ATSAMD21E18A-AFT - 48MHz Cortex-M0+ MCU, 256KB Flash | Microchip
MPN: ATSAMD21E18A-AFT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.2 | $4.20 |
| 10 | $3.78 | $37.80 |
| 100 | $3.4 | $340.00 |
| 500 | $3.05 | $1,525.00 |
| 1,000 | $2.72 | $2,720.00 |
ATSAMD21E18A-AFT Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, memory, and programmable peripherals. The ARM Cortex-M0+ is the smallest and most energy-efficient ARM core, designed for deeply embedded applications where deterministic interrupt response, low active power, and a compact instruction set are critical. SAM D21 devices sit in the Cortex-M0+ family as low-power, high-performance variants and target USB-equipped and analog-rich designs.
Key features of the ATSAMD21E18A-AFT include the Cortex-M0+ core reaching 2.46 CoreMark/MHz, a 12-channel Event System, a full-speed USB 2.0 device with integrated transceiver, up to six SERCOM configurable serial interfaces (UART/SPI/I2C), a 12-bit ADC with up to 20 channels, two analog comparators, and a 16-bit timer/counter for control loops. The Peripheral Touch Controller (PTC) supports capacitive touch buttons, sliders, and proximity sensing.
The architecture pairs a single-cycle hardware multiplier with the Cortex-M0+ core, and the SAM D21 family shares a linear address map and hex-compatible code across pin counts, simplifying migration between 32-, 48-, and 64-pin members. The integrated Full-Speed USB transceiver eliminates the need for external crystal or pull-up resistors on most designs.
Typical applications include home automation nodes, smart metering, industrial sensor hubs, USB HID peripherals, wearable fitness bands, consumer appliances, and capacitive touch user interfaces. The wide 1.62V-3.63V supply range and low-power Sleep/Idle modes support battery-powered deployments.
When designing with this part, allocate the 32-pin TQFP footprint carefully because several peripheral functions share pins (the SERCOMs are highly multiplexed). For new designs, plan to use Atmel/Microchip START or MPLAB X with MCC to configure pin assignments and clock tree.
This page synthesizes current distributor pricing, drop-in alternatives, and practical design notes beyond what the manufacturer datasheet alone provides, enabling faster BOM decisions and supply-chain resilience.
Drop-in alternatives for ATSAMD21E18A-AFT — 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 ATSAMD21E18A-AFT (same form factor and footprint) — differing in Package, ADC, USB, MSL Level, Operating Temperature Range.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATSAMD21E17A-AF
✅ Drop-In✓ In Stock
$2.34 / Unit
View Datasheet →ATSAMD21E16A-AF
✅ Drop-In📋 Reference alternative (not in catalog)
ATSAMD21E15A-AF
✅ Drop-In📋 Reference alternative (not in catalog)
ATSAMD21E17A-AU
✅ Drop-In✓ In Stock
$2.3 / Unit
View Datasheet →ATSAMD21E17A-MFT
✅ Drop-In✓ In Stock
$2.55 / Unit
View Datasheet →ATSAMD21E15B-AFT
✅ Drop-In✓ In Stock
$1.96 / Unit
View Datasheet →ATSAMD21E18A-AFT Maximum Ratings & Electrical Characteristics
| Core | ARM Cortex-M0+ (32-bit) |
| Series | SAM D21E (Functional Safety / FuSa) |
| Maximum CPU Clock | 48 MHz |
| CoreMark Performance | 2.46 CoreMark/MHz |
| Flash Memory | 256 KB (256K x 8) |
| SRAM | 32 KB |
| Operating Voltage | 1.62 V to 3.63 V |
| Operating Temperature | -40 C to +125 C |
| Package | 32-TQFP (7x7 mm) |
| Mounting Type | Surface Mount (Tape & Reel) |
| USB | Full-Speed USB 2.0 Device with integrated transceiver |
| Serial Interfaces (SERCOM) | Up to 6 (configurable UART/SPI/I2C) |
| ADC | 12-bit, up to 20 channels |
| Analog Comparators | 2 |
| Timers | 16-bit TC modules and TCC for PWM |
| Touch Controller | Peripheral Touch Controller (PTC) - capacitive touch |
| Event System | 12-channel |
| MSL Level | 3 |
| RoHS Status | Compliant |
ATSAMD21E18A-AFT Pin Configuration
| Pin 1 | PA00 — General-purpose I/O / SERCOM / ADC |
| Pin 2 | PA01 — General-purpose I/O / SERCOM / ADC |
| Pin 3 | PA02 — Analog comparator / ADC |
| Pin 4 | PA03 — Analog comparator / ADC / DAC |
| Pin 5 | PA04 — SERCOM / ADC |
| Pin 6 | PA05 — SERCOM / ADC |
| Pin 7 | PA06 — SERCOM / ADC |
| Pin 8 | PA07 — SERCOM / ADC |
| Pin 9 | VDDIO — Digital I/O supply (1.62-3.63V) |
| Pin 10 | GND — Common ground |
| Pin 11 | PA08 — SERCOM / NMI / pin X / pin 0 |
| Pin 12 | PA09 — SERCOM / pin 1 |
| Pin 13 | PA10 — SERCOM / pin 2 |
| Pin 14 | PA11 — SERCOM / pin 3 |
| Pin 15 | PA12 — SERCOM / pin 4 |
| Pin 16 | PA13 — SERCOM / pin 5 |
| Pin 17 | PA20 — USB D- |
| Pin 18 | PA21 — USB D+ |
| Pin 19 | PA22 — SERCOM / I2S SCK |
| Pin 20 | PA23 — SERCOM / I2S FS |
| Pin 21 | PA24 — SERCOM / USB ID |
| Pin 22 | PA25 — SERCOM / USB VBUS |
| Pin 23 | RESETN — Active-low reset input |
| Pin 24 | PA27 — SERCOM / pin 11 |
| Pin 25 | PA28 — SERCOM / pin 12 / Wake |
| Pin 26 | PA30 — SERCOM / SWCLK (programming) |
| Pin 27 | PA31 — SERCOM / SWDIO (programming) |
| Pin 28 | VDDANA — Analog supply (1.62-3.63V) |
| Pin 29 | GND — Common ground |
| Pin 30 | VBUS — USB VBUS detect (5V tolerant) |
| Pin 31 | XIN32 — 32.768 kHz crystal input |
| Pin 32 | XOUT32 — 32.768 kHz crystal output |
Typical Applications
ATSAMD21E18A-AFT is suitable for 6 applications: Home Automation Hub, USB HID Peripheral (Keyboard/Mouse/HID Gamepad), Industrial Sensor Node / Smart Metering, Capacitive Touch User Interface, Wearable Fitness Band, Consumer Appliance Control Board.
Home Automation Hub
The ATSAMD21E18A-AFT fits home automation hubs because it combines 256 KB Flash for gateway stacks, the integrated Full-Speed USB device for wired upstream links, and 32 KB SRAM to buffer MQTT and Zigbee/BLE bridge messages. Its 1.62-3.63V supply range supports direct battery or 3.3V LDO rails, and the 48 MHz Cortex-M0+ core executes FreeRTOS task switches with deterministic latency. The 12-channel Event System lets sensor interrupts wake the MCU from Sleep without CPU overhead, extending coin-cell runtimes in wall-mounted switches and PIR motion nodes.
Recommended
USB HID Peripheral (Keyboard/Mouse/HID Gamepad)
The ATSAMD21E18A-AFT integrates a Full-Speed USB 2.0 device with on-chip transceiver, so a USB HID keyboard, mouse, or gamepad needs no external PHY or precision pull-up. With 256 KB Flash it stores large HID descriptor sets and macro/mapping logic, while 32 KB SRAM handles USB endpoint buffering and key-scan queues. Up to six SERCOMs provide flexible SPI/I2C/UART connectivity to RGB LED drivers, NFC tags, or wireless modules.
Recommended
Industrial Sensor Node / Smart Metering
The ATSAMD21E18A-AFT, an FuSa variant of the SAM D21E family, supports IEC 60730 Class B safety libraries for industrial sensor nodes and smart metering. Its 12-bit ADC with up to 20 channels reads thermistor, current-sense, and voltage-divider signals for energy measurement, while the two analog comparators handle zero-cross detection. The 1.62-3.63V range and 48 MHz core enable real-time power-quality calculations within sub-millisecond cycles.
Recommended
Capacitive Touch User Interface
The ATSAMD21E18A-AFT integrates the Peripheral Touch Controller (PTC) which supports capacitive touch buttons, sliders, and proximity sensors without an external touch IC. The 256 KB Flash stores robust touch libraries, gesture recognition, and noise-immune scanning algorithms. Operating from 1.62-3.63V enables direct Li-ion or 3.3V supply to the touch panel in white goods and kitchen appliances.
Recommended
Wearable Fitness Band
The ATSAMD21E18A-AFT targets wearable fitness bands where low Sleep current and a small 32-pin TQFP footprint matter most. Its Sleep/Idle modes below 10uA extend coin-cell battery life, while 256 KB Flash stores pedometer, heart-rate, and BLE protocol stack code. The 12-bit ADC reads Li-ion battery voltage and PPG signals, and integrated USB simplifies firmware updates or charging dock enumeration.
Recommended
Consumer Appliance Control Board
The ATSAMD21E18A-AFT serves in consumer appliance control boards such as coffee machines, washing machines, and HVAC indoor units where Functional Safety libraries help meet IEC 60730 Class B. Up to six SERCOMs drive motor-control BLDC drivers via SPI, read encoders, and manage the user display. The 32-pin TQFP footprint fits compact control modules and the 125C operating temperature supports enclosed appliance environments.
Recommended
Recommended Products Summary
Engineering reference data for ATSAMD21E18A-AFT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAMD21E17A-AF | ATSAMD21E16A-AF | ATSAMD21E15A-AF | ATSAMD21E17A-MFT |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 32-TQFP (7x7 mm) | 32-TQFP (7x7 mm) - same | 32-TQFP (7x7 mm) - same | 32-TQFP (7x7 mm) - same | 32-TQFP (7x7 mm) - same |
| Flash Memory | 256 KB | 128 KB (-50%) | 64 KB (-75%) | 32 KB (-87%) | 128 KB (-50%) |
| SRAM | 32 KB | 16 KB (-50%) | 8 KB (-75%) | 4 KB (-87%) | 16 KB (-50%) |
| Maximum Clock | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz |
| Operating Voltage | 1.62 V to 3.63 V | 1.62 V to 3.63 V | 1.62 V to 3.63 V | 1.62 V to 3.63 V | 1.62 V to 3.63 V |
| Operating Temperature | -40 C to +125 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +125 C |
| Functional Safety (FuSa) | Yes (SAM D21E variant) | No (SAM D21E non-FuSa) | No | No | No |
| USB FS Device | Yes (integrated) | Yes (integrated) | Yes (integrated) | Yes (integrated) | Yes (integrated) |
| Approx. qty-1 Price (USD) | $4.20 | $3.50 | $3.10 | $2.80 | $3.65 |
Key Differentiators
- Full 256 KB Flash in 32-pin TQFP, with FuSa libraries (vs ATSAMD21E17A-AF (128 KB Flash))
- Functional Safety (FuSa) variant for safety-class B appliances (vs ATSAMD21E17A-AF (non-FuSa SAM D21E))
- 125C operating temperature, full industrial range (vs ATSAMD21E17A-AF (-40 to +85C commercial grade))
Design Notes
Estimated: at 48 MHz full CPU load and 3.3V supply, the ATSAMD21E18A-AFT consumes roughly 12 mA active, dropping to single-digit uA in Sleep with RTC running. Decouple VDDIO and VDDANA separately with a 100nF ceramic capacitor within 2 mm of each pin; the ADC's reference and conversions are referenced to VDDANA and are sensitive to digital supply noise. Place a ferrite bead or 10 ohm resistor between VDDIO and VDDANA to keep digital switching out of the analog rail.
SAM D21 multiplexes multiple peripherals onto the same GPIO; mis-assigning PA20/PA21 (USB D-/D+) away from the integrated USB controller disables USB without a hardware error. Always confirm the SERCOM, USB, and PTC pin maps in the latest version of the SAM D21E datasheet pinout tables and the errata document, which lists which peripheral assignments are restricted on each silicon revision.
Route the 32.768 kHz crystal traces short and symmetrical with a guard-ring GND stitch. Place the crystal within 5 mm of XIN32/XOUT32 and keep high-speed signals (USB, SPI clock) at least 3 mm away. For USB, route D+/D- as a 90 ohm differential pair with no stubs and add ESD protection diodes directly at the connector to pass IEC 61000-4-2.
Estimated: at full CPU load on the 32-pin TQFP, total package dissipation is below 100 mW and junction rise over ambient stays well under 10 C for standard 1 oz copper pours. The 125C junction rating is comfortable for sealed enclosures; however, if you use the TQFP version inside a closed metal box without airflow, validate with a thermocouple rather than relying on nominal thermal resistance alone.
