ATSAML21J18B-AUT - 48MHz Cortex-M0+ MCU 256KB Flash | Microchip
MPN: ATSAML21J18B-AUT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.07 | $7.07 |
| 10 | $6.36 | $63.60 |
| 100 | $5.7 | $570.00 |
| 500 | $5.07 | $2,535.00 |
| 1,000 | $4.55 | $4,550.00 |
ATSAML21J18B-AUT Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory (Flash), data memory (SRAM), and programmable peripherals into one IC. The Cortex-M0+ is ARM's smallest and most energy-efficient core, optimized for embedded applications that demand deterministic real-time behavior at very low active and sleep currents. Ultra-low-power MCUs sit in the broader hierarchy of embedded microcontrollers, which in turn belong to the wider family of microprocessors and digital semiconductors.
Key features include a 48MHz maximum CPU clock, 256KB program Flash, 32KB SRAM, an on-chip full-speed USB 2.0 device interface, multiple SERCOM serial interfaces, a 12-bit ADC, a 10-bit DAC, and integrated touch hardware (PTC). The SAM L21 family is engineered for ultra-low-power operation, drawing under 35 uA/MHz in active mode and approximately 200nA in Sleep mode, with multiple SleepWalking-enabled peripherals that allow autonomous wake-up based on sensor events without CPU intervention. The device supports a 1.62V to 3.63V supply range.
Architecturally, the ATSAML21J18B uses the Cortex-M0+ core with a single-cycle I/O port and a low-power 32.768kHz oscillator supporting RTC, brown-out detector, and supply voltage monitoring. The Functional Safety (FuSa) variant includes additional safety documentation, failure-mode analysis, and diagnostics for IEC 60730 class B safety compliance in home appliances and similar end products. The 64-pin TQFP footprint exposes 51 GPIO lines alongside USB, SERCOM, ADC, DAC, and analog comparator peripherals.
Typical applications include battery-powered IoT sensor nodes, smart home appliances, wearable health and fitness devices, industrial sensor transmitters, building automation controllers, and consumer electronics requiring Functional Safety class B compliance. The combination of USB device, deep-sleep current below 1uA, and a touch peripheral makes it suitable for HMI front panels that must run for years on a single battery.
When designing with this part, place a 100nF decoupling capacitor within 3mm of each VDD pin and a 4.7uF bulk capacitor near the device. Configure unused pins as inputs with pull-downs to minimize leakage, and use the SleepWalking peripheral event system to keep the CPU in deep sleep until a sensor threshold is crossed.
This page synthesizes distributor pricing, drop-in same-family SAM L21 and SAM D21 alternatives, and practical low-power design guidance not aggregated on a single manufacturer page.
Drop-in alternatives for ATSAML21J18B-AUT — 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 ATSAML21J18B-AUT (same form factor and footprint) — differing in ADC, Active Current, Functional Safety, Mounting Type, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATSAML21J17B-UUT
✅ Drop-In✓ In Stock
$2.18 / Unit
View Datasheet →ATSAML21J18B-AUT Maximum Ratings & Electrical Characteristics
| Core Architecture | ARM Cortex-M0+ (32-bit) |
| Series | SAM L21J, Functional Safety (FuSa) |
| Maximum CPU Frequency | 48 MHz |
| Program Flash | 256 KB (256K x 8) |
| SRAM | 32 KB (up to 40 KB reported by some sources) |
| Supply Voltage (Vcc/Vdd) | 1.62 V to 3.63 V |
| Operating Temperature | -40 C to +85 C (industrial) |
| Package | 64-pin TQFP (10x10 mm) |
| Mounting Type | Surface Mount (Tape & Reel, AUT suffix) |
| GPIO Count | 51 (per SAM L21J datasheet) |
| USB | USB 2.0 Full-Speed Device |
| Serial Interfaces | Multiple SERCOM (configurable as UART/SPI/I2C) |
| ADC | 12-bit |
| DAC | 10-bit |
| Touch Peripheral (PTC) | Yes (Peripheral Touch Controller) |
| Active Current | Under 35 uA/MHz |
| Sleep Current | 200 nA |
| Functional Safety | IEC 60730 Class B (FuSa variant) |
| RoHS Status | Compliant |
| Carrier Type | Tape & Reel (AUT suffix) |
ATSAML21J18B-AUT 64-pin tqfp (10x10 mm) Pin Configuration Guide
Pin configuration for ATSAML21J18B-AUT (64-pin tqfp (10x10 mm) package). This digital IC includes GPIO, communication interfaces (UART, SPI, I2C), and power pins. Refer to the manufacturer datasheet for alternate pin functions and configuration options. Essential for embedded system design and PCB layout.
No detailed pinout data available for ATSAML21J18B-AUT.
Refer to the datasheet for full pin configuration.
Typical Applications
ATSAML21J18B-AUT is suitable for 7 applications: Battery-Powered IoT Sensor Nodes, Smart Home Appliance HMI, Wearable Health and Fitness Devices, Industrial Sensor Transmitters, Building Automation Controllers, Consumer USB Peripherals, Smart Metering Endpoints.
Battery-Powered IoT Sensor Nodes
The ATSAML21J18B-AUT's 200nA retention sleep current and sub-35 uA/MHz active draw allow multi-year coin-cell operation in wireless sensor nodes. The 48MHz Cortex-M0+ and 256KB Flash handle BLE/Zigbee stacks plus application logic. Its 1.62-3.63V input range matches LiSOCl2 and alkaline batteries directly, eliminating boost converters. The integrated 12-bit ADC and Peripheral Touch Controller (PTC) enable direct sensor and electrode interfaces, while SERCOM peripherals drive SPI/IO sensors and I2C expanders. Compared with switching regulators, the part's 200nA sleep floor extends shelf life in shipped-but-deployed nodes.
Recommended
Smart Home Appliance HMI
The Functional Safety (FuSa) variant of ATSAML21J18B-AUT supports IEC 60730 Class B compliance for white goods, ovens, and washing machines. The integrated PTC handles capacitive touch keypads, replacing mechanical buttons and reducing BOM cost. USB Full-Speed enables firmware update ports and diagnostic interfaces in service shops. With 256KB Flash, designers can integrate graphics libraries for small TFT or segment LCDs. The wide 1.62-3.63V supply tolerates noisy 3.3V rails common in motor-driven appliances, while SleepWalking peripherals enable responsive wake from touch without polling.
Recommended
Wearable Health and Fitness Devices
The ATSAML21J18B-AUT's 200nA sleep current and tiny 64-pin TQFP package (10x10 mm) suit wrist-worn wearables where PCB area is at a premium. The 12-bit ADC captures heart-rate and SpO2 photodiode signals, while the 10-bit DAC drives bioimpedance stimulation waveforms. SERCOM peripherals interface to SPI displays, I2C sensors, and BLE modules. Retention sleep preserves session state across deep-sleep windows, allowing heart-rate monitors to run for weeks on a single charge. The 256KB Flash accommodates on-device ML inference for step counting and gesture recognition without cloud dependency.
Recommended
Industrial Sensor Transmitters
The ATSAML21J18B-AUT industrial-grade temperature range (-40C to +85C) suits 4-20mA loop-powered transmitters and field-mounted process sensors. The 12-bit ADC with internal reference achieves the linearity required for pressure, temperature, and flow measurement. The integrated USB port enables in-the-field calibration and firmware update via service laptop, eliminating the need for factory-only programming. The 1.62-3.63V supply directly operates from 3.6V lithium primary cells common in wirelessHART or IO-Link wireless nodes, simplifying the power tree and reducing PCB area versus discrete analog chains.
Recommended
Building Automation Controllers
The ATSAML21J18B-AUT powers HVAC, lighting, and access-control edge nodes with USB service ports for commissioning and firmware updates. With 51 GPIO and multiple SERCOM channels, it interfaces to RS-485 transceiver ICs, 0-10V analog dimmers, and dry-contact inputs. The 200nA sleep current allows battery-backed operation during grid outages, retaining last-known lighting state. The 256KB Flash supports BACnet, Modbus, or KNX application stacks. The -40C to +85C range handles unconditioned electrical closet environments without additional thermal management.
Recommended
Consumer USB Peripherals
The integrated USB 2.0 Full-Speed Device interface of ATSAML21J18B-AUT supports HID-class peripherals such as keyboards, mice, presenters, and custom HID input devices without an external PHY. The 256KB Flash holds USB stacks plus application logic, while the 48MHz CPU executes HID polling and LED matrix animation. The 200nA sleep current and USB suspend support enable bus-powered devices that meet USB-IF suspend-current requirements. The 64-pin TQFP offers enough GPIO for RGB matrix scanning, mechanical key matrices, and rotary encoder inputs in single-chip designs.
Recommended
Smart Metering Endpoints
The ATSAML21J18B-AUT supports electricity, water, and gas metering endpoints with its 12-bit ADC sampling current shunts or sensor pulses. The 200nA sleep floor enables 10+ year battery life in non-rechargeable metering endpoints that report over wireless M-Bus or LoRaWAN. The on-chip RTC with 32.768kHz oscillator provides accurate time-of-use billing intervals without an external RTC chip. The Functional Safety documentation assists utilities with regulatory submissions in IEC-based markets, while the industrial temperature range handles outdoor meter enclosures without derating.
Recommended
Recommended Products Summary
Engineering reference data for ATSAML21J18B-AUT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAML21J18B-MUT | ATSAML21J17B-UUT | ATSAML21J17B-MUT | ATSAMD21G18A-AUT |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 64-pin TQFP (10x10 mm) | 64-pin QFN — NOT pin-compatible with TQFP-64 | 64-pin TQFP (10x10 mm) — SAME | 64-pin QFN — NOT pin-compatible with TQFP-64 | 48-pin TQFP — NOT pin-compatible |
| Core | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ |
| Max CPU Frequency | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz |
| Flash | 256 KB | 256 KB | 128 KB (-50%) | 128 KB (-50%) | 256 KB |
| SRAM | 32 KB | 32 KB | 16 KB (-50%) | 16 KB (-50%) | 32 KB |
| 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 |
| Sleep Current | 200 nA | 200 nA | 200 nA | 200 nA | ~2 uA (higher, no Retention Sleep) |
| Functional Safety (FuSa) | Yes (IEC 60730 Class B) | Yes (IEC 60730 Class B) | Yes (IEC 60730 Class B) | Yes (IEC 60730 Class B) | No |
Key Differentiators
- Industry-leading 200nA retention sleep current with full SRAM retention (vs ATSAMD21G18A-AUT)
- Functional Safety (FuSa) documentation pack included (vs ATSAMD21G18A-AUT)
- 64-pin TQFP with 51 GPIO and integrated USB (vs ATSAML21J17B-UUT)
- Industrial temperature range with full Functional Safety documentation (vs ATSAML21J18A-AUT (A revision))
Design Notes
Place a 100nF X7R 0402 decoupling capacitor within 3mm of each VDD pin and a 4.7uF X5R bulk capacitor near the device to support inrush during peripheral wake events. Configure unused GPIO as input with internal pull-down to minimize leakage into the 200nA sleep budget. Use the Peripheral Event System and SleepWalking to keep the CPU gated until a configured ADC, RTC, or PTC threshold is crossed, avoiding active-mode polling.
Route the 32.768kHz crystal traces as short, symmetrical loops with a ground guard ring and keep them away from USB DP/DM and SERCOM switching traces. The 12-bit ADC requires a clean AVDD rail - decouple AVDD separately from VDDIN with a ferrite bead and a 100nF plus 10uF capacitor stack. For USB Full-Speed, route DP/DM as a 90-ohm differential pair with matched length and a common-mode choke within 5mm of the connector.
Do not exceed 3.63V on VDDIN or AVDD; this permanently damages the part. Avoid using the internal 32kHz oscillator for USB Full-Speed, which requires the 48MHz DFLL or an external crystal with proper load capacitor selection. When migrating code from SAM D21, revalidate SERCOM PAD mappings because the L21 mux table differs - referring to the SAME51/SAM L21 I/O Multiplexing table is mandatory. Do not skip the BOOTPROT fuse configuration if using the SAM-BA bootloader via USB.
Estimated: at maximum sustained active current of approximately 35 uA/MHz at 3.63V and 48MHz, internal dissipation is roughly 6 mW - well within the 64-pin TQFP 31.3 C/W theta_JA, producing under 1C junction rise in still air. Even in hot industrial enclosures at 85C ambient, no heatsink is required. Designers should still validate in thermally enclosed appliances where ambient can approach 70C.
Compliance Information
AUT suffix indicates industrial temperature grade (-40C to +85C) and Tape & Reel packaging per Microchip ordering code convention. IEC 60730 Class B Functional Safety documentation is available separately from Microchip. AEC-Q100 qualification is not applicable to the AUT suffix - look at -ANT variants for automotive. RoHS and REACH compliance are stated on the Microchip product page.
