ATSAML21J18B-UUT - 256KB Flash Cortex-M0+ MCU | Microchip
N.º de pieza: ATSAML21J18B-UUT ✓ Activo| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $5.89 | $5,89 |
| 10 | $5.31 | $53,10 |
| 100 | $4.73 | $473,00 |
| 500 | $4.2 | $2.100,00 |
| 1.000 | $3.78 | $3.780,00 |
ATSAML21J18B-UUT Descripción general
A microcontroller (MCU) is an integrated circuit containing a processor core, program and data memory, and programmable peripherals. ARM Cortex-M0+ cores target the lowest active power and smallest die area among the Cortex-M family, making them ideal for battery-powered embedded systems. Within that hierarchy the SAM L21 sits in Microchip's ultra-low-power tier alongside the SAM L11 secure family and the SAM D20/D21 mainstream tier, all built around the same ARM Cortex-M0+ instruction set. This particular J18B-UUT part is the WLCSP64 package variant - WLCSP (Wafer Level Chip Scale Package) is the smallest-footprint option of the SAM L21J family and is intended for space-constrained wearables and sensor nodes.
Key features include a 12-bit 1 MSPS ADC, a 10-bit DAC, four SERCOM channels that can each be configured as USART, I2C, or SPI, and a 32-bit RTC with calendar mode. Power management is the central design pillar: SleepWalking lets peripherals wake the CPU only when relevant events occur, while six flexible power domains allow unused logic to be powered down at run time. The 64-ball WLCSP package has a footprint of approximately 3.0 x 3.0 mm and a height under 0.5 mm, allowing direct attachment to a top-side PCB layer with minimal inductance.
The architecture pairs the Cortex-M0+ core with a 4-channel event system and a Peripheral Touch Controller (PTC) supporting capacitive touch sensing. The 12-bit ADC achieves up to 1 MSPS at full resolution and 2 MSPS at 8-bit resolution, providing enough bandwidth for sensor fusion and audio preprocessing. A hardware cryptographic module is not present on this family - it is delegated to the SAM L11 tier - so security-sensitive designs should add an external secure element.
Typical applications include battery-powered IoT sensor nodes, wearable fitness and health devices, smart metering, home automation endpoints, and industrial wireless sensor transmitters. The combination of Cortex-M0+ performance, 256 KB of Flash for application code, and SleepWalking peripheral architecture keeps the average system current below 1 mA in many typical duty-cycled scenarios.
When designing with this device, prioritize sleep-mode current draw as your primary figure of merit; idle power dominates battery life more than active throughput. The WLCSP64 footprint requires PCB pad design rules substantially different from QFP or QFN packages - the recommendation is non-solder-mask-defined (NSMD) pads with a diameter roughly 0.4 mm and a pitch matching the package balls. Reference the Microchip SAM L21 WLCSP64 land pattern application note for exact stack-up recommendations.
This page synthesizes distributor pricing, drop-in compatible alternatives from Microchip's SAM L21 family, and practical PCB/thermal design notes that are not collected in the manufacturer datasheet.
Alternativas directas para ATSAML21J18B-UUT — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Variantes de esta serie
Modelos de la misma serie compatibles directamente con ATSAML21J18B-UUT (mismo factor de forma y huella) — difiere en ADC, Mounting Type, Package, SRAM, Active Current.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
ATSAML21J17B-UUT
✅ Sustitución directa✓ En stock
$2.18 / unidad
Ver hoja de datos →ATSAML21J16B-UUT
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
ATSAML21J18B-AUT
✅ Sustitución directa✓ En stock
$4.55 / unidad
Ver hoja de datos →ATSAML21J18B-UUT Valores máximos y características eléctricas
| Core Architecture | ARM Cortex-M0+ (32-bit) |
| Maximum CPU Clock | 48 MHz |
| CoreMark per MHz | 2.46 CoreMark/MHz |
| Flash Program Memory | 256 KB |
| SRAM | 40 KB |
| Supply Voltage Range | 1.6 V to 3.6 V |
| Rango de temperatura de funcionamiento | -40C to +85C (industrial) |
| Active Current Consumption | < 35 uA/MHz |
| Sleep Mode Current | 200 nA |
| ADC | 12-bit, up to 1 MSPS (up to 20 channels) |
| DAC | 10-bit |
| SERCOM Channels | 4 (configurable USART/I2C/SPI) |
| RTC | 32-bit with calendar mode |
| Peripheral Touch Controller (PTC) | Yes - capacitive touch support |
| Encapsulado | WLCSP-64 (3.0 x 3.0 mm, wafer-level chip scale) |
| Tipo de montaje | Surface Mount (chip-scale) |
| Lead-Free / RoHS | Lead-free, RoHS compliant |
Guía de configuración de pines de ATSAML21J18B-UUT wlcsp-64 (3.0 x 3.0 mm, wafer-level chip scale)
Configuración de pines para ATSAML21J18B-UUT (encapsulado wlcsp-64 (3.0 x 3.0 mm, wafer-level chip scale)). Este CI digital incluye GPIO, interfaces de comunicación (UART, SPI, I2C) y pines de alimentación. Consulte la hoja de datos del fabricante para conocer las funciones alternativas de los pines y las opciones de configuración. Esencial para el diseño de sistemas embebidos y el diseño de PCB.
No hay datos detallados de patillaje disponibles para ATSAML21J18B-UUT.
Consulte la hoja de datos para ver la configuración completa de patillas.
Aplicaciones típicas
ATSAML21J18B-UUT es adecuado para 6 aplicacións: Battery-Powered IoT Sensor Node, Wearable Fitness & Health Device, Smart Metering & Utility Endpoints, Home Automation Endpoint, Industrial Wireless Sensor Transmitter, Capacitive Touch User Interface.
Battery-Powered IoT Sensor Node
The ATSAML21J18B-UUT is well suited for battery-powered IoT sensor nodes that transmit small packets over LoRa, BLE, or sub-GHz radios. Its 200 nA Sleep current and SleepWalking peripherals allow the MCU to remain in deep sleep while the ADC, PTC, or RTC autonomously monitor sensor activity and only wake the CPU when a real event occurs. The 256 KB Flash supports OTA dual-bank firmware updates, which is essential for deployed IoT nodes that cannot be physically re-flashed. 40 KB SRAM is sufficient for a TCP/IP or LoRaWAN protocol stack plus a sensor data buffer.
Recomendado
Wearable Fitness & Health Device
The ATSAML21J18B-UUT's WLCSP-64 package measures approximately 3.0 x 3.0 mm with sub-0.5 mm height, making it ideal for wearable fitness bands and smartwatches where PCB area is severely constrained. The integrated Peripheral Touch Controller (PTC) supports capacitive touch buttons and sliders without external components, and the 12-bit 1 MSPS ADC can sample PPG (photoplethysmography) heart-rate signals. The 35 uA/MHz active current and 200 nA Sleep current keep average system power below 50 uA for typical 24/7 heart-rate monitoring, enabling multi-day battery life on a small Li-Po cell.
Recomendado
Smart Metering & Utility Endpoints
Smart electricity, water, and gas meters require ultra-low Sleep current and long Flash retention to support 10-15 year battery or harvested-power operation. The ATSAML21J18B-UUT meets both constraints with its 200 nA Sleep current, 256 KB Flash for metering firmware plus DLMS/COSEM protocol stacks, and industrial -40C to +85C operating range. The 12-bit ADC can directly sample battery voltage and current shunts, while the 32-bit RTC tracks time-of-use billing intervals. The 4 SERCOM channels support M-Bus, Wireless M-Bus, or LoRaWAN connectivity.
Recomendado
Home Automation Endpoint
Home automation endpoints such as battery-powered door/window sensors, PIR motion detectors, and HVAC wireless thermostats benefit from the ATSAML21J18B-UUT's SleepWalking architecture. The PTC handles capacitive proximity or touch surfaces, while SERCOM channels support Zigbee, Thread, or BLE Mesh radios. The 256 KB Flash accommodates OTA-capable firmware for Matter/Thread commissioning flows, and the 1.6-3.6 V supply range is compatible with 2x AA alkaline or CR2032 coin cells common in residential sensors.
Recomendado
Industrial Wireless Sensor Transmitter
Industrial wireless sensor transmitters in factory automation monitor temperature, pressure, vibration, and flow on rotating or hard-to-wire equipment. The ATSAML21J18B-UUT's industrial -40C to +85C operating range, 12-bit 1 MSPS ADC, and 256 KB Flash support predictive-maintenance algorithms with on-device FFT and threshold detection. The Cortex-M0+ at 48 MHz is sufficient to run compressed vibration-analysis firmware at 1-2 kHz sampling rates, while SleepWalking peripherals enable duty-cycling below 1% for multi-year battery operation.
Recomendado
Capacitive Touch User Interface
The ATSAML21J18B-UUT's integrated Peripheral Touch Controller (PTC) supports up to 256 capacitive touch channels via a matrix scanning arrangement, making it ideal for touch keypads, sliders, and proximity sensors in appliances, access-control panels, and consumer electronics. The Cortex-M0+ core runs the touch acquisition state machine in hardware, freeing the CPU for HMI logic and communication tasks. Combined with 200 nA Sleep current, the device is ideal for battery-powered remote controls and wireless wall switches.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para ATSAML21J18B-UUT — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | ATSAML21J17B-UUT | ATSAML21J16B-UUT | ATSAML21J18B-AUT |
|---|---|---|---|---|
| Package | WLCSP-64 | WLCSP-64 (same) | WLCSP-64 (same) | TQFP-64 (drop-in for TQFP64 PCB) |
| Brand | Microchip Technology | Microchip Technology (same family) | Microchip Technology (same family) | Microchip Technology (same family) |
| Flash Memory | 256 KB | 128 KB (-50%) | 64 KB (-75%) | 256 KB (same die) |
| SRAM | 40 KB | 16 KB (-60%) | 8 KB (-80%) | 40 KB (same) |
| Core / Max Clock | Cortex-M0+ / 48 MHz | Cortex-M0+ / 48 MHz (same) | Cortex-M0+ / 48 MHz (same) | Cortex-M0+ / 48 MHz (same) |
| Active Current | < 35 uA/MHz | < 35 uA/MHz (same) | < 35 uA/MHz (same) | < 35 uA/MHz (same) |
| Sleep Current | 200 nA | 200 nA (same) | 200 nA (same) | 200 nA (same) |
| Operating Voltage | 1.6 V to 3.6 V | 1.6 V to 3.6 V (same) | 1.6 V to 3.6 V (same) | 1.6 V to 3.6 V (same) |
| Operating Temperature | -40C to +85C | -40C to +85C (same) | -40C to +85C (same) | -40C to +85C (same) |
Diferenciadores clave
- Smallest-footprint package option in the SAM L21J family (frente a ATSAML21J18B-AUT (TQFP-64))
- Pin-compatible density migration within WLCSP64 family (frente a ATSAML21J17B-UUT (128 KB) and ATSAML21J16B-UUT (64 KB))
- SleepWalking peripheral architecture for sub-1 mA average current (frente a ATSAMD21J18 (Cortex-M0+, 256 KB, TQFP/QFN))
Notas de diseño
WLCSP-64 packages require non-solder-mask-defined (NSMD) PCB pads because the WLCSP ball pitch is typically 0.4 mm. Per the Microchip SAM L21 WLCSP64 land-pattern application note, NSMD pads of approximately 0.27 mm diameter on a 0.4 mm pitch are recommended; solder-mask-defined pads risk pad float and unreliable reflow. The PCB stack-up must support microvia-in-pad for the inner-row balls to avoid solder starvation. Hand soldering is NOT feasible - use a reflow profile with peak temperature 245C +/- 5C.
The ATSAML21J18B-UUT is designed for ultra-low-power duty-cycled applications. To minimize Sleep current, disable unused peripherals in the AHBMASK and APBxMASK registers before entering Sleep mode, and use the Power Manager's static power-domain gating via SUPC->VREG. Typical current draw at 3.3 V with full peripheral clocks running is approximately 8 mA at 48 MHz; in Retention Sleep with RTC running it drops to approximately 1.5 uA. For battery applications, design the system power-on sequence to wait for the LDO/sleep-controller to stabilize before releasing reset.
The WLCSP-64 package has a small exposed die area, so thermal resistance theta_JA is approximately 38 C/W (typical, per Microchip SAM L21 thermal application note). At full 48 MHz active load, internal dissipation is roughly 12 mW, producing a junction temperature rise of only 0.5C above ambient - thermal management is generally not a concern. However, reflow-profile control is critical: WLCSP packages absorb less solder-joint stress than QFN packages, so use a JEDEC J-STD-020 profile with soak time 60-90 seconds and peak time within 30 seconds.
The 4 SERCOM channels on the ATSAML21J18B-UUT can each be assigned to any I/O pin via the IO multiplexing matrix, but switching SERCOM roles at run time requires a reconfiguration sequence. For SPI designs above 8 MHz, keep trace lengths under 50 mm and use source-terminated series resistors (22-33 ohm) to dampen reflections. For I2C, both standard-mode (100 kHz) and fast-mode (400 kHz) are supported without external pull-ups in most cases, but Fast-Mode Plus (1 MHz) requires external 1 kohm pull-ups to VDD.
Three common pitfalls when bringing up the ATSAML21J18B-UUT: (1) forgetting that the WLCSP64 package requires microvia-in-pad PCB technology - a standard 4-layer FR-4 stack-up will not work reliably; (2) failing to initialize the 32 kHz crystal oscillator (XOSC32K) before switching the GCLK main source from the internal 8 MHz OSC8M to XOSC32K, which causes lock-up; (3) not enabling the brown-out detector (BOD33) before first power-up, which can lead to flash corruption during brown-out events. Always run the Atmel/Microchip START code generator or MPLAB Harmony 3 project wizard for the initial peripheral setup.
Información de cumplimiento
RoHS compliant and lead-free per Microchip product page. AEC-Q100 automotive qualification does not apply - the SAM L21 family is industrial-grade only; automotive designs should use the SAM V71/SAM E70 family or PIC32MX automotive variants. Halogen-free status not explicitly stated in the verified web data.
