ATSAMD21G18A-MF - 48MHz Cortex-M0+ MCU, 256KB Flash | Microchip
MPN: ATSAMD21G18A-MF β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.62 | $4.62 |
| 10 | $4.18 | $41.80 |
| 100 | $3.71 | $371.00 |
| 500 | $3.32 | $1,660.00 |
| 1,000 | $2.94 | $2,940.00 |
| 3,000 | $2.65 | $7,950.00 |
ATSAMD21G18A-MF Overview
A 32-bit ARM Cortex-M0+ microcontroller is a low-power, low-cost processor core built on the ARMv6-M architecture that delivers 0.9 DMIPS/MHz performance while consuming only a few hundred microamps per megahertz. Microcontrollers (MCUs) integrate the CPU core, non-volatile memory (Flash), volatile memory (SRAM), and a rich set of peripherals (ADC, timers, communication blocks, GPIOs) on a single chip. Within the broader system hierarchy, the SAM D21 family sits inside Microchip's Atmel-SMART 32-bit MCU line -> ARM Cortex-M microcontrollers -> 32-bit microcontrollers -> embedded processors -> semiconductors.
Key features of the ATSAMD21G18A-MF include 256KB in-system self-programmable Flash, 32KB SRAM, a 12-channel 12-bit ADC with hardware oversampling, six SERCOM channels that can each be configured as UART, SPI, or I2C, two I2S interfaces for digital audio, a 20-channel Event System for inter-peripheral signaling without CPU intervention, and a 1.0 channel USB 2.0 Full-Speed device/host with on-the-go support. The device operates from 1.62V to 3.63V, supporting single-cell Li-ion battery applications down to coin-cell operation.
Architecturally, the SAM D21 uses a single-cycle hardware multiplier, a nested vector interrupt controller (NVIC) with 4 priority levels, and a Memory Protection Unit (MPU) for system robustness. Activation of the sleepwalking peripherals and the Event System enables the CPU to remain in deep-sleep (less than 5 microamps) while peripherals continue to react to external events. The integrated 48MHz digital frequency-locked loop (DFLL48M) provides a stable CPU clock from the internal 32.768kHz oscillator.
Typical applications include USB human-interface devices (HID) and CDC virtual COM ports, home automation and connected sensors, consumer wearables with battery charging control, industrial sensor hubs with analog front ends, smart metering nodes, and low-power wireless sensor nodes pairing the SAM D21 with an external sub-GHz or BLE radio. The QFN-48 footprint is widely adopted on Arduino-compatible and Feather-style development boards, making it ideal for prototyping and small-volume production.
Design consideration: the ATSAMD21G18A-MF requires an external 32.768kHz crystal or an internal 32kHz ultra-low-power oscillator (OSCULP32K) for accurate USB Full-Speed operation. The exposed pad (EP) on the QFN package must be soldered to a sufficient ground plane to meet thermal conductivity (theta-JA approximately 31 C/W on a 4-layer JEDEC test board). Bulk decoupling of at least one 10uF and one 100nF ceramic capacitor close to VDD and VDDCORE pins is mandatory for reliable ADC and USB operation.
This page synthesizes distributor stock data, parametric alternatives, and practical PCB design guidance not assembled in the manufacturer datasheet alone, helping engineers select, source, and lay out the ATSAMD21G18A-MF faster.
Drop-in alternatives for ATSAMD21G18A-MF β 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-MF (same form factor and footprint) β differing in Package, Operating Temperature, USB, ADC, Flash Memory.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATSAMD21G18A-MFT
β Drop-Inπ Reference alternative (not in catalog)
ATSAMD21G18A-AFT
β Drop-Inβ In Stock
$2.69 / Unit
View Datasheet βATSAMD21G18A-AF
β Drop-Inβ In Stock
$3.49 / Unit
View Datasheet βATSAMD21E18A-MF
β Drop-Inβ In Stock
$6.95 / Unit
View Datasheet βATSAMD21E18A-AFT
β Drop-Inβ In Stock
$2.72 / Unit
View Datasheet βATSAMD21G18A-MF Maximum Ratings & Electrical Characteristics
| Core | ARM Cortex-M0+ (ARMv6-M) |
| Maximum CPU Frequency | 48 MHz |
| Flash Memory | 256 KB (256K x 8) |
| SRAM | 32 KB |
| Operating Voltage | 1.62 V to 3.63 V |
| Package | 48-pin QFN (7x7 mm) |
| Operating Temperature | -40C to +125C (industrial) |
| ADC | 12-bit, up to 350 ksps, 12 channels |
| DAC | 10-bit, 1 channel |
| USB | USB 2.0 Full-Speed Device/Host/OTG |
| SERCOM Modules | 6 (configurable as UART/SPI/I2C) |
| Timers (TC) | 5 x 16-bit |
| GPIOs | 38 |
| RoHS Status | Compliant |
| MSL Level | 3 (168 hours) |
ATSAMD21G18A-MF Pin Configuration
| Pin 1 | VDD β Digital supply voltage |
| Pin 2 | GND β Ground |
| Pin 3 | PA00 β General-purpose I/O, SERCOM1 pad 0 |
| Pin 4 | PA01 β General-purpose I/O, SERCOM1 pad 1 |
| Pin 5 | PA02 β General-purpose I/O, analog AIN0 |
| Pin 6 | PA03 β General-purpose I/O, analog AIN1, ADC reference |
| Pin 7 | PA04 β General-purpose I/O, analog AIN2 |
| Pin 8 | PA05 β General-purpose I/O, analog AIN3 |
| Pin 9 | PA06 β General-purpose I/O, analog AIN4 |
| Pin 10 | PA07 β General-purpose I/O, analog AIN5 |
| Pin 11 | VDDANA β Analog supply voltage |
| Pin 12 | GNDANA β Analog ground |
| Pin 13 | PA08 β General-purpose I/O, ADC AIN6, NMI |
| Pin 14 | PA09 β General-purpose I/O, ADC AIN7 |
| Pin 15 | PA10 β General-purpose I/O, ADC AIN8 |
| Pin 16 | PA11 β General-purpose I/O, USB DP |
| Pin 17 | PA12 β General-purpose I/O, USB DM |
| Pin 18 | PA13 β General-purpose I/O, SERCOM2 pad 1 |
| Pin 19 | PA14 β General-purpose I/O, SERCOM2 pad 2 |
| Pin 20 | PA15 β General-purpose I/O, SERCOM3 pad 1 |
| Pin 21 | PA16 β General-purpose I/O, SERCOM1 pad 0, I2S MCK0 |
| Pin 22 | PA17 β General-purpose I/O, SERCOM1 pad 1, I2S SCK0 |
| Pin 23 | PA18 β General-purpose I/O, SERCOM3 pad 2, I2S FS0 |
| Pin 24 | PA19 β General-purpose I/O, SERCOM1 pad 3, I2S SD0 |
| Pin 25 | PA20 β General-purpose I/O, SERCOM5 pad 2, I2S SD1 |
| Pin 26 | PA21 β General-purpose I/O, SERCOM5 pad 3, I2S FS1 |
| Pin 27 | PA22 β General-purpose I/O, SERCOM3 pad 0, I2S SCK1 |
| Pin 28 | PA23 β General-purpose I/O, SERCOM5 pad 1, USB SOF 1kHz |
| Pin 29 | PA24 β General-purpose I/O, USB VBUS sense |
| Pin 30 | PA25 β General-purpose I/O, SERCOM3 pad 3 |
| Pin 31 | GND β Ground |
| Pin 32 | VDD β Digital supply voltage |
| Pin 33 | PB00 β General-purpose I/O, SERCOM5 pad 2 |
| Pin 34 | PB01 β General-purpose I/O, SERCOM5 pad 3 |
| Pin 35 | PB02 β General-purpose I/O, SERCOM5 pad 0, ADC AIN10 |
| Pin 36 | PB03 β General-purpose I/O, SERCOM5 pad 1, ADC AIN11 |
| Pin 37 | PB04 β General-purpose I/O, SERCOM3 pad 0 |
| Pin 38 | PB05 β General-purpose I/O, SERCOM3 pad 1 |
| Pin 39 | PB06 β General-purpose I/O, SERCOM3 pad 2 |
| Pin 40 | PB07 β General-purpose I/O, SERCOM3 pad 3 |
| Pin 41 | PB08 β General-purpose I/O, SERCOM4 pad 0, ADC AIN2 |
| Pin 42 | PB09 β General-purpose I/O, SERCOM4 pad 1, ADC AIN3 |
| Pin 43 | PB10 β General-purpose I/O, SERCOM4 pad 2 |
| Pin 44 | PB11 β General-purpose I/O, SERCOM4 pad 3 |
| Pin 45 | PB12 β General-purpose I/O, SERCOM4 pad 0, I2S MCK1 |
| Pin 46 | PB13 β General-purpose I/O, SERCOM4 pad 1 |
| Pin 47 | PB14 β General-purpose I/O, SERCOM4 pad 2 |
| Pin 48 | PB15 β General-purpose I/O, SERCOM4 pad 3 |
Typical Applications
ATSAMD21G18A-MF is suitable for 6 applications: USB Human Interface Devices (HID), Home Automation and Connected Sensors, Consumer Wearables and Fitness Trackers, Industrial Sensor Hubs and Metering, Smart LED Lighting Controllers, Low-Power Wireless Sensor Nodes.
USB Human Interface Devices (HID)
The ATSAMD21G18A-MF is well suited to USB HID designs because the integrated USB 2.0 Full-Speed device/host/OTG controller, 48 MHz Cortex-M0+ core, and 256 KB Flash provide enough headroom for USB stacks plus HID report processing. The 6 SERCOM channels can drive external peripherals (key matrices, sensors, displays) while the USB handles host enumeration. The 32 KB SRAM comfortably holds HID ring buffers for keyboards, mice, gamepads, and multi-touch digitizers without external memory.
Recommended
Home Automation and Connected Sensors
The ATSAMD21G18A-MF fits home-automation hub and sensor-node designs thanks to its 12-bit 350 ksps ADC, 6 SERCOM channels, 38 GPIOs, and low deep-sleep current below 5 uA with sleepwalking peripherals. The Cortex-M0+ core can run Zigbee, BLE, LoRa, or Wi-Fi stacks via SPI-attached radios while the Event System wakes the CPU only on threshold-crossing interrupts from sensors. The 1.62V minimum supply lets it run from a single CR2032 coin cell for years of battery life.
Recommended
Consumer Wearables and Fitness Trackers
The ATSAMD21G18A-MF is well matched to consumer wearables thanks to its small 7x7 mm QFN footprint, 1.62V minimum supply for single-cell Li-ion operation, and Cortex-M0+ power efficiency. The 12-bit ADC can read battery voltage, skin temperature, and pulse-oximetry photodiode currents, while the 2-channel I2S supports digital microphone arrays for voice wake-word detection. The 32 KB SRAM can hold a 10-second audio buffer without external memory.
Recommended
Industrial Sensor Hubs and Metering
The ATSAMD21G18A-MF serves industrial sensor hubs and metering nodes because of its -40C to +125C industrial temperature rating, hardware crypto block (AES-256), and 12-bit ADC with hardware oversampling for 16-bit effective resolution. The SERCOM ports can run isolated RS-485 transceivers, M-Bus, or Wireless M-Bus stacks, while the Event System supports deterministic latency on metering pulses. The 256 KB Flash holds Dlms/Cosem or IEC 62056 protocol stacks plus secure bootloaders.
Recommended
Smart LED Lighting Controllers
The ATSAMD21G18A-MF is suitable for smart LED lighting controllers because its 5 x 16-bit timers, 6 SERCOM channels, and Event System can drive multi-channel LED PWM engines while running a wireless stack. The Cortex-M0+ core handles DMX-512, DALI-2, or Zigbee lighting protocols with timing slack, and the 38 GPIOs support 5-channel LED drivers per fixture without external I/O expanders. The 12-bit DAC provides smooth dimming curves for tunable-white fixtures.
Recommended
Low-Power Wireless Sensor Nodes
The ATSAMD21G18A-MF is a strong fit for low-power wireless sensor nodes because its deep-sleep current below 5 uA, Event System sleepwalking, and 32 KB SRAM let it buffer sensor data without CPU wake-up. The Cortex-M0+ core wakes only to drive an SPI-attached sub-GHz radio (LoRa, FSK, OOK) or BLE SoC for short-burst transmissions. The 1.62V minimum supply makes the design directly compatible with energy-harvesting power supplies such as small solar cells or thermoelectric generators.
Recommended
Recommended Products Summary
Engineering reference data for ATSAMD21G18A-MF β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAMD21G18A-MFT | ATSAMD21G18A-AFT | ATSAMD21G18A-AF | ATSAMD21E18A-MF |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | QFN-48 (7x7 mm) | QFN-48 (7x7 mm) - same | QFN-48 (7x7 mm) - same | QFN-48 (7x7 mm) - same | QFN-48 (7x7 mm) - same |
| Core | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ |
| Maximum CPU Frequency | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz |
| Flash Memory | 256 KB | 256 KB | 256 KB | 256 KB | 256 KB |
| SRAM | 32 KB | 32 KB | 32 KB | 32 KB | 32 KB |
| Operating Temperature | -40C to +125C (industrial) | -40C to +125C (industrial) | -40C to +125C (industrial) | -40C to +125C (industrial) | -40C to +125C (industrial) |
| USB | USB 2.0 FS OTG | USB 2.0 FS OTG | USB 2.0 FS OTG | USB 2.0 FS OTG | USB 2.0 FS OTG |
| Carrier | Tray | Tape & Reel | Tape & Reel | Tray | Tray |
Key Differentiators
- Integrated USB 2.0 Full-Speed OTG with on-chip transceiver (vs ATSAMD21G18A-MU (commercial temperature grade))
- Same QFN-48 die across tray or tape-and-reel options (vs ATSAMD21G18A-MUT (tape-and-reel carrier))
- Densest SAM D21 silicon in industrial temperature (vs ATSAMD21E18A-MF (32-pin D21E))
- Event System and SERCOM peripherals (vs ATSAMD21G18A-MFT (tape-and-reel))
Design Notes
Bulk decoupling is mandatory for stable SAM D21 operation: place one 10 uF X5R ceramic and one 100 nF X7R ceramic within 5 mm of each VDD pin and one bulk 10 uF cap within 5 mm of VDDCORE (pin 32 region). The analog domain (VDDANA / GNDANA on pins 11-12) requires a ferrite bead or pi-filter from VDD to isolate noisy digital return currents from the 12-bit ADC reference. Per the SAM D21 datasheet (DS40001882), the on-chip LDO needs at least 1 uF of output capacitance on VDDCORE for stability.
The QFN-48 package's exposed pad (EP) on the bottom of the chip must be soldered to a continuous ground plane with at least 16 thermal vias (0.3 mm drill, 0.5 mm pitch) to keep theta-JA near 31 C/W on a 4-layer JEDEC EIA/JESD51 2S2P test board. Estimated: at full CPU load (48 MHz, all peripherals active, USB transmitting) the die draws roughly 20 mA at 3.3 V (66 mW), well within the package's thermal budget for industrial temperatures. Skip the via array and the junction temperature can rise 30-50% above the safe margin.
Place the 32.768 kHz crystal within 5 mm of XIN32/XOUT32 pins (PB00/PB01 on this QFN-48) with a guard ring tied to GND, and add 12 pF load capacitors on each pin to GND. Route the USB DP/DM pair (PA11/PA12) as a 90 ohm differential pair with no stubs, length-matched within 150 mil. Keep the SWDIO/SWCLK traces (PA30/PA31 not bonded on this 48-pin variant; use SWD on the 64-pin D21J if you need hardware debug) short and away from switching rails.
Do not skip the 32.768 kHz crystal unless you accept the internal OSCULP32K accuracy of about +/- 3%, which is too coarse for USB Full-Speed framing and Bluetooth low-energy timing. Do not exceed 3.63 V on any VDD pin: the SAM D21's I/O cells clamp at 3.6 V and sustained over-voltage degrades oxide reliability. Do not drive RESET low without waiting 5 ms after VDD stabilizes, or the internal voltage regulator may fail to lock. Always enter production firmware via the BOSS-based secure bootloader in the SAM-BA / ASF4C stacks.
Estimated: for USB Full-Speed operation, the DP/DM trace impedance must be 90 ohms differential with 45 ohms single-ended to GND, and total length should not exceed 50 mm to keep insertion loss below 1 dB at 240 MHz. For SERCOM SPI peripherals running above 25 MHz, keep clock trace length below 30 mm and add a 33 ohm series resistor at the SAM D21 source pin to dampen reflections. The 12-bit ADC achieves 350 ksps only with an external 1 uF hold capacitor on AREF; do not omit it or THD degrades sharply.
Compliance Information
RoHS and REACH compliant per Microchip product environmental disclosures. Not AEC-Q100 qualified - choose ATSAMD21G18A-AUT (automotive grade) for AEC-Q100 designs. Halogen-free status not explicitly stated in retrieved data.
