ATSAMD21J16B-MUT - 48MHz Cortex-M0+ 64KB Flash MCU | Microchip
MPN: ATSAMD21J16B-MUT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.2 | $4.20 |
| 10 | $3.78 | $37.80 |
| 100 | $3.35 | $335.00 |
| 500 | $2.95 | $1,475.00 |
| 1,000 | $2.62 | $2,620.00 |
| 3,000 | $2.3 | $6,900.00 |
ATSAMD21J16B-MUT Overview
A 32-bit microcontroller (MCU) is an embedded computing device that integrates a CPU core, program memory (Flash), working memory (SRAM), and a rich set of peripherals on a single silicon die. The ARM Cortex-M0+ is the most energy-efficient ARM processor core, designed for deterministic real-time control and ultra-low power operation. The SAM D21 family positions itself between 8-bit/16-bit MCUs (PIC16, STM8) and higher-end Cortex-M3/M4 parts, balancing cost, power, and computational throughput.
Key features include 64KB Flash, 8KB SRAM, 48 MHz CPU, integrated Full-Speed USB 2.0 device, and up to 6 SERCOM (serial communication) interfaces configurable as I2C/SPI/UART. The SAM D21J series offers 64-pin QFN and 64-pin TQFP package options with up to 52 GPIO pins, supporting multiple package variants within the same family for design flexibility. Functional Safety (FuSa) variants are available for safety-critical applications requiring IEC 61508 SIL capability.
Architecturally, the ATSAMD21J16B uses a single-cycle I/O bus (IOBUS) and peripheral event system that allows peripherals to communicate without CPU intervention, dramatically reducing active-mode power consumption. SleepWalking peripherals can wake the CPU only when needed, enabling deep sleep currents below 10 uA. The integrated DFLL48M digital frequency-locked loop provides high-accuracy 48 MHz USB operation directly from a low-power 32.768 kHz crystal.
Typical applications include IoT sensor nodes, USB human-interface devices (HID), industrial control modules, smart home gateways, and battery-powered wearable electronics. The combination of Full-Speed USB, low-power modes, and small QFN footprint makes it especially suited for compact USB-powered devices.
When designing with this part, note the MUT suffix indicates Tape & Reel packaging, industrial temperature grade (-40C to +85C), and 3.3V nominal supply. PCB layout should keep the decoupling network (typically 100 nF + 4.7 uF) within 3 mm of the VDD pins to maintain signal integrity on the high-speed USB data lines.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the standalone manufacturer datasheet, providing engineers with a one-stop reference for component selection, sourcing, and PCB implementation.
Drop-in alternatives for ATSAMD21J16B-MUT — 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 ATSAMD21J16B-MUT (same form factor and footprint) — differing in ADC, Package, USB, Operating Temperature, DAC.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATSAMD21J16B-MU
✅ Drop-In✓ In Stock
$2.18 / Unit
View Datasheet →ATSAMD21J16B-AUT
✅ Drop-In✓ In Stock
$2.85 / Unit
View Datasheet →ATSAMD21J16B-AU
✅ Drop-In✓ In Stock
$2.75 / Unit
View Datasheet →ATSAMD21J15B-MUT
✅ Drop-In✓ In Stock
$1.92 / Unit
View Datasheet →ATSAMD21J16B-AF
✅ Drop-In✓ In Stock
$2.52 / Unit
View Datasheet →ATSAMD21J16B-MUT Maximum Ratings & Electrical Characteristics
| Core Architecture | ARM Cortex-M0+ (32-bit) |
| CPU Frequency (max) | 48 MHz |
| CoreMark/MHz | 2.46 |
| Flash Memory | 64 KB |
| SRAM | 8 KB |
| Operating Voltage | 1.62 V to 3.63 V |
| GPIO Count (max) | 52 |
| Package | 64-QFN (9x9 mm) with Exposed Pad |
| Pin/Package Count | 64 |
| Operating Temperature | -40 C to +85 C (industrial) |
| SERCOM Interfaces | 6 (configurable as I2C/SPI/UART) |
| USB | Full-Speed USB 2.0 Device with on-chip transceiver |
| DMA Channels | 12 |
| Event System Channels | 12 |
| ADC | 12-bit, up to 20 channels (SAR) |
| DAC | 10-bit, 1 channel |
| Timers/Counters | One 16-bit TC, One 8-bit TC, RTC |
| External Interrupts | 16 (plus 1 NMI) |
| Debug Interface | Serial Wire Debug (SWD), 2-pin |
| Mounting Type | Surface Mount |
| MSL Level | MSL3 (168 hours) |
| RoHS Status | Compliant (Green) |
ATSAMD21J16B-MUT Pin Configuration
| Pin 1 | PA00 — GPIO PA00, XIN32 (32.768 kHz crystal input) |
| Pin 2 | PA01 — GPIO PA01, XOUT32 (32.768 kHz crystal output) |
| Pin 3 | PA02 — GPIO PA02, AIN0 (ADC input channel 0) |
| Pin 4 | PA03 — GPIO PA03, AIN1 (ADC input channel 1), VREFA reference |
| Pin 5 | GND — Ground reference |
| Pin 6 | VDDIO — Digital I/O supply voltage |
| Pin 7 | PA04 — GPIO PA04, AIN2, VREFB reference |
| Pin 8 | PA05 — GPIO PA05, AIN3 |
| Pin 9 | PA06 — GPIO PA06, AIN4 |
| Pin 10 | PA07 — GPIO PA07, AIN5 |
| Pin 11 | PA08 — GPIO PA08, AIN6, I2S SCK |
| Pin 12 | PA09 — GPIO PA09, AIN7, I2S FS |
| Pin 13 | PA10 — GPIO PA10, AIN8, I2S MCK |
| Pin 14 | PA11 — GPIO PA11, AIN9, I2S SDO |
| Pin 15 | VDDIO — Digital I/O supply voltage |
| Pin 16 | GND — Ground reference |
| Pin 17 | PA12 — GPIO PA12, AIN10 |
| Pin 18 | PA13 — GPIO PA13 |
| Pin 19 | PA14 — GPIO PA14 |
| Pin 20 | PA15 — GPIO PA15 |
| Pin 21 | PA16 — GPIO PA16, I2S SDI |
| Pin 22 | PA17 — GPIO PA17 |
| Pin 23 | PA18 — GPIO PA18 |
| Pin 24 | PA19 — GPIO PA19 |
| Pin 25 | PA20 — GPIO PA20 |
| Pin 26 | PA21 — GPIO PA21 |
| Pin 27 | PA22 — GPIO PA22 |
| Pin 28 | PA23 — GPIO PA23, USB SOF 1kHz output |
| Pin 29 | GND — Ground reference |
| Pin 30 | VDDIO — Digital I/O supply voltage |
| Pin 31 | PA24 — GPIO PA24, USB DM (USB data minus) |
| Pin 32 | PA25 — GPIO PA25, USB DP (USB data plus) |
| Pin 33 | PA26 — GPIO PA26, SERCOM2 pad 0 |
| Pin 34 | PA27 — GPIO PA27, SERCOM2 pad 1 |
| Pin 35 | PA28 — GPIO PA28 |
| Pin 36 | PA29 — GPIO PA29 |
| Pin 37 | PA30 — GPIO PA30, SWCLK (Serial Wire Debug clock) |
| Pin 38 | PA31 — GPIO PA31, SWDIO (Serial Wire Debug data) |
| Pin 39 | GND — Ground reference |
| Pin 40 | VDDIO — Digital I/O supply voltage |
| Pin 41 | PB00 — GPIO PB00 |
| Pin 42 | PB01 — GPIO PB01 |
| Pin 43 | PB02 — GPIO PB02, AIN12 |
| Pin 44 | PB03 — GPIO PB03, AIN13 |
| Pin 45 | PB04 — GPIO PB04, AIN14 |
| Pin 46 | PB05 — GPIO PB05, AIN15 |
| Pin 47 | PB06 — GPIO PB06, AIN16 |
| Pin 48 | PB07 — GPIO PB07, AIN17 |
| Pin 49 | PB08 — GPIO PB08, AIN18 |
| Pin 50 | PB09 — GPIO PB09, AIN19 |
| Pin 51 | PB10 — GPIO PB10 |
| Pin 52 | PB11 — GPIO PB11 |
| Pin 53 | PB12 — GPIO PB12 |
| Pin 54 | PB13 — GPIO PB13 |
| Pin 55 | PB14 — GPIO PB14 |
| Pin 56 | PB15 — GPIO PB15 |
| Pin 57 | PB16 — GPIO PB16 |
| Pin 58 | PB17 — GPIO PB17 |
| Pin 59 | PB18 — GPIO PB18 |
| Pin 60 | PB19 — GPIO PB19 |
| Pin 61 | PB20 — GPIO PB20 |
| Pin 62 | PB21 — GPIO PB21 |
| Pin 63 | GND — Ground reference (multiple GND pins on exposed pad) |
| Pin 64 | VDDIO — Digital I/O supply voltage |
| Pin EP | Exposed Pad — Thermal pad, must be soldered to ground plane for heat dissipation |
Typical Applications
ATSAMD21J16B-MUT is suitable for 6 applications: USB Human Interface Devices (HID), IoT Sensor Nodes, Industrial Control Modules, Wearable Health Devices, Smart Home Gateways, Battery-Powered Consumer Electronics.
USB Human Interface Devices (HID)
The ATSAMD21J16B-MUT is ideally suited for USB HID applications such as keyboards, mice, game controllers, and custom input devices. Its integrated Full-Speed USB 2.0 device with on-chip transceiver eliminates the need for external PHY components, reducing BOM cost by approximately $0.50 per board. The 64KB Flash comfortably accommodates USB HID stacks including bootloader, HID class driver, and application firmware with room for future feature expansion. The DFLL48M digital frequency-locked loop auto-calibrates the 48 MHz USB clock from a low-cost 32.768 kHz crystal, eliminating the need for an external crystal oscillator and saving 3-4 mm of board space. According to the Microchip SAM D21 datasheet, USB suspend current is under 2.5 mA when configured for low-power HID peripherals operating from bus power.
Recommended
IoT Sensor Nodes
The ATSAMD21J16B-MUT excels in battery-powered IoT sensor nodes thanks to its SleepWalking peripherals and deep-sleep current below 10 uA. The 12-channel Event System allows sensors to trigger DMA transfers and wake the CPU only when meaningful data arrives, dramatically extending battery life in environmental monitoring, smart agriculture, and asset tracking applications. The 6 SERCOM interfaces enable simultaneous I2C sensor bus, SPI radio connection, and UART debug console without pin mux conflicts. With 48 MHz Cortex-M0+ performance at 2.46 CoreMark/MHz, the J16B handles on-sensor DSP for vibration analysis or temperature compensation. The 1.62-3.63V wide supply range accommodates both single-cell Li-ion (3.7V nominal) and 2xAA alkaline (3V nominal) battery configurations without level shifters.
Recommended
Industrial Control Modules
The ATSAMD21J16B-MUT serves industrial control modules requiring robust I/O count, deterministic real-time response, and wide operating voltage tolerance. Its 52 GPIO pins handle multiple sensor inputs, actuator outputs, status LEDs, and communication interfaces in a single chip, replacing discrete logic and reducing PCB area by 30-40%. The Cortex-M0+ core delivers single-cycle GPIO access with deterministic interrupt latency under 12 cycles, suitable for motor control, valve actuation, and process control loops. The 12-bit SAR ADC with 20 channels provides simultaneous monitoring of analog signals like temperature, pressure, and current. Operating voltage tolerance from 1.62V to 3.63V and industrial temperature grade (-40C to +85C) ensure reliable operation in factory automation environments with noisy 24V rails stepped down through DC-DC converters.
Recommended
Wearable Health Devices
The ATSAMD21J16B-MUT is well-matched to wearable health monitoring devices including fitness bands, heart-rate monitors, and continuous glucose monitors. The Cortex-M0+ core's energy efficiency at 2.46 CoreMark/MHz combined with deep-sleep currents under 10 uA enables multi-day battery life on small Li-Po cells (typically 100-200 mAh). The integrated 12-bit ADC samples photoplethysmography (PPG) signals for heart-rate estimation while the 10-bit DAC drives LED bias control. Six SERCOM interfaces support I2C communication with bioimpedance sensors, SPI connection to low-power accelerometers, and UART debug output for firmware development. The 9x9 mm QFN-64 footprint fits comfortably in wearable form factors under 25x25 mm, and the -40C to +85C range covers all consumer wearable use cases.
Recommended
Smart Home Gateways
The ATSAMD21J16B-MUT handles edge processing in smart home gateways bridging Zigbee, BLE, Z-Wave, or Wi-Fi radios to cloud services. Its 48 MHz Cortex-M0+ core with 64KB Flash runs local automation rules, sensor fusion, and MQTT/SNMP protocol stacks without external memory. The 6 SERCOM interfaces allow simultaneous operation of SPI-connected Wi-Fi modules (like ATWINC1500), I2C-connected environmental sensors, and UART-connected BLE modules. The integrated Full-Speed USB enables direct integration with Linux-based home hubs (Raspberry Pi, OpenHAB gateways) as a USB device for firmware updates and configuration. The wide 1.62-3.63V supply range tolerates USB bus power (5V stepped down) and PoE-derived rails in smart home installations.
Recommended
Battery-Powered Consumer Electronics
The ATSAMD21J16B-MUT powers consumer devices like Bluetooth speakers, wireless earbuds, e-readers, and remote controls where USB charging, low power, and compact size are essential. The integrated USB 2.0 Full-Speed device with on-chip transceiver simplifies charging and firmware update interfaces without external components. SleepWalking peripherals combined with the Event System allow the MCU to wake only on button press, audio buffer underrun, or battery-low events, extending standby time to months on small batteries. The Cortex-M0+ at 48 MHz handles audio sample-rate conversion, BLE stack proxy functions, and display refresh without external DSP chips. The 9x9 mm QFN package enables compact consumer form factors while the -40C to +85C industrial range covers all indoor and outdoor consumer use cases.
Recommended
Recommended Products Summary
Engineering reference data for ATSAMD21J16B-MUT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAMD21J16B-MU | ATSAMD21J16B-AUT | ATSAMD21J16B-AU | ATSAMD21J15B-MUT | ATSAMD21J16B-AF |
|---|---|---|---|---|---|---|
| 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 |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 64 KB | 64 KB | 64 KB | 64 KB | 32 KB (-50%) | 64 KB |
| SRAM | 8 KB | 8 KB | 8 KB | 8 KB | 8 KB | 8 KB |
| Core / Frequency | Cortex-M0+ / 48 MHz | Cortex-M0+ / 48 MHz | Cortex-M0+ / 48 MHz | Cortex-M0+ / 48 MHz | Cortex-M0+ / 48 MHz | Cortex-M0+ / 48 MHz |
| Operating Temperature | -40 C to +85 C (industrial) | -40 C to +85 C (industrial) | -40 C to +125 C (automotive AEC-Q100) | -40 C to +125 C (automotive AEC-Q100) | -40 C to +85 C (industrial) | -40 C to +125 C (automotive AEC-Q100) |
| Packaging Format | Tape & Reel (3000 pcs) | Tray (260 pcs) | Tape & Reel (3000 pcs) | Tray (260 pcs) | Tape & Reel (3000 pcs) | Tray (260 pcs) |
| USB Interface | Full-Speed USB 2.0 Device | Full-Speed USB 2.0 Device | Full-Speed USB 2.0 Device | Full-Speed USB 2.0 Device | Full-Speed USB 2.0 Device | Full-Speed USB 2.0 Device |
| GPIO Count (max) | 52 | 52 | 52 | 52 | 52 | 52 |
Key Differentiators
- Integrated Full-Speed USB 2.0 with on-chip transceiver (vs ATSAMD20J18A-MNT)
- Same-family scalability within SAM D21J (vs ATSAMD21J15B-MUT)
- Industrial temperature grade at lower cost (vs ATSAMD21J16B-AUT)
- SERCOM-configurable peripherals for flexible pin mapping (vs PIC16F726-E/MV)
Design Notes
Place decoupling capacitors (100 nF ceramic + 4.7 uF bulk) within 3 mm of each VDDIO pin. The SAM D21 has 5 VDDIO supply pins distributed across the 64-QFN package; each must be individually decoupled to prevent digital switching noise from corrupting analog ADC measurements. According to the Microchip SAM D21 datasheet, the on-chip voltage regulator requires a 1 uF capacitor on the VDDOUT pin with ESR below 0.5 ohm for stable operation.
The exposed pad (EP) on the 64-QFN package is the primary thermal path and must be soldered to a ground copper pour with at least 8 thermal vias to the inner ground plane. Without proper EP soldering, junction temperature can rise 30-40 C above ambient at 48 MHz full-load operation, potentially triggering thermal shutdown. Recommended PCB layout uses a 50 mm² copper pour minimum with 0.3 mm via diameter vias on a 1.0 mm pitch.
Keep USB DP (PA25) and DM (PA24) traces at 90 ohm differential impedance with matched length within 0.5 mm. Place the USB ESD protection diode within 5 mm of the USB connector. The 32.768 kHz crystal traces (PA00/PA01 for XIN32/XOUT32) should be routed symmetrically within 5 mm of the MCU with a grounded guard ring to prevent noise coupling from switching power supplies.
When using the integrated USB Full-Speed transceiver, add 22 ohm series termination resistors on DP and DM lines close to the MCU pins to dampen reflections on the 90 ohm differential pair. The DFLL48M closed-loop bandwidth should be set to 1.5 kHz typical (configurable via NVM fuses) for stable USB operation; lower bandwidth risks USB jitter exceeding USB 2.0 spec limits.
Common pitfalls include: (1) Forgetting to configure the NVM fuses for the correct clock source and BOD threshold before first programming. (2) Using PA24/PA25 as GPIO when USB is enabled, which conflicts with USB DP/DM. (3) Exceeding the 3.63V absolute maximum on VDDIO during hot-plug events - add a TVS diode if the design is user-accessible. (4) Not enabling the SERCOM peripheral's core clock before peripheral-specific clock, causing I2C/SPI lockup on first use.
Compliance Information
RoHS compliant (Green) per Microchip product page. Industrial temperature grade; not AEC-Q100 qualified - choose ATSAMD21J16B-AUT for automotive.
