ATSAML21G17B-U - 48MHz Cortex-M0+ 128KB MCU | Microchip
MPN: ATSAML21G17B-U ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.2 | $5.20 |
| 10 | $4.62 | $46.20 |
| 100 | $3.95 | $395.00 |
| 500 | $3.45 | $1,725.00 |
| 1,000 | $2.98 | $2,980.00 |
ATSAML21G17B-U Overview
What is an ultra-low-power microcontroller? An ultra-low-power MCU (ULP MCU) is a microcontroller designed specifically to minimize energy consumption across all operating states (active, sleep, deep-sleep, backup), enabling battery-powered products to operate for years on a single cell. ULPs combine low-leakage process technology, multi-domain power gating, and multiple low-power sleep modes; they sit within the broader category of embedded microcontrollers and are the heart of IoT, wearable, and energy-harvesting systems.
Key features include 128KB Flash, 16KB SRAM, a Cortex-M0+ core with single-cycle multiplier, full-speed USB 2.0 device, and a rich peripheral set: SERCOM (configurable serial communication), 12-bit ADC, DAC, comparators, and PTC (Peripheral Touch Controller). Functional Safety (FuSa) features and a wide 1.62V-3.6V operating voltage range support industrial-grade applications.
The SAM L21 architecture integrates an advanced power management unit (PMU) with multiple sleep modes (Sleep, Deep-Sleep, Backup, Off) and on-chip voltage regulators that power only the required logic domains. This fine-grained power gating, combined with Event System hardware interconnects, allows the CPU to stay in deep sleep while peripherals continue operating autonomously.
Typical applications include IoT sensor nodes, wearable fitness bands, smart home devices, secure element companion MCUs, battery-powered medical monitors, and industrial wireless sensors. The integrated USB 2.0 full-speed device also makes it suitable for human-interface devices (HID) such as wireless presenters and BLE/LoRa sensor dongles.
When designing with this MCU, ensure the supply decoupling follows the SAM L21 reference design: place 100nF X7R ceramic capacitors adjacent to each VDDCORE/VDDIO pin pair. The Backup domain requires a coin-cell or super-capacitor if RTC retention is needed during main power loss.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone, with the verified snapshot as of 2026-10-07.
Drop-in alternatives for ATSAML21G17B-U — 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 ATSAML21G17B-U (same form factor and footprint) — differing in ADC, Operating Temperature, Package, Core Architecture, RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATSAML21G17B-MUT
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$2.25 / Unit
View Datasheet →ATSAML21G18B-U
✅ Drop-In📋 Reference alternative (not in catalog)
ATSAML21G16B-U
✅ Drop-In📋 Reference alternative (not in catalog)
ATSAMD21G18A-MU
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$3.15 / Unit
View Datasheet →ATSAMD21G17D-MUT
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$1.31 / Unit
View Datasheet →ATSAMC21G18A-AU
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$3.05 / Unit
View Datasheet →ATSAML21G17B-U Maximum Ratings & Electrical Characteristics
| Core Processor | ARM Cortex-M0+ |
| Core Size | 32-Bit |
| Maximum Clock Frequency | 48 MHz |
| Program Memory Size (Flash) | 128 KB (128K x 8) |
| RAM Size | 16 KB |
| Package | 48-WLCSP |
| Mounting Type | Surface Mount |
| Supply Voltage Range | 1.62 V to 3.6 V |
| Active Mode Current | < 35 µA/MHz |
| Sleep Mode Current | 200 nA (typical) |
| Connectivity | I²C, LINbus, SCI, SPI, UART/USART, USB |
| Peripherals | DMA, POR, PWM, WDT |
| USB | USB 2.0 Full-Speed Device |
| ADC | 12-bit (SAR) |
| Operating Temperature Range | -40 °C to +85 °C |
| RoHS Status | Compliant |
| Functional Safety (FuSa) | Yes |
| Touch Sensing | PTC (Peripheral Touch Controller) |
ATSAML21G17B-U Pin Configuration
| Pin A1 | VDDIO — Digital I/O supply voltage |
| Pin A2 | PA00 — GPIO / SERCOM0 / ADC0 |
| Pin A3 | PA01 — GPIO / SERCOM0 / ADC0 |
| Pin A4 | PA02 — GPIO / SERCOM0 / ADC0 |
| Pin A5 | PA03 — GPIO / SERCOM0 / ADC0 / DAC |
| Pin A6 | GND — Ground |
| Pin A7 | PA04 — GPIO / SERCOM0 / ADC0 / VREF |
| Pin A8 | PA05 — GPIO / SERCOM0 / ADC0 |
| Pin B1 | PA06 — GPIO / SERCOM0 / ADC1 |
| Pin B2 | PA07 — GPIO / SERCOM0 / ADC1 |
| Pin B3 | PA08 — GPIO / SERCOM0 / ADC1 |
| Pin B4 | PA09 — GPIO / SERCOM0 / ADC1 |
| Pin B5 | PA10 — GPIO / SERCOM0 / ADC1 |
| Pin B6 | PA11 — GPIO / SERCOM0 / ADC1 |
| Pin B7 | PA12 — GPIO / SERCOM2 / USB DP |
| Pin B8 | PA13 — GPIO / SERCOM2 / USB DM |
| Pin C1 | PA14 — GPIO / SERCOM2 |
| Pin C2 | PA15 — GPIO / SERCOM2 |
| Pin C3 | PA16 — GPIO / SERCOM1 |
| Pin C4 | PA17 — GPIO / SERCOM1 |
| Pin C5 | PA18 — GPIO / SERCOM1 / INT[VD] = DAC VREF |
| Pin C6 | PA19 — GPIO / SERCOM1 |
| Pin C7 | PA20 — GPIO / SERCOM3 |
| Pin C8 | PA21 — GPIO / SERCOM3 |
| Pin D1 | PA22 — GPIO / SERCOM3 |
| Pin D2 | PA23 — GPIO / SERCOM3 |
| Pin D3 | PA24 — GPIO / SERCOM1 / USB SOF |
| Pin D4 | PA25 — GPIO / SERCOM1 / NRESET |
| Pin D5 | PA27 — GPIO |
| Pin D6 | PA28 — GPIO / Backup domain |
| Pin D7 | VBAT — Backup battery supply |
| Pin D8 | GND — Ground |
| Pin E1 | PB02 — GPIO / SERCOM5 / ADC0 |
| Pin E2 | PB03 — GPIO / SERCOM5 / ADC1 |
| Pin E3 | PB04 — GPIO / SERCOM5 / TC0 |
| Pin E4 | PB05 — GPIO / SERCOM5 / TC0 |
| Pin E5 | PB06 — GPIO / SERCOM4 / TC1 |
| Pin E6 | PB07 — GPIO / SERCOM4 / TC1 |
| Pin E7 | PB08 — GPIO / SERCOM4 / TC1 |
| Pin E8 | PB09 — GPIO / SERCOM4 / TC1 |
| Pin F1 | PB10 — GPIO / SERCOM4 / TC0 |
| Pin F2 | PB11 — GPIO / SERCOM4 / TC0 |
| Pin F3 | PB12 — GPIO / SERCOM4 / TC0 / PTC X0 |
| Pin F4 | PB13 — GPIO / SERCOM4 / TC0 / PTC X1 |
| Pin F5 | PB14 — GPIO / SERCOM4 / TC0 / PTC X3 |
| Pin F6 | PB15 — GPIO / SERCOM4 / TC0 / PTC X4 |
| Pin F7 | PB16 — GPIO / SERCOM5 / TC0 / PTC Y0 |
| Pin F8 | PB17 — GPIO / SERCOM5 / TC0 / PTC Y1 |
| Pin GND_PADDLE_Pad | GND — Thermal/exposed pad, must be soldered to ground plane |
Typical Applications
ATSAML21G17B-U is suitable for 6 applications: Battery-Powered IoT Sensor Nodes, Wearable Fitness Bands, Smart Home Wireless Sensor Hubs, USB Human Interface Devices (HID), Portable Medical Monitoring Devices, Industrial Wireless Sensor Nodes.
Battery-Powered IoT Sensor Nodes
The ATSAML21G17B-U is purpose-built for coin-cell IoT sensor nodes thanks to its 200 nA Sleep current with full SRAM retention and 35 µA/MHz Active current. The 128 KB Flash holds a secure bootloader, OTA image slot, and application code; 16 KB SRAM is sufficient for sensor fusion buffers and TLS record fragments. SERCOM peripherals (I²C/SPI/UART) interface directly to environmental sensors, while the integrated 12-bit ADC reads analog sensors without an external ADC. At 1% duty cycle, a CR2032-powered node can run 5+ years. Compared to the SAM D21, the SAM L21G halves the Sleep current while keeping the same Cortex-M0+ toolchain (MPLAB X, ASF, Harmony).
Recommended
Wearable Fitness Bands
Wearables demand very low average power, small footprint, and reliable touch/display interfaces. The ATSAML21G17B-U WLCSP package fits a 20 mm-diameter wristband PCB, and its integrated PTC (Peripheral Touch Controller) supports capacitive touch buttons and sliders without external touch ICs. The 200 nA Sleep current allows always-on step counting on a single CR2032 for 6-12 months. The Cortex-M0+ core drives a small OLED display via SPI while the 12-bit ADC samples a PPG heart-rate sensor. USB 2.0 FS enables charging and firmware upgrade without an external PHY, saving both BOM cost and PCB area in space-critical wrist form factors.
Recommended
Smart Home Wireless Sensor Hubs
The ATSAML21G17B-U powers Zigbee/BLE/LoRa sensor endpoints via SERCOM-connected radio modules. With 128 KB Flash, the device can host a full Z-Stack or LoRaWAN stack plus application logic. Its Functional Safety (FuSa) features are valuable for smoke/CO detectors requiring IEC 60730-1 class B compliance. Deep-Sleep mode below 1 µA allows battery-powered door/window sensors to last the full 10-year warranty period. USB 2.0 FS simplifies commissioning by allowing the hub to enumerate as a CDC device and stream firmware update logs. Compared to larger Cortex-M4 alternatives, the L21G cuts average power by 40-60%.
Recommended
USB Human Interface Devices (HID)
The ATSAML21G17B-U integrates USB 2.0 Full-Speed Device with on-chip transceiver, eliminating external PHY and reducing BOM cost for HID products (keyboards, mice, presenters, game controllers). 48 MHz Cortex-M0+ easily handles HID class drivers and consumer-control descriptors. The WLCSP-48 footprint suits ultra-thin wireless presenter dongles. The 12-bit ADC and PWM controllers drive haptic feedback motors and LED animations. With 200 nA Sleep current, battery-powered wireless mice can stay in standby for months between user interactions while still waking instantly via GPIO interrupt to a paired RF receiver.
Recommended
Portable Medical Monitoring Devices
The ATSAML21G17B-U suits portable medical devices such as pulse oximeters, thermometers, and continuous glucose monitors (CGM) that demand long battery life and small size. The 12-bit SAR ADC samples PPG/thermistor signals directly with 12-bit ENOB, sufficient for heart-rate and SpO2 algorithms. Functional Safety (FuSa) supports IEC 60730-1 class B compliance required by many medical standards. USB 2.0 FS enables data download to a phone without external PHY. WLCSP-48 supports a fingertip form factor. Compared to discrete analog front-ends, the integrated ADC + MCU reduces BOM by 30-40%.
Recommended
Industrial Wireless Sensor Nodes
The ATSAML21G17B-U's -40°C to +85°C industrial temperature range and Functional Safety features make it suitable for industrial sensor nodes: vibration monitors on motors, temperature/humidity loggers, and pressure transmitters. The Cortex-M0+ core runs edge FFT / envelope analysis at 48 MHz while staying under 35 µA/MHz. The integrated 12-bit ADC samples 4-20 mA loop signals via a 250 Ω sense resistor. USB 2.0 FS supports field-firmware updates via a service port. Compared to competing Cortex-M0+ parts, the SAM L21G halves Sleep current which is critical for battery- or energy-harvesting-powered IIoT endpoints in factory automation.
Recommended
Recommended Products Summary
Engineering reference data for ATSAML21G17B-U — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAML21G18B-U | ATSAML21G16B-U | ATSAMD21G18A-MU | ATSAMC21G18A-AU |
|---|---|---|---|---|---|
| Package | 48-WLCSP | 48-WLCSP - same | 48-WLCSP - same | 48-QFN - different footprint | 48-TQFP - different footprint |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Core | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ |
| Max Clock | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz |
| Flash | 128 KB | 256 KB | 64 KB | 256 KB | 256 KB |
| SRAM | 16 KB | 32 KB | 8 KB | 32 KB | 32 KB |
| Sleep Current | 200 nA | 200 nA | 200 nA | 1 µA (typical) | 500 nA (typical) |
| Active Current | < 35 µA/MHz | < 35 µA/MHz | < 35 µA/MHz | ~70 µA/MHz | ~40 µA/MHz |
| Functional Safety (FuSa) | Yes | Yes | Yes | No | Yes |
| CAN-FD | No | No | No | No | Yes |
Key Differentiators
- Lowest Sleep current in SAM L21 family (vs ATSAMD21G18A-MU)
- Pin-compatible upgrade path with double Flash (vs ATSAML21G16B-U)
- CAN-FD not available in SAM L21G (vs ATSAMC21G18A-AU)
- Functional Safety (FuSa) IEC 60730-1 class B ready (vs ATSAMD21G18A-MU)
Design Notes
Estimated: at 48 MHz with all peripherals enabled, Active current is ~1.7 mA. Power dissipation is therefore negligible (~5.6 mW at 3.3 V) - no thermal design needed. However, when Sleep current dominates (200 nA typical), a poorly designed LDO or boost converter can leak 10-100x more current than the MCU itself. Choose a low-Iq regulator such as Microchip MCP1643 or MCP1711 to keep total Sleep current under 1 µA. Decouple each VDDCORE/VDDIO pair with a 100 nF X7R ceramic placed within 2 mm of the pin pair.
For the 48-WLCSP package, use non-solder-mask-defined (NSMD) pads with 0.4 mm pitch and 0.25 mm solder paste apertures per Microchip's WLCSP footprint recommendation. Route signals in microstrip, not stripline, to keep impedance control easier. The GND paddle must be soldered to a contiguous ground plane for thermal and electrical performance; microvia arrays under the WLCSP balls improve reliability. Keep high-speed USB DP/DN as a 90 Ω differential pair with maximum 3 mm length mismatch.
Do not omit the decoupling capacitors on each VDDCORE pin - even at low Sleep current, missing decoupling causes spurious resets during wake-up events. The Backup domain VBAT pin requires its own 1 µF decoupling if RTC retention is used during main power loss. The USB DP pull-up resistor (1.5 kΩ to VDDIO) must be present, otherwise USB enumeration will fail. For code-locked devices, do not lock the NVMCTRL via the security bit until you have verified the bootload is functional, or you may brick the part permanently.
Compliance Information
RoHS/REACH compliant per Microchip product page. Industrial temperature grade -40°C to +85°C. For AEC-Q100 automotive grade consider ATSAMC21 family (SAM C21 with CAN-FD).
