ATSAM3U2CA-AU - 96MHz Cortex-M3 MCU 128KB Flash | Microchip
MPN: ATSAM3U2CA-AU β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.85 | $6.85 |
| 10 | $6.17 | $61.70 |
| 100 | $5.48 | $548.00 |
| 500 | $4.93 | $2,465.00 |
| 1,000 | $4.45 | $4,450.00 |
ATSAM3U2CA-AU Overview
A microcontroller (MCU) is a single integrated circuit that combines a processor core, memory, and peripherals into one chip, forming the lowest tier of the embedded computing hierarchy (MCU -> embedded processor -> SoC -> application processor). The SAM3U family belongs to Atmel's (now Microchip's) ARM-based flash MCU portfolio and is positioned as a high-performance, USB-centric microcontroller for data-intensive embedded systems.
Key features of the ATSAM3U2CA-AU include a High-Speed USB 2.0 Device port with embedded transceiver running at 480 Mbps, a 4 KB dedicated FIFO with up to 7 bidirectional endpoints and dedicated DMA, and a High-Speed MultiMedia Card Interface (HSMCI) supporting SDIO/SD/MMC. These peripherals distinguish the SAM3U series as one of the few Cortex-M3 MCUs with native 480 Mbps USB device capability.
The memory subsystem provides 128-bit wide Flash access with a memory accelerator and dual-bank architecture, sustaining near-zero-wait-state execution at 96 MHz. The ARM Cortex-M3 revision 2.0 core includes a Memory Protection Unit (MPU) and Thumb-2 instruction set, while the peripheral set offers up to 4 USARTs (ISO7816, IrDA, flow control, SPI, and Manchester support), one UART, 2 TWI (I2C-compatible), 1 SPI, and 1 SSC (I2S). Backup features include a VDDBU domain with RTC and 32 backup registers, with an ultra-low-power RTC drawing only 0.6 uA.
Typical applications include high-speed USB data loggers, mass-storage-class devices, audio bridging via I2S/SSC, and industrial gateways requiring SD-card storage. The combination of 480 Mbps USB and HSMCI makes the device well suited to moving large data volumes between USB hosts and removable media.
A key design consideration is supply integrity: the device operates from a 1.62 V to 3.6 V single supply, and the High-Speed USB transceiver requires careful decoupling and controlled routing to pass USB signal-integrity compliance.
This page synthesizes distributor pricing, drop-in same-family alternatives, comparison tables, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATSAM3U2CA-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 ATSAM3U2CA-AU (same form factor and footprint) β differing in Package, USB.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATSAM3U4CA-AU
β Drop-Inπ Reference alternative (not in catalog)
ATSAM3U1CA-AU
β Drop-Inβ In Stock
$12.7 / Unit
View Datasheet βATSAM3U2CA-CU
β Drop-Inπ Reference alternative (not in catalog)
ATSAM3U2CA-AU Maximum Ratings & Electrical Characteristics
| Core Processor | ARM Cortex-M3 revision 2.0 |
| Core Size | 32-bit |
| Maximum Clock Frequency | 96 MHz |
| Flash Memory | 128 KB (128K x 8) |
| SRAM | 36 KB |
| Memory Protection Unit | Yes (MPU) |
| Instruction Set | Thumb-2 |
| USB | USB 2.0 High-Speed Device, 480 Mbps, embedded transceiver, 4 KB FIFO, up to 7 endpoints, dedicated DMA |
| USART/UART | Up to 4 USARTs (ISO7816, IrDA, flow control, SPI, Manchester) + 1 UART |
| Serial Interfaces | 2 x TWI (I2C-compatible), 1 x SPI, 1 x SSC (I2S), 1 x HSMCI (SDIO/SD/MMC) |
| Supply Voltage | 1.62 V to 3.6 V |
| RTC Current (backup domain) | 0.6 uA |
| Backup Registers | 32 registers in VDDBU domain |
| Operating Temperature | -40C to +85C (A grade) |
| Package | 100-LQFP (14 x 14 mm) |
| Mounting Type | Surface Mount |
| Life Cycle Stage | ACTIVE |
ATSAM3U2CA-AU 100-lqfp (14 x 14 mm) Pin Configuration Guide
Pin configuration for ATSAM3U2CA-AU (100-lqfp (14 x 14 mm) package). This digital IC includes GPIO, communication interfaces (UART, SPI, I2C), and power pins. Refer to the manufacturer datasheet for alternate pin functions and configuration options. Essential for embedded system design and PCB layout.
No detailed pinout data available for ATSAM3U2CA-AU.
Refer to the datasheet for full pin configuration.
Typical Applications
ATSAM3U2CA-AU is suitable for 6 applications: High-Speed USB Data Acquisition, SD Card Data Logger with Mass Storage, USB Audio Bridging, Industrial Communication Gateway, Portable Battery-Powered Instruments, Embedded Host-to-Device Media Transfer.
High-Speed USB Data Acquisition
The ATSAM3U2CA-AU's native USB 2.0 High-Speed Device port at 480 Mbps, backed by a 4 KB endpoint FIFO and dedicated DMA, allows streaming sensor or instrument data to a PC host at rates that Full-Speed-only (12 Mbps) Cortex-M MCUs cannot reach. Typical designs place the MCU between an ADC or sensor front end and the USB connector, with the HSMCI or SRAM acting as an intermediate buffer for burst absorption. The 128-bit wide, accelerated Flash sustains 96 MHz core execution while DMA moves data off the CPU path. The result is a single-chip USB instrument front end without external USB controller or FIFO chips, reducing BOM cost and board area.
Recommended
SD Card Data Logger with Mass Storage
The High-Speed MCI (HSMCI) peripheral supports SDIO/SD/MMC cards, and paired with the 480 Mbps USB Device port the ATSAM3U2CA-AU can both write logs to removable media and present the same card as a USB mass-storage device to a host. The dedicated DMA controller keeps FAT-filesystem writes off the CPU, and the 36 KB SRAM provides sector buffers and ring buffers for sustained logging. The 0.6 uA RTC in the VDDBU backup domain with 32 backup registers enables timestamped, battery-backed logging that wakes on alarm. This architecture suits industrial recorders, vehicle black-box loggers, and portable diagnostic instruments where data must survive power cycles.
Recommended
USB Audio Bridging
The SSC peripheral provides I2S timing, and combined with the High-Speed USB Device port the ATSAM3U2CA-AU implements USB audio class streaming between a PC and an external audio codec. High-Speed USB removes the bandwidth ceiling that constrains Full-Speed audio devices, supporting higher sample rates and channel counts within the 480 Mbps envelope and 4 KB endpoint FIFO. DMA-driven I2S transfers maintain glitch-free playback while the 96 MHz Cortex-M3 handles USB enumeration, volume control, and protocol processing. Designers should budget SRAM carefully, since audio endpoint buffers plus descriptors consume a meaningful fraction of the 36 KB available.
Recommended
Industrial Communication Gateway
With up to 4 USARTs supporting ISO7816, IrDA, hardware flow control, SPI, and Manchester coding, plus 2 TWI buses, 1 SPI, and 1 UART, the ATSAM3U2CA-AU aggregates multiple field-bus interfaces and forwards data over High-Speed USB or to SD storage. This makes it effective as a protocol-conversion gateway in factory automation, translating legacy serial links into modern USB or removable-media outputs. The Memory Protection Unit supports partitioned firmware images, and the wide Flash bus keeps protocol stack execution responsive at 96 MHz. Multi-interface designs should verify peripheral multiplexing conflicts in the datasheet signal tables before pin assignment.
Recommended
Portable Battery-Powered Instruments
The ATSAM3U2CA-AU supports a 1.62 V to 3.6 V single supply and provides multiple low-power modes, with the backup RTC drawing only 0.6 uA for timekeeping between measurements. Portable instruments benefit from waking on RTC alarm or external event, sampling through the analog and serial peripherals, storing results to SD card via HSMCI, and resuming full USB operation when docked. The 32 backup registers preserve state across the main-supply shutdown without external non-volatile memory. Firmware should structure the application so USB enumeration and HSMCI clocks are gated in sleep, since the 480 Mbps transceiver is a major active-mode current contributor.
Recommended
Embedded Host-to-Device Media Transfer
Because the ATSAM3U2CA-AU couples HSMCI (SDIO/SD/MMC) with a High-Speed USB Device port and dual-bank accelerated Flash, it serves as a compact bridge that reads content from removable media and streams it to a USB host at up to 480 Mbps. Use cases include photo kiosks, badge readers, and music players that ingest SD cards and deliver data to PCs or docking stations. The 4 KB FIFO with up to 7 bidirectional endpoints supports concurrent control and bulk transfers, while dedicated DMA sustains throughput without core intervention. Firmware must manage FAT access latency so that USB bulk endpoints do not NAK excessively during card writes.
Recommended
Recommended Products Summary
Engineering reference data for ATSAM3U2CA-AU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAM3U4CA-AU | ATSAM3U1CA-AU | ATSAM3U2CA-CU |
|---|---|---|---|---|
| Package | 100-LQFP (14x14) | 100-LQFP (14x14) - same | 100-LQFP (14x14) - same | 100-LQFP (14x14) - same |
| Brand | Microchip Technology (Atmel) | Microchip Technology | Microchip Technology | Microchip Technology |
| Core / Max Clock | Cortex-M3, 96 MHz | Cortex-M3, 96 MHz | Cortex-M3, 96 MHz | Cortex-M3, 96 MHz |
| Flash | 128 KB | 256 KB (dual-bank) | 64 KB | 128 KB |
| SRAM | 36 KB | 52 KB | 16 KB | 36 KB |
| USB | HS Device 480 Mbps | HS Device 480 Mbps | HS Device 480 Mbps | HS Device 480 Mbps |
| HSMCI (SDIO/SD/MMC) | Yes | Yes | Yes | Yes |
| Pin Compatibility | Reference (100-LQFP) | Pin-to-pin identical | Pin-to-pin identical | Pin-to-pin identical |
Key Differentiators
- Native 480 Mbps High-Speed USB Device with embedded transceiver (vs TM4C1237E6PZI)
- Pin-compatible memory scaling within the family (vs ATSAM3U4CA-AU)
- SD-card interface plus USB in one chip (vs ATSAM3U1CA-AU)
Design Notes
The embedded High-Speed (480 Mbps) USB transceiver means USB D+/D- traces leave the chip directly. Route as a 90-ohm differential pair with length matching within 1.5 mm, place the USB connector within 50 mm of the MCU where possible, and follow the datasheet's recommended series/termination components. Poor HS USB routing is the most common cause of eye-diagram failures on SAM3U boards - at 480 Mbps there is no margin for stubs or unmatched pairs. Verify with a USB compliance test fixture before production.
The device runs from a single 1.62 V to 3.6 V supply, but the High-Speed USB transceiver and Flash erase/write operations create significant transient current. Provide at least one 10 uF bulk capacitor plus multiple 0.1 uF ceramics at VDDIO/VDDCORE/VDDUSB pins, placed within 2 mm of each supply pin. If connecting VDDBU to a coin cell for the 0.6 uA RTC backup domain, isolate it with an RC or diode-OR scheme from the main 3.3 V rail per the datasheet power-supply section.
Peripheral signal multiplexing is the top integration pitfall: up to 4 USARTs, 2 TWI, SPI, SSC, and HSMCI share the 100 pins, and not all functions are simultaneously available. Build the pin-assignment matrix from the datasheet peripheral multiplexing tables before layout - changing one USART pin late can cascade into HSMCI conflicts. Also note the 128-bit wide Flash accelerator requires code aligned for dual-bank operation if executing while programming the other bank; misuse stalls the 96 MHz core with wait states.
The 100-LQFP (14x14) has 0.5 mm pitch leads; specify a solder-mask-defined or non-solder-mask-defined pad per IPC recommendations and use a 1:1 stencil with 100-120 um laser-cut apertures to avoid bridging. No exposed pad exists on this package, so thermal dissipation relies on trace and via spreading - adequate for the typical 100-200 mW active dissipation, but verify junction temperature with your own estimated power figure for continuous USB operation.
Compliance Information
RoHS/REACH/lead-free status was not present in the provided verified web data. The AU ordering suffix conventionally denotes Atmel/Microchip green (RoHS-compliant, lead-free) packaging, but this must be confirmed against the official Microchip product page before use in compliance documentation.