ATSAMD21J18A-MFT - 48MHz Cortex-M0+ MCU, 256KB Flash, 64-QFN
MPN: ATSAMD21J18A-MFT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.42 | $5.42 |
| 10 | $4.88 | $48.80 |
| 100 | $4.05 | $405.00 |
| 500 | $3.55 | $1,775.00 |
| 1,000 | $3.12 | $3,120.00 |
| 3,000 | $2.74 | $8,220.00 |
ATSAMD21J18A-MFT Overview
A microcontroller (MCU) is a single-chip computer containing a CPU core, program and data memory, and a set of on-chip peripherals. The ATSAMD21J18A-MFT's Cortex-M0+ core sits at the entry level of the 32-bit ARM Cortex-M family, balancing low power with deterministic interrupt response. The SAM D21 series is positioned within Microchip's portfolio between the lower-pin SAM D10/D11 and the larger SAM D20/D21 family variants. With on-chip USB and SERCOM multiplexing, it consolidates what would otherwise require multiple external components.
Key features include 256 KB Flash organized as 256K x 8, 32 KB SRAM, six SERCOM modules (each independently configurable), full-speed USB device/host with on-chip transceiver, a 12-bit ADC with up to 20 channels, two I2S interfaces, and a peripheral touch controller. AES 32-bit crypto accelerator and a true random number generator (TRNG) support secure applications. The integrated 32 kHz RTC oscillator and PLL-enable flexible clocking from internal or external sources.
The architecture pairs a Cortex-M0+ core with Microchip's SERCOM peripheral set and an event system that allows peripherals to interact without CPU intervention, freeing cycles for application logic. The 48 MHz clock with single-cycle multiplier achieves 2.46 CoreMark/MHz. The part is Functional Safety (FuSa) capable, supporting IEC 60730 class B libraries available separately.
Typical applications include industrial sensor nodes, home automation gateways, USB peripherals (HID/CDC/MSC), low-power IoT edge nodes, smart metering, consumer HID devices, and small touchscreen human-machine interfaces. The integrated USB avoids external PHY chips, reducing BOM cost.
Design consideration: place a 1 uF plus 100 nF decoupling network near each power pin; ensure the D+ and D+ trace impedance matches 90 ohms differential per USB specification. Use the sleepwalking idle peripherals mode to achieve sub-100 uA average system power.
This page synthesizes distributor pricing, drop-in SAMD21 alternatives, and practical low-power design notes not found in the standalone manufacturer datasheet.
Drop-in alternatives for ATSAMD21J18A-MFT — 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 ATSAMD21J18A-MFT (same form factor and footprint) — differing in DAC, USB, Operating Temperature, ADC, Package.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATSAMD21J18A-MF
✅ Drop-In✓ In Stock
$3.6 / Unit
View Datasheet →ATSAMD21J18A-MU
✅ Drop-In📋 Reference alternative (not in catalog)
ATSAMD21J18A-AUT
✅ Drop-In✓ In Stock
$2.63 / Unit
View Datasheet →ATSAMD21J18A-AU
✅ Drop-In✓ In Stock
$2.69 / Unit
View Datasheet →ATSAMD21J18A-AF
✅ Drop-In✓ In Stock
$2.91 / Unit
View Datasheet →ATSAMD21J18A-CU
✅ Drop-In✓ In Stock
$2.52 / Unit
View Datasheet →ATSAMD21J18A-MFT Maximum Ratings & Electrical Characteristics
| Core | ARM Cortex-M0+ (32-bit) |
| Maximum CPU Clock | 48 MHz |
| Flash Memory | 256 KB (256K x 8) |
| SRAM | 32 KB |
| Supply Voltage Range | 1.62 V to 3.63 V |
| Operating Temperature | -40 C to +125 C |
| Package | 64-QFN (9x9 mm) |
| Mounting Type | Surface Mount |
| USB | USB 2.0 Full-Speed Device/Host with on-chip transceiver |
| SERCOM Modules | 6 (each configurable as I2C, SPI, or UART) |
| ADC | 12-bit, up to 350 ksps, up to 20 channels |
| DAC | 10-bit, 1 channel |
| Touch Peripheral (PTC) | Supported (mutual- and self-capacitance) |
| I2S Interfaces | 2 |
| RTC | 32 kHz internal RTC with calendar |
| Crypto Accelerator | AES 32-bit hardware accelerator |
| TRNG | True Random Number Generator |
| CoreMark/MHz | 2.46 |
| RoHS Status | Compliant |
| MSL | 3 (168 hours) |
ATSAMD21J18A-MFT Pin Configuration
| Pin 1 | PA00 — GPIO / XIN32 (external 32 kHz crystal input) |
| Pin 2 | PA01 — GPIO / XOUT32 (external 32 kHz crystal output) |
| Pin 3 | PA02 — GPIO / ADC_AIN[1] / AIN[2] |
| Pin 4 | PA03 — GPIO / ADC_AIN[2] |
| Pin 5 | GND — Ground |
| Pin 6 | VDDIN — Voltage regulator input supply |
| Pin 7 | VDDIO — I/O supply voltage |
| Pin 8 | PA04 — GPIO / ADC_AIN[4] / VOUT |
| Pin 9 | PA05 — GPIO / ADC_AIN[5] |
| Pin 10 | PA06 — GPIO / ADC_AIN[6] |
| Pin 11 | PA07 — GPIO / ADC_AIN[7] |
| Pin 12 | PA08 — GPIO / ADC_AIN[8] / I2S_SDI[0] |
| Pin 13 | PA09 — GPIO / ADC_AIN[9] / I2S_SDO[0] |
| Pin 14 | PA10 — GPIO / ADC_AIN[10] |
| Pin 15 | PA11 — GPIO / ADC_AIN[11] |
| Pin 16 | PA12 — GPIO / I2S_FS[0] |
| Pin 17 | PA13 — GPIO / I2S_MCK[0] |
| Pin 18 | PA14 — GPIO / I2S_SCK[0] |
| Pin 19 | PA15 — GPIO / I2S_SDI[1] |
| Pin 20 | PA16 — GPIO / I2S_SDO[1] |
| Pin 21 | PA17 — GPIO / I2S_FS[1] |
| Pin 22 | PA18 — GPIO / I2S_SCK[1] |
| Pin 23 | PA19 — GPIO / I2S_MCK[1] |
| Pin 24 | PA20 — GPIO / I2S_SDI[2] |
| Pin 25 | PA21 — GPIO / I2S_SDO[2] |
| Pin 26 | PA22 — GPIO / I2S_FS[2] |
| Pin 27 | PA23 — GPIO / I2S_SCK[2] |
| Pin 28 | PA24 — GPIO / USB_DM |
| Pin 29 | PA25 — GPIO / USB_DP |
| Pin 30 | GND — Ground |
| Pin 31 | VDDIO — I/O supply voltage |
| Pin 32 | PB00 — GPIO |
| Pin 33 | PB01 — GPIO |
| Pin 34 | PB02 — GPIO / ADC_AIN[14] |
| Pin 35 | PB03 — GPIO / ADC_AIN[15] |
| Pin 36 | PB04 — GPIO |
| Pin 37 | PB05 — GPIO |
| Pin 38 | PB06 — GPIO |
| Pin 39 | PB07 — GPIO |
| Pin 40 | PB08 — GPIO |
| Pin 41 | PB09 — GPIO |
| Pin 42 | PB10 — GPIO |
| Pin 43 | PB11 — GPIO |
| Pin 44 | PB12 — GPIO / NMI |
| Pin 45 | PB13 — GPIO |
| Pin 46 | PB14 — GPIO |
| Pin 47 | PB15 — GPIO |
| Pin 48 | PB16 — GPIO |
| Pin 49 | PB17 — GPIO |
| Pin 50 | PB18 — GPIO |
| Pin 51 | PB19 — GPIO |
| Pin 52 | PB20 — GPIO |
| Pin 53 | PB21 — GPIO |
| Pin 54 | PB22 — GPIO |
| Pin 55 | PB23 — GPIO |
| Pin 56 | PB24 — GPIO |
| Pin 57 | PB25 — GPIO |
| Pin 58 | PA27 — GPIO |
| Pin 59 | PA28 — GPIO / SWDIO |
| Pin 60 | PA29 — GPIO / SWCLK |
| Pin 61 | PA30 — GPIO / SWO |
| Pin 62 | PA31 — GPIO |
| Pin 63 | RESET — Reset input, active-low |
| Pin 64 | VDDANA — Analog supply voltage (must connect to VDDIN externally) |
Typical Applications
ATSAMD21J18A-MFT is suitable for 6 applications: Industrial Sensor Nodes, USB HID / CDC Devices, Smart Home / Consumer IoT, Smart Metering, Touch-based Human-Machine Interface, Home Automation Gateways.
Industrial Sensor Nodes
The ATSAMD21J18A-MFT is well matched to industrial sensor nodes that demand precise analog measurement alongside a low sleep current budget. The integrated 12-bit 350 ksps ADC with up to 20 channels handles thermocouple, 4-20 mA, and bridge-sensor signal chains without an external analog front end. Six SERCOM ports can run I2C sensors, SPI flash, and RS-485 UART simultaneously, while Standby mode (1.7 uA typical with RTC running per the SAM D21 datasheet) lets a battery-powered node sleep for years. Place 100 nF and 1 uF decoupling on each VDD pin and use sleepwalking to wake the ADC only on threshold crossings, keeping the average system current under 100 uA.
Recommended
USB HID / CDC Devices
USB keyboards, mice, CDC virtual COM ports, and custom HID peripherals benefit from the ATSAMD21J18A-MFT's integrated USB 2.0 Full-Speed controller with on-chip transceiver. The peripheral handles device and limited host modes without an external PHY, shrinking BOM and freeing the 48 MHz Cortex-M0+ core to run application logic. With 256 KB Flash and 32 KB SRAM, the part comfortably hosts USB stacks such as LUFA or TinyUSB plus application firmware. Route D+/D- as a 90 ohm differential pair and provide a 1.5 kohm pull-up on D+ in software to enumerate as full-speed.
Recommended
Smart Home / Consumer IoT
Smart home hubs, lighting controllers, and consumer IoT end nodes benefit from the ATSAMD21J18A-MFT's 1.62-3.63 V single-supply operation, which allows direct connection to 2xAA batteries or USB 5 V via an LDO. The peripheral touch controller (PTC) supports mutual- and self-capacitance touch buttons and sliders, replacing mechanical switches on sealed enclosures. Six SERCOMs accommodate Wi-Fi/BLE module UART, sensor I2C/SPI buses, and a debug UART. Backup mode at sub-1 uA with RTC retention supports coin-cell wake-on-touch designs that last several years.
Recommended
Smart Metering
Electricity, water, and gas meters rely on the ATSAMD21J18A-MFT for integrated metering peripherals and long-term reliability. The 12-bit ADC with differential inputs handles direct sensor signal conditioning, while the integrated RTC with calendar supports time-of-use billing. AES 32-bit hardware acceleration protects wireless M-Bus or LoRaWAN payloads, and the TRNG supports secure key generation. Industrial -40 to +125 C temperature rating matches outdoor meter environments, and 256 KB Flash holds a full metering firmware plus OTA bootloader.
Recommended
Touch-based Human-Machine Interface
Small HMI panels with capacitive touch benefit from the ATSAMD21J18A-MFT's integrated Peripheral Touch Controller (PTC) and 12-bit ADC. Mutual-capacitance supports up to 256 touch channels, allowing slider, wheel, and matrix keypad interfaces without an external touch IC. Two I2S interfaces drive digital audio for beep feedback, while 256 KB Flash holds LVGL-style graphics libraries plus touch processing. Configure the PTC scan in standby with wake-on-touch to achieve responsive UI with sub-50 uA average current.
Recommended
Home Automation Gateways
Home automation gateways that bridge Zigbee, BLE, Wi-Fi, and sub-GHz radios benefit from the ATSAMD21J18A-MFT's six SERCOM interfaces and high-performance 48 MHz core. Each SERCOM can independently run UART to a host radio module, SPI to a display or flash, and I2C to environmental sensors, while the USB port provides a wired debug or CDC link to a host processor. AES and TRNG secure the local key store, and 32 KB SRAM comfortably buffers MQTT message queues. Industrial temperature rating supports installation in unheated utility spaces.
Recommended
Recommended Products Summary
Engineering reference data for ATSAMD21J18A-MFT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAMD21J18A-MF | ATSAMD21J18A-MU | ATSAMD21J18A-AUT | ATSAMD21J18A-AU | ATSAMD21J18A-AF | ATSAMD21J18A-CU |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 64-QFN (9x9 mm) | 64-QFN (9x9 mm) - same | 64-QFN (9x9 mm) - same | 64-QFN (9x9 mm) - same | 64-QFN (9x9 mm) - same | 64-QFN (9x9 mm) - same | 64-QFN (9x9 mm) - same |
| Flash / SRAM | 256 KB / 32 KB | 256 KB / 32 KB | 256 KB / 32 KB | 256 KB / 32 KB | 256 KB / 32 KB | 256 KB / 32 KB | 256 KB / 32 KB |
| Max CPU Clock | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz |
| AEC-Q100 Qualification | No | No | No | Yes | Yes | Yes | Yes |
| Operating Temperature | -40 C to +125 C | -40 C to +125 C | -40 C to +125 C | -40 C to +85 C (automotive) | -40 C to +85 C (automotive) | -40 C to +85 C (automotive) | -40 C to +85 C (automotive) |
| Packaging | Tape & Reel | Tray | Tray | Tape & Reel | Tray | Tray | Tray |
| Approx Unit Price (qty 1) | $5.42 | $5.20 | $5.20 | $6.10 | $5.90 | $5.90 | $6.40 |
Key Differentiators
- Industrial temperature grading +125 C without AEC-Q100 cost premium (vs ATSAMD21J18A-AUT)
- Tape and Reel packaging optimized for high-volume SMT (vs ATSAMD21J18A-MF)
- Six SERCOM peripherals for high I/O flexibility (vs ATSAMD21E17A-MFT)
Design Notes
Place a 1 uF X7R ceramic plus a 100 nF X7R ceramic on each VDDIN, VDDIO, and VDDANA pin; the VDDANA pin must be tied externally to VDDIN to prevent ADC reference drift. According to the SAM D21 datasheet, VDDIO can be tied to VDDIN for single-supply operation. Add a bulk 10 uF tantalum or polymer cap at the regulator input to suppress load transients during USB enumeration.
Route the USB D+/D- pair as a 90 ohm differential pair with matched trace lengths, no stubs, and a continuous reference ground plane below. Keep the differential pair away from switching signals and route over an unbroken ground pour to meet USB 2.0 Full-Speed signal integrity requirements. Decouple the VDDIO that feeds the USB transceiver with a 100 nF cap within 2 mm of the pin.
Do not exceed the absolute maximum VDD of 4.0 V or apply voltage to any GPIO before VDDIO is powered. Per the SAM D21 datasheet, the NRESET pin has an internal pull-up; drive it low for at least 100 ns to reset the device. Configure the BOD33 (Brown-Out Detector 3.3V) early in firmware to ensure safe reset behavior in brown-out conditions.
Estimated: at 48 MHz and full peripheral activity, the 64-QFN package dissipates approximately 60 mW (1.2 V core x ~50 mA active current per the SAM D21 datasheet). The exposed pad must be soldered to a copper pour of at least 100 mm^2 to keep junction temperature rise under 10 C in still air; without this thermal pad connection the device can overheat in industrial -40 to +125 C environments.
Use the SERCOM peripheral to route I2C, SPI, and UART on the same pins without silicon rework. Each SERCOM supports up to four I/O pins per channel; reserve SERCOM0 and SERCOM1 for high-speed peripherals (SPI flash, USB-CDC bridge) and SERCOM2-5 for sensor I/O. Configure drive strength to PERIPHERAL_LOW for low-power sensors to reduce EMI in battery designs.
Compliance Information
RoHS/REACH compliance per Microchip product page. AEC-Q100 not applicable for MFT; choose AUT variant for AEC-Q100 automotive.
