ATSAMD21J18A-AUT - 32-bit Cortex-M0+ MCU 256KB Flash 64-TQFP | Microchip
MPN: ATSAMD21J18A-AUT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.2 | $4.20 |
| 10 | $3.78 | $37.80 |
| 100 | $3.35 | $335.00 |
| 500 | $2.98 | $1,490.00 |
| 1,000 | $2.63 | $2,630.00 |
ATSAMD21J18A-AUT Overview
What is a Cortex-M0+ microcontroller? An MCU (microcontroller unit) is a single-chip computer integrating a CPU core, program memory (Flash), working memory (SRAM), and a rich set of peripherals. The ARM Cortex-M0+ is the most energy-efficient core in the Cortex-M family, optimized for low-power embedded designs. The ATSAMD21J18A-AUT sits in the power-management IC and microcontroller hierarchy as an industrial-grade general-purpose MCU suitable for home automation, consumer, metering, and industrial applications.
Key features of this part include a full-speed USB 2.0 device/host with on-chip transceiver, up to six SERCOM (serial communication) interfaces configurable as UART/SPI/I2C, a 12-bit 350 ksps ADC with up to 20 channels, two analog comparators, a 10-bit 350 ksps DAC, up to six 16-bit timer/counters, a 32-bit RTC, and a Peripheral Touch Controller (PTC) for capacitive touch sensing. The device operates from 1.62 V to 3.63 V and includes a built-in DMA controller, Event System, and SleepWalking peripherals for sub-microamp sleep current.
The ATSAMD21J18A-AUT uses a two-cycle pipeline Harvard architecture with single-cycle I/O access and a hardware multiplier, providing 0.9 DMIPS/MHz CoreMark performance. On-chip voltage regulation and an integrated POR/BOD circuit simplify power-tree design and reduce BOM count in 3.3 V systems.
Typical applications include IoT sensor nodes, USB HID devices, smart-home controllers, industrial HMI panels, and low-power wireless sensor hubs. The combination of USB, SERCOM, ADC, DAC, and touch sensing makes the part flexible for multi-protocol gateways. Designers should consult the device 40001882A datasheet for full peripheral mapping and the SAME70/SAM D21 Xplained Pro board schematics for reference designs.
Drop-in alternatives for ATSAMD21J18A-AUT — 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 ATSAMD21J18A-AUT (same form factor and footprint) — differing in Operating Temperature, ADC, DAC, Package, USB.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATSAMD21J18A-AU
✅ Drop-In✓ In Stock
$2.69 / Unit
View Datasheet →ATSAMD21J18A-AFT
✅ Drop-In📋 Reference alternative (not in catalog)
ATSAMD21J18A-AF
✅ Drop-In✓ In Stock
$2.91 / Unit
View Datasheet →ATSAMD21J17A-AUT
✅ Drop-In✓ In Stock
$3.3 / Unit
View Datasheet →ATSAMD21J18A-AUT Maximum Ratings & Electrical Characteristics
| Core | ARM Cortex-M0+ (32-bit) |
| Max CPU Clock | 48 MHz |
| Program Memory (Flash) | 256 KB |
| SRAM | 32 KB |
| Operating Voltage (VDDIN) | 1.62 V to 3.63 V |
| I/O Voltage (VDDIO) | 1.62 V to 3.63 V |
| Package | 64-pin TQFP (10x10 mm) |
| GPIO Count | 52 |
| ADC | 12-bit, up to 350 ksps, up to 20 channels |
| DAC | 10-bit, 350 ksps, 1 channel |
| Analog Comparators | 2 |
| SERCOM | 6 (each configurable as UART/SPI/I2C) |
| USB | USB 2.0 Full-Speed Device/Host with on-chip transceiver |
| Timers | 6 x 16-bit TC, 1 x 24-bit TCC, 1 x 32-bit RTC |
| PTC (Touch Controller) | Yes |
| DMA Channels | 12 |
| Operating Temperature | -40 C to +85 C (industrial, AUT grade) |
| RoHS Status | Compliant |
| AEC-Q100 | Not qualified (AUT = tape & reel, not automotive grade) |
| Lead-Free / Halogen-Free | Yes (Green) |
ATSAMD21J18A-AUT Pin Configuration
| Pin 1 | PB23 — GPIO PB23, SERCOM5/PTC |
| Pin 2 | PB22 — GPIO PB22, SERCOM5/PTC |
| Pin 3 | PA27 — GPIO PA27, GCLK input |
| Pin 4 | VBUS — USB VBUS sense input |
| Pin 5 | USB_DP — USB D+ line |
| Pin 6 | USB_DM — USB D- line |
| Pin 7 | XIN32 — 32.768 kHz crystal input |
| Pin 8 | XOUT32 — 32.768 kHz crystal output |
| Pin 9 | VDDIO — I/O supply voltage |
| Pin 10 | GND — Ground |
| Pin 11 | PA28 — GPIO PA28 |
| Pin 12 | PA30 — GPIO PA30, SWDIO |
| Pin 13 | PA31 — GPIO PA31, SWCLK |
| Pin 14 | PA15 — GPIO PA15, SERCOM3 |
| Pin 15 | PA16 — GPIO PA16, SERCOM3 |
| Pin 16 | PA17 — GPIO PA17, SERCOM3 |
| Pin 17 | PA18 — GPIO PA18, SERCOM3 |
| Pin 18 | PA19 — GPIO PA19, SERCOM3 |
| Pin 19 | PA20 — GPIO PA20, SERCOM5 |
| Pin 20 | PA21 — GPIO PA21, SERCOM5 |
| Pin 21 | PA22 — GPIO PA22, SERCOM3/I2C |
| Pin 22 | PA23 — GPIO PA23, SERCOM3/I2C |
| Pin 23 | PA24 — GPIO PA24, USB SOF |
| Pin 24 | USB_DP_2 — Reserved / NC depending on routing |
| Pin 25 | USB_DM_2 — Reserved / NC depending on routing |
| Pin 26 | GND — Ground |
| Pin 27 | VDDIO — I/O supply voltage |
| Pin 28 | VDDIN — Main regulator input |
| Pin 29 | PA25 — GPIO PA25, USB ID |
| Pin 30 | PB02 — GPIO PB02, ADC |
| Pin 31 | PB03 — GPIO PB03, ADC |
| Pin 32 | PB00 — GPIO PB00, ADC |
| Pin 33 | PB01 — GPIO PB01, ADC |
| Pin 34 | PB04 — GPIO PB04, ADC |
| Pin 35 | PB05 — GPIO PB05, ADC |
| Pin 36 | PB06 — GPIO PB06, ADC |
| Pin 37 | PB07 — GPIO PB07, ADC |
| Pin 38 | PB08 — GPIO PB08, ADC |
| Pin 39 | PB09 — GPIO PB09, ADC |
| Pin 40 | PA08 — GPIO PA08, ADC/PTC |
| Pin 41 | PA09 — GPIO PA09, ADC/PTC |
| Pin 42 | PA10 — GPIO PA10, ADC/PTC |
| Pin 43 | PA11 — GPIO PA11, ADC/PTC |
| Pin 44 | VDDANA — Analog supply voltage |
| Pin 45 | GND — Ground |
| Pin 46 | PA02 — GPIO PA02, DAC/VREFP |
| Pin 47 | PA03 — GPIO PA03, DAC/VREFN |
| Pin 48 | PA04 — GPIO PA04, AC0 |
| Pin 49 | PA05 — GPIO PA05, AC1 |
| Pin 50 | PA06 — GPIO PA06, AC2 |
| Pin 51 | PA07 — GPIO PA07, AC3 |
| Pin 52 | PB12 — GPIO PB12, SERCOM4 |
| Pin 53 | PB13 — GPIO PB13, SERCOM4 |
| Pin 54 | PB14 — GPIO PB14, SERCOM4 |
| Pin 55 | PB15 — GPIO PB15, SERCOM4 |
| Pin 56 | PA12 — GPIO PA12, SERCOM2 |
| Pin 57 | PA13 — GPIO PA13, SERCOM2 |
| Pin 58 | PA14 — GPIO PA14, SERCOM2 |
| Pin 59 | PB16 — GPIO PB16, SERCOM5 |
| Pin 60 | PB17 — GPIO PB17, SERCOM5 |
| Pin 61 | PB10 — GPIO PB10, SERCOM4 |
| Pin 62 | PB11 — GPIO PB11, SERCOM4 |
| Pin 63 | PA00 — GPIO PA00, XIN |
| Pin 64 | PA01 — GPIO PA01, XOUT |
Typical Applications
ATSAMD21J18A-AUT is suitable for 7 applications: IoT Sensor Node / Smart Home Hub, USB HID / CDC Device, Industrial HMI / Control Panel, Capacitive Touch Control Interface, Portable Consumer Medical Devices, Smart Energy Meter / Sub-GHz Hub, Educational Maker Board / Arduino Compatible.
IoT Sensor Node / Smart Home Hub
The ATSAMD21J18A-AUT is well suited to IoT sensor nodes thanks to its 48 MHz Cortex-M0+ core, 256 KB Flash, and sub-microamp SleepWalking peripherals. Six SERCOM channels can simultaneously drive I2C sensors, an SPI radio module, and a UART debug console, while the 12-bit ADC reads up to 20 analog sensors. The 1.62-3.63 V operating range allows direct battery or energy-harvested supply. USB Full-Speed support enables easy firmware updates and CDC-ACM bridges to gateways.
Recommended
USB HID / CDC Device
The ATSAMD21J18A-AUT's integrated USB 2.0 Full-Speed transceiver with on-chip pull-up simplifies HID peripherals, CDC-ACM bridges, and HID-input devices like keyboards and game controllers. The 48 MHz Cortex-M0+ executes USB stack callbacks with ample headroom, and the 12-channel DMA offloads bulk transfers. Designers benefit from Microchip's free ASF/Atmel Start USB stack, reducing firmware development time. The +85 C industrial rating supports kiosk and POS HID peripherals.
Recommended
Industrial HMI / Control Panel
The ATSAMD21J18A-AUT fits industrial HMI panels with its 52 GPIO capable of driving keypads, character LCDs, and rotary encoders while still leaving pins for RS-485, Modbus, and CAN-style soft-links. The 12-bit ADC and two analog comparators handle sensor conditioning, and the 16-bit TC timers provide accurate PWM for backlight and motor control. Its 1.62-3.63 V range survives industrial 24 V step-down supply transients. Industrial-grade -40 C to +85 C operation ensures factory-floor reliability.
Recommended
Capacitive Touch Control Interface
The ATSAMD21J18A-AUT integrates the Peripheral Touch Controller (PTC) supporting mutual- and self-capacitance sensing with hardware-driven scanning and noise-immunity algorithms. This enables robust touch buttons, sliders, and wheels for appliances and consumer electronics without an external touch IC. Combined with 256 KB Flash and the 12-bit ADC for proximity sensing, the part serves as a single-chip UI controller for induction cooktops, washing machines, and smart thermostats.
Recommended
Portable Consumer Medical Devices
The ATSAMD21J18A-AUT supports battery-powered medical and wellness devices thanks to its low-power Run, Wait, and Sleep modes with sub-microamp RTC retention. The 12-bit 350 ksps ADC captures biosensor signals, while the DAC drives reference or stimulation waveforms. Six SERCOM ports communicate with BLE companions and OLED displays. The Cortex-M0+ integrates deterministic interrupt handling suitable for safety-critical wellness firmware. Note: this part is not AEC-Q100 or IEC 60730 qualified; for medical-grade designs add a separate safety MCU.
Recommended
Smart Energy Meter / Sub-GHz Hub
The ATSAMD21J18A-AUT's Cortex-M0+ at 48 MHz provides enough throughput to run metering algorithms on sampled ADC streams while offloading sub-GHz radio control over SPI. Its 256 KB Flash fits the metering state machine plus TLS-friendly wireless stacks when paired with an external AT86RF215 or SAM R35 module. The 52 GPIO can drive metrology front ends, tamper-detection switches, and LCD segments directly. Industrial temperature range supports outdoor meter enclosures.
Recommended
Educational Maker Board / Arduino Compatible
The ATSAMD21J18A-AUT is fully supported by the Arduino Zero bootloader and is widely used in maker and educational boards thanks to its 32-bit Cortex-M0+ performance and Atmel Studio / Arduino IDE tooling. The 64-pin TQFP gives students access to many peripherals in a breadboard-friendly footprint, and the integrated USB eliminates the need for an external programmer. Demos include motor control, audio synthesis, IoT nodes, and introductory RTOS labs with FreeRTOS SAM D21 ports.
Recommended
Recommended Products Summary
Engineering reference data for ATSAMD21J18A-AUT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAMD21J18A-AU | ATSAMD21J18A-AFT | ATSAMD21J18A-AF | ATSAMD21J17A-AUT |
|---|---|---|---|---|---|
| Package | TQFP-64 (10x10 mm) | TQFP-64 - same | TQFP-64 - same | TQFP-64 - same | TQFP-64 - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash | 256 KB | 256 KB | 256 KB | 256 KB | 128 KB |
| SRAM | 32 KB | 32 KB | 32 KB | 32 KB | 16 KB |
| Operating Temperature | -40 C to +85 C | -40 C to +85 C | -40 C to +125 C | -40 C to +125 C | -40 C to +85 C |
| Carrier Type | Tape & Reel | Tray | Tape & Reel | Tray | Tape & Reel |
| Max CPU Clock | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz |
| GPIO Count | 52 | 52 | 52 | 52 | 52 |
| Unit Price (1-pc) | $4.20 | ~$4.10 | ~$4.55 | ~$4.55 | ~$3.60 |
Key Differentiators
- Highest GPIO count in the SAM D21 family (vs ATSAMD21G18A-AUT)
- On-chip Full-Speed USB with internal transceiver (vs ATSAMD20J18A-MN)
- Industrial +85 C grade in Tape & Reel (vs ATSAMD21J18A-AU)
Design Notes
The ATSAMD21J18A-AUT contains an on-chip 1.2 V LDO that derives the core supply from VDDIN (1.62-3.63 V). Bypass VDDIN with 1 x 10 uF + 1 x 100 nF ceramic placed within 3 mm of the pin, and decouple each VDDIO/VDDANA pin with its own 100 nF cap. For USB applications, place a 10 uF cap on VBUS and a 0.1 uF cap on the 3.3 V rail derived from VBUS. Failure to decouple can result in USB enumeration failures and ADC noise coupling.
Route the USB DP/DM pair as a 90 ohm differential on the top layer with no splits and length-matched to within 150 mil. Keep the 32.768 kHz crystal traces short and surrounded by ground; place a guard ground ring around the crystal and its load caps. Avoid routing high-speed SERCOM SPI signals across the analog ADC inputs to minimize crosstalk in metering applications.
Do not assume all 52 GPIO are 5 V tolerant - all I/O are 3.3 V max regardless of supply. The SWDIO/SWCLK pins (PA30/PA31) must not be repurposed as outputs during reset or the debugger will lose contact; the BOOTPROT fuse disables SWD after lock. Use the Microchip Flash Security Bit to lock JTAG/SWD if your design ships outside the lab, but plan for field firmware update with a secure bootloader before locking.
At 48 MHz over 3.3 V the ATSAMD21J18A-AUT typically draws about 7 mA active and 7 uA in standby. Estimated: at 85 C ambient and a TQFP-64 theta_JA of about 60 C/W, internal dissipation never exceeds 30 mW even at full CPU load, so no heatsink is needed. For sealed enclosures with poor air flow verify temperature with a thermocouple on the package top in worst-case PWM and ADC sampling duty cycles.
Compliance Information
AUT suffix = Tape & Reel industrial grade, not AEC-Q100. RoHS and REACH per Microchip product page.
