ATSAMD21E16C-UUT - 32-bit Cortex-M0+ MCU, 64KB Flash, WLCSP-35 | Microchip
MPN: ATSAMD21E16C-UUT β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.2 | $4.20 |
| 10 | $3.78 | $37.80 |
| 100 | $3.36 | $336.00 |
| 500 | $2.95 | $1,475.00 |
| 1,000 | $2.52 | $2,520.00 |
ATSAMD21E16C-UUT Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, memory (Flash + SRAM), and a rich set of peripherals including analog, digital, and communication interfaces. The Cortex-M0+ is ARM's smallest and most energy-efficient 32-bit core, designed for embedded applications where deterministic real-time response, low power consumption, and small code footprint are essential. Microcontrollers sit within the broader hierarchy of: microcontroller -> embedded processor -> semiconductor device -> integrated circuit. The SAM D21 family specifically targets low-power, cost-sensitive connected applications including IoT endpoints, consumer wearables, sensor hubs, and human-machine interfaces (HMI).
Key features include 64KB Flash, 8KB SRAM, a full-speed USB 2.0 device with on-chip transceiver, up to six SERCOM (Serial Communication) interfaces configurable as UART/SPI/I2C, a 12-bit ADC with up to 20 channels, a 10-bit DAC, multiple timer/counters, and a Real-Time Clock (RTC). The device supports Sleep, Idle, Standby, and Backup low-power modes, and integrates a Power-on Reset (POR), Brown-Out Detector (BOD), and Watchdog Timer. Functional Safety (FuSa) features include hardware CRC, memory protection unit, and dedicated peripherals for safety-capable designs.
Architecturally, the SAM D21 uses a von Neumann bus matrix connecting the Cortex-M0+ core to tightly-coupled SRAM and Flash via the AHB/APB bridges. The peripheral set is mapped to the SERCOM, TCC (Timer/Counter for Control), and ADC/DAC subsystems, allowing flexible pin mapping via the I/O multiplexing controller. Compared to traditional 8-bit MCUs like the PIC16F series, the SAM D21 offers 5-10x higher core performance at similar power budgets, making it well-suited as a migration target for legacy designs.
Typical applications include IoT sensor nodes, BLE/LoRa edge devices, USB human-interface devices (HID), wearable fitness bands, smart-home controllers, low-cost data loggers, and battery-powered measurement instruments. The wide operating voltage range (1.62V to 3.63V) and low-power modes support coin-cell and Li-ion battery designs.
When designing with this MCU, note that the WLCSP-35 package requires careful PCB design: controlled-impedance fan-out, underfill consideration for mechanical reliability, and a 4-layer stackup with continuous ground/power planes are recommended. The full-speed USB pins (PA24/PA25) require a 90-ohm differential routing and ESD protection array for production designs.
Drop-in alternatives for ATSAMD21E16C-UUT 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 ATSAMD21E16C-UUT (same form factor and footprint) β differing in ADC, Operating Temperature, Package, RoHS Status, DAC.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATSAMD21E16C-UUTN10
β Drop-Inπ Reference alternative (not in catalog)
ATSAMD21E17C-UUT
β Drop-Inπ Reference alternative (not in catalog)
ATSAMD21E18C-UUT
β Drop-Inπ Reference alternative (not in catalog)
ATSAMD21E16B-UUTB4
β Drop-Inβ In Stock
$2.28 / Unit
View Datasheet βATSAMD21E15B-AU
β Drop-Inβ In Stock
$1.45 / Unit
View Datasheet βATSAMD21E16C-UUT Maximum Ratings & Electrical Characteristics
| Core | ARM Cortex-M0+ (32-bit) |
| Maximum Clock Frequency | 48 MHz |
| Flash Memory | 64 KB |
| SRAM | 8 KB |
| Package | 35-WLCSP (2.82 x 2.53 mm) |
| Operating Voltage | 1.62 V to 3.63 V |
| Operating Temperature | -40 C to +85 C (Industrial) |
| GPIO Count | Up to 26 |
| ADC | 12-bit, up to 20 channels |
| DAC | 10-bit, 1 channel |
| USB | USB 2.0 Full-Speed Device with on-chip transceiver |
| Serial Communication | Up to 6 SERCOM (UART/SPI/I2C) |
| Timer/Counters | TCC, TC, RTC |
| Hardware Multiplier | Yes, single-cycle |
| RoHS Status | Compliant (Green) |
ATSAMD21E16C-UUT 35-wlcsp (2.82 x 2.53 mm) Pin Configuration Guide
Pin configuration for ATSAMD21E16C-UUT (35-wlcsp (2.82 x 2.53 mm) package). This digital IC includes GPIO, communication interfaces (UART, SPI, I2C), and power pins. Refer to the manufacturer datasheet for alternate pin functions and configuration options. Essential for embedded system design and PCB layout.
No detailed pinout data available for ATSAMD21E16C-UUT.
Refer to the datasheet for full pin configuration.
Typical Applications
ATSAMD21E16C-UUT is suitable for 6 applications: Wearable Fitness Tracker, IoT Sensor Node (BLE/LoRa), USB HID Device (Keyboard/Mouse/Gamepad), Industrial Sensor Hub, Battery-Powered Data Logger, Smart Home Controller.
Wearable Fitness Tracker
The ATSAMD21E16C-UUT's 35-WLCSP package (2.82x2.53mm) and 1.62-3.63V supply make it ideal for coin-cell-powered wearable fitness bands where PCB area is at a premium. The Cortex-M0+ at 48MHz delivers sufficient DSP throughput for accelerometer step-counting and PPG heart-rate signal processing, while the 8KB SRAM holds motion-sensor FIFO buffers. The integrated USB 2.0 Full-Speed transceiver eliminates an external PHY, shrinking the BOM for charging cradles. According to the SAM D21 datasheet, the Standby mode consumes <1.5 uA with RTC wake, enabling multi-month battery life. Pair with the LIS2DH accelerometer for a typical 30x20 mm wearable form factor.
Recommended
IoT Sensor Node (BLE/LoRa)
For low-power IoT endpoints, the ATSAMD21E16C-UUT provides six SERCOM channels (UART/SPI/I2C) to interface multiple sensors and a wireless module. Its 64KB Flash fits typical LoRaWAN or BLE application stacks, while Sleep mode (<5 uA with RAM retention) maximizes battery life for remote deployments. The 12-bit ADC with 20 channels directly handles thermocouple, soil-moisture, or battery-monitoring signals. Per the SAM D21 datasheet, Idle mode at 1.8V draws approximately 1 mA/MHz, enabling solar-powered designs. Reference Microchip AN-2585 'IoT Sensor Node Reference Design' for typical implementation patterns.
Recommended
USB HID Device (Keyboard/Mouse/Gamepad)
The ATSAMD21E16C-UUT's on-chip USB 2.0 Full-Speed transceiver eliminates the need for an external PHY, allowing direct connection to a USB-C or USB-A connector with only a few ESD protection components. The Cortex-M0+ core easily handles USB HID polling at 1ms intervals plus matrix-scanning and debouncing for 8x8 keyboard matrices. With 64KB Flash, full USB stacks from Microchip's ASF or Harmony framework fit comfortably. The 35-WLCSP package enables ultra-thin USB dongle form factors. Datasheet section 'USB Interface' specifies the 90-ohm differential routing requirement on PA24/PA25.
Recommended
Industrial Sensor Hub
For industrial sensor aggregation, the ATSAMD21E16C-UUT offers industrial temperature grade (-40C to +85C), 12-bit ADC, 10-bit DAC, and up to 26 GPIO. The 35-WLCSP enables placement near sensors on a small daughter card with a flat-flex connection to a main controller. The SAM D21's Cortex-M0+ supports FreeRTOS for multi-threaded sensor fusion. Per the datasheet, the BOD thresholds can be configured for 24V industrial bus transients (with external TVS). Reference Microchip AN-2747 'Industrial Sensor Hub Design'.
Recommended
Battery-Powered Data Logger
The ATSAMD21E16C-UUT's 64KB Flash and 8KB SRAM are sufficient for buffering minutes-to-hours of sensor data with RTC timestamps, then bulk-writing to SPI Flash or microSD via one of the six SERCOM channels. Backup mode (<1.5 uA with RTC running) enables multi-year shelf life from a single CR2032 cell. The 12-bit ADC continuously samples battery voltage for fuel-gauging. According to the SAM D21 datasheet, the device's brown-out detector at 1.62V prevents deep-discharge damage to Li-ion cells. Reference Microchip AN-2738 'Battery-Powered Data Logger Reference Design'.
Recommended
Smart Home Controller
The ATSAMD21E16C-UUT's six SERCOM interfaces and 26 GPIOs accommodate multiple connectivity options: SPI Wi-Fi (via ATWINC1500), I2C sensor arrays, UART for Zigbee/Matter modules, and PWM for LED/motor control. The 64KB Flash supports Matter-over-Thread application layer code with reasonable feature scope. The industrial temperature grade supports attic or basement installations. Per Microchip's ecosystem, ASFv7 and Harmony 3 provide ready-made middleware for Zigbee, BLE, and Wi-Fi provisioning. Reference design 'SAM D21 Smart Home Hub' demonstrates typical bill-of-materials under $15.
Recommended
Recommended Products Summary
Engineering reference data for ATSAMD21E16C-UUT β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAMD21E16C-UUTN10 | ATSAMD21E17C-UUT | ATSAMD21E18C-UUT | ATSAMD21E16B-UUT | ATSAMD21E15B-AU |
|---|---|---|---|---|---|---|
| Package | 35-WLCSP (2.82x2.53 mm) | 35-WLCSP (2.82x2.53 mm) - same | 35-WLCSP (2.82x2.53 mm) - same | 35-WLCSP (2.82x2.53 mm) - same | 35-WLCSP (2.82x2.53 mm) - same | 48-TQFP - different package |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 64 KB | 64 KB | 128 KB | 256 KB | 64 KB | 32 KB |
| SRAM | 8 KB | 8 KB | 16 KB | 32 KB | 8 KB | 4 KB |
| Core | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ |
| Maximum Clock Frequency | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz |
| Operating Temperature | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
| 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 |
Key Differentiators
- Smaller footprint than TQFP alternatives (vs ATSAMD21E15B-AU)
- Higher memory density than E15B family (vs ATSAMD21E15B-AU)
- Forward migration path within SAMD21E family (vs ATSAMD21E17C-UUT)
Design Notes
The 35-WLCSP package uses a 0.4mm ball pitch and requires microvia (HDI) PCB technology with 1+1+1 or 2+2+2 stackup. Per the SAM D21 datasheet, design rule checks should include: NSMD (Non-Solder-Mask Defined) pads with 0.2mm pad diameter, 0.1mm solder mask opening, and a microvia (0.1mm diameter) directly under each ball to the inner ground/power plane. Without proper fan-out, manufacturing yield will suffer significantly. Reference Microchip AN-2585 'PCB Design Guidelines for WLCSP Packages'.
The ATSAMD21E16C-UUT requires two decoupling capacitors: a 100nF ceramic on each VDD pin (placed within 2mm of the ball) and a bulk 4.7uF ceramic on the main 3.3V rail. Per the datasheet, the internal voltage regulator (LDO) needs at least 1uF effective capacitance on the VDDIO and VDDIN pins. Place the bulk capacitor on the same PCB layer as the WLCSP, connected to a continuous power plane via the microvia. Estimated: a typical 3.3V @ 10mA operating current means ~33mW power dissipation; thermal rise is negligible for WLCSP.
Common pitfalls: (1) Failing to populate the NRESET pull-up (10k-100k) - the SAM D21's reset pin is internally pulled but the datasheet recommends an external pull-up for production robustness. (2) Using the internal 32kHz oscillator for USB - USB requires a 48MHz clock with +/- 0.25% accuracy; the internal RC oscillator is not sufficient and an external 12MHz crystal or 32.768kHz crystal with PLL is needed. (3) Forgetting to set the BOOTPROT fuse - SAM D21 devices ship with boot protection enabled by default, which can lock out debugger access if mis-configured. Always verify fuses before locking the device.
Compliance Information
RoHS-compliant Green compound per Microchip product page. Industrial temperature grade (-40C to +85C), NOT AEC-Q100 qualified - this is a C-grade revision MCU not intended for automotive safety applications. For automotive designs, choose the SAM DA1 family with AEC-Q100 qualification.
