ATSAM3S2BA-AU - 64MHz Cortex-M3 MCU 128KB Flash | Microchip
MPN: ATSAM3S2BA-AU β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.83 | $5.83 |
| 10 | $5.54 | $55.40 |
| 100 | $5.25 | $525.00 |
| 500 | $4.95 | $2,475.00 |
| 1,000 | $4.66 | $4,660.00 |
ATSAM3S2BA-AU Overview
A microcontroller unit (MCU) is a single integrated circuit that combines a processor core, memory, and programmable peripherals into one chip, forming the lowest layer of the embedded-system hierarchy above discrete logic and below application processors and systems-on-chip. The SAM3S family belongs to Microchip's SMART ARM-based MCU portfolio, targeting cost-sensitive 32-bit industrial and consumer designs.
Key features of the ATSAM3S2BA-AU include the ARM Cortex-M3 revision 2.0 core with Thumb-2 instruction set and Memory Protection Unit (MPU), a 128-bit-wide Flash memory interface with an accelerator for efficient 64 MHz execution, and pin-to-pin compatibility with the earlier AT91SAM7S series in 48- and 64-pin versions, which simplifies migration of legacy designs.
Technical depth: the device integrates typical SAM3S peripherals such as USARTs, SPI, TWI (I2C), PWM channels, an ADC, USB 2.0 full-speed device port, and a flexible clock tree with fast RC oscillators and crystal inputs. The suffix 'AU' identifies the 64-pin LQFP, industrial temperature range, and lead-free tray packaging, making the part suited to standard reflow assembly.
Typical applications include industrial control panels, battery-charged portable instruments, consumer appliances, motor-control front ends, and USB-connected sensor interfaces, where 128 KB of Flash and rich connectivity cover mid-complexity firmware without external memory.
Design consideration: verify supply-voltage decoupling on VDDCORE and VDDIO domains and confirm Flash capacity against growth headroom, since larger SAM3S variants such as the ATSAM3S4BA share the same footprint for upward migration.
This page synthesizes distributor pricing, drop-in alternatives, comparison data, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATSAM3S2BA-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 ATSAM3S2BA-AU (same form factor and footprint) β differing in RoHS Status, Peripherals, Core Processor, Package, Flash Memory.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATSAM3S4BA-AU
β Drop-Inπ Reference alternative (not in catalog)
ATSAM3S1BA-AU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATSAM3S8BA-AU
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$6.4 / Unit
View Datasheet βATSAM3SD8BA-AU
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$8.05 / Unit
View Datasheet βATSAM3S2BA-AU Maximum Ratings & Electrical Characteristics
| Core Processor | ARM Cortex-M3 revision 2.0 |
| Core Size | 32-bit |
| Maximum Clock Frequency | 64 MHz |
| Flash Memory | 128 KB (128K x 8) |
| SRAM | 32 KB |
| Instruction Set | Thumb-2 |
| Memory Protection | MPU (Memory Protection Unit) |
| Supply Voltage | 1.8 V / 3.3 V |
| Package | 64-LQFP (10x10 mm) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (industrial) |
| Series | SAM3S |
| Compatibility | Pin-to-pin compatible with AT91SAM7S (48- and 64-pin versions) |
| USB | USB 2.0 full-speed device |
| Connectivity Peripherals | USART, SPI, TWI (I2C), PWM, ADC |
| RoHS Status | RoHS Compliant |
| Packaging | Tray |
ATSAM3S2BA-AU Pin Configuration
| Pin 1 | VDDIN β Internal regulator input supply |
| Pin 2 | VDDOUT β Internal regulator output (1.8 V core supply) |
| Pin 3 | GND β Ground |
| Pin 4 | PA0 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 5 | PA1 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 6 | PA2 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 7 | PA3 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 8 | PA4 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 9 | PA5 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 10 | PA6 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 11 | PA7 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 12 | PA8 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 13 | PA9 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 14 | PA10 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 15 | PA11 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 16 | PA12 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 17 | PA13 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 18 | PA14 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 19 | PA15 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 20 | PA16 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 21 | PA17 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 22 | PA18 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 23 | PA19 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 24 | PA20 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 25 | PA21 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 26 | PA22 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 27 | PA23 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 28 | PA24 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 29 | PA25 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 30 | PA26 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 31 | PA27 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 32 | PA28 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 33 | VDDCORE β Core power supply |
| Pin 34 | GND β Ground |
| Pin 35 | PA29 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 36 | PA30 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 37 | PA31 β Parallel I/O port A, multiplexed peripheral functions |
| Pin 38 | PB0 β Parallel I/O port B, multiplexed peripheral functions |
| Pin 39 | PB1 β Parallel I/O port B, multiplexed peripheral functions |
| Pin 40 | PB2 β Parallel I/O port B, multiplexed peripheral functions |
| Pin 41 | PB3 β Parallel I/O port B, multiplexed peripheral functions |
| Pin 42 | PB4 β Parallel I/O port B, multiplexed peripheral functions |
| Pin 43 | PB5 β Parallel I/O port B, multiplexed peripheral functions |
| Pin 44 | PB6 β Parallel I/O port B, multiplexed peripheral functions |
| Pin 45 | PB7 β Parallel I/O port B, multiplexed peripheral functions |
| Pin 46 | PB8 β Parallel I/O port B, multiplexed peripheral functions |
| Pin 47 | PB9 β Parallel I/O port B, multiplexed peripheral functions |
| Pin 48 | PB10 β Parallel I/O port B, multiplexed peripheral functions |
| Pin 49 | PB11 β Parallel I/O port B, multiplexed peripheral functions |
| Pin 50 | PB12 β Parallel I/O port B, multiplexed peripheral functions |
| Pin 51 | PB13 β Parallel I/O port B, multiplexed peripheral functions |
| Pin 52 | VDDIO β I/O power supply |
| Pin 53 | GND β Ground |
| Pin 54 | VDDUTMI β USB transceiver power supply |
| Pin 55 | XIN β Main crystal oscillator input |
| Pin 56 | XOUT β Main crystal oscillator output |
| Pin 57 | VDDPLL β PLL power supply |
| Pin 58 | XIN32 β 32.768 kHz slow crystal oscillator input |
| Pin 59 | XOUT32 β 32.768 kHz slow crystal oscillator output |
| Pin 60 | NRST β Bidirectional reset pin with internal pull-up |
| Pin 61 | ERASE β Flash erase pin (assert to erase Flash content) |
| Pin 62 | TST β Test mode pin (ground in normal operation) |
| Pin 63 | VDDIO β I/O power supply |
| Pin 64 | VDDIO β I/O power supply |
Typical Applications
ATSAM3S2BA-AU is suitable for 6 applications: Industrial Control Panels, USB-Connected Portable Instruments, Motor Control Front Ends, Smart Metering and Energy Monitoring, Building Automation and Access Control, Consumer Appliance Control Boards.
Industrial Control Panels
The ATSAM3S2BA-AU fits industrial panel controllers where its -40C to +85C industrial temperature rating and MPU-protected Cortex-M3 core deliver dependable operation near motors and drives. Its USART, SPI, and TWI peripherals connect HMIs, RS-485 transceivers, and EEPROM configuration stores, while roughly 45 GPIO on the 64-pin LQFP drive relays, keypads, and indicators directly. The 128 KB Flash accelerator sustains zero-wait-state execution at 64 MHz, keeping control-loop jitter low. Designers typically run an RTOS with the MPU partitioning safety-critical tasks; pin compatibility with AT91SAM7S64/128 lets legacy panels upgrade without PCB changes.
Recommended
USB-Connected Portable Instruments
Handheld meters, dataloggers, and battery instruments benefit from the ATSAM3S2BA-AU's USB 2.0 full-speed device port for charging negotiation and PC connectivity, combined with a low-power architecture that stretches battery life. The 1.8 V/3.3 V supply operation matches single-cell Li-Ion rails via an LDO, and fast RC oscillators allow rapid wake-up from low-power modes for interrupt-driven sampling. The 128-bit-wide Flash eliminates stall cycles during 64 MHz execution, giving consistent ADC-sampling performance, while the industrial temperature range supports outdoor test equipment. Its SAM3S family scalability means firmware can later move to the 256 KB ATSAM3S4BA on the same board.
Recommended
Motor Control Front Ends
The ATSAM3S2BA-AU serves as the supervisory controller in motor-drive systems, generating PWM outputs for inverter bridges and reading current/voltage feedback through its ADC while the power stage is driven by dedicated MOSFET drivers. At 64 MHz, the Cortex-M3 executes field-oriented-control housekeeping, protection sequencing, and communication to a host PLC over USART or TWI. The MPU isolates fault-handling firmware from the main loop, improving robustness under transient conditions. Because the device is 5 V-tolerant on appropriately configured I/O domains and operates from 3.3 V, it interfaces cleanly with gate-driver logic, and the 64-LQFP footprint leaves routing channels for gate signals.
Recommended
Smart Metering and Energy Monitoring
Energy meters and submetering modules use the ATSAM3S2BA-AU's ADC for voltage/current sampling, its USART for communication with metering front-ends or RF modules, and the 32 KB SRAM for buffer management during burst data logging. The device's deterministic 64 MHz core processes RMS calculations and tariff logic while the USB device port supports optical-probe reading per utility service workflows. Industrial temperature operation from -40C to +85C covers outdoor meter enclosures, and the MPU prevents tampering code from corrupting measurement firmware. The 128 KB Flash stores firmware, calibration tables, and a bootloader for remote field updates without external memory.
Recommended
Building Automation and Access Control
Door controllers, HVAC zone boards, and lighting control nodes leverage the ATSAM3S2BA-AU's TWI (I2C) and USART ports to network with sensors and actuators, while PWM channels drive dimming outputs or damper servos. The Cortex-M3's Thumb-2 code density keeps protocol stacks (Modbus RTU over USART, for example) comfortably inside 128 KB Flash alongside application logic. The 64-pin LQFP exposes enough GPIO for Wiegand reader inputs, relay outputs, and tamper switches, and the MPU assists in partitioning audit-logging code. Family pin compatibility allows a single PCB to be populated with the 64 KB ATSAM3S1BA-AU for basic nodes or the ATSAM3S4BA-AU for gateway-grade units.
Recommended
Consumer Appliance Control Boards
Appliance main boards - coffee machines, air purifiers, small kitchen equipment - adopt the ATSAM3S2BA-AU for its balance of 64 MHz processing, USB service port, and low BOM cost at the ~$5.83 unit-price level (as of 2026-09-19). The ADC reads user-interface potentiometers and NTC sensors, PWM drives displays, backlight, or heater Triac firing logic via optocouplers, and the TWI bus manages touch controllers and EEPROMs. Compliance-focused procurement benefits from the RoHS-compliant, lead-free 'AU' package in standard tray packing for high-volume SMT lines. Upgradability to the pin-compatible 256 KB ATSAM3S4BA-AU protects the platform when feature-rich firmware revisions arrive.
Recommended
Recommended Products Summary
Engineering reference data for ATSAM3S2BA-AU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAM3S4BA-AU | ATSAM3S1BA-AU | ATSAM3S8BA-AU | ATSAM3SD8BA-AU |
|---|---|---|---|---|---|
| Package | 64-LQFP (10x10 mm) | 64-LQFP (10x10 mm) - same | 64-LQFP (10x10 mm) - same | 64-LQFP (10x10 mm) - same | 64-LQFP (10x10 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Core | ARM Cortex-M3, 64 MHz | ARM Cortex-M3, 64 MHz | ARM Cortex-M3, 64 MHz | ARM Cortex-M3, 64 MHz | ARM Cortex-M3, 64 MHz |
| Flash Memory | 128 KB | 256 KB | 64 KB | 512 KB | 512 KB |
| SRAM | 32 KB | 48 KB | 16 KB | 64 KB | 96 KB |
| USB | Full-speed device | Full-speed device | Full-speed device | Full-speed device | High-speed device |
Key Differentiators
- Balanced 128 KB Flash / 32 KB SRAM memory point (vs ATSAM3S1BA-AU)
- Cost-effective mid-memory position with upgrade path (vs ATSAM3S4BA-AU)
- Legacy migration compatibility (vs ATSAM3S8BA-AU)
- Trade-off: standard full-speed USB only (vs ATSAM3SD8BA-AU)
Design Notes
The SAM3S uses a dual-rail power architecture: VDDIN accepts the 3.3 V main supply and feeds the on-chip regulator whose VDDOUT output powers VDDCORE. Place a 1.3 uF (typical per datasheet family recommendation) or [DATA_NEEDED: exact datasheet value] capacitor on VDDOUT and decouple every VDDIO pin with 100 nF ceramics placed within 2 mm of the pins. Do not drive VDDOUT externally - it is a regulator output. If the on-chip regulator is bypassed in low-power designs, follow the datasheet VDDCORE external-supply procedure exactly.
ERASE and TST pins control security/test states: tie ERASE to GND through the recommended resistor and hold TST low in production builds; floating these pins can unintentionally erase Flash or enter test mode during ESD events. Route NRST as a short protected trace with the internal pull-up and optional external 100 nF, avoiding proximity to switching nets. Keep the XIN/XOUT crystal loop compact with guard ground, and place VDDUTMI USB-rail decoupling close to pin 54 for signal-integrity on the USB DP/DM pair.
Do not assume the ATSAM3S2BA-AU and 48-pin ATSAM3S2AA-AU are interchangeable - they share the same die family but differ in package (64-LQFP vs 48-LQFP), so verify the board footprint before substitution. When migrating firmware from AT91SAM7S parts, remember the SAM3S register map and Flash controller differ despite pin-to-pin compatibility. Also plan Flash wear: this generation uses single-plane Flash, so avoid frequent in-application rewrites of the same sectors; use external EEPROM for high-cycle data logging.
On the USB full-speed port, keep the DP/DM traces matched in length (within 2 mm), routed 90-ohm differential over a continuous ground reference, with series termination per the datasheet USB layout guidance. For ADC accuracy, provide a clean analog supply domain, add an RC filter on VREF-relevant inputs, and route high-dV/dt PWM traces away from analog channels. Since the 64 MHz system clock derives from PLL, excessive ripple on VDDPLL will show up as clock jitter - use a dedicated ferrite and decoupling network.
Compliance Information
RoHS compliant and lead-free per distributor listings for the 'AU' suffix (LQFP, tray). REACH, halogen-free, and conflict-minerals status should be confirmed via the Microchip environmental compliance portal.