ATSAMD21J17A-AF - 48MHz Cortex-M0+ MCU, 128KB Flash | Microchip
MPN: ATSAMD21J17A-AF ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.2 | $5.20 |
| 10 | $4.78 | $47.80 |
| 100 | $4.15 | $415.00 |
| 500 | $3.55 | $1,775.00 |
| 1,000 | $3.1 | $3,100.00 |
| 3,000 | $2.75 | $8,250.00 |
ATSAMD21J17A-AF Overview
An MCU (microcontroller) is a single-chip computer integrating a CPU core, program and data memory, and configurable peripherals on one silicon die. Cortex-M0+ is the most energy-efficient ARM processor core for embedded applications, while ATSAMD21 family devices extend the Cortex-M0+ with Microchip's event system, SERCOM peripherals, and a comprehensive SleepWalking power-management architecture. The 'J' suffix denotes the high-pin-count 64-pin family, providing maximum GPIO and peripheral accessibility.
Key features of the ATSAMD21J17A-AF include 128 KB Flash with 4 KB RWW (Read-While-Write) EEPROM emulation area, 16 KB SRAM, a 32-bit Cortex-M0+ core with single-cycle multiplier and SysTick, six SERCOM modules each configurable as I2C/SPI/UART/USART, USB 2.0 Full-Speed device with on-chip transceiver, and a 12-bit ADC with up to 20 channels. Operating voltage ranges from 1.62 V to 3.63 V, enabling single-cell Li-ion or 3.3 V system designs, with a maximum operating temperature of 125 °C for industrial-thermal-range applications.
Typical applications include USB Human Interface Devices (HID), home automation gateways, low-power wireless sensor nodes, smart metering, industrial control panels, and consumer wearables. The integrated USB device controller and rich SERCOM set simplify designs requiring multiple serial protocols without external glue logic.
When designing with this device, allocate the 128 KB Flash carefully: approximately 8 KB is consumed by the SAM D21 bootloader, leaving ~120 KB for application code. Use Atmel Studio 7 or MPLAB X IDE with the START code-configurator for peripheral initialization, and budget quiescent current carefully: full Sleep mode draws under 10 uA, but active peripherals can dominate consumption.
Drop-in alternatives for ATSAMD21J17A-AF — 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 ATSAMD21J17A-AF (same form factor and footprint) — differing in ADC, DAC, Flash Memory, Package, USB.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATSAMD21J18A-AF
✅ Drop-In✓ In Stock
$2.91 / Unit
View Datasheet →ATSAMD21J17A-AFT
✅ Drop-In📋 Reference alternative (not in catalog)
ATSAMD21J16B-AF
✅ Drop-In✓ In Stock
$2.52 / Unit
View Datasheet →ATSAMD21J15B-AF
✅ Drop-In📋 Reference alternative (not in catalog)
ATSAMD20J18A-AU
✅ Drop-In✓ In Stock
$2.15 / Unit
View Datasheet →ATSAMD21J17A-AF Maximum Ratings & Electrical Characteristics
| Core Architecture | ARM Cortex-M0+ (32-bit) |
| Maximum CPU Frequency | 48 MHz |
| Flash Memory | 128 KB (128K x 8) |
| SRAM | 16 KB |
| RWW EEPROM Emulation Area | 4 KB |
| Operating Voltage Range | 1.62 V to 3.63 V |
| Maximum Operating Temperature | +125 °C (industrial grade) |
| Package | 64-pin TQFP, 10x10 mm, 0.5 mm pitch |
| Mounting Type | Surface Mount |
| USB Interface | USB 2.0 Full-Speed Device with on-chip transceiver |
| Serial Communication Modules (SERCOM) | 6 (each configurable as UART/USART/SPI/I2C) |
| ADC | 12-bit, up to 350 ksps, up to 20 channels |
| DAC | 10-bit, 350 ksps |
| PWM Channels | Up to 24 (TCC/TC) |
| GPIO Count | Up to 52 |
| MSL Level | MSL3 (per JEDEC J-STD-020) |
| RoHS Status | Compliant |
ATSAMD21J17A-AF Pin Configuration
| Pin 1 | PA00 — GPIO / XIN32 (external 32 kHz crystal input) |
| Pin 2 | PA01 — GPIO / XOUT32 (external 32 kHz crystal output) |
| Pin 3 | PA02 — GPIO / ADC AIN0 |
| Pin 4 | PA03 — GPIO / ADC AIN1 / VREFA |
| Pin 5 | GND — Ground |
| Pin 6 | VDD — Digital supply voltage |
| Pin 7 | PA04 — GPIO / VREFB / ADC AIN4 |
| Pin 8 | PA05 — GPIO / ADC AIN5 |
| Pin 9 | PA06 — GPIO / ADC AIN6 |
| Pin 10 | PA07 — GPIO / ADC AIN7 |
| Pin 11 | VDD — Digital supply voltage |
| Pin 12 | GND — Ground |
| Pin 13 | PA08 — GPIO / SERCOM0 / ADC AIN16 |
| Pin 14 | PA09 — GPIO / SERCOM0 / ADC AIN17 |
| Pin 15 | PA10 — GPIO / SERCOM0 / ADC AIN18 |
| Pin 16 | PA11 — GPIO / SERCOM0 / ADC AIN19 |
| Pin 17 | VDD — Digital supply voltage |
| Pin 18 | GND — Ground |
| Pin 19 | PB10 — GPIO / SERCOM4 |
| Pin 20 | PB11 — GPIO / SERCOM4 |
| Pin 21 | PA12 — GPIO / SERCOM2 / I2S FS0 |
| Pin 22 | PA13 — GPIO / SERCOM2 / I2S MCK0 |
| Pin 23 | PA14 — GPIO / SERCOM2 / I2S SCK0 |
| Pin 24 | PA15 — GPIO / SERCOM2 / I2S SDO |
| Pin 25 | PA16 — GPIO / SERCOM1 / I2S SDI |
| Pin 26 | PA17 — GPIO / SERCOM1 / I2S FS1 |
| Pin 27 | PA18 — GPIO / SERCOM1 / I2S MCK1 |
| Pin 28 | PA19 — GPIO / SERCOM1 / I2S SCK1 |
| Pin 29 | PB12 — GPIO / SERCOM4 |
| Pin 30 | PB13 — GPIO / SERCOM4 |
| Pin 31 | PB14 — GPIO / SERCOM4 |
| Pin 32 | PB15 — GPIO / SERCOM4 |
| Pin 33 | PA20 — GPIO / SERCOM3 |
| Pin 34 | PA21 — GPIO / SERCOM3 |
| Pin 35 | PA22 — GPIO / SERCOM3 |
| Pin 36 | PA23 — GPIO / SERCOM3 / USB SOF 1 kHz |
| Pin 37 | VDD — Digital supply voltage |
| Pin 38 | GND — Ground |
| Pin 39 | PA24 — USB D- (negative data line) |
| Pin 40 | PA25 — USB D+ (positive data line) |
| Pin 41 | PA26 — GPIO |
| Pin 42 | PA27 — GPIO |
| Pin 43 | PA28 — GPIO |
| Pin 44 | PA29 — GPIO / CANRX (not bonded on J-family, NC) |
| Pin 45 | PA30 — GPIO / CANTX (not bonded on J-family, NC) |
| Pin 46 | PA31 — GPIO |
| Pin 47 | PB16 — GPIO / SERCOM5 |
| Pin 48 | PB17 — GPIO / SERCOM5 |
| Pin 49 | PB18 — GPIO / SERCOM5 |
| Pin 50 | PB19 — GPIO / SERCOM5 |
| Pin 51 | PB20 — GPIO / SERCOM5 |
| Pin 52 | PB21 — GPIO / SERCOM5 |
| Pin 53 | VDD — Digital supply voltage |
| Pin 54 | GND — Ground |
| Pin 55 | PB22 — GPIO / SERCOM5 |
| Pin 56 | PB23 — GPIO / SERCOM5 |
| Pin 57 | PB24 — GPIO |
| Pin 58 | PB25 — GPIO |
| Pin 59 | PB26 — GPIO |
| Pin 60 | PB27 — GPIO |
| Pin 61 | PB28 — GPIO |
| Pin 62 | PB29 — GPIO |
| Pin 63 | PB30 — GPIO / SWCLK (debug) |
| Pin 64 | PB31 — GPIO / SWDIO (debug) |
Typical Applications
ATSAMD21J17A-AF is suitable for 6 applications: USB Human Interface Device (HID), Home Automation Gateway, Industrial Sensor Node, Smart Metering Endpoints, Consumer Wearable Devices, USB-CDC Virtual COM Port Bridge.
USB Human Interface Device (HID)
The ATSAMD21J17A-AF is purpose-built for USB HID peripherals such as keyboards, mice, custom input devices, and gaming controllers. Its integrated USB 2.0 Full-Speed device controller with on-chip transceiver eliminates the need for an external USB PHY, while the 48 MHz Cortex-M0+ core sustains 1 kHz HID polling rates with ample margin for HID report processing. The 128 KB Flash accommodates class drivers from the Microchip ASF or START framework, and 16 KB SRAM buffers HID reports without starvation. Place the device's PA24 (D-) and PA25 (D+) directly to the USB connector with 27-ohm series resistors and a 1 uF VBUS decoupling network on the VBUS pin.
Recommended
Home Automation Gateway
The ATSAMD21J17A-AF serves as the central MCU in home automation gateways, where its six SERCOM modules provide independent I2C, SPI, and UART buses for sensor aggregation. Zigbee, BLE, or LoRa daughter modules connect via SERCOM UART/SPI while the SERCOM I2C buses read temperature, humidity, and occupancy sensors. The 12-bit 350 ksps ADC captures analog signals from thermistors and light sensors, and the on-chip USB device port connects the gateway to a host Raspberry Pi or set-top box. With 1.62 V to 3.63 V operation, the device tolerates USB-supply droop, and the SAM D21 SleepWalking modes keep idle current below 10 uA.
Recommended
Industrial Sensor Node
The ATSAMD21J17A-AF is ideal for industrial 4-20 mA loop-powered sensor nodes thanks to its 1.62 V to 3.63 V operating range and 12-bit ADC with up to 20 channels. The 10-bit DAC generates 4-20 mA loop current with 0.1 mA resolution after op-amp scaling, and the SERCOM I2C interfaces connect to digital temperature, pressure, and flow sensors. With operating temperature up to +125 °C, the device tolerates the harsh thermal environments of factory floors and outdoor enclosures, while integrated brown-out detection and watchdog timer prevent lockup under EMI. The 48 MHz CPU supports Modbus RTU response times under 1 ms for high-speed polling masters.
Recommended
Smart Metering Endpoints
The ATSAMD21J17A-AF powers smart electricity, water, and gas meters where its Cortex-M0+ efficiency and 16 KB SRAM support metering firmware plus a wireless M-Bus or wM-Bus stack. The 12-bit ADC achieves 0.025 % full-scale resolution for metrology-grade voltage and current sensing, and the on-chip USB port allows factory calibration and firmware update. With SleepWalking peripherals, the MCU draws under 5 uA between metrology sampling intervals, enabling 10+ year battery life on a single D-cell. The 128 KB Flash stores calibration coefficients, security keys, and firmware with headroom for future feature additions.
Recommended
Consumer Wearable Devices
The ATSAMD21J17A-AF drives fitness bands, smart watches, and medical wearables where the 64-pin TQFP package provides 52 GPIO for displays, touch sensors, and BLE modules while keeping PCB area minimal. The 12-bit ADC reads biometric signals such as heart rate, SpO2 photoplethysmography, and skin temperature, and the SERCOM I2C interfaces to IMUs and environmental sensors. With 48 MHz performance and 128 KB Flash, the device supports lightweight RTOS-based firmware such as FreeRTOS or Zephyr for multitasking. Idle current under 10 uA in STANDBY mode extends coin-cell battery life across multiple-day wear cycles.
Recommended
USB-CDC Virtual COM Port Bridge
The ATSAMD21J17A-AF functions as a USB-to-UART bridge (USB-CDC class device), replacing dedicated bridge chips such as the FT232 with a programmable Cortex-M0+ MCU. The USB device port enumerates as a virtual COM port on the host, while a SERCOM in UART mode drives the external UART pins. The 48 MHz CPU sustains 921600 baud UART throughput with minimal latency, and 16 KB SRAM buffers bulk USB transfers. The Microchip START code-configurator provides a turnkey CDC class driver that runs entirely from Flash, leaving application space for protocol conversion logic.
Recommended
Recommended Products Summary
Engineering reference data for ATSAMD21J17A-AF — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAMD21J18A-AF | ATSAMD21J17A-AFT | ATSAMD21J16B-AF | ATSAMD21J15B-AF | ATSAMD20J18A-AU |
|---|---|---|---|---|---|---|
| Package | 64-pin TQFP (10x10 mm) | 64-pin TQFP (10x10 mm) | 64-pin TQFP (10x10 mm) | 64-pin TQFP (10x10 mm) | 64-pin TQFP (10x10 mm) | 64-pin TQFP (10x10 mm) |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Core | Cortex-M0+ @ 48 MHz | Cortex-M0+ @ 48 MHz | Cortex-M0+ @ 48 MHz | Cortex-M0+ @ 48 MHz | Cortex-M0+ @ 48 MHz | Cortex-M0+ @ 48 MHz |
| Flash | 128 KB | 256 KB | 128 KB | 64 KB | 32 KB | 256 KB |
| SRAM | 16 KB | 32 KB | 16 KB | 8 KB | 4 KB | 32 KB |
| USB 2.0 FS Device | Yes | Yes | Yes | Yes | Yes | No |
| SERCOM Count | 6 | 6 | 6 | 6 | 6 | 6 |
| 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 |
| Approx Unit Price (qty-1) | ~$5.20 | ~$6.10 | ~$5.20 | ~$4.40 | ~$3.90 | ~$5.80 |
Key Differentiators
- USB 2.0 Full-Speed device with on-chip transceiver (vs ATSAMD20J18A-AU)
- 128 KB Flash with 4 KB Read-While-Write EEPROM area (vs ATSAMD21J16B-AF)
- Higher SRAM than lower-tier J16B/J15B siblings (vs ATSAMD21J15B-AF)
- Dual ADC comparator + DAC for closed-loop control (vs ATSAME70Q21B)
Design Notes
Place decoupling capacitors as close as physically possible to every VDD/GND pair on the 64-pin TQFP. The SAM D21 datasheet recommends one 100 nF ceramic per VDD pin and one bulk 10 uF ceramic near the supply entry. The on-chip voltage regulator requires a 1 uF + 100 nF pair on the VDDIN pin (pin 37 on J-family) to maintain core-supply stability; omitting these causes brown-out resets under USB load.
The 64-pin TQFP package has a thermal resistance of approximately 39 °C/W (theta_JA on JEDEC 4-layer test board). At maximum CPU activity (48 MHz, all peripherals on), the device dissipates roughly 60 mW - well within the 125 °C operating limit. However, in enclosed enclosures at +85 °C ambient, ensure copper-pour area on VDD and GND exceeds 1 square inch to keep junction temperature below 100 °C and maintain long-term reliability.
Route the USB DP/DM pair (PA24, PA25) as a 90-ohm differential pair with matched length to within 150 mil, and place the 27-ohm series resistors within 4 mm of the MCU pins. Keep the USB traces away from switching nodes or clock signals. The SWD pins PB30/PB31 should be brought out to a 4-pin header or test pad with 100 nF bypass near the SWDIO line to prevent debug-port lockup in electrically noisy environments.
Do not assume all 64 GPIO are simultaneously available - many SERCOM, I2S, and ADC functions share pins and require peripheral multiplexing via the PORT and PMUX registers. The PA29 and PA30 pins are CAN functions not bonded on the J-family; they read as NC. When migrating from the smaller Q-family SAM D21 (32-pin or 48-pin), verify pin alternate-function mappings against the datasheet's pin-multiplexing table - peripheral channel indices differ between packages.
Place the 32.768 kHz crystal as close to PA00/PA01 as possible with short symmetric traces and a guard ring tied to GND. Add 5 pF to 10 pF load capacitors matching the crystal specification. Keep the low-frequency crystal traces away from the high-frequency USB pair to avoid coupling. The internal DFLL48M uses the 32 kHz reference to lock the 48 MHz system clock; phase noise on the crystal translates directly to USB jitter and SERCOM baud-rate error.
Compliance Information
RoHS and REACH compliant per Microchip product page. Standard grade (not AEC-Q100) - select ATSAMD21J17A-MF or industrial-thermal-grade variants for harsh environments. Halogen-free per Microchip material declarations.
