ATSAML21J16B-MUT - 48MHz Cortex-M0+ 64KB Flash MCU | Microchip
MPN: ATSAML21J16B-MUT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.55 | $3.55 |
| 10 | $3.19 | $31.90 |
| 100 | $2.74 | $274.00 |
| 500 | $2.4 | $1,200.00 |
| 1,000 | $2.18 | $2,180.00 |
ATSAML21J16B-MUT Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory (Flash), working memory (SRAM), and programmable peripherals on one die. The Cortex-M0+ is an ARM 32-bit core optimized for minimum silicon area and energy consumption, while Thumb-2 instruction set compatibility gives it the code density of larger cores. The SAM L21 family extends this ultra-low-power positioning by adding Sleepwalking peripherals (SERCOM, ADC, PTC) that wake the CPU only on meaningful events, and by providing multiple low-power domains controlled via the Power Manager (PM) and Supply Controller (SUPC) blocks.
Key features of the ATSAML21J16B-MUT include 64 KB Flash, 8 KB SRAM, up to 48 MHz operation (2.46 CoreMark/MHz), a 12-bit 1 Msps ADC, a 10-bit 350 ksps DAC, up to six SERCOM serial interfaces (configurable as I2C/SPI/UART/USART), a 64-pin QFN package with high pin count for I/O expansion, and integrated PTC touch-overlays support. The device also includes a full-speed USB 2.0 device/host interface in select package options and a flexible Event System for hardware-triggered peripheral interactions.
Architecturally, the ATSAML21J16B-MUT separates logic into three power domains: Backup, Voltage Regulator, and Core. Each domain can be independently switched off by the SUPC, allowing the chip to enter BACKUP mode drawing only a few hundred nanoamps while preserving the RTC and selected I/O wake events. SERCOM modules can be runtime-reconfigured to any of UART, SPI, or I2C, simplifying BOM reuse across product variants.
Typical applications include IoT sensor nodes, wearable health and fitness devices, smart-home and building-automation end nodes, low-power wireless-connected products (when paired with an external sub-GHz or BLE transceiver), battery-backed industrial data loggers, and human-machine interface (HMI) panels using capacitive touch.
When designing with this device, plan the sleep/wake architecture first: route wake-up sources through the Event System to avoid CPU wake-ups on every interrupt. Use the integrated DC-DC converter (L21 has switched-mode regulation) when VDD > 1.8 V to maximize efficiency.
This page synthesizes distributor pricing, same-family drop-in alternatives, application notes, and design considerations not found on the manufacturer datasheet alone, optimized for engineers selecting low-power Cortex-M0+ silicon for battery and energy-harvesting products.
Drop-in alternatives for ATSAML21J16B-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 ATSAML21J16B-MUT (same form factor and footprint) — differing in Package, ADC, SRAM, Flash Memory, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATSAML21J18B-MUT
✅ Drop-In✓ In Stock
$4.68 / Unit
View Datasheet →ATSAML21J17B-MUT
✅ Drop-In✓ In Stock
$2.49 / Unit
View Datasheet →ATSAML21J15B-MUT
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
ATSAME53J19A-MUT
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$4.95 / Unit
View Datasheet →ATSAMG55J19B-MUT
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$5.74 / Unit
View Datasheet →ATSAML21J16B-MUT Maximum Ratings & Electrical Characteristics
| Core Processor | ARM Cortex-M0+ |
| Core Size | 32-Bit Single-Core |
| Series | SAM L21J |
| Maximum Clock Speed | 48 MHz |
| CoreMark/MHz | 2.46 |
| Program Memory (Flash) | 64 KB (64K x 8) |
| Supply Voltage (VDD) | 1.62 V to 3.63 V |
| Active Mode Current | < 35 uA/MHz |
| Sleep Mode Current | 200 nA (typical) |
| ADC | 12-bit, up to 1 Msps |
| DAC | 10-bit, 350 ksps |
| SERCOM Modules | Up to 6 (UART/SPI/I2C/LIN configurable) |
| Package | 64-QFN (9x9 mm), surface mount |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C |
| RoHS Status | Compliant |
| Lead-Free / Halogen-Free | Lead-free (per Microchip product page) |
ATSAML21J16B-MUT Pin Configuration
| Pin 1 | VDDIO — I/O supply voltage |
| Pin 2 | PA02 — GPIO / peripheral function |
| Pin 3 | PA03 — GPIO / peripheral function |
| Pin 4 | PA04 — GPIO / peripheral function |
| Pin 5 | PA05 — GPIO / peripheral function |
| Pin 6 | PA06 — GPIO / peripheral function |
| Pin 7 | PA07 — GPIO / peripheral function |
| Pin 8 | VDDIN — Main supply voltage input |
| Pin 9 | GND — Ground |
| Pin 10 | PB00 — GPIO / peripheral function |
| Pin 11 | PB01 — GPIO / peripheral function |
| Pin 12 | PB02 — GPIO / SERCOM |
| Pin 13 | PB03 — GPIO / SERCOM |
| Pin 14 | PB04 — GPIO / SERCOM |
| Pin 15 | PB05 — GPIO / SERCOM |
| Pin 16 | PB06 — GPIO / SERCOM |
| Pin 17 | PB07 — GPIO / SERCOM |
| Pin 18 | PB08 — GPIO / SERCOM |
| Pin 19 | PB09 — GPIO / SERCOM |
| Pin 20 | PA08 — GPIO / peripheral function |
| Pin 21 | PA09 — GPIO / peripheral function |
| Pin 22 | PA10 — GPIO / peripheral function |
| Pin 23 | PA11 — GPIO / peripheral function |
| Pin 24 | PA12 — GPIO / peripheral function |
| Pin 25 | PA13 — GPIO / peripheral function |
| Pin 26 | PA14 — GPIO / peripheral function |
| Pin 27 | PA15 — GPIO / peripheral function |
| Pin 28 | PA16 — GPIO / peripheral function |
| Pin 29 | PA17 — GPIO / peripheral function |
| Pin 30 | PA18 — GPIO / peripheral function |
| Pin 31 | PA19 — GPIO / peripheral function |
| Pin 32 | PA20 — GPIO / peripheral function |
| Pin 33 | PA21 — GPIO / peripheral function |
| Pin 34 | PA22 — GPIO / peripheral function |
| Pin 35 | PA23 — GPIO / peripheral function |
| Pin 36 | PA24 — GPIO / peripheral function |
| Pin 37 | PA25 — GPIO / peripheral function |
| Pin 38 | GND — Ground |
| Pin 39 | VDDCORE — Internal core voltage output |
| Pin 40 | PA27 — GPIO / peripheral function |
| Pin 41 | RESET_N — Reset (active low) |
| Pin 42 | PA28 — GPIO / peripheral function |
| Pin 43 | PA29 — GPIO / peripheral function |
| Pin 44 | PA30 — GPIO / peripheral function |
| Pin 45 | PA31 — GPIO / peripheral function |
| Pin 46 | PB10 — GPIO / SERCOM |
| Pin 47 | PB11 — GPIO / SERCOM |
| Pin 48 | PB12 — GPIO / SERCOM |
| Pin 49 | PB13 — GPIO / SERCOM |
| Pin 50 | PB14 — GPIO / SERCOM |
| Pin 51 | PB15 — GPIO / SERCOM |
| Pin 52 | PB16 — GPIO / SERCOM |
| Pin 53 | PB17 — GPIO / SERCOM |
| Pin 54 | PB18 — GPIO / peripheral function |
| Pin 55 | PB19 — GPIO / peripheral function |
| Pin 56 | PB20 — GPIO / peripheral function |
| Pin 57 | PB21 — GPIO / peripheral function |
| Pin 58 | PA00 — GPIO / peripheral function (XIN) |
| Pin 59 | PA01 — GPIO / peripheral function (XOUT) |
| Pin 60 | VDDIO — I/O supply voltage |
| Pin 61 | GND — Ground |
| Pin 62 | SWDIO — Serial Wire Debug I/O |
| Pin 63 | SWCLK — Serial Wire Debug Clock |
| Pin 64 | EP — Exposed thermal pad (connect to GND) |
Typical Applications
ATSAML21J16B-MUT is suitable for 6 applications: Battery-Powered IoT Sensor Nodes, Wearable Health and Fitness Devices, Smart Home and Building Automation, Industrial Data Loggers and Meters, Capacitive Touch HMI Panels, Low-Power Wireless Connected Products.
Battery-Powered IoT Sensor Nodes
The ATSAML21J16B-MUT is purpose-built for battery-powered IoT sensor nodes that must run for years on a single coin cell or AA battery. Its <35 uA/MHz active current and 200 nA Sleep current with full SRAM retention mean a duty-cycled sensor node (1 second wake every minute) can extend battery life to 5-10 years on a 2400 mAh cell. Sleepwalking peripherals wake the core only on threshold-crossing ADC events or qualified capacitive-touch events, avoiding unnecessary CPU wake-ups. Pair this MCU with a sub-GHz or BLE transceiver to build a wireless sensor product.
Recommended
Wearable Health and Fitness Devices
Wearable fitness trackers and medical wearables benefit from the ATSAML21J16B-MUT's combination of ultra-low-power operation, integrated 12-bit ADC for sensor acquisition, and 64-pin QFN package that fits small enclosures. The integrated PTC (Peripheral Touch Controller) supports capacitive touch buttons and sliders without external components, useful for sleek wearable UI designs. The device's Sleepwalking ADC can monitor a heart-rate or motion sensor continuously at microamp-level current, only waking the CPU on significant motion or signal change.
Recommended
Smart Home and Building Automation
Smart-home end nodes such as battery-powered door/window sensors, occupancy sensors, and HVAC controllers leverage the ATSAML21J16B-MUT's ultra-low-power budget and 64 GPIO pins for interfacing multiple sensors and actuators. The SERCOM modules (up to 6) can be runtime-configured as I2C for sensors, SPI for displays or radios, and UART for debug or external connectivity. The Event System enables hardware-triggered peripheral chains (timer -> ADC -> DMA -> radio transmit) without CPU intervention, saving power on every transaction.
Recommended
Industrial Data Loggers and Meters
Industrial data loggers measuring temperature, pressure, vibration, or flow can use the ATSAML21J16B-MUT to capture sensor data for years on battery or solar power. The 12-bit 1 Msps ADC and 10-bit DAC support process-control loops, while the integrated RTC with backup power domain keeps time-stamping accurate even in BACKUP mode drawing only nanoamps. Six SERCOM channels connect to multiple sensor buses simultaneously. The -40C to +85C industrial operating temperature range makes it suitable for factory-floor and outdoor installations.
Recommended
Capacitive Touch HMI Panels
The ATSAML21J16B-MUT integrates Microchip's PTC (Peripheral Touch Controller), enabling robust capacitive touch buttons, sliders, and wheels with up to 256 touch channels via external driver. Combined with the 12-bit ADC and SERCOM channels for display connectivity, it can drive small TFT or OLED HMI panels in appliances, audio equipment, or industrial control surfaces. The 64-QFN package leaves ample GPIO for LED indicators and rotary encoder inputs. Sleepwalking PTC detects user gestures in <1 uA, enabling instant-on user interfaces with battery-friendly standby.
Recommended
Low-Power Wireless Connected Products
When paired with an external sub-GHz transceiver (e.g., SAM R34, SAM R35, or third-party LoRa/Sigfox modules), the ATSAML21J16B-MUT serves as the application host MCU for low-power wireless end nodes in LoRaWAN, Sigfox, or proprietary sub-GHz networks. It runs the application stack, sensor acquisition, and user-interface logic while the transceiver handles RF modulation. The ultra-low-power profile extends battery life to 10+ years in typical metering or asset-tracking deployments. The 64-pin package exposes enough GPIO for multi-sensor interfaces and display connectivity.
Recommended
Recommended Products Summary
Engineering reference data for ATSAML21J16B-MUT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAML21J18B-MUT | ATSAML21J17B-MUT | ATSAML21J15B-MUT | ATSAME53J19A-MUT | ATSAMG55J19B-MUT |
|---|---|---|---|---|---|---|
| Brand | 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 |
| Core | ARM Cortex-M0+ 48 MHz | ARM Cortex-M0+ 48 MHz | ARM Cortex-M0+ 48 MHz | ARM Cortex-M0+ 48 MHz | ARM Cortex-M4F 120 MHz | ARM Cortex-M4 120 MHz |
| Flash | 64 KB | 256 KB | 128 KB | 32 KB | 512 KB | 512 KB |
| SRAM | 8 KB | 32 KB | 16 KB | 4 KB | 192 KB | 128 KB |
| Active Current | <35 uA/MHz | <35 uA/MHz (same family) | <35 uA/MHz (same family) | <35 uA/MHz (same family) | ~80 uA/MHz (M4F higher perf) | ~80 uA/MHz (M4 higher perf) |
| Sleep Current | 200 nA | 200 nA | 200 nA | 200 nA | ~3 uA (higher due to M4F caches) | ~5 uA (higher due to M4) |
| Supply 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 | 1.62 V to 3.6 V |
| Pin-Compatible Footprint | Yes (reference) | Yes - drop-in upgrade | Yes - drop-in upgrade | Yes - drop-in downgrade | Same package; peripheral mapping differs | Same package; peripheral mapping differs |
Key Differentiators
- Ultra-low Sleep current with full SRAM retention (vs ATSAME53J19A-MUT)
- Drop-in Flash scalability within SAM L21 family (vs ATSAMV71Q20B-AABT)
- Integrated Sleepwalking peripherals and Event System (vs STM32L0 (STMicroelectronics))
Design Notes
Plan the sleep/wake architecture first. The ATSAML21J16B-MUT has multiple power domains (BACKUP, Voltage Regulator, Core) that can be independently switched off. Use Sleepwalking peripherals so the ADC, SERCOM, or PTC can qualify events without waking the CPU. Estimate: a duty-cycled sensor node waking 1 second per minute consumes approximately 0.6 uA average (1 sec * 35 uA/MHz * 48 MHz / 60 = 28 uA-sec/min, averaged). Use the DC-DC converter mode when VDD > 1.8 V for maximum efficiency; switch to LDO mode below 1.8 V.
Place decoupling capacitors (100 nF and 1 uF ceramic) as close as possible to VDDIN, VDDIO, and VDDCORE pins. Connect the exposed thermal pad (pin 64 on 64-QFN) to a large ground pour with at least 8 thermal vias for heat dissipation - although this part dissipates little heat, the pad is also a low-impedance ground return. Keep SWDIO/SWCLK traces short (< 5 cm) and route them away from switching signals to prevent debug interface noise susceptibility. Place the 32.768 kHz crystal (XIN/XOUT) close to the MCU with a guard ring to GND for RTC accuracy.
Do not exceed the absolute maximum VDDIN of 3.63 V - this includes USB bus-powered scenarios where VBUS may transiently exceed 3.6 V. Add a clamping diode or current-limit resistor. Be aware that the part-variant suffix codes Flash density and SRAM size; verify your linker script matches the actual silicon revision. For low-power designs, the SERCOM modules must be explicitly disabled before entering Sleep mode, or they will keep their internal clocks running and add leakage current. Finally, when migrating from SAM D20/D21, note that the SERCOM peripheral count and Event System routing differ - software rework is mandatory.
Compliance Information
RoHS compliant per Microchip product page and DigiKey listings. Not AEC-Q100 qualified - SAM V71 family is the Microchip automotive-grade alternative. Lead-free matte-tin plating. Conflict-minerals compliant per Microchip policy.
