ATSAMD21J16B-AU - SAM D21 48MHz Cortex-M0+ MCU | Microchip
MPN: ATSAMD21J16B-AU β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.5 | $4.50 |
| 10 | $4.05 | $40.50 |
| 100 | $3.55 | $355.00 |
| 500 | $3.1 | $1,550.00 |
| 1,000 | $2.75 | $2,750.00 |
ATSAMD21J16B-AU Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory (Flash), data memory (SRAM), and programmable peripherals. Within the semiconductor hierarchy, MCUs sit under microcontrollers -> embedded processors -> digital ICs. The Cortex-M0+ is ARM's smallest and most energy-efficient application processor core, optimized for low-power deterministic real-time control. The SAM D21 series extends this with Microchip's Event System for inter-peripheral signaling without CPU intervention, dramatically reducing wake-up latency and power.
Key features of the ATSAMD21J16B-AU include 64KB Flash (16K x 8), 8KB SRAM, full-speed USB 2.0 with on-the-go (OTG) support, an 8-channel 12-bit ADC with up to 350 ksamples/s, two Analog Comparators, a 10-bit DAC, and up to six SERCOM configurable serial interfaces (UART/SPI/I2C). The device operates from 1.62V to 3.63V, draws typical 70 uA/MHz active current, and supports Idle and Standby sleep modes with SleepWalking peripherals. It is pin- and code-compatible with the SAM D20 family, simplifying migration.
The ATSAMD21J16B-AU is fabricated using a low-power CMOS process and integrates an internal 48MHz Digital Frequency Locked Loop (DFLL48M) and a Fractional PLL up to 96MHz, providing flexible clocking. Its 64-pin TQFP footprint accommodates 52 programmable I/O pins, and its ARM Cortex-M0+ core delivers 2.46 CoreMark/MHz, the highest energy efficiency in ARM's M-class lineup.
Typical applications include IoT sensor nodes, USB HID peripherals, smart-home controllers, industrial sensor hubs, low-power wearables, and capacitive touch human-machine interfaces. The wide operating voltage and temperature range (up to 85C for the -AU grade) also suit industrial sensor conditioning boards. The robust Event System and DMAC enable complex signal-processing chains without CPU overhead, making the part ideal for battery-powered edge devices.
When designing with the ATSAMD21J16B-AU, ensure the 1.62-3.63V supply is decoupled with 100nF and 4.7uF capacitors placed close to VDDCORE and VDDIO pins. The 32.768kHz crystal is recommended for RTC accuracy in standby; load capacitors must match the crystal specification. For USB applications, the D+/D- traces must be routed as a 90-ohm differential pair.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, giving engineers an actionable summary for sourcing, replacement, and PCB layout decisions in a single view.
Drop-in alternatives for ATSAMD21J16B-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 ATSAMD21J16B-AU (same form factor and footprint) β differing in ADC, DAC, Package, USB, Operating Temperature.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATSAMD21J16B-AF
β Drop-Inβ In Stock
$2.52 / Unit
View Datasheet βATSAMD21J16B-MZ
β Drop-Inπ Reference alternative (not in catalog)
ATSAMD21J15B-AUT
β Drop-Inβ In Stock
$2.4 / Unit
View Datasheet βATSAMD20J16A-AU
β Drop-Inπ Reference alternative (not in catalog)
ATSAML21J16B-AUT
β Drop-Inπ Reference alternative (not in catalog)
ATSAMD21J16B-AU Maximum Ratings & Electrical Characteristics
| Core | ARM Cortex-M0+ (M0+) |
| CPU Architecture | 32-bit RISC |
| Maximum Clock Frequency | 48 MHz |
| Program Memory (Flash) | 64 KB (64K x 8) |
| Data Memory (SRAM) | 8 KB |
| Operating Voltage Range | 1.62 V to 3.63 V |
| Supply Voltage (nominal) | 3.3 V |
| Operating Temperature Range | -40 C to +85 C |
| Package | 64-pin TQFP (10x10 mm) |
| I/O Pins | 52 programmable |
| ADC | 12-bit, 8-channel, up to 350 ksps |
| DAC | 10-bit, 1-channel |
| USB | USB 2.0 Full-Speed with OTG |
| SERCOM | 6 configurable (UART/SPI/I2C) |
| Timers | 16-bit TC, 8-bit TC, RTC |
| DMAC | 12-channel |
| Event System | 12-channel |
| External Interrupts (EIC) | 16 |
| Debug Interface | 2-pin Serial Wire Debug (SWD) |
| Mounting Type | Surface Mount |
| MSL Level | 3 (168 hours) |
| RoHS Status | Compliant |
| Lead-Free | Yes |
| Functional Safety | FuSa capable |
| Active Current (typ.) | 70 uA/MHz |
ATSAMD21J16B-AU Pin Configuration
| Pin 1 | PA03 β General purpose I/O / ADC AIN1 / VREFA |
| Pin 2 | PA04 β General purpose I/O / ADC AIN4 / VREFB |
| Pin 3 | PA05 β General purpose I/O / ADC AIN5 |
| Pin 4 | PA06 β General purpose I/O / ADC AIN6 |
| Pin 5 | PA07 β General purpose I/O / ADC AIN7 |
| Pin 6 | VDDIO β Digital I/O supply voltage |
| Pin 7 | GND β Ground |
| Pin 8 | PA08 β General purpose I/O / SERCOM0 PAD0 / I2S SCK |
| Pin 9 | PA09 β General purpose I/O / SERCOM0 PAD1 / I2S MCK |
| Pin 10 | PA10 β General purpose I/O / SERCOM0 PAD2 / I2S FS |
| Pin 11 | PA11 β General purpose I/O / SERCOM0 PAD3 / I2S SDO |
| Pin 12 | PA12 β General purpose I/O / SERCOM2 PAD0 |
| Pin 13 | PA13 β General purpose I/O / SERCOM2 PAD1 |
| Pin 14 | PA14 β General purpose I/O / SERCOM2 PAD2 / XIN32 |
| Pin 15 | PA15 β General purpose I/O / SERCOM2 PAD3 / XOUT32 |
| Pin 16 | PA16 β General purpose I/O / SERCOM1 PAD0 / I2S SDI |
| Pin 17 | PA17 β General purpose I/O / SERCOM1 PAD1 |
| Pin 18 | PA18 β General purpose I/O / SERCOM1 PAD2 |
| Pin 19 | PA19 β General purpose I/O / SERCOM1 PAD3 |
| Pin 20 | VDDIO β Digital I/O supply voltage |
| Pin 21 | GND β Ground |
| Pin 22 | PA20 β General purpose I/O / SERCOM3 PAD0 / USB D- |
| Pin 23 | PA21 β General purpose I/O / SERCOM3 PAD1 / USB D+ |
| Pin 24 | PA22 β General purpose I/O / SERCOM3 PAD2 |
| Pin 25 | PA23 β General purpose I/O / SERCOM3 PAD3 / USB SOF |
| Pin 26 | PA24 β General purpose I/O / USB_NEG |
| Pin 27 | PA25 β General purpose I/O / USB_POS |
| Pin 28 | PA26 β General purpose I/O |
| Pin 29 | PA27 β General purpose I/O |
| Pin 30 | PA28 β General purpose I/O |
| Pin 31 | PA29 β General purpose I/O / DMAC trigger source |
| Pin 32 | PA30 β General purpose I/O / SWCLK |
| Pin 33 | PA31 β General purpose I/O / SWDIO |
| Pin 34 | PB00 β General purpose I/O |
| Pin 35 | PB01 β General purpose I/O |
| Pin 36 | PB02 β General purpose I/O / SERCOM5 PAD0 / ADC AIN10 |
| Pin 37 | PB03 β General purpose I/O / SERCOM5 PAD1 / ADC AIN11 |
| Pin 38 | PB04 β General purpose I/O / SERCOM5 PAD2 |
| Pin 39 | PB05 β General purpose I/O / SERCOM5 PAD3 |
| Pin 40 | PB06 β General purpose I/O / ADC AIN14 |
| Pin 41 | PB07 β General purpose I/O / ADC AIN15 |
| Pin 42 | PB08 β General purpose I/O / SERCOM4 PAD0 / I2S MCK |
| Pin 43 | PB09 β General purpose I/O / SERCOM4 PAD1 / I2S SCK |
| Pin 44 | PB10 β General purpose I/O / SERCOM4 PAD2 / I2S FS |
| Pin 45 | PB11 β General purpose I/O / SERCOM4 PAD3 / I2S SDO |
| Pin 46 | PB12 β General purpose I/O / SERCOM0 PAD0 |
| Pin 47 | PB13 β General purpose I/O / SERCOM0 PAD1 |
| Pin 48 | PB14 β General purpose I/O / SERCOM0 PAD2 |
| Pin 49 | PB15 β General purpose I/O / SERCOM0 PAD3 |
| Pin 50 | PB16 β General purpose I/O / SERCOM1 PAD0 |
| Pin 51 | PB17 β General purpose I/O / SERCOM1 PAD1 |
| Pin 52 | PB18 β General purpose I/O / SERCOM1 PAD2 |
| Pin 53 | PB19 β General purpose I/O / SERCOM1 PAD3 |
| Pin 54 | PB20 β General purpose I/O |
| Pin 55 | PB21 β General purpose I/O |
| Pin 56 | PB22 β General purpose I/O |
| Pin 57 | PB23 β General purpose I/O |
| Pin 58 | PB24 β General purpose I/O |
| Pin 59 | PB25 β General purpose I/O |
| Pin 60 | VDDCORE β Core voltage regulator output (decoupling) |
| Pin 61 | VDDIO β Digital I/O supply voltage |
| Pin 62 | GND β Ground |
| Pin 63 | RESETN β Reset input (active low) |
| Pin 64 | VDDIN β Voltage regulator input supply |
Typical Applications
ATSAMD21J16B-AU is suitable for 6 applications: IoT Sensor Node / Edge Device, USB HID / Human Interface Device, Industrial Sensor Hub / Data Logger, Capacitive Touch HMI Panel, Battery-Powered Wearable, Smart Home Controller / Bridge.
IoT Sensor Node / Edge Device
The ATSAMD21J16B-AU fits IoT sensor nodes because it combines a 48MHz Cortex-M0+ core, 64KB Flash, and an Event System with SleepWalking that wakes peripherals without CPU intervention. Its 70 uA/MHz active current and sub-2 uA standby extend battery life for coin-cell or single Li-ion designs, while six SERCOM channels support I2C sensors, SPI radios, and UART debug. Engineers pair it with sub-GHz or BLE modules for Matter, Thread, or LoRa-based edge nodes that run sampling and pre-processing locally before transmitting.
Recommended
USB HID / Human Interface Device
The ATSAMD21J16B-AU's integrated USB 2.0 Full-Speed with on-the-go (OTG) makes it a natural fit for USB HID peripherals such as keyboards, mice, touch panels, and game controllers. The 48MHz core handles HID report polling within microsecond budgets while 8KB SRAM buffers descriptor tables. Combined with the 12-bit ADC and 52 I/O pins, the part also drives capacitive touch buttons, sliders, and wheels, replacing multiple dedicated touch ICs in compact USB HID designs.
Recommended
Industrial Sensor Hub / Data Logger
The ATSAMD21J16B-AU's 12-bit 8-channel ADC, six SERCOM, and 12-channel DMAC suit industrial 4-20mA loop sensors, RTD conditioning boards, and Modbus data loggers. Operating from -40C to +85C, the part handles factory-floor temperature swings. The DMAC moves ADC samples to SRAM without CPU involvement, freeing the Cortex-M0+ to run calibration and protocol stacks. Engineers pair it with external op-amps for accurate thermocouple and 4-20mA signal conditioning.
Recommended
Capacitive Touch HMI Panel
The ATSAMD21J16B-AU supports Microchip's QTouch library for capacitive touch buttons, sliders, and wheels, replacing dedicated touch ICs. Its 52 I/O pins and 12-bit ADC provide scanning flexibility, while the Event System triggers peripheral activity without CPU wake-ups. Designers use it in white-goods front panels, IoT thermostats, and consumer appliances where BOM consolidation is critical and the part's 1.62-3.63V supply simplifies battery-backed or 3.3V-rail designs.
Recommended
Battery-Powered Wearable
For wearables and fitness bands, the ATSAMD21J16B-AU delivers low active power (70 uA/MHz) and standby currents well below 2 uA, extending coin-cell life. Its small 10x10 mm 64-pin TQFP footprint simplifies compact PCB layouts, while the 12-bit ADC reads heart-rate, SpO2, and temperature sensor front-ends. The integrated RTC with 32.768kHz crystal support enables accurate timestamping and sleep scheduling on a coin cell for weeks or months at a time.
Recommended
Smart Home Controller / Bridge
The ATSAMD21J16B-AU serves as a smart-home bridge controller because six SERCOM channels connect multiple radios (BLE, Wi-Fi co-processor, sub-GHz) and sensors simultaneously. With 64KB Flash the part hosts Zigbee or Matter bridge stacks, while the Cortex-M0+ runs real-time schedules. The integrated USB OTG enables direct host connection to a Wi-Fi module or external storage, simplifying OTA firmware update paths for hub-class devices.
Recommended
Recommended Products Summary
Engineering reference data for ATSAMD21J16B-AU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAMD21J16B-AF | ATSAMD21J16B-MZ | ATSAMD21J15B-AUT | ATSAMD20J16A-AU | ATSAML21J16B-AUT |
|---|---|---|---|---|---|---|
| Package | 64-pin TQFP (10x10 mm) | 64-pin TQFP - same | 64-pin TQFP - same | 64-pin TQFP - same | 64-pin TQFP - same | 64-pin TQFP - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash | 64 KB | 64 KB | 64 KB | 32 KB (-50%) | 64 KB | 32 KB (-50%) |
| SRAM | 8 KB | 8 KB | 8 KB | 4 KB (-50%) | 8 KB | 4 KB (-50%) |
| USB | USB 2.0 Full-Speed OTG | USB 2.0 FS OTG | USB 2.0 FS OTG | USB 2.0 FS OTG | No USB | No USB |
| Core | ARM Cortex-M0+ 48MHz | ARM Cortex-M0+ 48MHz | ARM Cortex-M0+ 48MHz | ARM Cortex-M0+ 48MHz | ARM Cortex-M0+ 48MHz | ARM Cortex-M0+ 48MHz |
| 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 |
| Active Current (typ.) | 70 uA/MHz | 70 uA/MHz | 70 uA/MHz | 70 uA/MHz | 70 uA/MHz | 35 uA/MHz (lower) |
| Approx. Unit Price (USD) | 4.50 | 4.50 | 4.40 | 3.80 | 4.20 | 5.10 |
Key Differentiators
- Integrated USB 2.0 Full-Speed OTG controller (vs ATSAMD20J16A-AU)
- Event System with SleepWalking peripherals (vs PIC16F723)
- 64KB Flash in the J16B variant vs 32KB in J15B (vs ATSAMD21J15B-AUT)
- Pin-compatible with SAM D20 for migration (vs ATSAMD20J16A-AU)
Design Notes
Decouple VDDCORE with a 1uF and 100nF ceramic capacitor pair placed within 2 mm of the pin; VDDIO needs a single 100nF cap. The internal 1.2V LDO from VDDIN supplies VDDCORE, so VDDIN must be tied to VDDIO at the board level. Add bulk capacitance (4.7uF) near VDDIN for ADC and USB transients. Brown-Out Detection (BOD) thresholds should be left at default unless battery operation requires lower thresholds.
Route the USB D+/D- pair as a 90-ohm differential trace with continuous reference plane on layer 2. Keep the pair length-matched within 150 mil. Place the SWD header (SWCLK on PA30, SWDIO on PA31) at the board edge for programming access. Provide a test point on RESETN to allow external reset during debug. The exposed pad area beneath the chip is a thermal pad on QFN variants only - the TQFP version (this part) has no thermal pad.
Do not exceed 3.63V on any I/O pin or supply; damage is not reversible. The Cortex-M0+ core does not tolerate floating RESETN - tie it to VDDIO through a 10k resistor with a 100nF cap to ground for noise immunity. When using the internal DFLL48M without an external crystal, ensure the system is not exposed to high EMI on the XIN/XOUT traces. USB operation requires a 32.768kHz crystal or USB clock recovery; otherwise enumeration fails at low temperatures.
Keep analog and digital ground returns separated - connect AGND (if used) to GND only at one point near the ADC reference pin. The ADC VREFA input should be bypassed with a 100nF capacitor and a small ferrite bead if reference noise is critical. For capacitive touch, group touch channels on adjacent pins to minimize scan-time variance and keep I/O traces short.
Compliance Information
RoHS and REACH compliant per Microchip product page. Not AEC-Q100 qualified - choose ATSAMx automotive variants for automotive designs. Lead-free and halogen-free per Microchip material declaration. The SAM D21J family is functional-safety capable (FuSa).
