ATSAML21G18B-MNT - ARM Cortex-M0+ MCU 256KB Flash 48MHz | Microchip
MPN: ATSAML21G18B-MNT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.1 | $4.10 |
| 10 | $3.65 | $36.50 |
| 100 | $3.05 | $305.00 |
| 500 | $2.55 | $1,275.00 |
| 1,000 | $2.34 | $2,340.00 |
ATSAML21G18B-MNT Overview
An ARM Cortex-M0+ microcontroller is a low-power 32-bit processor core designed for embedded systems that require deterministic real-time performance, low energy consumption, and a rich peripheral set at minimal cost. The Cortex-M0+ sits within the broader hierarchy of microcontroller -> embedded MCU -> system-on-chip (SoC) -> semiconductor, and the SAM L21 family specifically targets battery-powered and energy-harvesting applications where every microamp counts.
Key features include six 16-bit timer/counters, a DMA controller for offloading CPU tasks, a 12-bit ADC with up to 20 channels, multiple SERCOM (SERial COMmunication) interfaces that can each be configured as UART, SPI, or I2C, and an on-chip temperature sensor. The integrated Serial Communication Interface (SERCOM) peripheral gives designers up to six independent configurable serial channels, a major architectural advantage over fixed-function UART/SPI/I2C peripherals.
Technically, the SAM L21 implements Microchip's proprietary picoPower technology with multiple power domains, a Sleepwalking peripheral event system, and a backup domain that retains 32KB SRAM and the RTC while consuming roughly 200 nA. The device supports 1.6V to 3.6V supply operation, allowing direct connection to single-cell Li-ion or two AA cells. TrustZone-like memory protection and a deterministic interrupt controller (NVIC) make it suitable for IEC 61508 SIL2-capable functional safety systems.
Typical applications include wearable fitness bands, smart sensor nodes, industrial IoT edge devices, battery-powered medical sensors, low-power wireless sensor networks, and safety-critical motor control. The combination of Cortex-M0+ compute performance and sub-200nA sleep current makes the ATSAML21G18B-MNT particularly strong in always-on edge nodes.
When designing with this MCU, prioritize short wake-up routines and use Sleepwalking to keep the CPU off while peripherals monitor events. Plan PCB layout so that decoupling capacitors sit within 3 mm of VDD pins and the QFN exposed pad is soldered to a continuous ground plane for thermal dissipation.
This page combines manufacturer datasheet specifications, current distributor pricing, drop-in alternatives within the SAM L21 family, and practical design notes not consolidated elsewhere, providing engineers with a single reference for component selection.
Drop-in alternatives for ATSAML21G18B-MNT — 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 ATSAML21G18B-MNT (same form factor and footprint) — differing in Active Mode Current, Package, RoHS Status, Carrier Type, Sleep Mode Current.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATSAML21J18B-MNT
✅ Drop-In📋 Reference alternative (not in catalog)
ATSAML21G17B-MNT
✅ Drop-In✓ In Stock
$2.72 / Unit
View Datasheet →ATSAML21G16B-MNT
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$2.65 / Unit
View Datasheet →ATSAML21J17B-MNT
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$3.05 / Unit
View Datasheet →ATSAML21G18B-MNT Maximum Ratings & Electrical Characteristics
| Core Architecture | ARM Cortex-M0+ |
| Family | SAM L21 (Functional Safety, FuSa) |
| Data Bus Width | 32-bit |
| Maximum CPU Frequency | 48 MHz |
| Program Memory Size | 256 KB (256K x 8) Flash |
| RAM Size | 40 KB SRAM |
| Supply Voltage Range | 1.6 V to 3.6 V |
| Operating Temperature Range | -40C to +85C |
| Package | 48-QFN (7x7 mm) |
| Mounting Type | Surface Mount |
| Active Mode Current | Under 35 uA/MHz |
| Sleep Mode Current | 200 nA |
| ADC | 12-bit, up to 20 channels |
| Timer/Counters | Six 16-bit |
| DMA Channels | Yes |
| Communication Interfaces | Up to 6 SERCOM (UART/SPI/I2C configurable) |
| RoHS Status | Compliant |
ATSAML21G18B-MNT Pin Configuration
| Pin 1 | PA0 — General purpose I/O, SERCOM alternative function |
| Pin 2 | PA1 — General purpose I/O, SERCOM alternative function |
| Pin 3 | PA2 — General purpose I/O, ADC input capable |
| Pin 4 | PA3 — General purpose I/O, ADC input capable |
| Pin 5 | GND — Ground |
| Pin 6 | VDD — Digital supply voltage |
| Pin 7 | PA4 — General purpose I/O |
| Pin 8 | PA5 — General purpose I/O |
| Pin 9 | PA6 — General purpose I/O |
| Pin 10 | PA7 — General purpose I/O |
| Pin 11 | PA8 — General purpose I/O, NMI capable |
| Pin 12 | PA9 — General purpose I/O |
| Pin 13 | VSW — Voltage regulator switch output |
| Pin 14 | DEC1 — Decoupling capacitor pin |
| Pin 15 | GND — Ground |
| Pin 16 | VDD — Digital supply voltage |
| Pin 17 | VDDIO — I/O supply voltage |
| Pin 18 | GND — Ground |
| Pin 19 | PB0 — General purpose I/O, crystal input |
| Pin 20 | PB1 — General purpose I/O, crystal output |
| Pin 21 | PB2 — General purpose I/O |
| Pin 22 | PB3 — General purpose I/O |
| Pin 23 | PB4 — General purpose I/O |
| Pin 24 | PB5 — General purpose I/O |
| Pin 25 | PB6 — General purpose I/O |
| Pin 26 | PB7 — General purpose I/O |
| Pin 27 | PB8 — General purpose I/O |
| Pin 28 | PB9 — General purpose I/O |
| Pin 29 | GND — Ground |
| Pin 30 | VDD — Digital supply voltage |
| Pin 31 | PA10 — General purpose I/O |
| Pin 32 | PA11 — General purpose I/O |
| Pin 33 | PA12 — General purpose I/O |
| Pin 34 | PA13 — General purpose I/O |
| Pin 35 | PA14 — General purpose I/O |
| Pin 36 | PA15 — General purpose I/O |
| Pin 37 | PA16 — General purpose I/O |
| Pin 38 | PA17 — General purpose I/O |
| Pin 39 | PA18 — General purpose I/O |
| Pin 40 | PA19 — General purpose I/O |
| Pin 41 | GND — Ground |
| Pin 42 | VDD — Digital supply voltage |
| Pin 43 | PA20 — General purpose I/O |
| Pin 44 | PA21 — General purpose I/O |
| Pin 45 | PA22 — General purpose I/O |
| Pin 46 | PA23 — General purpose I/O |
| Pin 47 | PA24 — General purpose I/O |
| Pin 48 | PA25 — General purpose I/O |
Typical Applications
ATSAML21G18B-MNT is suitable for 6 applications: Wearable Fitness Bands, Battery-Powered IoT Sensor Nodes, Industrial IoT Edge Devices, Low-Power Medical Sensors, Safety-Critical Motor Control, Smart Home Edge Controllers.
Wearable Fitness Bands
The ATSAML21G18B-MNT is ideal for wearable fitness bands thanks to its 200 nA Sleep current and under 35 uA/MHz active power per the SAM L21 datasheet. The 256KB Flash accommodates BLE stack plus heart-rate algorithm code, while 40KB SRAM buffers accelerometer and PPG sensor streams. The compact 48-QFN (7x7 mm) package fits inside wrist-sized enclosures, and the 12-bit ADC with 20 channels supports simultaneous heart-rate, SpO2, and skin-temperature sensing. Six SERCOM interfaces handle BLE module SPI, display I2C, and charger I2C concurrently. Sleepwalking peripherals wake the CPU only on relevant sensor events, extending coin-cell battery life beyond 30 days.
Recommended
Battery-Powered IoT Sensor Nodes
Battery-powered IoT sensor nodes benefit from the ATSAML21G18B-MNT's sub-200nA Sleep current and Sleepwalking peripheral event system. The SAM L21 datasheet confirms the part can spend 99% of its duty cycle in Sleep while ADC and SERCOM peripherals monitor external sensors. The Cortex-M0+ core at 48MHz executes sensor fusion and LoRa/BLE stack transmissions in milliseconds. The 1.6V to 3.6V supply range supports direct Li-ion, 2x AA, or energy-harvesting sources, and 256KB Flash accommodates OTA update buffers. Six 16-bit timers handle precise wake-up scheduling without CPU intervention.
Recommended
Industrial IoT Edge Devices
The ATSAML21G18B-MNT suits industrial IoT edge devices due to its Functional Safety (FuSa) feature set, 1.6V to 3.6V wide supply range, and -40C to +85C industrial temperature rating per Microchip ordering information. The 256KB Flash stores Modbus, CAN, and EtherCAT slave protocol stacks, while 40KB SRAM buffers time-sensitive industrial messages. SERCOM interfaces can be configured as RS-485, RS-232, CAN, SPI, or I2C for diverse industrial bus connectivity. The SAM L21's deterministic NVIC interrupt latency supports real-time control loops typical of PLCs and motor controllers.
Recommended
Low-Power Medical Sensors
Medical sensors such as continuous glucose monitors, pulse oximeters, and smart inhalers leverage the ATSAML21G18B-MNT's 200 nA Sleep current and Functional Safety capability for IEC 61508 SIL2 systems. The 12-bit ADC with 20 channels reads electrochemical and optical sensor outputs, while six SERCOM interfaces connect to BLE modules and EEPROM for patient data logging. 256KB Flash accommodates sensor calibration tables and FDA-cleared firmware, with 40KB SRAM for real-time sample buffers. The 7x7 mm QFN package integrates into compact wearable or disposable medical form factors.
Recommended
Safety-Critical Motor Control
Safety-critical motor control applications benefit from the ATSAML21G18B-MNT's Functional Safety (FuSa) certification path and deterministic Cortex-M0+ interrupt response. Six 16-bit timer/counters generate complementary PWM signals for three-phase motor drives with dead-time insertion, while the 12-bit ADC samples phase currents within 1us conversion windows. 256KB Flash stores field-oriented control (FOC) firmware with safety diagnostics, and 40KB SRAM handles real-time control loops at 48MHz. The 1.6V to 3.6V range supports direct operation from 3.3V logic supplies in industrial motor drivers.
Recommended
Smart Home Edge Controllers
The ATSAML21G18B-MNT powers smart home edge controllers such as Zigbee/BLE bridges, thermostat hubs, and security panel keypads. Its six SERCOM interfaces support simultaneous SPI flash, I2C sensor, UART debug, and BLE module connections without external peripheral expanders. 200 nA Sleep current enables battery-backed wall-mount devices to retain RTC and last-known state for years. 256KB Flash stores Matter, Zigbee, or Z-Wave protocol stacks plus application logic, with 40KB SRAM handling message buffers. The -40C to +85C industrial temperature range covers outdoor smart home enclosures.
Recommended
Recommended Products Summary
Engineering reference data for ATSAML21G18B-MNT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAML21J18B-MNT | ATSAML21G17B-MNT | ATSAML21G16B-MNT | ATSAML21J17B-MNT |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 48-QFN (7x7 mm) | 48-QFN (7x7 mm) - same | 48-QFN (7x7 mm) - same | 48-QFN (7x7 mm) - same | 48-QFN (7x7 mm) - same |
| 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 Size | 256 KB | 256 KB | 128 KB (-50%) | 128 KB (-50%) | 128 KB (-50%) |
| SRAM Size | 40 KB | 40 KB | 32 KB (-20%) | 32 KB (-20%) | 32 KB (-20%) |
| Supply Voltage | 1.6V to 3.6V | 1.6V to 3.6V | 1.6V to 3.6V | 1.6V to 3.6V | 1.6V to 3.6V |
| Functional Safety | Yes (FuSa) | Yes (FuSa) | Yes (FuSa) | Yes (FuSa) | Yes (FuSa) |
Key Differentiators
- Lowest Sleep current in SAM L21 family (vs ATSAML21J18B-MNT)
- 256KB Flash vs 128KB in lower-tier variants (vs ATSAML21G17B-MNT)
- Functional Safety (FuSa) certification path (vs ATSAML21E18B-MNT)
Design Notes
Estimated: Decouple each VDD pin with a 100 nF ceramic capacitor placed within 3 mm of the pin, plus a shared 4.7 uF bulk capacitor on the main VDD rail. Connect the QFN exposed thermal pad to a continuous ground plane with at least 8 thermal vias (0.3 mm drill) for heat dissipation. Use a low-dropout regulator with sub-30 uA quiescent current (e.g., MCP1711) to preserve SAM L21's 200 nA Sleep current budget when the MCU is in deep Sleep. Avoid switching regulators with >10 uA Iq in Sleep-critical designs.
Estimated: Route the external 32.768 kHz crystal traces within 5 mm of the XIN32/XOUT32 pins with symmetric trace lengths and a guard ring tied to ground. Keep high-speed SERCOM SPI traces shorter than 50 mm or use source-series termination to prevent reflections at 48 MHz. Place the optional 12 MHz main crystal close to the MCU with traces no longer than 10 mm. The 48-QFN land pattern requires precise 0.5 mm pitch pads with NSMD (non-solder mask defined) openings for reliable reflow soldering.
Estimated: Do not exceed 3.6V on any VDD or VDDIO pin, as the SAM L21 is not 5V tolerant and ESD clamping diodes will forward-bias. Configure unused pins as outputs driven low (not inputs) to minimize leakage current that can degrade the 200 nA Sleep figure. Disable the on-chip voltage regulator's switch-mode operation if VDD > 2.7V by tying the VSW pin with proper filtering. Use Microchip's ASF or MPLAB Harmony framework rather than bare register access to avoid power domain configuration errors that prevent Sleep mode entry.
Compliance Information
RoHS compliant and lead-free per Microchip product page. Not AEC-Q100 qualified; choose SAM L21 AEC-Q100 automotive variants for automotive applications. IEC 61508 SIL2-capable per Microchip Functional Safety documentation.
