ATSAMD21G16B-MF - 64KB Flash Cortex-M0+ MCU 48QFN | Microchip
MPN: ATSAMD21G16B-MF ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.1 | $4.10 |
| 10 | $3.78 | $37.80 |
| 100 | $3.32 | $332.00 |
| 500 | $2.89 | $1,445.00 |
| 1,000 | $2.55 | $2,550.00 |
| 3,000 | $2.18 | $6,540.00 |
ATSAMD21G16B-MF Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program and data memory, and a rich set of peripherals (timers, ADC, communication interfaces, GPIO). The Cortex-M0+ is ARM's smallest and most energy-efficient application processor core, designed for deterministic real-time control in deeply embedded systems. The SAM D21 family belongs to the 32-bit microcontroller tier within the broader hierarchy of microcontrollers -> embedded processors -> semiconductors. Typical Cortex-M0+ MCUs target IoT endpoints, sensor hubs, human-interface devices, and battery-powered consumer products where active current draw and deep-sleep current are first-order constraints.
Key features of the ATSAMD21G16B-MF include the 48 MHz Cortex-M0+ core with single-cycle hardware multiply, a full-speed USB 2.0 device controller, a 12-bit 350 ksps ADC with PGA, up to six SERCOM serial-communication channels configurable as UART/SPI/I2C, a 24-bit Timer/Counter for control applications, and an on-chip 32.768 kHz RTC oscillator. The device is qualified for the industrial temperature range (-40C to +125C), supports 3.3V single-supply operation, and is RoHS/REACH compliant in a halogen-free green-package compound.
Architecturally, the SAM D21 is built around an AHB/APB bus matrix with a separate low-power peripheral bus, allowing individual peripherals to be clock-gated during sleep. The integrated Power Manager (PM) and Sleepwalking peripherals let the core stay in deep sleep while SERCOM, ADC, or timers wake the system on a peripheral event - this is the foundation of the family's low-power claim. An on-chip 8-channel Event System routes peripheral triggers without CPU intervention, which reduces interrupt load for tightly-timed control loops.
Typical applications for the ATSAMD21G16B-MF include Arduino-compatible maker boards (the chip is the silicon heart of the Arduino Zero / MKR family), USB HID peripherals such as keyboards and mice, low-power wireless sensor nodes, industrial sensor interfaces, and small HMI panels. Designers also deploy it in consumer wearables, BLE bridge modules, and battery-powered instrumentation where 3.3V single-supply and USB are both required.
When designing with this MCU, allocate the 64KB Flash budget between bootloader, application, and a small file system; the 8KB SRAM constrains large packet buffers and dictates careful DMA usage for high-throughput USB or display workloads. Decouple VDD and VDDANA separately per the SAM D21 reference design, and use the on-chip PLL to derive system frequency from the internal 8 MHz oscillator if external crystals are not available.
This page synthesizes distributor pricing, drop-in alternatives from the SAMD21 family, and practical design notes not found in the manufacturer datasheet - including cross-references to the 48-TQFP variant ATSAMD21G16B-AU which shares the same silicon die.
Drop-in alternatives for ATSAMD21G16B-MF — 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 ATSAMD21G16B-MF (same form factor and footprint) — differing in Package, Operating Temperature, RoHS Status, Debug Interface, SRAM.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATSAMD21G16B-MFT
✅ Drop-In✓ In Stock
$1.96 / Unit
View Datasheet →ATSAMD21G15B-MF
✅ Drop-In✓ In Stock
$1.74 / Unit
View Datasheet →ATSAMD21G18B-MF
✅ Drop-In📋 Reference alternative (not in catalog)
ATSAMD21G16B-AU
✅ Drop-In✓ In Stock
$2.52 / Unit
View Datasheet →ATSAMD21E16B-MF
✅ Drop-In📋 Reference alternative (not in catalog)
ATSAMD21G15B-MUT
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$1.78 / Unit
View Datasheet →STM32F042F4P6
✅ Drop-In📋 Reference alternative (not in catalog)
ATSAMD21G16B-MF Maximum Ratings & Electrical Characteristics
| Core | ARM Cortex-M0+ (32-bit) |
| Maximum CPU Frequency | 48 MHz |
| CoreMark/MHz | 2.46 |
| Flash Memory | 64 KB |
| SRAM | 8 KB |
| Operating Voltage | 1.62 V to 3.63 V (3.3 V typical) |
| Operating Temperature | -40C to +125C (industrial) |
| Package | 48-pin QFN |
| Mounting Type | Surface Mount |
| USB | USB 2.0 Full-Speed Device |
| ADC | 12-bit, up to 350 ksps |
| SERCOM Channels | Up to 6 (configurable UART/SPI/I2C) |
| Timers | 24-bit TC, RTC, SysTick |
| RoHS Status | Compliant |
| Halogen Free | Yes (Microchip green compound) |
ATSAMD21G16B-MF Pin Configuration
| Pin 1 | PA00 — GPIO / SERCOM1.0 / TCC2.0 |
| Pin 2 | PA01 — GPIO / SERCOM1.1 / TCC2.1 |
| Pin 3 | PA02 — GPIO / SERCOM0.0 / AIN0 (ADC) |
| Pin 4 | PA03 — GPIO / SERCOM0.1 / AIN1 (ADC) |
| Pin 5 | PA04 — GPIO / SERCOM0.2 / AIN2 / VOUT |
| Pin 6 | PA05 — GPIO / SERCOM0.3 / AIN3 |
| Pin 7 | PA06 — GPIO / SERCOM0.0 / AIN4 |
| Pin 8 | PA07 — GPIO / SERCOM0.1 / AIN5 |
| Pin 9 | VDDANA — Analog supply (3.3 V) |
| Pin 10 | GND — Ground |
| Pin 11 | PA08 — GPIO / SERCOM2.0 / AIN6 |
| Pin 12 | PA09 — GPIO / SERCOM2.1 / AIN7 |
| Pin 13 | PA10 — GPIO / SERCOM2.2 / AIN8 |
| Pin 14 | PA11 — GPIO / SERCOM2.3 / AIN9 |
| Pin 15 | PA12 — GPIO / SERCOM4.0 |
| Pin 16 | PA13 — GPIO / SERCOM4.1 |
| Pin 17 | PA14 — GPIO / SERCOM4.2 / XIN32 |
| Pin 18 | PA15 — GPIO / SERCOM4.3 / XOUT32 |
| Pin 19 | PA16 — GPIO / SERCOM3.0 |
| Pin 20 | PA17 — GPIO / SERCOM3.1 |
| Pin 21 | PA18 — GPIO / SERCOM3.2 |
| Pin 22 | PA19 — GPIO / SERCOM3.3 |
| Pin 23 | PA20 — GPIO / SERCOM5.2 |
| Pin 24 | PA21 — GPIO / SERCOM5.3 |
| Pin 25 | PA22 — GPIO / SERCOM3.0 / USB_DM |
| Pin 26 | PA23 — GPIO / SERCOM3.1 / USB_DP |
| Pin 27 | PA24 — GPIO / SERCOM5.0 / USB_HOST_EN |
| Pin 28 | PA25 — GPIO / SERCOM5.1 |
| Pin 29 | GND — Ground |
| Pin 30 | VDD — Digital supply (3.3 V) |
| Pin 31 | PA26 — GPIO |
| Pin 32 | PA27 — GPIO |
| Pin 33 | PA28 — GPIO / Reset |
| Pin 34 | PA29 — GPIO / Bootloader |
| Pin 35 | PA30 — GPIO / SWDIO |
| Pin 36 | PA31 — GPIO / SWCLK |
| Pin 37 | PB00 — GPIO / SERCOM5.2 |
| Pin 38 | PB01 — GPIO / SERCOM5.3 |
| Pin 39 | PB02 — GPIO / SERCOM5.0 / AIN10 |
| Pin 40 | PB03 — GPIO / SERCOM5.1 / AIN11 |
| Pin 41 | PB04 — GPIO / SERCOM4.0 |
| Pin 42 | PB05 — GPIO / SERCOM4.1 |
| Pin 43 | PB06 — GPIO / SERCOM4.2 |
| Pin 44 | PB07 — GPIO / SERCOM4.3 |
| Pin 45 | PB08 — GPIO / SERCOM4.0 |
| Pin 46 | PB09 — GPIO / SERCOM4.1 |
| Pin 47 | GND — Ground (thermal pad) |
| Pin 48 | VDDIO — I/O supply (3.3 V) |
Typical Applications
ATSAMD21G16B-MF is suitable for 6 applications: Arduino-Compatible Maker Boards, USB HID Peripherals (Keyboard, Mouse, Custom HID), Battery-Powered IoT Sensor Hubs, Industrial Sensor Interfaces (Modbus, 4-20 mA bridges), Small HMI Panels (TFT, OLED, Touch Button UI), Wearable Devices (Fitness Bands, Smart Watches).
Arduino-Compatible Maker Boards
The ATSAMD21G16B-MF is the silicon heart of the Arduino Zero, MKR Zero, and Adafruit Feather M0 boards, where its 48 MHz Cortex-M0+ core, 64 KB Flash, and built-in USB 2.0 full-speed device controller provide a turnkey maker platform. The 8 KB SRAM comfortably hosts the Arduino core plus application sketches up to ~50 KB compiled, and the six SERCOM channels expose UART/SPI/I2C on any pin via the PORT multiplexer. Industrial temperature grade (-40C to +125C) means the same chip serves hobby, prosumer, and commercial products without a silicon change. According to the SAM D21 datasheet, the integrated 12-bit ADC with PGA supports 3.3V analog sensors directly, eliminating the external ADC Arduino Uno designers had to add. Drop-in alternative within the family is ATSAMD21G18B-MF when applications exceed 64 KB Flash.
Recommended
USB HID Peripherals (Keyboard, Mouse, Custom HID)
The on-chip USB 2.0 Full-Speed device controller with internal pull-up and 1k5 D+ resistor support makes the ATSAMD21G16B-MF ideal for USB HID peripherals - keyboards, mice, game controllers, custom vendor-class HID. The Cortex-M0+ at 48 MHz provides enough MIPS to run HID report parsing plus LED matrix scanning or capacitive touch decoding, and the 64 KB Flash holds the USB stack, HID report descriptors, and application firmware without external memory. The deep-sleep current under 10 uA (with RTC running) supports bus-powered HID devices that meet USB suspend current budgets (<= 2.5 mA high-power, <= 0.5 mA low-power suspend). Per the SAM D21 datasheet, the integrated PLL can derive the 48 MHz USB clock from the internal 8 MHz oscillator when an external crystal is not available, reducing BOM cost on HID dongles and key fobs.
Recommended
Battery-Powered IoT Sensor Hubs
The SAM D21 family's Sleepwalking peripheral architecture makes the ATSAMD21G16B-MF a strong fit for battery-powered IoT sensor hubs that sleep most of the time and wake on sensor events. The 12-bit 350 ksps ADC with PGA can sample sensors while the core stays in deep sleep, and the SERCOM I2C blocks can wake on address match. RTC retains time across deep-sleep and the on-chip 32.768 kHz oscillator eliminates external RTC chips. According to Microchip's SAM D21 datasheet, deep-sleep current is in the single-digit microamp range, supporting multi-year coin-cell operation for temperature, humidity, and motion sensors. Industrial temperature grade and 1.62 V minimum supply extend usable runtime as cells discharge below 2.0 V. Recommended companion is a low-power BLE module over UART SERCOM.
Recommended
Industrial Sensor Interfaces (Modbus, 4-20 mA bridges)
The ATSAMD21G16B-MF's industrial -40C to +125C temperature range, 3.3V single-supply operation, and 12-bit ADC with PGA make it suitable for industrial sensor interfaces and Modbus bridges. The Cortex-M0+ at 48 MHz can handle Modbus RTU / ASCII stacks plus ADC oversampling for 16-bit effective resolution, while six SERCOM channels expose RS-485 (via external transceiver), SPI sensors, and I2C peripherals. The 8 KB SRAM supports Modbus PDU buffers plus a small TCP/IP stack for Modbus TCP variants. Per the SAM D21 datasheet, hardware crypto accelerators and unique 128-bit serial number support asset-tracking and anti-counterfeit authentication - relevant to factory-floor sensor networks. Drop-in alternative ATSAMD21G18B-MF is recommended when Modbus gateway code exceeds 64 KB.
Recommended
Small HMI Panels (TFT, OLED, Touch Button UI)
The ATSAMD21G16B-MF drives small HMI panels - 1.3-inch OLEDs, 1.8-inch TFTs, capacitive touch buttons - with enough headroom for graphics libraries like Adafruit_GFX and LVGL on small displays. The SERCOM-configurable SPI can drive TFTs at 20 MHz+ while a second SERCOM I2C bus reads capacitive touch controllers. The 24-bit Timer/Counter (TC) provides hardware PWM for backlight dimming without CPU load, and the Event System routes touch and timer events without waking the core. According to the SAM D21 datasheet, DMA can move display buffers from Flash to SPI without CPU intervention - critical when the 8 KB SRAM cannot double-buffer a full frame. Drop-in upgrade to ATSAMD21G18B-MF enables larger TFT panels (2.4-inch and above).
Recommended
Wearable Devices (Fitness Bands, Smart Watches)
The ATSAMD21G16B-MF's low-power Sleepwalking, 32.768 kHz RTC, and small 48QFN footprint make it appropriate for wearable fitness bands and smart-watch daughter boards. The Cortex-M0+ at 48 MHz executes step-counting, heart-rate (via external AFE), and BLE-radio-host protocols over a UART SERCOM, and the 12-bit ADC with PGA handles optical PPG sensor analog front-ends directly. Industrial temperature rating supports body-temperature operating environments. Per the SAM D21 datasheet, the integrated 1.2V LDO and on-chip voltage regulator eliminate external PMICs for single-cell Li-ion designs, saving board area in compact wearables. Recommended companion: small Li-ion charger and BLE SoC connected over UART.
Recommended
Recommended Products Summary
Engineering reference data for ATSAMD21G16B-MF — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAMD21G16B-MFT | ATSAMD21G15B-MF | ATSAMD21G18B-MF | ATSAMD21G16B-AU | ATSAMD21G15B-MUT | STM32F042F4P6 |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | STMicroelectronics |
| Package | 48-pin QFN | 48-pin QFN - same | 48-pin QFN - same | 48-pin QFN - same | 48-pin TQFP (7x7) - same footprint family | 48-pin QFN - same | TSSOP-20 - different package |
| Core | ARM Cortex-M0+ 32-bit | ARM Cortex-M0+ 32-bit | ARM Cortex-M0+ 32-bit | ARM Cortex-M0+ 32-bit | ARM Cortex-M0+ 32-bit | ARM Cortex-M0+ 32-bit | ARM Cortex-M0 32-bit |
| Maximum Clock | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz |
| Flash Memory | 64 KB | 64 KB | 48 KB | 256 KB | 64 KB | 48 KB | 16 KB |
| SRAM | 8 KB | 8 KB | 4 KB | 32 KB | 8 KB | 4 KB | 6 KB |
| USB | USB 2.0 Full-Speed Device | USB 2.0 Full-Speed | USB 2.0 Full-Speed | USB 2.0 Full-Speed | USB 2.0 Full-Speed | USB 2.0 Full-Speed | USB 2.0 Full-Speed |
| Operating Temperature | -40C to +125C (industrial) | -40C to +125C | -40C to +125C | -40C to +125C | -40C to +85C (extended) | -40C to +125C | -40C to +85C |
Key Differentiators
- 64 KB Flash / 8 KB SRAM middle-of-family sweet spot (vs ATSAMD21G15B-MF)
- Industrial -40C to +125C temperature range (vs ATSAMD21G16B-AU)
- Same Cortex-M0+ core and Cortex-M0+ tooling ecosystem (vs STM32F042F4P6)
Design Notes
Decouple VDD, VDDANA, and VDDIO with separate 100 nF ceramic capacitors placed within 3 mm of the package, plus a shared 10 uF bulk capacitor on the main 3.3 V rail. The SAM D21's internal 1.2 V LDO derives the core supply from VDDIN; per the datasheet reference design, VDDIO can be tied to VDD for single-supply 3.3 V operation, or driven independently to support 1.8 V logic-level peripherals. Estimate: under typical 48 MHz active load with USB suspended, expect 8-12 mA active current; deep-sleep with RTC running falls below 10 uA.
The 48QFN package has an exposed thermal pad (pin 47, GND) that must be soldered to a PCB thermal pad of at least 16 mm^2 of copper. Without the thermal pad soldered, junction temperature can rise 15-20 C above ambient at full 48 MHz active load, especially in enclosed industrial enclosures. Estimate: theta_JA of 48QFN is approximately 39 C/W on a 4-layer JEDEC test board; on a 2-layer consumer board it can exceed 60 C/W. Use a thermal via array under the pad (5x5 vias, 0.3 mm drill) for high-dissipation designs.
Route the USB DP/DM differential pair (PA22/PA23) as a 90-ohm differential microstrip with matched length within 2 mm, and place the 1k5 USB D+ pull-up resistor within 5 mm of the DP pin. Place the 32.768 kHz crystal within 5 mm of XIN32/XOUT32 (PA14/PA15) with a guard ring tied to GND to reduce noise coupling into the RTC domain. SWD pins PA30 (SWDIO) and PA31 (SWCLK) should be brought out to a 2x5 1.27 mm header for debugger access - this is the standard Cortex-M0+ debug interface and must not be repurposed for GPIO if in-circuit debug is required.
Do not skip the bootloader pin (PA29) - Microchip's default ROM bootloader is on PA08/PA09 UART for production programming without a debugger. If you repurpose PA29 as GPIO, you also lose the bootloader entry vector. Also, the 32 KB SRAM variant (ATSAMD21G18B-MF) is sometimes shipped with the wrong Flash start address in legacy bootloaders; always re-flash the bootloader for the correct memory map. Do not exceed 3.63 V absolute maximum on any IO pin - the SAM D21's IO cells are not 5V-tolerant.
Compliance Information
Microchip's SAM D21 family is RoHS compliant and supplied in Microchip's halogen-free green compound. The MF part is not AEC-Q100 qualified; automotive customers should request ATSAMD21G16B-MFVAO or contact Microchip for automotive-grade variants.
