |
| Pin 22 | PC5 — GPIO |
| Pin 23 | PC6 — GPIO |
| Pin 24 | PC7 — GPIO |
| Pin 25 | GND — Ground |
| Pin 26 | VCC — Power supply |
| Pin 27 | PD0 — GPIO / USART1 RXD |
| Pin 28 | PD1 — GPIO / USART1 TXD |
| Pin 29 | PD2 — GPIO / XCK1 |
| Pin 30 | PD3 — GPIO |
| Pin 31 | PD4 — GPIO |
| Pin 32 | PD5 — GPIO |
| Pin 33 | PD6 — GPIO |
| Pin 34 | PD7 — GPIO |
| Pin 35 | PE0 — GPIO / OC0A (Timer 0) |
| Pin 36 | PE1 — GPIO / OC0B |
| Pin 37 | PE2 — GPIO / OC0C |
| Pin 38 | PE3 — GPIO / OC1A |
| Pin 39 | USB_VCC — USB 3.3 V regulator output / pad |
| Pin 40 | USB_DP — USB D+ differential data |
| Pin 41 | USB_DM — USB D- differential data |
| Pin 42 | PDI_CLK — PDI programming clock / RESET |
| Pin 43 | PDI_DATA — PDI programming data |
| Pin 44 | AVCC — Analog power supply (must be tied to VCC) |
Typical Applications
ATXMEGA128A4U-AUR is suitable for 6 applications: USB HID Peripheral Device, Industrial USB Sensor Hub, Low-Power Data Logger, USB Audio Streaming Accessory, USB Mass Storage Controller, Battery-Powered Handheld Instrument.
USB HID Peripheral Device
The ATXMEGA128A4U-AUR is purpose-built for USB HID peripherals such as keyboards, mice, custom input controllers, and industrial control panels. Its integrated USB 2.0 Full-Speed device controller with on-die transceiver eliminates external PHY components, reducing BOM and board area. The 128 KB Flash accommodates full HID descriptor tables plus application code, while the 12-bit ADC reads analog inputs for gaming peripherals or sensor interfaces. Typical implementation places the MCU directly on the USB bus with 5 V tolerant I/O via external resistor dividers and routes D+/D- as a 90 ohm differential pair. The 32 MIPS throughput ensures low-latency HID report generation below 1 ms.
Recommended
Industrial USB Sensor Hub
The ATXMEGA128A4U-AUR suits industrial sensor hubs that aggregate multiple analog and digital sensors and expose the readings over USB to a host PC. The 12-bit ADC samples analog sensor outputs while the DMA controller transfers data to the USB endpoint without CPU intervention, freeing the 32 MIPS core for filtering and protocol handling. The 1.6 V to 3.6 V operating range supports 3.3 V regulated industrial rails. Compared to discrete sensor-to-USB bridges, the integrated MCU plus USB simplifies the BOM and provides 128 KB Flash for vendor-specific USB descriptors, calibration tables, and command interpreters.
Recommended
Low-Power Data Logger
The ATXMEGA128A4U-AUR delivers battery-friendly operation for portable data loggers that record sensor data to internal Flash or EEPROM and download via USB. The deep-sleep modes consume sub-microamp current while preserving the RTC and event system for periodic wake-ups, and the 32 MHz burst mode delivers 32 MIPS only during active sampling windows. The 128 KB Flash stores thousands of timestamped samples while 8 KB SRAM buffers bursts before compression. Typical loggers use a CR2032 coin cell or USB bus power and survive weeks of unattended logging with duty-cycled ADC sampling at 1 Hz.
Recommended
USB Audio Streaming Accessory
The ATXMEGA128A4U-AUR serves in USB audio streaming accessories such as USB-to-I2S bridges, headset adapters, and microphone arrays. Its 12-bit DAC generates headphone or line outputs while the USB Full-Speed endpoint streams audio at 48 kHz mono or 16 kHz stereo. The DMA controller moves audio samples between USB and DAC buffers without CPU intervention, eliminating jitter artifacts. Designers add a low-noise LDO such as an ADP or TPS7A series regulator to supply the clean analog rail to the DAC, isolating it from the noisy digital 3.3 V supply used by the MCU core.
Recommended
USB Mass Storage Controller
The ATXMEGA128A4U-AUR functions as a USB mass storage controller when paired with an external SD card or NAND Flash via the external bus interface. The DMA controller transfers blocks between the USB endpoint and the memory device at sustained Full-Speed rates above 800 KB/s, while the 8 KB SRAM caches sector writes for wear leveling. The 128 KB Flash holds the SCSI transparent command set plus FAT file system layer. Implementation typically adds a level shifter for the SD card and a 3.3 V LDO; the result is a compact, low-power USB stick-style device with custom firmware for secure or encrypted storage.
Recommended
Battery-Powered Handheld Instrument
The ATXMEGA128A4U-AUR powers handheld measurement instruments such as digital multimeters, temperature probes, and field service tools where battery life and USB charging are both required. Its wide 1.6 V to 3.6 V range accepts a single-cell Li-ion directly without a boost converter, and the USB interface provides charging plus data upload over the same connector. The 12-bit ADC drives the measurement front end with 1 LSB resolution per millivolt, while the 2 KB EEPROM stores calibration constants across battery cycles. Designers pair it with a low-power op-amp such as the AD8237ARMZ for sensor signal conditioning and a TI BQ-series fuel gauge for state-of-charge reporting.
Recommended
Recommended Products Summary
Engineering reference data for ATXMEGA128A4U-AUR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATXMEGA128A4U-AU | ATXMEGA64A4U-AUR | ATXMEGA128A4U-CU | ATXMEGA128A3U-AUR | ATXMEGA32A4U-AU |
|---|---|---|---|---|---|---|
| Package | 44-TQFP (10x10 mm) | 44-TQFP (10x10 mm) - same | 44-TQFP (10x10 mm) - same | 49-VFBGA - smaller footprint | 64-TQFP - larger package | 44-TQFP (10x10 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 128 KB | 128 KB | 64 KB (-50%) | 128 KB | 128 KB | 32 KB (-75%) |
| SRAM | 8 KB | 8 KB | 8 KB | 8 KB | 8 KB | 8 KB |
| EEPROM | 2 KB | 2 KB | 2 KB | 2 KB | 2 KB | 2 KB |
| USB Interface | USB 2.0 FS Device/Host | USB 2.0 FS Device/Host | USB 2.0 FS Device/Host | USB 2.0 FS Device/Host | No USB | USB 2.0 FS Device/Host |
| Operating Voltage | 1.6 V to 3.6 V | 1.6 V to 3.6 V | 1.6 V to 3.6 V | 1.6 V to 3.6 V | 1.6 V to 3.6 V | 1.6 V to 3.6 V |
| Max CPU Speed | 32 MHz (32 MIPS) | 32 MHz (32 MIPS) | 32 MHz (32 MIPS) | 32 MHz (32 MIPS) | 32 MHz (32 MIPS) | 32 MHz (32 MIPS) |
Key Differentiators
- Integrated USB 2.0 Full-Speed with on-die PHY in 44-TQFP (vs ATXMEGA128A3U-AUR)
- Tape-and-reel packaging for automated SMT assembly (vs ATXMEGA128A4U-AU)
- Largest Flash in the 44-pin A4U family (vs ATXMEGA64A4U-AUR)
Design Notes
Route USB D+ and D- as a 90 ohm differential pair with matched length within 150 mil, keeping the pair away from clock traces and switching power nodes. Place the 47 nF USB VBUS decoupling capacitor as close as possible to the USB_VCC pin. Maintain a continuous ground plane beneath the entire USB signal path to control impedance and suppress common-mode noise. Source: Microchip ATxmega128A4U datasheet and USB 2.0 specification.
Decouple each VCC/GND pin pair with a 100 nF ceramic plus 4.7 uF bulk capacitor within 3 mm of the package. AVCC must be tied to VCC externally even if the ADC is unused, and a ferrite bead between VCC and AVCC is recommended when the ADC is active. The internal 1.6 V Brown-Out Detector (BOD) protects Flash during undervoltage events - configure it via fuses for the lowest acceptable VCC of the application. Source: Microchip ATxmega128A4U datasheet, section "Power Management".
Do not confuse the ATXMEGA128A4U-AUR (44-TQFP, with USB) with the ATXMEGA128A3U-AUR (64-TQFP, no USB). The PDI programming pins are shared with the reset pin; an external reset capacitor larger than 10 nF may interfere with PDI timing. The XMEGA core requires the AVR-GCC-XMEGA toolchain or Atmel Studio 7 - standard AVR-GCC for ATmega parts will not compile XMEGA-specific peripheral headers. Source: Microchip ATxmega128A4U datasheet, section "Programming and Debug Interfaces".
Compliance Information
RoHS and REACH compliant per Microchip product page and DigiKey/Mouser listings. MSL-3 (168 hours) moisture sensitivity rating. Industrial temperature grade -40C to +85C. Not AEC-Q100 qualified - use SAM or automotive-grade MCU for vehicle applications.