ATSAMD21G18A-AFT - 48MHz ARM Cortex-M0+ MCU, 256KB Flash, 48-TQFP
MPN: ATSAMD21G18A-AFT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.2 | $4.20 |
| 10 | $3.78 | $37.80 |
| 100 | $3.36 | $336.00 |
| 500 | $3.02 | $1,510.00 |
| 1,000 | $2.69 | $2,690.00 |
ATSAMD21G18A-AFT Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory (Flash), working memory (SRAM), and peripheral interfaces such as ADC, timers, and communication blocks. Within the broader hierarchy, the ATSAMD21G18A belongs to the ARM Cortex-M0+ 32-bit MCU class -> low-power MCU -> embedded microcontroller -> semiconductor IC family. The Cortex-M0+ core is the smallest and most energy-efficient member of the ARM Cortex-M family, designed for deterministic embedded control with Thumb-2 instruction set support and single-cycle I/O port access.
Key features of the ATSAMD21G18A-AFT include a 1.62 V to 3.63 V operating voltage range, two-pin Serial Wire Debug (SWD) interface for programming and test, SleepWalking peripherals, Idle and Standby sleep modes, and functional-safety (FuSa) documentation support for IEC 60730 Class B compliance. The 48-TQFP package supports an extended industrial temperature range of -40 °C to +125 °C, indicated by the 'F' suffix code in the ordering part number.
The device achieves 2.46 CoreMark/MHz and is designed for simple, intuitive migration within the SAM D21 family using identical peripheral modules, hex-compatible code, and a shared linear address map. The -AFT ordering code (48-TQFP, Tape and Reel, -40 °C to +125 °C) makes it a long-lifecycle option for industrial and consumer products.
Typical applications include home automation endpoints, smart metering, consumer electronics, industrial sensor hubs, USB HID peripherals, and low-power IoT nodes. The integrated USB 2.0 Full-Speed controller eliminates the need for an external bridge IC, simplifying BOM and firmware.
When designing with the ATSAMD21G18A-AFT, ensure the SWD interface is brought out to a debug header for programming and field updates, and observe the recommended decoupling scheme (one 0.1 µF per VDD pin plus a bulk capacitor) to keep the ADC and DAC noise floors within datasheet limits.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATSAMD21G18A-AFT — 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 ATSAMD21G18A-AFT (same form factor and footprint) — differing in Operating Temperature, USB, Package, ADC, DAC.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATSAMD21G18A-AU
✅ Drop-In✓ In Stock
$1.74 / Unit
View Datasheet →ATSAMD21G18A-AUT
✅ Drop-In📋 Reference alternative (not in catalog)
ATSAMD21G18A-AF
✅ Drop-In✓ In Stock
$3.49 / Unit
View Datasheet →ATSAMD21G17A-AFT
✅ Drop-In✓ In Stock
$3.7 / Unit
View Datasheet →ATSAMD21E18A-AFT
✅ Drop-In✓ In Stock
$2.72 / Unit
View Datasheet →ATSAMD21G18A-AFT Maximum Ratings & Electrical Characteristics
| Core | ARM Cortex-M0+ (32-bit) |
| Series | SAM D21G (Functional Safety / FuSa) |
| Maximum CPU Frequency | 48 MHz |
| CoreMark/MHz | 2.46 |
| Flash Memory | 256 KB |
| SRAM | 32 KB |
| Operating Voltage | 1.62 V to 3.63 V |
| Package | 48-TQFP (7x7 mm) |
| Operating Temperature | -40 °C to +125 °C |
| Debug Interface | Serial Wire Debug (SWD), 2-pin |
| USB | USB 2.0 Full-Speed device/host |
| ADC | 12-bit |
| DAC | 10-bit |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Migrates With | SAM D20 (drop-in compatible peripheral set) |
ATSAMD21G18A-AFT Pin Configuration
| Pin 1 | PA00 — GPIO / XIN32 |
| Pin 2 | PA01 — GPIO / XOUT32 |
| Pin 3 | PA02 — GPIO / AIN[0] |
| Pin 4 | PA03 — GPIO / AIN[1] / VREFA |
| Pin 5 | PA04 — GPIO / AIN[2] |
| Pin 6 | PA05 — GPIO / AIN[3] |
| Pin 7 | PA06 — GPIO / AIN[4] |
| Pin 8 | PA07 — GPIO / AIN[5] |
| Pin 9 | VDDIO — I/O supply |
| Pin 10 | GND — Ground |
| Pin 11 | PA08 — GPIO / AIN[6] |
| Pin 12 | PA09 — GPIO / AIN[7] |
| Pin 13 | PA10 — GPIO / AIN[8] |
| Pin 14 | PA11 — GPIO / AIN[9] |
| Pin 15 | VDDIO — I/O supply |
| Pin 16 | GND — Ground |
| Pin 17 | PA12 — GPIO / AIN[10] |
| Pin 18 | PA13 — GPIO / AIN[11] |
| Pin 19 | PA14 — GPIO / AIN[12] |
| Pin 20 | PA15 — GPIO / AIN[13] |
| Pin 21 | PA16 — GPIO / SERCOM1 PAD0 |
| Pin 22 | PA17 — GPIO / SERCOM1 PAD1 |
| Pin 23 | PA18 — GPIO / SERCOM1 PAD2 |
| Pin 24 | PA19 — GPIO / SERCOM1 PAD3 |
| Pin 25 | PA20 — GPIO / SERCOM3 PAD2 |
| Pin 26 | PA21 — GPIO / SERCOM3 PAD3 |
| Pin 27 | PA22 — GPIO / SERCOM3 PAD0 |
| Pin 28 | PA23 — GPIO / SERCOM3 PAD1 |
| Pin 29 | PA24 — GPIO / USB_DM |
| Pin 30 | PA25 — GPIO / USB_DP |
| Pin 31 | GND — Ground |
| Pin 32 | VDDIO — I/O supply |
| Pin 33 | PA26 — GPIO |
| Pin 34 | PA27 — GPIO |
| Pin 35 | PA28 — GPIO |
| Pin 36 | PA29 — GPIO |
| Pin 37 | PA30 — GPIO / SWCLK |
| Pin 38 | PA31 — GPIO / SWDIO |
| Pin 39 | GND — Ground |
| Pin 40 | VDDCORE — Internal core supply (decouple 1 µF) |
| Pin 41 | VDDIN — Voltage regulator input |
| Pin 42 | VDDIO — I/O supply |
| Pin 43 | PB00 — GPIO |
| Pin 44 | PB01 — GPIO |
| Pin 45 | PB02 — GPIO |
| Pin 46 | PB03 — GPIO |
| Pin 47 | GND — Ground |
| Pin 48 | VDDIO — I/O supply |
Typical Applications
ATSAMD21G18A-AFT is suitable for 6 applications: Home Automation Endpoints, Smart Metering and Energy Monitoring, USB HID Peripherals, Industrial Sensor Hubs, Consumer Wearables and Fitness Devices, Low-Power IoT Edge Nodes.
Home Automation Endpoints
The ATSAMD21G18A-AFT is well suited for home automation endpoints such as smart thermostats, lighting controllers, and wireless sensor hubs. Its 256 KB Flash supports full Wi-Fi/BLE stacks (for example Microchip's WINC3400 firmware or Zigbee 3.0), while 32 KB SRAM accommodates the TCP/IP and TLS 1.2 buffers needed for secure cloud connectivity. The 1.62-3.63 V range enables direct Li-ion or 2xAA battery operation. Pin-to-pin migration within the SAM D21 family makes it easy to scale across endpoint tiers without PCB redesign.
Recommended
Smart Metering and Energy Monitoring
In smart metering applications, the ATSAMD21G18A-AFT's 12-bit ADC and integrated op-amps allow direct interface to current shunts and voltage dividers, eliminating an external analog front-end. The integrated 10-bit DAC supports calibration trim and analog waveform generation. Functional Safety (FuSa) documentation under IEC 60730 Class B simplifies the qualification path required for utility and white-goods metering products, while the -40 °C to +125 °C operating range supports outdoor enclosure placement.
Recommended
USB HID Peripherals
The ATSAMD21G18A-AFT integrates a USB 2.0 Full-Speed controller with on-chip transceiver, eliminating external bridge ICs and reducing BOM for HID peripherals such as keyboards, mice, custom input devices, and USB-to-UART replacement boards. Its 48 MHz CPU and 256 KB Flash comfortably fit the USB HID class driver plus vendor-specific bulk or interrupt endpoints. Microchip's MPLAB Harmony 3 framework provides ready-to-use HID, CDC, and composite USB stacks, shortening firmware development by 2-3 months.
Recommended
Industrial Sensor Hubs
For industrial sensor hubs and motor-control gate-driver bridges, the ATSAMD21G18A-AFT provides up to five 16-bit Timer/Counter (TC) channels, a 12-channel Event System, and a 12-channel DMAC that offloads deterministic data movement from the CPU. Its 48 MHz throughput is sufficient for sensor fusion (for example 6-axis IMU + barometer), while the -40 °C to +125 °C junction range meets harsh-factory-floor thermal requirements. Up to six SERCOM channels allow concurrent I2C, SPI, and UART sensor fan-out without external mux ICs.
Recommended
Consumer Wearables and Fitness Devices
Battery-powered wearables benefit from the ATSAMD21G18A-AFT's Idle and Standby sleep modes plus SleepWalking peripherals, which let the MCU service sensor interrupts without CPU wake-up. Active current at 48 MHz is roughly 6 mA, dropping to single-digit microamps in standby, suitable for multi-day fitness band battery life. The on-chip 12-bit ADC and 10-bit DAC support biometric front-ends (PPG, GSR) without external signal-chain ICs.
Recommended
Low-Power IoT Edge Nodes
Edge IoT nodes combining local sensing with cloud telemetry are well served by the ATSAMD21G18A-AFT's combination of 32 KB SRAM (large enough for TLS 1.2 sessions), 256 KB Flash (OTA-capable), and Cortex-M0+ efficiency at 2.46 CoreMark/MHz. The SERCOM peripheral count (up to 6) supports concurrent SPI flash, I2C sensors, and UART debug, while the integrated 12-bit ADC handles analog transducer readouts. Pin compatibility with the lower-memory ATSAMD21G17A-AFT lets designers cost-down for entry-tier SKUs without board redesign.
Recommended
Recommended Products Summary
Engineering reference data for ATSAMD21G18A-AFT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAMD21G18A-AU | ATSAMD21G17A-AFT | STM32G031K8T6 |
|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | STMicroelectronics |
| Package | 48-TQFP (7x7 mm) | 48-TQFP (7x7 mm) - same | 48-TQFP (7x7 mm) - same | 32-LQFP - different |
| Core | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ |
| Maximum CPU Frequency | 48 MHz | 48 MHz | 48 MHz | 64 MHz |
| Flash Memory | 256 KB | 256 KB | 128 KB (-50%) | 64 KB (-75%) |
| SRAM | 32 KB | 32 KB | 16 KB (-50%) | 8 KB (-75%) |
| Operating Voltage | 1.62 V to 3.63 V | 1.62 V to 3.63 V | 1.62 V to 3.63 V | 2.0 V to 3.6 V |
| Operating Temperature | -40 °C to +125 °C | -40 °C to +85 °C | -40 °C to +125 °C | -40 °C to +85 °C |
| USB Controller | USB 2.0 Full-Speed | USB 2.0 Full-Speed | USB 2.0 Full-Speed | No integrated USB |
Key Differentiators
- Integrated USB 2.0 Full-Speed with on-chip transceiver (vs STM32G031K8T6)
- Functional Safety (FuSa) documentation for IEC 60730 Class B (vs ATSAMD21G18A-AU)
- Extended industrial temperature range (-40 °C to +125 °C) (vs ATSAMD21G18A-AU)
Design Notes
Place one 0.1 µF ceramic decoupling capacitor on each VDDIO pin (and one on VDDIN), as close to the package as the layout allows, with a single 1 µF bulk capacitor on VDDIN. Estimated: the ATSAMD21G18A-AFT draws up to ~6 mA active at 48 MHz and ~5 µA in Standby; the four-capacitor scheme keeps VDDIO ripple below 20 mV, which is required for clean ADC and DAC operation at the datasheet ENOB of 9.5 bits.
The 48-TQFP package has a junction-to-ambient thermal resistance of about 53 °C/W on a 4-layer JEDEC test board. Estimated: at full 48 MHz active with all peripherals on, the device dissipates roughly 70 mW, producing a 4 °C rise above ambient. No heatsink is required; however, designers should follow Microchip's PCB land pattern and use the exposed thermal pad of the 48-QFN variant (not present on TQFP) for higher-power designs.
Do not leave the SWD pins (PA30 = SWCLK, PA31 = SWDIO) floating during normal operation - although the SAM D21 enables internal pull-ups by default, noisy industrial environments can cause spurious debugger disconnect events. Bring SWD to a 5-pin or 10-pin Cortex Debug header and consider adding 33 Ω series resistors on SWDIO/SWCLK for EMI protection. Also, the -AFT suffix denotes tape-and-reel + extended -40 °C to +125 °C; using -AU in a +100 °C application is a common spec error.
Route the USB DP (PA25) and DM (PA24) differential pair with 90 Ω differential impedance, length-matched to within 150 mil, and keep them clear of switching nodes. Add 33 pF shunt capacitors on each line near the connector for ESD. The Microchip AN7724 layout guide is the recommended reference and should be cited in any design-for-manufacturing documentation.
Compliance Information
RoHS and REACH compliance per Microchip product environmental statements. Halogen-free per Microchip 2017 statement. Not AEC-Q100 qualified; the ATSAMD21G18A-AFT is part of the Functional Safety (FuSa) IEC 60730 Class B documentation package, but does not carry an automotive grade qualification - choose ATSAM D21 variants ending in -MZVAO or -UUT for AEC-Q100 where required.
