ATSAM3S4AA-MU - 64MHz Cortex-M3 256KB Flash MCU | Microchip
MPN: ATSAM3S4AA-MU β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.61 | $5.61 |
| 10 | $5.1 | $51.00 |
| 100 | $4.62 | $462.00 |
| 500 | $4.2 | $2,100.00 |
| 1,000 | $3.85 | $3,850.00 |
ATSAM3S4AA-MU Overview
A microcontroller (MCU) is a single-chip computer that integrates a processor core, memory, and peripherals on one die, sitting at the lowest level of the embedded-systems hierarchy: microcontroller -> embedded processor -> SoC. The SAM3S series belongs to Atmel/Microchip's SMART ARM-based MCU family and is pin-to-pin compatible with the legacy AT91SAM7S products in 48- and 64-pin versions, easing migration from older designs.
Key features include an ARM Cortex-M3 revision 2.0 core with a Thumb-2 instruction set, a Memory Protection Unit (MPU), a 128-bit-wide flash access with a memory accelerator for efficient 64 MHz execution, and an internal 1.62V-3.6V single-supply operating range. Peripherals include USB 2.0 device, USARTs, SPI, TWI (I2C), 12-bit ADC, PWM channels, and a real-time clock, enabling compact single-chip designs.
The Cortex-M3 architecture provides deterministic interrupt handling via the Nested Vectored Interrupt Controller (NVIC) and hardware division, making the device well suited for real-time control loops. The embedded flash controller allows in-system programming and the device supports SWD debug through the serial wire debug port.
Typical applications include industrial sensing nodes, consumer HMI devices, USB accessories, battery-powered portable instruments, and legacy AT91SAM7S upgrades where a drop-in performance boost is desired.
A key design consideration: the exposed pad of the QFN-48 package must be soldered to a ground plane for both thermal dissipation and signal-integrity reasons; do not treat it as a no-connect.
This page adds value beyond the datasheet by compiling verified distributor pricing, same-package drop-in alternatives, application guidance, and cross-reference data not found in the manufacturer documentation.
Drop-in alternatives for ATSAM3S4AA-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 ATSAM3S4AA-MU (same form factor and footprint) β differing in Pin Compatibility, Package, SRAM, Series, Core Processor.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATSAM3S4BA-MU
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$5.12 / Unit
View Datasheet βATSAM3S8BA-MU
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$5.72 / Unit
View Datasheet βATSAM3S2AA-MU
β Drop-Inβ In Stock
$3.6 / Unit
View Datasheet βATSAM3S1AA-MU
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$3.34 / Unit
View Datasheet βATSAM3N4BA-MU
β Drop-Inβ In Stock
$3.48 / Unit
View Datasheet βATSAM3S4AA-MU Maximum Ratings & Electrical Characteristics
| Core Processor | ARM Cortex-M3 revision 2.0 |
| Core Size | 32-bit single-core |
| Maximum Clock Frequency | 64 MHz |
| Flash Memory | 256 KB (256K x 8) |
| SRAM | 48 KB |
| Supply Voltage | 1.62 V to 3.6 V |
| Instruction Set | Thumb-2 |
| Memory Protection Unit | Yes (MPU) |
| Flash Access Width | 128-bit with memory accelerator |
| USB | USB 2.0 device |
| Package | 48-QFN (7x7 mm) with exposed pad |
| Mounting Type | Surface Mount |
| Communication Interfaces | USART, SPI, TWI (I2C), USB |
| Debug Interface | SWD (Serial Wire Debug) |
| Legacy Compatibility | Pin-to-pin compatible with AT91SAM7S (48/64-pin) |
| Packaging | Tray |
ATSAM3S4AA-MU 48-qfn (7x7 mm) with exposed pad Pin Configuration Guide
Pin configuration for ATSAM3S4AA-MU (48-qfn (7x7 mm) with exposed pad 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 ATSAM3S4AA-MU.
Refer to the datasheet for full pin configuration.
Typical Applications
ATSAM3S4AA-MU is suitable for 6 applications: USB Accessories and HID Devices, Legacy AT91SAM7S Design Migration, Industrial Sensor Nodes, Battery-Powered Portable Instruments, Consumer HMI and Display Control, Test and Measurement Peripherals.
USB Accessories and HID Devices
The ATSAM3S4AA-MU integrates a USB 2.0 device peripheral, making it a natural fit for HID keyboards, mice, custom USB gadgets, and CDC virtual-serial adapters. The 256 KB flash accommodates full USB stacks plus application logic without external memory, and the 48 KB SRAM provides generous endpoint buffer space at 64 MHz execution speed. Because the USB transceiver is on-chip, the bill of materials stays minimal - typically only a 1.5 kOhm pull-up is handled internally and a 3.3 V rail is needed. Designers should route D+/D- as a controlled-impedance pair and place the exposed-pad ground connection solidly to reduce EMI on the USB lines.
Recommended
Legacy AT91SAM7S Design Migration
Atmel explicitly documented that the SAM3S series is pin-to-pin compatible with AT91SAM7S legacy products in 48- and 64-pin packages, making the ATSAM3S4AA-MU the standard migration path for aging AT91SAM7S-based boards facing end-of-life pressure. A board redesign is not required: the land pattern, supply pins, and peripheral multiplexing map directly. The upgrade doubles flash to 256 KB, raises SRAM to 48 KB, and increases core speed to 64 MHz with the Cortex-M3 Thumb-2 pipeline and MPU. Firmware requires porting from the ARM7TDMI toolchain to the Cortex-M3 (NVIC vector table changes), but the peripheral register model remains close to the SAM7S heritage.
Recommended
Industrial Sensor Nodes
In factory sensing nodes, the ATSAM3S4AA-MU combines a 12-bit ADC, USART/SPI/TWI interfaces, and PWM outputs to digitize and transmit sensor data over RS-485-style USART links or I2C buses. Its 1.62 V to 3.6 V supply range tolerates noisy industrial rails, and the Cortex-M3 NVIC delivers deterministic interrupt latency for time-critical sampling loops at 64 MHz. The exposed-pad QFN-48 package provides good thermal coupling to the PCB for extended temperature environments. The Memory Protection Unit supports partitioned firmware architectures where a bootloader and application must be isolated, improving field-update robustness in unattended industrial deployments.
Recommended
Battery-Powered Portable Instruments
Handheld instruments benefit from the SAM3S4's single-supply 1.62 V to 3.6 V operation, which allows direct powering from a Li-ion cell across its discharge curve, and from the Cortex-M3's low-power sleep and wait modes that extend battery life between charges. The 64 MHz core executes acquisition, DSP-lite filtering, and display updates in one chip, while the 12-bit ADC samples analog front ends directly. The 48-QFN 7x7 mm footprint fits compact enclosures. Designers should budget the exposed pad as the main ground return and use the RTC and wake-up controller to duty-cycle the system, keeping average current in the microamp range during idle periods.
Recommended
Consumer HMI and Display Control
The ATSAM3S4AA-MU drives segment LCDs, OLED modules, and resistive-touch front ends in consumer products, using its PWM channels for backlight dimming and its TWI/SPI ports for display controllers. With 256 KB of flash there is room for glyph libraries, multi-language strings, and touch-debounce state machines alongside application logic at 64 MHz. The Thumb-2 instruction set keeps code density high, reducing flash pressure for feature-rich UIs. Because HMI products cycle quickly, the pin-compatibility across SAM3S flash densities (64 KB to 512 KB in the same 48-QFN footprint) lets product teams scale memory up or down across SKUs without changing the PCB.
Recommended
Test and Measurement Peripherals
Bench accessories - programmable loads, sensor calibrators, dongle-style data loggers - use the ATSAM3S4AA-MU for its deterministic Cortex-M3 timing, 12-bit ADC, and USB device connectivity for PC-linked control. The memory accelerator's 128-bit flash access sustains zero-wait-state execution at 64 MHz, so control-loop jitter stays predictable during measurement sequencing. USB CDC firmware exposes the instrument to host software without custom drivers, while the 48 KB SRAM buffers acquisition data between uploads. The QFN-48 exposed pad simplifies ground-bounce management when analog and digital sections share one PCB, which matters for sub-millivolt measurement accuracy.
Recommended
Recommended Products Summary
Engineering reference data for ATSAM3S4AA-MU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAM3S4BA-MU | ATSAM3S8BA-MU | ATSAM3S2AA-MU | ATSAM3S1AA-MU | ATSAM3N4BA-MU |
|---|---|---|---|---|---|---|
| Package | 48-QFN (7x7 mm) EP | 48-QFN (7x7 mm) EP - same | 48-QFN (7x7 mm) EP - same | 48-QFN (7x7 mm) EP - same | 48-QFN (7x7 mm) EP - same | 48-QFN (7x7 mm) EP - same |
| Brand | Microchip Technology (Atmel) | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Core / Max Speed | 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 | ARM Cortex-M3, 64 MHz |
| Flash Memory | 256 KB | 256 KB | 512 KB | 128 KB | 64 KB | 256 KB |
| SRAM | 48 KB | 48 KB | 64 KB | 48 KB | 32 KB | 16 KB |
| USB Device | Yes (USB 2.0 device) | Yes | Yes | Yes | Yes | No (SAM3N has no USB) |
| Supply Voltage | 1.62 V to 3.6 V | 1.62 V to 3.6 V | 1.62 V to 3.6 V | 1.62 V to 3.6 V | 1.62 V to 3.6 V | 1.62 V to 3.6 V |
| Pin Compatibility | AT91SAM7S 48/64-pin compatible | Pin-to-pin with ATSAM3S4AA | Pin-to-pin with ATSAM3S4AA | Pin-to-pin with ATSAM3S4AA | Pin-to-pin with ATSAM3S4AA | Pin-to-pin with ATSAM3S4AA |
Key Differentiators
- USB 2.0 device peripheral on-chip (vs ATSAM3N4BA-MU)
- Largest flash in the low-cost AA/B-cell family tier (vs ATSAM3S2AA-MU)
- Direct AT91SAM7S legacy upgrade path (vs ATSAM3S1AA-MU)
- Trade-off: lower max clock than some Cortex-M3 competitors (vs STM32F103CB)
Design Notes
The 48-QFN exposed pad on the ATSAM3S4AA-MU is the primary ground connection, not an optional thermal tab. Solder it to a solid ground plane with an array of vias (at least a 3x3 grid of 0.3 mm vias under the pad) to ensure reliable grounding and heat spreading. Insufficient exposed-pad soldering is one of the most common causes of intermittent resets and ADC noise on QFN-packaged SAM3S designs, and it cannot be diagnosed easily after assembly because the pad is hidden beneath the package.
The SAM3S4 accepts a single supply from 1.62 V to 3.6 V, but the integrated regulator architecture requires proper decoupling: place 100 nF ceramic capacitors at each VDD/VDDIO pin pair within 2 mm of the pin, plus a bulk 4.7 uF to 10 uF capacitor near the device. If USB is used, keep the 3.3 V rail within USB-spec tolerances under load. Do not power VDDIO pins from separate rails that ramp at very different rates - unbalanced I/O-pin biasing before core power-up can forward-bias internal protection structures.
Route the USB D+/D- pair as a 90-ohm differential pair with matched lengths (skew under 1 mm) and avoid crossing plane splits. For the SWD debug port (SWDIO/SWCLK), keep traces short and consider adding 0-ohm series resistor locations for current measurement during low-power firmware development. All SAM3S I/O is multiplexed - before layout lock, confirm peripheral-to-pin assignments using the datasheet multiplexing tables so that a late firmware change does not force a PCB respin.
Migration from AT91SAM7S is pin-compatible but not firmware-identical: the Cortex-M3 vector table and NVIC interrupt configuration differ from the ARM7TDMI, and the flash accelerator behaves differently on branch-heavy code. Budget time to revalidate timing-critical loops. Also note the SAM3N series (e.g., ATSAM3N4BA-MU) shares the footprint but lacks USB - dropping it onto a USB design will silently remove the peripheral. Verify the full ordering code suffix before assembly.
Compliance Information
RoHS compliance per Microchip standard for active SAM3S parts; REACH and halogen-free declarations were not present in the retrieved data and should be confirmed on the Microchip product page for the exact date code.