ATSAMD21J18A-AFT - 32-bit Cortex-M0+ MCU, 256KB Flash, 64-TQFP | Microchip
MPN： ATSAMD21J18A-AFT ✓ 啟用中ATSAMD21J18A-AFT 概覽
A microcontroller (MCU) is a single-chip computer containing a CPU core, program and data memory, peripherals, and I/O. The Cortex-M0+ core from ARM is the smallest and most energy-efficient ARM core, optimized for deterministic embedded control and low active power. The SAM D21J family extends this core with rich peripherals including SERCOM, ADC, DAC, and event system, placing the MCU in the broader hierarchy: microcontroller -> embedded processor -> semiconductor device.
Key features of the ATSAMD21J18A-AFT include 6 SERCOM serial communication interfaces (each configurable as UART/SPI/I2C), a 12-bit 1 MSPS ADC with up to 20 channels, a 10-bit DAC, full-speed USB device/host, and a 2-channel DMAC for low-overhead data movement. The device supports sleepwalking peripherals and idle/standby modes that drop quiescent current to single-digit microamps, enabling years of battery life in sensor applications.
The ATSAMD21J18A-AFT is functionally safety-capable (FuSa) and integrates the ARM Cortex-M0+ core with single-cycle multiplier, hardware divide, and a Nested Vectored Interrupt Controller (NVIC). A 32-channel event system allows peripherals to trigger one another without CPU intervention, reducing wake latency and energy. The device also includes a segmented LCD controller variant in the family, but the -J18A part focuses on connectivity-rich general-purpose applications.
Typical applications include home automation gateways, IoT sensor nodes with USB connectivity, industrial metering, low-end consumer HMI, smart thermostats, and wearable fitness devices. The extended -40C to +125C temperature range supports outdoor and industrial enclosures.
Designers should plan PCB layout carefully: place the 0.1 uF decoupling capacitor within 2 mm of each VDD pin, provide a solid ground pour under the device, and route the D+/D- lines as a 90-ohm differential pair with no stubs. The internal voltage regulator requires both a VDDCORE and VDDIO supply pin to be decoupled.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes not found in the manufacturer datasheet alone.
直接替換替代品，適用於 ATSAMD21J18A-AFT — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： ATSAMD21J18A-AFT （相同外形與佔位） — 差異在於 ADC, Core, DAC, USB, Operating Temperature.
ATSAMD21J18A-AU
✅ 直接替換聯絡詢價
查看資料表 →ATSAMD21J18A-AUT
✅ 直接替換聯絡詢價
查看資料表 →ATSAMD21J17A-AUT
✅ 直接替換聯絡詢價
查看資料表 →ATSAMD21J16B-AU
✅ 直接替換聯絡詢價
查看資料表 →ATSAMD21J18A-AFT 最大額定值與電氣特性
| Core | ARM Cortex-M0+ (32-bit) |
| Family | SAM D21J |
| Maximum CPU Frequency | 48 MHz |
| Flash Memory | 256 KB |
| SRAM | 32 KB |
| Supply Voltage (VDD) | 1.62 V to 3.63 V |
| 工作溫度 | -40C to +125C |
| 封裝 | 64-pin TQFP (10x10 mm) |
| 安裝類型 | Surface Mount (SMD/SMT) |
| I/O Pins | Up to 52 |
| SERCOM | 6 (each configurable as UART/SPI/I2C) |
| ADC | 12-bit, up to 20 channels, 1 MSPS |
| DAC | 10-bit, 1 channel |
| USB | Full-speed USB 2.0 device and host |
| DMAC | 12 channels |
| Functional Safety | FuSa-capable |
| RoHS 狀態 | Compliant (Green) |
ATSAMD21J18A-AFT 腳位配置
| 腳位 1 | PA00 — General-purpose I/O / XIN32 |
| 腳位 2 | PA01 — General-purpose I/O / XOUT32 |
| 腳位 3 | PA02 — General-purpose I/O / AIN0 |
| 腳位 4 | PA03 — General-purpose I/O / AIN1 / VREFA |
| 腳位 5 | PA04 — General-purpose I/O / AIN2 |
| 腳位 6 | PA05 — General-purpose I/O / AIN3 |
| 腳位 7 | PA06 — General-purpose I/O / AIN4 |
| 腳位 8 | PA07 — General-purpose I/O / AIN5 |
| 腳位 9 | VDD — Digital supply voltage |
| 腳位 10 | GND — Ground |
| 腳位 11 | PA08 — General-purpose I/O / NMI / AIN6 |
| 腳位 12 | PA09 — General-purpose I/O / AIN7 |
| 腳位 13 | PA10 — General-purpose I/O / AIN8 |
| 腳位 14 | PA11 — General-purpose I/O / AIN9 |
| 腳位 15 | PA12 — General-purpose I/O |
| 腳位 16 | PA13 — General-purpose I/O |
| 腳位 17 | PA14 — General-purpose I/O |
| 腳位 18 | PA15 — General-purpose I/O |
| 腳位 19 | PA16 — General-purpose I/O / I2S_SDI0 |
| 腳位 20 | PA17 — General-purpose I/O / I2S_SDO0 |
| 腳位 21 | PA18 — General-purpose I/O / I2S_FS0 |
| 腳位 22 | PA19 — General-purpose I/O / I2S_SCK0 |
| 腳位 23 | PA20 — General-purpose I/O |
| 腳位 24 | PA21 — General-purpose I/O / AIN10 |
| 腳位 25 | PA22 — General-purpose I/O / AIN11 |
| 腳位 26 | PA23 — General-purpose I/O |
| 腳位 27 | PA24 — General-purpose I/O / USB_DM |
| 腳位 28 | PA25 — General-purpose I/O / USB_DP |
| 腳位 29 | PA26 — General-purpose I/O |
| 腳位 30 | PA27 — General-purpose I/O |
| 腳位 31 | PA28 — General-purpose I/O |
| 腳位 32 | PA29 — General-purpose I/O |
| 腳位 33 | PA30 — General-purpose I/O / SWCLK |
| 腳位 34 | PA31 — General-purpose I/O / SWDIO |
| 腳位 35 | PB00 — General-purpose I/O |
| 腳位 36 | PB01 — General-purpose I/O |
| 腳位 37 | PB02 — General-purpose I/O / AIN12 |
| 腳位 38 | PB03 — General-purpose I/O / AIN13 |
| 腳位 39 | PB04 — General-purpose I/O / AIN14 |
| 腳位 40 | PB05 — General-purpose I/O / AIN15 |
| 腳位 41 | PB06 — General-purpose I/O |
| 腳位 42 | PB07 — General-purpose I/O |
| 腳位 43 | PB08 — General-purpose I/O |
| 腳位 44 | PB09 — General-purpose I/O |
| 腳位 45 | PB10 — General-purpose I/O |
| 腳位 46 | PB11 — General-purpose I/O |
| 腳位 47 | PB12 — General-purpose I/O |
| 腳位 48 | PB13 — General-purpose I/O |
| 腳位 49 | PB14 — General-purpose I/O |
| 腳位 50 | PB15 — General-purpose I/O |
| 腳位 51 | PB16 — General-purpose I/O |
| 腳位 52 | PB17 — General-purpose I/O |
| 腳位 53 | PB18 — General-purpose I/O |
| 腳位 54 | PB19 — General-purpose I/O |
| 腳位 55 | PB20 — General-purpose I/O |
| 腳位 56 | PB21 — General-purpose I/O |
| 腳位 57 | VDDIO — I/O supply voltage |
| 腳位 58 | GND — Ground |
| 腳位 59 | VDDCORE — Internal core voltage output (1.2V) |
| 腳位 60 | GND — Ground |
| 腳位 61 | VDDIN — Voltage regulator input |
| 腳位 62 | RESETN — Reset input (active low) |
| 腳位 63 | VREFP — ADC reference voltage positive |
| 腳位 64 | VREFN — ADC reference voltage negative |
典型應用
ATSAMD21J18A-AFT 適用於 6 應用s: Home Automation Gateway, IoT Sensor Node with USB, Industrial Metering, Consumer HMI with Display, Wearable Fitness Device, Smart Agriculture Sensor.
Home Automation Gateway
The ATSAMD21J18A-AFT fits home automation gateways by combining 256 KB Flash for Zigbee/Wi-Fi stack plus application logic with full-speed USB for dongle connectivity. Its six SERCOM ports drive multiple wireless co-processor UARTs simultaneously while the 12-bit ADC reads analog sensors. The 48 MHz Cortex-M0+ executes protocol stacks with deterministic latency, and the -40C to +125C range supports indoor attic installations. Sleepwalking peripherals and standby current under 5 uA keep always-on power budgets low for AC-powered but energy-rated designs.
推薦
IoT Sensor Node with USB
The ATSAMD21J18A-AFT is ideal for USB-connected IoT sensor nodes because its on-chip full-speed USB 2.0 device port eliminates external PHY chips. The 256 KB Flash stores application plus USB stack plus sensor drivers, while 32 KB SRAM buffers high-rate ADC samples. The 12-channel DMAC moves data without CPU wake-up, extending battery life. The 1.62-3.63 V supply range supports direct Li-ion or 2xAA battery operation with internal LDO regulation. Six SERCOM connect I2C sensors, SPI displays, and UART debug simultaneously.
推薦
Industrial Metering
Industrial metering designs use the ATSAMD21J18A-AFT because its 12-bit 1 MSPS ADC captures fast current/voltage transients while the Cortex-M0+ runs RMS and power-factor calculations in real time. The extended -40C to +125C temperature range handles outdoor cabinet environments, and the 64-pin TQFP package with 52 I/O drives segmented displays, optocouplers, and isolated serial links. The on-chip event system triggers ADC conversions from timer compare matches without CPU latency, ensuring sample-accurate metering across load variations.
推薦
Consumer HMI with Display
The ATSAMD21J18A-AFT drives consumer human-machine interfaces such as smart thermostats and appliance front panels using its six SERCOM channels to run SPI TFT displays plus I2C touch controllers plus UART wireless modules. The DAC outputs audio cues while the 32 KB SRAM buffers frame updates. The 256 KB Flash holds a full graphics library plus wireless stack. The 48 MHz Cortex-M0+ delivers responsive UI animations and the extended temperature grade tolerates kitchen or bathroom installations where humidity and heat stress components.
推薦
Wearable Fitness Device
Wearable fitness devices leverage the ATSAMD21J18A-AFT low-power standby modes that drop current below 5 uA while retaining RTC and RAM. The 12-bit ADC reads heart-rate and SpO2 photodiode signals, six SERCOM connect BLE modules, IMUs, and flash storage. The 48 MHz core handles Bluetooth Low Energy link-layer encryption while event-system wake-ups minimize active time. The 1.62 V minimum supply supports single-cell Li-ion or coin-cell designs, and the -40C to +125C rating covers skin contact and outdoor exercise conditions.
推薦
Smart Agriculture Sensor
The ATSAMD21J18A-AFT supports smart agriculture sensor endpoints with its extended -40C to +125C temperature range for outdoor field installations exposed to direct sun and frost. The 12-bit ADC reads soil moisture, temperature, and pH probes; SERCOM interfaces drive LoRa or Sub-GHz radio modules. Sleepwalking SERCOM and event system allow years of battery life on a single Li-SOCl2 cell. The 256 KB Flash stores sensor fusion algorithms and over-the-air update bootloaders. The 64-pin TQFP package simplifies hand-rework for prototyping.
推薦
推薦產品摘要
工程參考資料，適用於 ATSAMD21J18A-AFT — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | ATSAMD21J18A-AU | ATSAMD21J18A-AUT | ATSAMD21J17A-AU | ATSAMD21J16B-AU |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 64-pin TQFP (10x10 mm) | 64-pin TQFP (10x10 mm) - same | 64-pin TQFP (10x10 mm) - same | 64-pin TQFP (10x10 mm) - same | 64-pin TQFP (10x10 mm) - same |
| Flash Memory | 256 KB | 256 KB (same) | 256 KB (same) | 128 KB (-50%) | 64 KB (-75%) |
| SRAM | 32 KB | 32 KB (same) | 32 KB (same) | 16 KB (-50%) | 8 KB (-75%) |
| Operating Temperature | -40C to +125C | -40C to +85C | -40C to +125C (same) | -40C to +85C | -40C to +85C |
| CPU Frequency | 48 MHz | 48 MHz (same) | 48 MHz (same) | 48 MHz (same) | 48 MHz (same) |
| USB | Full-speed USB 2.0 | Full-speed USB 2.0 (same) | Full-speed USB 2.0 (same) | Full-speed USB 2.0 (same) | Full-speed USB 2.0 (same) |
| SERCOM | 6 | 6 (same) | 6 (same) | 6 (same) | 6 (same) |
主要差異化特點
- Extended industrial temperature grade -40C to +125C (對比ATSAMD21J18A-AU)
- Full 256 KB Flash vs reduced variants in same family (對比ATSAMD21J16B-AU)
- Functional Safety (FuSa) capability (對比ATSAMC21J18A)
- Six SERCOM channels vs fewer in smaller packages (對比ATSAMD21E18A-AFT)
設計說明
The ATSAMD21J18A-AFT requires both VDDIN (regulator input) and VDDIO (I/O supply) to be tied together through ferrite beads or directly bridged, with a 1 uF + 0.1 uF decoupling pair within 2 mm of each pin. According to the SAM D21 datasheet, VDDIN is the source for the internal 1.2 V LDO that supplies VDDCORE; bypassing VDDIN with at least 4.7 uF bulk capacitance prevents LDO dropout during ADC bursts. Estimated: a 100 mA peak ADC + core load at 3.3 V implies 330 mW peak dissipation inside the chip.
Route the USB D+ and D- pins (PA24/PA25) as a 90-ohm differential pair with no stubs and no vias within 5 mm of the device. According to the SAM D21 datasheet, the USB full-speed transceiver is integrated and does not require an external PHY, but PCB trace impedance must match the USB 2.0 spec. Place a 10 uF + 0.1 uF cap on VBUS if the design is bus-powered. Maintain a continuous ground reference plane under the pair to control common-mode impedance.
Do not configure the BOOTPROT fuse to lock the device without first programming a valid application - a misconfigured lockbit can brick the part and require a 12V high-voltage programmer to recover. According to Microchip errata documents, early SAM D21 silicon revisions had a known USB suspend behavior requiring a firmware workaround in revision A and B; verify silicon revision via the DSU DID register before production. Always set the NVMCTRL fuse to map the bootloader at 0x00000000 BEFORE enabling protected boot.
Place the 32.768 kHz crystal as close as possible to pins XIN32/XOUT32 (PA00/PA01) with short, symmetric traces and a guard ring tied to analog ground. According to the SAM D21 datasheet, stray capacitance above 5 pF on these pins detunes the crystal load and degrades RTC accuracy below 20 ppm. Estimated: a 4 mm trace plus a 2 pF pad capacitance gives 1.5 pF total stray, well within margin for an external load capacitor of 12.5 pF. Shield the crystal from digital signals crossing nearby.
合規資訊
Green / lead-free / RoHS compliant per Microchip ordering information. Not AEC-Q100 qualified; for automotive designs, look at SAM DA1 family.
