ATSAMD21E15B-AU - 32KB Flash ARM Cortex-M0+ MCU | Microchip
MPN: ATSAMD21E15B-AU ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.85 | $2.85 |
| 10 | $2.56 | $25.60 |
| 100 | $2.21 | $221.00 |
| 500 | $1.94 | $970.00 |
| 1,000 | $1.72 | $1,720.00 |
| 3,000 | $1.45 | $4,350.00 |
ATSAMD21E15B-AU Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, memory, and programmable I/O peripherals. Within the broader semiconductor hierarchy, the ATSAMD21E15B-AU belongs to the ARM Cortex-M0+ class of microcontrollers, which are designed for energy-efficient 32-bit computing in cost-sensitive applications. The SAM D21 series extends Cortex-M0+ with Microchip's Event System, SERCOM peripherals, and full-speed USB support on selected variants.
Key differentiating features include a 12-channel 350 µs minimum sample time 12-bit ADC, up to 26 GPIO lines, and six SERCOM interfaces that can each be configured as UART, I²C, or SPI. The integrated Event System allows peripherals to communicate without CPU intervention, reducing active time and current draw. SleepWalking peripherals continue to monitor external events while the CPU sleeps, achieving standby currents measured in microamperes.
Architecturally, the ATSAMD21E15B-AU uses a single-cycle hardware multiplier and a Nested Vector Interrupt Controller (NVIC) to deliver deterministic interrupt response. The advanced analog peripherals, including a 10-bit DAC and two analog comparators, make it suitable for sensor signal conditioning. The on-chip Full-Speed USB 2.0 device interface (selected variants) simplifies connectivity for hardware peripherals.
Typical applications include IoT sensor nodes, home automation controllers, wearable fitness bands, USB human-interface devices, and industrial control subsystems. The combination of low power, USB connectivity, and capacitive touch support makes it popular in consumer electronics and connected home products.
When designing with this MCU, allocate sufficient decoupling capacitance near each VDD pin and route the SWD signals (SWDIO/SWDCLK) as short as possible for reliable debug. The on-chip 32.768 kHz oscillator should be configured for low-power RTC modes. Verify the specific variant's peripheral count against your BOM requirements.
Drop-in alternatives for ATSAMD21E15B-AU — 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 ATSAMD21E15B-AU (same form factor and footprint) — differing in ADC, Package, Operating Temperature, Timer/Counters, RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATSAMD21E15B-AUT
✅ Drop-In✓ In Stock
$1.4 / Unit
View Datasheet →ATSAMD21E15A-AU
✅ Drop-In📋 Reference alternative (not in catalog)
ATSAMD21E15B-MU
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
ATSAMD21E16B-AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.1 / Unit
View Datasheet →ATSAMD20E15B-AUT
✅ Drop-In✓ In Stock
$2.52 / Unit
View Datasheet →ATSAMD21E15B-AFT
✅ Drop-In✓ In Stock
$1.96 / Unit
View Datasheet →ATSAMD21E15B-AU Maximum Ratings & Electrical Characteristics
| Core | ARM Cortex-M0+ (32-bit) |
| Maximum Clock Frequency | 48 MHz |
| Flash Memory | 32 KB |
| SRAM | 4 KB |
| Supply Voltage | 1.62 V to 3.6 V (3.3 V nominal) |
| Operating Temperature | -40 °C to +85 °C (industrial) |
| Package | 32-pin TQFP |
| GPIO Count | Up to 26 |
| ADC | 12-bit, 20 channels |
| DAC | 10-bit, 1 channel |
| SERCOM | 6 configurable (UART/SPI/I²C) |
| Timers/Counters | TC x6, TCC x2 |
| Analog Comparators | 2 |
| RTC | Yes (32.768 kHz) |
| Programming Interface | Serial Wire Debug (SWD) |
| RoHS Status | Compliant |
ATSAMD21E15B-AU Pin Configuration
| Pin 1 | PA00 — General-purpose I/O, ADC input |
| Pin 2 | PA01 — General-purpose I/O, ADC input |
| Pin 3 | PA02 — General-purpose I/O, ADC input, DAC output |
| Pin 4 | PA03 — General-purpose I/O, ADC input, analog comparator |
| Pin 5 | PA04 — General-purpose I/O, ADC input, VREFA |
| Pin 6 | PA05 — General-purpose I/O, ADC input, VREFB |
| Pin 7 | PA06 — General-purpose I/O, ADC input |
| Pin 8 | PA07 — General-purpose I/O, ADC input |
| Pin 9 | VDD — Digital supply voltage |
| Pin 10 | GND — Ground |
| Pin 11 | PA08 — General-purpose I/O, NMI |
| Pin 12 | PA09 — General-purpose I/O |
| Pin 13 | PA10 — General-purpose I/O |
| Pin 14 | PA11 — General-purpose I/O |
| Pin 15 | PA14 — General-purpose I/O, SWDIO |
| Pin 16 | PA15 — General-purpose I/O |
| Pin 17 | PA16 — General-purpose I/O |
| Pin 18 | PA17 — General-purpose I/O |
| Pin 19 | PA18 — General-purpose I/O |
| Pin 20 | PA19 — General-purpose I/O |
| Pin 21 | PA20 — General-purpose I/O |
| Pin 22 | PA21 — General-purpose I/O, SERCOM |
| Pin 23 | PA22 — General-purpose I/O, SERCOM |
| Pin 24 | PA23 — General-purpose I/O, SERCOM |
| Pin 25 | PA24 — General-purpose I/O |
| Pin 26 | PA25 — General-purpose I/O, SWDCLK |
| Pin 27 | PA27 — General-purpose I/O |
| Pin 28 | PA28 — General-purpose I/O, RESET |
| Pin 29 | PB00 — General-purpose I/O |
| Pin 30 | PB01 — General-purpose I/O |
| Pin 31 | PB02 — General-purpose I/O, ADC input |
| Pin 32 | PB03 — General-purpose I/O, ADC input |
Typical Applications
ATSAMD21E15B-AU is suitable for 7 applications: IoT Sensor Nodes, USB Human Interface Devices, Home Automation Controllers, Wearable Fitness Bands, Industrial Control Subsystems, Capacitive Touch User Interfaces, Educational and Maker Boards.
IoT Sensor Nodes
The ATSAMD21E15B-AU fits IoT sensor node designs through its 48 MHz Cortex-M0+ core and 4KB SRAM that comfortably run wireless stacks and sensor-fusion tasks. The 12-bit ADC with 20 channels interfaces directly with analog temperature, humidity, and gas sensors without external converters. SleepWalking peripherals allow the MCU to wake only when a meaningful sensor event occurs, extending coin-cell battery life to years. Compared to discrete 8-bit MCU designs, the integrated SERCOM blocks reduce PCB footprint by eliminating external UART/I²C expanders, making it ideal for sub-1GHz wireless sensor motes.
Recommended
USB Human Interface Devices
For USB HID peripherals such as keyboards, mice, and game controllers, the ATSAMD21E15B-AU (in the USB-capable -MU/-CU suffix variants) integrates a Full-Speed USB 2.0 device controller with on-chip transceivers. The 48 MHz Cortex-M0+ executes HID report generation with negligible latency, while six SERCOM blocks handle additional I/O for mechanical switches, encoders, or RGB lighting. Compared to external USB controller chips, the integrated peripheral saves BOM cost and PCB area, ideal for low-cost consumer peripherals.
Recommended
Home Automation Controllers
The ATSAMD21E15B-AU is well-suited for home automation hubs where multiple communication protocols must coexist. Six SERCOM interfaces can simultaneously drive RS-485 for Modbus, SPI for an external display controller, I²C for sensors, and UART for debug logging without CPU overhead. The 12-bit ADC monitors battery or supply voltage rails for predictive maintenance, while the Event System routes peripheral-to-peripheral signals at hardware speed. With 32KB Flash, designers can implement Zigbee or Matter protocol stacks with room for application-layer customization.
Recommended
Wearable Fitness Bands
For wearable fitness trackers, the ATSAMD21E15B-AU delivers the energy efficiency required for multi-day battery life. SleepWalking peripherals monitor accelerometer interrupts while the CPU stays in standby, drawing only single-digit microamps. The Cortex-M0+ core wakes in microseconds to update OLED displays and BLE radio modules. Compared to larger Cortex-M4 alternatives, the ATSAMD21E15B-AU's compact 32-pin TQFP enables ultra-thin wearable form factors without sacrificing analog performance for heart-rate sensing.
Recommended
Industrial Control Subsystems
In industrial control systems, the ATSAMD21E15B-AU provides deterministic interrupt response through its NVIC and SERCOM peripherals that handle multi-protocol field-bus communication. The industrial -40 °C to +85 °C temperature range covers most factory-floor environments, and the 12-bit ADC reads 4-20 mA loop signals directly. The integrated Event System enables safety-critical interlocks without CPU latency, satisfying real-time control requirements. Compared to discrete PLC logic, this MCU reduces cost while maintaining deterministic behaviour for motor-control and process-control subsystems.
Recommended
Capacitive Touch User Interfaces
The ATSAMD21E15B-AU supports capacitive touch buttons, sliders, and wheels through its built-in Peripheral Touch Controller (PTC). The PTC handles electrode scanning in hardware, freeing the Cortex-M0+ to manage communication tasks. With up to 26 GPIO-capable pins, designers can implement 10+ touch zones in a single MCU. Compared to dedicated touch ICs, integrating the PTC reduces BOM and PCB complexity for kitchen appliances, IoT switches, and consumer electronics that benefit from sealed, glass-fronted interfaces.
Recommended
Educational and Maker Boards
The ATSAMD21E15B-AU is widely deployed on Arduino-compatible boards and SparkFun development kits because of its accessible Cortex-M0+ core and rich peripherals. With 32KB Flash and 4KB SRAM, it handles beginner-level sketches, real-time operating systems, and Bluetooth Low Energy stacks. The integrated Serial Wire Debug interface supports plug-and-play programming through Atmel Studio, PlatformIO, and Arduino IDE. Compared to legacy 8-bit AVR MCUs, this MCU brings 32-bit performance and modern peripherals to maker and educational applications.
Recommended
Recommended Products Summary
Engineering reference data for ATSAMD21E15B-AU — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAMD21E15B-AUT | ATSAMD21E15A-AU | ATSAMD20E15B-AU |
|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 32-pin TQFP | 32-pin TQFP - same | 32-pin TQFP - same | 32-pin TQFP - same |
| Flash | 32 KB | 32 KB | 32 KB | 32 KB |
| SRAM | 4 KB | 4 KB | 4 KB | 4 KB |
| Maximum Clock | 48 MHz | 48 MHz | 48 MHz | 48 MHz |
| ADC Resolution | 12-bit | 12-bit | 12-bit | 10-bit |
| USB Support | No (base variant) | No | No | No |
| Event System | Yes | Yes | Yes | No |
| Operating Temperature | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C |
Key Differentiators
- Integrated Event System hardware routing (vs ATSAMD20E15B-AU)
- Higher-resolution 12-bit ADC vs 10-bit on D20 family (vs ATSAMD20E15B-AU)
- Lower active current with SleepWalking peripherals (vs ATSAMD21E15B-AU vs larger Cortex-M4 MCUs)
Design Notes
Place 100 nF decoupling capacitors as close as possible to every VDD pin and a bulk 10 µF capacitor near the package supply entry. The ATSAMD21E15B-AU supports separate VDDANA and VDDIO supply rails; tying them together via ferrite beads improves noise isolation for the analog ADC reference. According to the SAM D21 datasheet, configuring the on-chip voltage regulator's low-dropout mode reduces quiescent current to single-digit microamps in standby.
Route the SWDIO and SWDCLK traces with ground shielding and avoid crossing noisy signal paths. The 32-pin TQFP package supports 0.8 mm pitch routing on a 4-layer PCB with continuous ground plane beneath the device. Per Microchip layout guidelines, keep crystal traces short and symmetric to the GND plane to minimize oscillator start-up jitter and EMI.
Do not program the NMI pin (PA08) without considering its alternate function - leaving it floating can cause unexpected wake events. The 32.768 kHz external crystal requires proper load capacitor selection per the crystal vendor's CL specification; typical values are 12 pF. Ensure NVMCTRL locked regions are unlocked before any flash erase operation to prevent silent programming failures during firmware updates.
When using the SERCOM blocks for high-speed SPI above 12 MHz, add series source termination resistors near the MCU output pins to dampen reflections on long PCB traces. For I²C buses, use external 4.7 kΩ pull-ups rather than relying on weak internal pull-ups, especially when multiple slaves are connected. The 12-bit ADC's input impedance requires careful source-impedance budgeting; a 1 kΩ external series resistor with 10 nF input capacitance forms a suitable anti-alias filter.
Compliance Information
RoHS and REACH compliance per product page. Not AEC-Q100 qualified in this suffix; automotive variants (-AN/-AUT) are AEC-Q100 Grade 1 qualified.
