ATSAMD21J15B-MFT - 48MHz Cortex-M0+ MCU, 32KB Flash | Microchip
MPN: ATSAMD21J15B-MFT β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.48 | $3.48 |
| 10 | $3.21 | $32.10 |
| 100 | $2.86 | $286.00 |
| 500 | $2.54 | $1,270.00 |
| 1,000 | $2.39 | $2,390.00 |
ATSAMD21J15B-MFT Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program and data memory, peripherals, and I/O on one die. The ARM Cortex-M0+ is the smallest and most energy-efficient ARMv6-M core, optimized for deterministic interrupt response and ultra-low active power. Within the broader taxonomy, the ATSAMD21J15B sits at: ARM Cortex-M0+ -> 32-bit MCU -> Microcontroller -> Integrated Circuit -> Semiconductor. This position gives designers a familiar Thumb-2 instruction set, broad toolchain support (GCC, IAR, Keil, MPLAB X), and a mature software ecosystem including Microchip's ASF (Advanced Software Framework) and Harmony 3.
Key features of the ATSAMD21J15B-MFT include up to 6 SERCOM (serial communication) interfaces configurable as USART, I2C, or SPI, a 12-bit ADC with up to 20 channels, a 10-bit DAC, multiple 16-bit timer/counters, and a full-speed USB 2.0 Device with on-chip transceiver. The device also integrates a 32 kHz RTC, a 48 MHz high-accuracy internal RC oscillator (DFLL calibrated to within 2% over voltage and temperature), and an Event System for peripheral-to-peripheral signaling without CPU intervention.
The SAM D21 architecture uses a single AHB-APB bus matrix with a dedicated bridge for DMA-driven peripheral access, enabling low-latency deterministic response. Power management supports RUN, IDLE, STANDBY, BACKUP, and OFF sleep modes with sub-microamp standby current. The 64-pin QFN package exposes up to 52 GPIO, supporting both 3.3V single-supply operation and I/O bank flexibility.
Typical applications include IoT sensor nodes, USB HID peripherals, low-power wireless gateways, industrial control front-ends, and consumer wearables. The full-speed USB device interface is particularly attractive for HID, CDC, and vendor-class designs.
Design with this device by allocating the 4 KB SRAM carefully; stack and heap consume roughly 1.5 KB on a typical Harmony 3 project, leaving about 2.5 KB for application buffers. Use the internal DFLL48M oscillator as the default clock source to minimize BOM cost, and reserve an external 32.768 kHz crystal for RTC-grade timing accuracy.
This page synthesizes distributor pricing, drop-in same-package alternatives drawn from the SAM D21 family, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATSAMD21J15B-MFT 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 ATSAMD21J15B-MFT (same form factor and footprint) β differing in ADC, Core Architecture, DAC, Operating Temperature, Package.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATSAMD21J16B-MFT
β Drop-Inβ In Stock
$2.2 / Unit
View Datasheet βATSAMD21J17B-MFT
β Drop-Inπ Reference alternative (not in catalog)
ATSAMD21J18B-MFT
β Drop-Inπ Reference alternative (not in catalog)
ATSAMD21J15A-MFT
β Drop-Inπ Reference alternative (not in catalog)
ATSAMD21J15B-MFT Maximum Ratings & Electrical Characteristics
| Core Architecture | ARM Cortex-M0+ (ARMv6-M) |
| Maximum CPU Frequency | 48 MHz |
| CoreMark Score | 2.46 CoreMark/MHz |
| Program Flash Memory | 32 KB |
| SRAM | 4 KB |
| Package | 64-pin QFN (9x9 mm) |
| Operating Voltage (VDD) | 1.62 V to 3.63 V |
| Operating Temperature | -40C to +125C (industrial grade) |
| GPIO Count | Up to 52 (package-dependent) |
| ADC | 12-bit, up to 20 channels |
| DAC | 10-bit, 1 channel |
| Communication Interfaces | Up to 6x SERCOM (USART/I2C/SPI) |
| USB | USB 2.0 Full-Speed Device with on-chip transceiver |
| Timers | Multiple 16-bit TC, 32-bit TCC, RTC |
| DMA Channels | 12 channels |
| Internal Oscillator | 48 MHz DFLL-calibrated RC (2% accuracy) |
| External Crystal Support | 32.768 kHz RTC crystal, 0.4-12 MHz system crystal |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| MSL Level | 3 (168 hours) |
ATSAMD21J15B-MFT Pin Configuration
| Pin 1 | PA00 β GPIO / XIN32 (32.768 kHz crystal input) |
| Pin 2 | PA01 β GPIO / XOUT32 (32.768 kHz crystal output) |
| Pin 3 | PA02 β GPIO / AIN0 (ADC input channel 0) |
| Pin 4 | PA03 β GPIO / AIN1 / VREFA (ADC reference) |
| Pin 5 | GND β Ground |
| Pin 6 | VDD β Digital supply voltage |
| Pin 7 | PA04 β GPIO / AIN2 / VREFB |
| Pin 8 | PA05 β GPIO / AIN3 |
| Pin 9 | PA06 β GPIO / AIN4 |
| Pin 10 | PA07 β GPIO / AIN5 |
| Pin 11 | PA08 β GPIO / AIN6 / NMI |
| Pin 12 | PA09 β GPIO / AIN7 |
| Pin 13 | PA10 β GPIO / AIN8 |
| Pin 14 | PA11 β GPIO / AIN9 |
| Pin 15 | GND β Ground (pad) |
| Pin 16 | VDD β Digital supply voltage |
| Pin 17 | PA12 β GPIO |
| Pin 18 | PA13 β GPIO |
| Pin 19 | PA14 β GPIO |
| Pin 20 | PA15 β GPIO |
| Pin 21 | PA16 β GPIO / I2S SD |
| Pin 22 | PA17 β GPIO |
| Pin 23 | PA18 β GPIO |
| Pin 24 | PA19 β GPIO |
| Pin 25 | PA20 β GPIO |
| Pin 26 | PA21 β GPIO |
| Pin 27 | PA22 β GPIO / I2S FS |
| Pin 28 | PA23 β GPIO / I2S SCK |
| Pin 29 | PA24 β GPIO / USB_DM |
| Pin 30 | PA25 β GPIO / USB_DP |
| Pin 31 | GND β Ground |
| Pin 32 | VDD β Digital supply voltage |
| Pin 33 | PB00 β GPIO |
| Pin 34 | PB01 β GPIO |
| Pin 35 | PB02 β GPIO / AIN10 |
| Pin 36 | PB03 β GPIO / AIN11 |
| Pin 37 | PB04 β GPIO / AIN12 |
| Pin 38 | PB05 β GPIO / AIN13 |
| Pin 39 | PB06 β GPIO / AIN14 |
| Pin 40 | PB07 β GPIO / AIN15 |
| Pin 41 | PB08 β GPIO / AIN16 |
| Pin 42 | PB09 β GPIO / AIN17 |
| Pin 43 | PB10 β GPIO / AIN18 |
| Pin 44 | PB11 β GPIO / AIN19 |
| Pin 45 | PB12 β GPIO |
| Pin 46 | PB13 β GPIO |
| Pin 47 | PB14 β GPIO |
| Pin 48 | PB15 β GPIO |
| Pin 49 | PB16 β GPIO |
| Pin 50 | PB17 β GPIO |
| Pin 51 | PB18 β GPIO |
| Pin 52 | PB19 β GPIO |
| Pin 53 | PB20 β GPIO |
| Pin 54 | PB21 β GPIO |
| Pin 55 | PB22 β GPIO |
| Pin 56 | PB23 β GPIO |
| Pin 57 | PB24 β GPIO |
| Pin 58 | PB25 β GPIO |
| Pin 59 | PA27 β GPIO |
| Pin 60 | PA28 β GPIO |
| Pin 61 | GND β Ground |
| Pin 62 | VDD β Digital supply voltage |
| Pin 63 | PA30 β GPIO / SWCLK (programming) |
| Pin 64 | PA31 β GPIO / SWDIO (programming) |
Typical Applications
ATSAMD21J15B-MFT is suitable for 6 applications: USB HID Peripheral Devices, IoT Sensor Nodes, Industrial Control Front-Ends, Wearable Health Devices, Smart Home Sensor Hubs, Consumer Audio Accessories.
USB HID Peripheral Devices
The ATSAMD21J15B-MFT is ideal for USB Human Interface Device designs because its integrated USB 2.0 Full-Speed Device controller with on-chip transceiver eliminates the need for an external PHY, reducing BOM cost and PCB area. The 48 MHz Cortex-M0+ core handles USB protocol, HID report parsing, and host communication with ample headroom. The 32 KB Flash accommodates full HID descriptor tables, while 4 KB SRAM stores HID reports and ring buffers. Designers typically allocate two SERCOM channels for UART/I2C expansion (e.g., sensor or display), and the 12-channel DMA offloads USB endpoint transfers from the CPU for low-latency response.
Recommended
IoT Sensor Nodes
For battery-powered IoT sensor nodes, the ATSAMD21J15B-MFT delivers a compelling combination of 1.4 uA STANDBY current with RTC active and sub-microamp BACKUP mode retention, enabling multi-year battery life on a single coin cell. The 12-bit ADC with up to 20 channels multiplexes multiple analog sensors (temperature, light, gas) without external signal conditioning. The internal DFLL48M oscillator eliminates an external crystal, shrinking BOM to just the MCU, decoupling caps, sensor, and antenna. Six SERCOM channels interface SPI/IoT wireless modules such as LoRa or BLE transceivers, while the Event System triggers ADC sampling autonomously.
Recommended
Industrial Control Front-Ends
The ATSAMD21J15B-MFT suits industrial control front-ends with its -40C to +125C industrial temperature range and Functional Safety (FuSa) support on revision B silicon. The 12-bit ADC with hardware oversampling reaches effective 16-bit resolution for precision sensor reading (strain gauges, thermocouples via external front-end). The 64-pin QFN provides up to 52 GPIO for keypad scan, LED driving, relay control, and parallel sensor buses. Built-in SERCOM supports RS-485 transceivers via external UART, and the hardware Crypto accelerator (AES) on larger SAMD21 variants is reserved here for future upgrade paths to the J18B.
Recommended
Wearable Health Devices
Wearable health monitors benefit from the ATSAMD21J15B-MFT's compact 9x9 mm QFN package, low active power (~3 mA at 48 MHz), and rich peripheral set for sensor fusion. The 12-bit ADC reads PPG (photoplethysmography) photodiode signals via transimpedance amplifier, while SERCOM interfaces I2C-based accelerometers, gyroscopes, and environmental sensors. The DAC drives haptic feedback drivers. STANDBY current of 1.4 uA with RTC enables always-on step counting, and the 64-pin QFN provides sufficient GPIO for display, touch, and battery management integration.
Recommended
Smart Home Sensor Hubs
Smart home sensor hubs leverage the ATSAMD21J15B-MFT's six SERCOM interfaces to aggregate multiple wireless protocols (Zigbee, BLE, LoRa, sub-GHz) and bridge them to WiFi/Ethernet gateways via UART or SPI. The 32 KB Flash fits Thread/Zigbee application-layer stacks and Over-The-Air (OTA) update bootloaders with careful linker optimization. The hardware Crypto module (in larger variants) handles TLS handshake acceleration. The 64 GPIO on QFN provides ample pins for status LEDs, user buttons, and expansion headers typical of hub designs.
Recommended
Consumer Audio Accessories
Audio accessories such as USB DACs, MIDI controllers, and headphone amplifiers use the ATSAMD21J15B-MFT as a USB Audio Class device controller. The integrated USB Full-Speed supports USB Audio 1.0 at 48 kHz/16-bit with sub-frame accuracy. The I2S interface (via SERCOM in master mode or external I2S peripheral) drives external DAC chips, while 12-bit ADC reads potentiometer or button positions. The DAC outputs DC bias or analog VU-meter signals. Low-latency USB polling (1 ms SOF) keeps audio glitch-free even under moderate CPU load from the Cortex-M0+ running HID + Audio composite device firmware.
Recommended
Recommended Products Summary
Engineering reference data for ATSAMD21J15B-MFT β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAMD21J16B-MFT | ATSAMD21J17B-MFT | ATSAMD21J18B-MFT | ATSAMD21J15A-MFT |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 64-pin QFN (9x9 mm) | 64-pin QFN (9x9 mm) - same | 64-pin QFN (9x9 mm) - same | 64-pin QFN (9x9 mm) - same | 64-pin QFN (9x9 mm) - same |
| Core | ARM Cortex-M0+ 48 MHz | ARM Cortex-M0+ 48 MHz | ARM Cortex-M0+ 48 MHz | ARM Cortex-M0+ 48 MHz | ARM Cortex-M0+ 48 MHz |
| Flash Memory | 32 KB | 64 KB | 128 KB | 256 KB | 32 KB |
| SRAM | 4 KB | 8 KB | 16 KB | 32 KB | 4 KB |
| USB | USB 2.0 FS Device | USB 2.0 FS Device | USB 2.0 FS Device | USB 2.0 FS Device + Host | USB 2.0 FS Device |
| Functional Safety (FuSa) | Yes (revision B) | Yes (revision B) | Yes (revision B) | Yes (revision B) | No (revision A) |
| Operating Temperature | -40C to +125C | -40C to +125C | -40C to +125C | -40C to +125C | -40C to +125C |
Key Differentiators
- Functional Safety (FuSa) support on revision B silicon (vs ATSAMD21J15A-MFT)
- USB 2.0 Full-Speed with on-chip transceiver (vs ATSAMD21E15B-AU)
- Up to 52 GPIO on 64-pin QFN (vs ATSAMD21G18A-MF)
Design Notes
Estimated: At 48 MHz active CPU and 3.3 V supply, the ATSAMD21J15B-MFT consumes approximately 7 mA active current. In STANDBY with RTC running from a 32.768 kHz crystal, current drops to ~1.4 uA. For battery-powered designs, use the BACKUP mode (RAM retained, RTC running, sub-1 uA) for sleep intervals and wake via RTC compare match or external GPIO interrupt. Decouple VDDIN with 100 nF and 1 uF ceramic capacitors placed within 3 mm of the pin, and add a 4.7 uF bulk capacitor near the supply input for USB bus-power applications.
The 64-pin QFN (9x9 mm) package has an exposed thermal pad (EP) that must be soldered to a ground pad of at least 50% package area on the PCB for mechanical reliability and thermal dissipation. Use a via array (typically 9 vias in a 3x3 grid, 0.3 mm diameter) connecting the EP to the internal ground plane. Route high-speed USB DP/DM traces as a 90-ohm differential pair with matched length, and place the 27-ohm series termination resistors within 5 mm of the MCU pins. Keep the D+ pull-up resistor (1.5 kohm to 3.3 V) close to the D+ pin.
Common pitfalls when designing with the ATSAMD21J15B-MFT include: (1) Forgetting to enable the DFLL48M closed-loop mode after startup causes the 48 MHz internal oscillator to drift up to 5% over voltage and temperature. (2) Configuring SERCOM pads without checking the peripheral multiplexing (PMUX) register results in non-functional I/O. (3) Exceeding the absolute maximum VDD of 3.63 V during ESD events damages the USB transceiver. (4) Failing to bit-bang the ERASE pin sequence before SWD programming on locked devices causes debugger connection failures.
Compliance Information
RoHS and REACH compliance per Microchip product declaration. Halogen-free per IEC 61249-2-21. AEC-Q100 not qualified; for automotive applications use ATSAMx21E/SAMx21G variants with explicit automotive grade suffix.
