ATSAMD21G16B-AU - 48MHz ARM M0+ MCU 64KB Flash 48-TQFP | Microchip
MPN: ATSAMD21G16B-AU β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.95 | $3.95 |
| 10 | $3.55 | $35.50 |
| 100 | $3.16 | $316.00 |
| 500 | $2.83 | $1,415.00 |
| 1,000 | $2.52 | $2,520.00 |
ATSAMD21G16B-AU Overview
What is an ARM Cortex-M0+ microcontroller? The Cortex-M0+ is an ultra-low-power 32-bit processor core from Arm targeting embedded and IoT applications. Within the system hierarchy it sits as: Cortex-M0+ -> ARM Cortex-M family -> 32-bit RISC microcontroller -> embedded MCU -> semiconductor. The SAM D21 family adds Microchip's peripheral set (SERCOM, TCC, ADC, DAC) on top of this core to deliver a balance of power efficiency and deterministic real-time performance.
Key features include a 48 MHz DFLL48M digital frequency-locked loop with a 48 MHz to 96 MHz Fractional DFLL option, internal and external clock sources, brown-out detection (BOD), power-on reset (POR), and a Sleepwalking peripheral event system. The device offers up to six SERCOM interfaces configurable as UART/SPI/I2C, a 12-bit 350 ksps ADC, a 10-bit DAC, and multiple 16-bit timer/counter channels for PWM and capture. Functional Safety (FuSa) variants in this family include additional diagnostic features for IEC 60730 Class B compliance.
The architecture pairs the Cortex-M0+ core with a multi-layer AHB/APB bus matrix, deterministic latency from Flash (single-cycle access via the 2.62 CoreMark/MHz implementation), and a Peripheral Event System allowing peripherals to wake the CPU autonomously. The integrated Full-Speed USB 2.0 Device with on-chip transceiver is a notable feature on select SAM D21 pins, simplifying connectivity for HID, CDC, and vendor-class USB devices without an external PHY.
Typical applications include Arduino MKR-series compatible boards, IoT sensor nodes, USB HID peripherals, low-power wearables, industrial sensor interfaces, home automation gateways, and battery-powered data loggers. The combination of low active current, multiple SERCOM instances, and built-in USB makes it well suited for connected edge devices.
When designing with this device, pay attention to the SERCOM pin-mapping table because each SERCOM can be routed to several I/O sets, and choosing the right mapping early prevents costly PCB rework. The BOD threshold level is fuse-configurable and should be set to match your supply rail tolerance to avoid unintended resets during battery droop events.
This page synthesizes distributor pricing, verified drop-in alternatives, application-specific design notes, and SAM D21 family comparison data not consolidated in the manufacturer datasheet, helping engineers shorten the BOM selection and qualification cycle.
Drop-in alternatives for ATSAMD21G16B-AU 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 ATSAMD21G16B-AU (same form factor and footprint) β differing in Flash Memory, SRAM, Operating Temperature, RoHS Status, ADC.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATSAMD21G15B-AU
β Drop-Inβ In Stock
$1.65 / Unit
View Datasheet βATSAMD21G18A-AU
β Drop-Inβ In Stock
$1.74 / Unit
View Datasheet βATSAMD21G16B-AUT
β Drop-Inβ In Stock
$2.45 / Unit
View Datasheet βATSAMD21G15B-AUT
β Drop-Inπ Reference alternative (not in catalog)
ATSAMD21G17D-AU
β Drop-Inπ Reference alternative (not in catalog)
ATSAMD21G16B-AU Maximum Ratings & Electrical Characteristics
| Core Architecture | ARM Cortex-M0+ (32-bit) |
| Family | SAM D21G |
| Maximum CPU Frequency | 48 MHz |
| CoreMark/MHz | 2.46 |
| Flash Memory | 64 KB (in-system self-programmable) |
| SRAM | 8 KB |
| Supply Voltage (VDD) | 1.62 V to 3.63 V |
| I/O Pins | 38 (maximum) |
| External Interrupts (EIC) | 16 |
| Debug Interface | Serial Wire Debug (SWD), 2-pin |
| Package | 48-pin TQFP (7x7 mm) |
| Operating Temperature | -40 C to +85 C (industrial) |
| Hardware Multiplier | Single-cycle 32-bit |
| DFLL48M | 48 MHz Digital Frequency Locked Loop |
| RoHS Status | Compliant (Green) |
| MSL Level | MSL3 (per JEDEC J-STD-020) |
| Carrier Type | Tray |
| Brown-Out Detection | Yes, fuse-configurable |
ATSAMD21G16B-AU Pin Configuration
| Pin 1 | PA00 β I/O pin, SERCOM1 PAD0, ADC AIN0 |
| Pin 2 | PA01 β I/O pin, SERCOM1 PAD1, ADC AIN1 |
| Pin 3 | PA02 β I/O pin, SERCOM0 PAD0, AIN2, DAC VOUT |
| Pin 4 | PA03 β I/O pin, SERCOM0 PAD1, AIN3, REF positive |
| Pin 5 | PA04 β I/O pin, SERCOM0 PAD2, AIN4, VREF |
| Pin 6 | PA05 β I/O pin, SERCOM0 PAD3, AIN5 |
| Pin 7 | PA06 β I/O pin, SERCOM0 PAD0 alt, AIN6, alternative function |
| Pin 8 | PA07 β I/O pin, SERCOM0 PAD1 alt, AIN7 |
| Pin 9 | VDDCORE β Internal core voltage decoupling pin, requires 1 uF + 100 nF |
| Pin 10 | GND β Common ground |
| Pin 11 | VDDIN β Main digital supply input (1.62-3.63 V) |
| Pin 12 | PA08 β I/O pin, SERCOM2 PAD0, NMI, ADC AIN16 |
| Pin 13 | PA09 β I/O pin, SERCOM2 PAD1, AIN17 |
| Pin 14 | PA10 β I/O pin, SERCOM2 PAD2, AIN18 |
| Pin 15 | PA11 β I/O pin, SERCOM2 PAD3, AIN19 |
| Pin 16 | PA12 β I/O pin, SERCOM4 PAD0 |
| Pin 17 | PA13 β I/O pin, SERCOM4 PAD1 |
| Pin 18 | PA14 β I/O pin, SERCOM4 PAD2, XIN32 |
| Pin 19 | PA15 β I/O pin, SERCOM4 PAD3, XOUT32 |
| Pin 20 | PA16 β I/O pin, SERCOM1 PAD0 alt, I2S SCK0 |
| Pin 21 | PA17 β I/O pin, SERCOM1 PAD1 alt, I2S MCK0 |
| Pin 22 | PA18 β I/O pin, SERCOM1 PAD2 alt, I2S FS0 |
| Pin 23 | PA19 β I/O pin, SERCOM1 PAD3 alt, I2S SD0 |
| Pin 24 | PA20 β I/O pin, SERCOM5 PAD2, I2S SD0 alt |
| Pin 25 | PA21 β I/O pin, SERCOM5 PAD3, I2S FS0 alt |
| Pin 26 | PA22 β I/O pin, SERCOM5 PAD0, I2S SCK0 alt, USB D- |
| Pin 27 | PA23 β I/O pin, SERCOM5 PAD1, I2S MCK0 alt, USB D+ |
| Pin 28 | PA24 β I/O pin, SERCOM3 PAD2, USB ID |
| Pin 29 | PA25 β I/O pin, SERCOM3 PAD3, USB VBUS |
| Pin 30 | GND β Common ground |
| Pin 31 | VDDIO β I/O supply voltage input |
| Pin 32 | PA26 β I/O pin |
| Pin 33 | PA27 β I/O pin |
| Pin 34 | PA28 β I/O pin, boot loader entry |
| Pin 35 | PA29 β I/O pin |
| Pin 36 | PA30 β I/O pin, SWD clock input on alt |
| Pin 37 | PA31 β I/O pin, SWD data on alt |
| Pin 38 | PB02 β I/O pin, SERCOM5 PAD0 alt, ADC AIN10 |
| Pin 39 | PB03 β I/O pin, SERCOM5 PAD1 alt, ADC AIN11 |
| Pin 40 | PB04 β I/O pin, SERCOM3 PAD0 alt, ADC AIN12 |
| Pin 41 | PB05 β I/O pin, SERCOM3 PAD1 alt, ADC AIN13 |
| Pin 42 | PB06 β I/O pin, SERCOM3 PAD2 alt, ADC AIN14 |
| Pin 43 | PB07 β I/O pin, SERCOM3 PAD3 alt, ADC AIN15 |
| Pin 44 | PB08 β I/O pin, SERCOM4 PAD0 alt, AIN2 alt |
| Pin 45 | PB09 β I/O pin, SERCOM4 PAD1 alt, AIN3 alt |
| Pin 46 | PB10 β I/O pin, SERCOM4 PAD2 alt |
| Pin 47 | PB11 β I/O pin, SERCOM4 PAD3 alt |
| Pin 48 | GND β Common ground (corner pin) |
Typical Applications
ATSAMD21G16B-AU is suitable for 6 applications: IoT Sensor Node / Edge Device, USB HID Peripheral / Consumer Dongle, Arduino-Compatible Development Platform, Wearable Fitness / Health Monitor, Industrial Sensor Interface / Modbus Node, Smart Home Lighting / DMX Controller.
IoT Sensor Node / Edge Device
The ATSAMD21G16B-AU's 48 MHz Cortex-M0+ core, 64 KB Flash, and 8 KB SRAM make it well suited for low-power IoT sensor nodes running lightweight protocols like LoRaWAN, MQTT-SN, or BLE-beacon firmware. Its 6 SERCOM interfaces can be routed as I2C for sensors, SPI for an external radio module, and UART for debug, while the 12-bit ADC samples battery voltage and analog sensor channels at up to 350 ksps. With Sleep/Standby current below 5 uA and RTC wake from any peripheral, average current on a duty-cycled node stays under 50 uA per Microchip application note AT03442, supporting multi-year battery life on 2x AA cells.
Recommended
USB HID Peripheral / Consumer Dongle
The ATSAMD21G16B-AU integrates a Full-Speed USB 2.0 Device controller with on-chip transceiver, eliminating the need for an external PHY in HID, CDC, or vendor-class USB peripherals. Its 48 MHz Cortex-M0+ provides sufficient headroom for HID report parsing and 1 ms polling-rate USB frames. The 64 KB Flash accommodates the Atmel ASF USB stack plus application code; 8 KB SRAM handles HID report buffers and USB endpoint FIFOs. Industrial-grade -40 to +85 C operation supports consumer accessories and industrial USB input devices.
Recommended
Arduino-Compatible Development Platform
The ATSAMD21G16B-AU powers the Arduino MKR GSM 1400, MKR WiFi 1010, and Arduino Zero boards, making it a de-facto standard for hobbyist and professional rapid-prototyping environments. Its 64 KB Flash and 8 KB SRAM are sufficient for Arduino sketches, and the SAM D21 Arduino core provides out-of-the-box USB bootloader support. The Cortex-M0+ instruction set is binary-compatible with the M0 used in lower-tier SAM D11 boards, simplifying code migration. The 48-pin TQFP also exposes all I/O needed for breadboard-friendly shields.
Recommended
Wearable Fitness / Health Monitor
The ATSAMD21G16B-AU's small 48-pin TQFP footprint (7x7 mm), low active current around 4 mA at 48 MHz, and SERCOM-rich peripheral set suit battery-powered wearable designs such as fitness bands and heart-rate monitors. The 12-bit ADC reads PPG (photoplethysmography) sensor outputs while the DAC generates bias for LED drivers; a hardware Crypto module is absent but optional external ATECC608B secure-element pairing is supported over I2C. Sleepwalking peripherals can wake the CPU only when meaningful sensor events occur, keeping idle current in single-digit microamps.
Recommended
Industrial Sensor Interface / Modbus Node
With its -40 C to +85 C industrial temperature rating and 38 GPIO, the ATSAMD21G16B-AU fits industrial Modbus RTU sensor interfaces and 4-20 mA loop-powered transmitters. The Cortex-M0+ executes Modbus stack and calibration routines within the 64 KB Flash budget; 8 KB SRAM holds Modbus PDU buffers and floating-point sensor compensation tables. The brown-out detection (BOD) with fuse-configurable threshold protects against supply droops on long cable runs, and the SERCOM-based RS-485 interface connects directly to a transceiver like the MAX3485.
Recommended
Smart Home Lighting / DMX Controller
The ATSAMD21G16B-AU's 16-bit TCC timer/counter channels generate high-resolution PWM signals suitable for multi-channel RGBW LED dimming and DMX-512 lighting fixture control. Six SERCOMs allow simultaneous SPI for APA102 LEDs and UART for DMX or RS-485 bus communication. The 48 MHz Cortex-M0+ executes DMX receive-and-transmit tasks at the required 250 kbaud with cycle budget to spare for color-mixing algorithms. The 48-TQFP exposes ample I/O for up to 6 hardware PWM channels and additional low-side MOSFET drivers.
Recommended
Recommended Products Summary
Engineering reference data for ATSAMD21G16B-AU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAMD21G15B-AU | ATSAMD21G18A-AU | ATSAMD21G16B-AUT | ATSAMD21G17D-AU | ATSAMD21G15B-AUT |
|---|---|---|---|---|---|---|
| Package | 48-pin TQFP (7x7) | 48-pin TQFP (7x7) - same | 48-pin TQFP (7x7) - same | 48-pin TQFP (7x7) - same | 48-pin TQFP (7x7) - same | 48-pin TQFP (7x7) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Core | ARM Cortex-M0+ @ 48 MHz | ARM Cortex-M0+ @ 48 MHz | ARM Cortex-M0+ @ 48 MHz | ARM Cortex-M0+ @ 48 MHz | ARM Cortex-M0+ @ 48 MHz | ARM Cortex-M0+ @ 48 MHz |
| Flash | 64 KB | 32 KB | 256 KB | 64 KB | 128 KB | 32 KB |
| SRAM | 8 KB | 4 KB | 32 KB | 8 KB | 16 KB | 4 KB |
| Operating Voltage | 1.62 V to 3.63 V | 1.62 V to 3.63 V | 1.62 V to 3.63 V | 1.62 V to 3.63 V | 1.62 V to 3.63 V | 1.62 V to 3.63 V |
| Operating Temperature | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| Carrier Type | Tray | Tray | Tray | Tape & Reel | Tray | Tape & Reel |
| Unit Price (qty 1) | $3.95 | $3.45 | $4.85 | $3.95 | $4.40 | $3.45 |
Key Differentiators
- Drop-in upgrade path to 256 KB Flash on identical footprint (vs ATSAMD21G15B-AU)
- Tape and reel carrier without die change (vs ATSAMD21G16B-AUT)
- Mid-density sweet spot with proven SAM D21 ecosystem (vs ATSAMD21G17D-AU)
Design Notes
Place a 1 uF X7R ceramic decoupling capacitor as close as possible to the VDDCORE pin (pin 9) with a 100 nF X7R bypass in parallel; the internal 1.2 V core LDO requires this for stable operation across the full 1.62-3.63 V input range. VDDIN (pin 11) and VDDIO (pin 31) need their own 100 nF + 4.7 uF bulk capacitors. Failure to decouple the VDDCORE pin correctly is the single most common cause of SAM D21 brown-out resets and erratic USB enumeration on production boards.
The USB D- (PA24, pin 26) and D+ (PA25, pin 27) traces must be routed as a 90 ohm differential pair with matched length and continuous ground reference plane beneath them. Keep total trace length under 25 mm to stay within USB 2.0 Full-Speed signal-integrity budget. Place the USB connector shield-to-ground ESD diode near the connector; do not route the USB signals over the on-board switching regulator or any high-dV/dt nodes to avoid EMI-induced enumeration failures.
SERCOM peripheral pin mapping must be planned at schematic capture time because each SERCOM can be routed to multiple I/O sets; an incorrect early choice will force a PCB respin. Additionally, the SAM D21 bootloader entry pin (PA28, pin 34) must be left accessible or tied through a header so firmware recovery via Atmel-ICE / J-Link is possible after field-locked production units are deployed. Failing to expose the SWDIO (PA31, pin 37) and SWCLK (PA30, pin 36) signals prevents all future debugging and firmware updates.
Compliance Information
RoHS compliant Green per Microchip product page; not AEC-Q100 qualified (industrial grade -40 to +85 C only, automotive applications require SAM DA1 or SAM V71 family). REACH SVHC compliant per Microchip substance declaration. Halogen-free per Microchip Green package designation.
