ATSAMD21E16B-AU - 48MHz Cortex-M0+ MCU, 64KB Flash | Microchip
MPN: ATSAMD21E16B-AU ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.95 | $3.95 |
| 10 | $3.55 | $35.50 |
| 100 | $2.95 | $295.00 |
| 500 | $2.45 | $1,225.00 |
| 1,000 | $2.1 | $2,100.00 |
ATSAMD21E16B-AU Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, memory (Flash for code, SRAM for data), and programmable I/O peripherals. The SAM D21E line targets cost-sensitive designs and provides a Cortex-M0+ core - the most energy-efficient ARM core - while preserving the full ARM Thumb instruction set for code density. Within Microchip's portfolio, this device sits in the 32-pin SAM D21E sub-family of the broader SAM D21 series (which spans 32 to 64 pins).
Key features include 2.46 CoreMark/MHz performance, a full-speed USB 2.0 device with on-chip transceiver, 6 SERCOM serial-communication modules (each assignable as UART/SPI/I2C), a 12-bit 350ksps ADC, two analog comparators, a 16-bit TC/PWM timer array, and up to 26 GPIO. The device operates from 1.62V to 3.63V, supports SleepWalking for event-driven wake-up, and offers a built-in 32kHz RTC and event system for inter-peripheral signaling.
The architecture pairs the Cortex-M0+ core with a single-cycle hardware multiplier and a separate bus matrix for peripherals, with DMA available on most serial and analog channels. The peripheral event system allows deterministic inter-peripheral triggers without CPU intervention, enabling low-latency, low-power responses in motor, sensor, and lighting control loops.
Typical applications include USB HID peripherals (keyboards, mice, custom input devices), capacitive touch user interfaces, low-power IoT sensor nodes, wearable electronics, hobby servos, and industrial control front-ends. The combination of USB, touch, and SERCOM flexibility makes it a popular choice for prototyping and consumer products.
When designing with this part, follow Microchip's recommendations for decoupling (100 nF plus 4.7 uF bulk) and route the USB DP/DM lines as a 90-ohm differential pair with a 1.5 kohm pull-up on D+. For first-time users, the SAM D21 Xplained Pro board provides an Atmel Studio / MPLAB X compatible starter kit.
This page synthesizes distributor pricing, drop-in alternatives from the SAMD20/SAMD21 family, and practical design notes not consolidated on any single manufacturer page.
Drop-in alternatives for ATSAMD21E16B-AU — 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 ATSAMD21E16B-AU (same form factor and footprint) — differing in ADC, Package, Operating Temperature, DAC, SERCOM Modules.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATSAMD21E16B-AUT
✅ Drop-In📋 Reference alternative (not in catalog)
ATSAMD21E16B-MU
✅ Drop-In✓ In Stock
$2.65 / Unit
View Datasheet →ATSAMD21E15B-AU
✅ Drop-In✓ In Stock
$1.45 / Unit
View Datasheet →ATSAMD21E18A-AU
✅ Drop-In📋 Reference alternative (not in catalog)
ATSAMD20E16A-AUT
✅ Drop-In✓ In Stock
$1.44 / Unit
View Datasheet →ATSAMD20E16B-AU
✅ Drop-In✓ In Stock
$1.84 / Unit
View Datasheet →ATSAMD21E16B-AU Maximum Ratings & Electrical Characteristics
| Core Processor | ARM Cortex-M0+ |
| Core Size | 32-Bit Single-Core |
| Maximum CPU Speed | 48 MHz |
| Performance | 2.46 CoreMark/MHz |
| Program Memory (Flash) | 64 KB (32K x 16) |
| RAM | 8 KB |
| Operating Voltage | 1.62 V to 3.63 V |
| I/O Pins | Up to 26 |
| Package | 32-TQFP (7x7 mm) |
| Connectivity | I2C, LINbus, SPI, UART/USART, USB |
| ADC | 12-bit, up to 350 ksps |
| Analog Comparators | 2 |
| Timers/Counters | TC (16-bit), TCC (24-bit) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C |
| RoHS Status | Compliant |
ATSAMD21E16B-AU Pin Configuration
| Pin 1 | PA00 — GPIO / XIN32 (32 kHz crystal input) |
| Pin 2 | PA01 — GPIO / XOUT32 (32 kHz crystal output) |
| Pin 3 | PA02 — GPIO / AIN0 (analog input 0) |
| Pin 4 | PA03 — GPIO / AIN1 (analog input 1) |
| Pin 5 | PA04 — GPIO / AIN2 / VREF |
| Pin 6 | PA05 — GPIO / AIN3 |
| Pin 7 | PA06 — GPIO / AIN4 |
| Pin 8 | PA07 — GPIO / AIN5 |
| Pin 9 | VDD — Main supply voltage (1.62V to 3.63V) |
| Pin 10 | GND — Ground |
| Pin 11 | PA08 — GPIO / NMI (non-maskable interrupt) |
| Pin 12 | PA09 — GPIO / SERCOM2 PAD0 |
| Pin 13 | PA10 — GPIO / SERCOM2 PAD1 |
| Pin 14 | PA11 — GPIO / SERCOM2 PAD2 / USB DP |
| Pin 15 | PA14 — GPIO / SERCOM2 PAD3 / USB DM |
| Pin 16 | PA15 — GPIO / SERCOM3 PAD0 |
| Pin 17 | PA16 — GPIO / SERCOM3 PAD1 |
| Pin 18 | PA17 — GPIO / SERCOM3 PAD2 |
| Pin 19 | PA18 — GPIO / SERCOM3 PAD3 |
| Pin 20 | PA19 — GPIO / SERCOM1 PAD0 |
| Pin 21 | PA20 — GPIO / SERCOM1 PAD1 |
| Pin 22 | PA21 — GPIO / SERCOM1 PAD2 |
| Pin 23 | PA22 — GPIO / SERCOM1 PAD3 |
| Pin 24 | PA23 — GPIO / USB DM |
| Pin 25 | PA24 — GPIO / USB DP |
| Pin 26 | PA25 — GPIO / SERCOM0 PAD0 |
| Pin 27 | PA27 — GPIO / SERCOM0 PAD1 |
| Pin 28 | PA28 — GPIO / SERCOM0 PAD2 |
| Pin 29 | PA29 — GPIO / SERCOM0 PAD3 |
| Pin 30 | PA30 — SWDIO (Serial Wire Debug I/O) |
| Pin 31 | PA31 — SWCLK (Serial Wire Debug clock) |
| Pin 32 | VDDCORE — Internal voltage regulator output (decouple 1 uF to GND) |
Typical Applications
ATSAMD21E16B-AU is suitable for 6 applications: USB HID Input Devices, Capacitive Touch User Interface, Battery-Powered IoT Sensor Nodes, Wearable Electronics & Fitness Bands, Industrial Control & Automation, Hobby Servos & Drone Flight Controllers.
USB HID Input Devices
The ATSAMD21E16B-AU's full-speed USB 2.0 device with on-chip transceiver and 6 SERCOM modules make it ideal for USB HID peripherals such as keyboards, mice, game controllers, and custom input devices. The 48MHz Cortex-M0+ delivers 2.46 CoreMark/MHz, sufficient for 1000Hz polling rates in high-end gaming peripherals. The integrated 1.5 kohm D+ pull-up and on-chip voltage regulator simplify the USB bus-powered design, eliminating external PHY or LDO. Compared to discrete 8-bit USB solutions, the SAMD21E consumes less PCB area and supports HID, CDC, MSD, and vendor-class USB stacks from Microchip's ASF/MPLAB Harmony libraries.
Recommended
Capacitive Touch User Interface
The ATSAMD21E16B-AU integrates the PTC (Peripheral Touch Controller) supporting up to 256-channel capacitive touch buttons, sliders, and wheels without external touch ICs. The PTC hardware engine performs capacitance-to-digital conversion with automatic calibration, enabling reliable touch UI in noisy environments. With 26 GPIO and SERCOM flexibility, the part can multiplex touch electrodes with LCD segment displays or LED indicators for a complete user-interface MCU. The ARM Cortex-M0+ core runs the touch-decision algorithm, while SleepWalking wakes the CPU only on validated touch events.
Recommended
Battery-Powered IoT Sensor Nodes
The ATSAMD21E16B-AU's 1.62V to 3.63V supply, SleepWalking peripherals, and <1 uA standby current with RTC running make it well-suited for battery-powered IoT sensor nodes. The 6 SERCOM modules interface SPI sensors, I2C peripherals, and UART radios (LoRa, BLE modules) concurrently. The Event System allows ADC oversampling or I2C address-match events to wake the MCU on physical-signal triggers without CPU polling, reducing average current to the sensor's quiescent level. 8KB SRAM holds sensor buffers and radio protocol stacks (Simple LoRa, sensor firmware) for compact wireless nodes.
Recommended
Wearable Electronics & Fitness Bands
The ATSAMD21E16B-AU's small 32-TQFP footprint, integrated 12-bit ADC for heart-rate/bio-impedance sensing, and low-power SleepWalking features suit wearable designs such as fitness bands, smart watches, and BLE sensor patches. The Cortex-M0+ runs BLE application profiles through an external radio (RN487A or nRF52840GL) on SERCOM2 SPI, while the on-chip DAC drives haptic feedback. Compared to multi-chip architectures, this single-MCU approach reduces BOM, PCB area, and standby current in continuous-monitoring wearable devices.
Recommended
Industrial Control & Automation
The ATSAMD21E16B-AU's 64KB Flash, 8KB SRAM, and industrial -40C to +85C operating range support industrial-control applications such as programmable logic controllers, sensor hubs, and field-bus nodes. The 350 ksps 12-bit ADC interfaces 4-20 mA analog sensors, while SERCOM modules support RS-485, CAN (via external transceiver), or LIN slave protocols. The event system provides deterministic peripheral-to-peripheral triggers for motor-control or safety loops, and the Cortex-M0+ core runs Modbus, IO-Link, or proprietary protocols in real time.
Recommended
Hobby Servos & Drone Flight Controllers
The ATSAMD21E16B-AU's 16-bit TC and 24-bit TCC timers with 4-channel DMA support servo PWM outputs at 50Hz/400Hz refresh rates up to 8 servo channels, and its 48MHz clock provides 5x servo-loop headroom. The SAMD21 is widely used in opensource hobby projects (Arduino MKR ZERO uses a SAMD21) and as a co-processor in PX4 and Ardupilot drone stacks. With 6 SERCOM modules, the MCU can interface GPS, telemetry radio, IMU, and ESC protocol streams concurrently, while USB exposes a USB-CDC virtual COM port for parameter tuning.
Recommended
Recommended Products Summary
Engineering reference data for ATSAMD21E16B-AU — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAMD21E16B-AUT | ATSAMD21E16B-MU | ATSAMD21E15B-AU | ATSAMD21E18A-AU | ATSAMD20E16A-AU |
|---|---|---|---|---|---|---|
| Package | 32-TQFP (7x7 mm) | 32-TQFP (7x7 mm) - same | 32-TQFP (7x7 mm) - same | 32-TQFP (7x7 mm) - same | 32-TQFP (7x7 mm) - same | 32-TQFP (7x7 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash | 64 KB | 64 KB | 64 KB | 32 KB | 256 KB | 64 KB |
| RAM | 8 KB | 8 KB | 8 KB | 8 KB | 32 KB | 8 KB |
| Max Clock | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz |
| USB FS | Yes (integrated) | Yes | Yes | Yes | Yes | No |
| Capacitive Touch (PTC) | Yes | Yes | Yes | Yes | Yes | No |
| Operating Voltage | 1.62V to 3.63V | 1.62V to 3.63V | 1.62V to 3.63V | 1.62V to 3.63V | 1.62V to 3.63V | 1.62V to 3.63V |
Key Differentiators
- Highest Flash density in SAM D21E pin-compatible family (vs ATSAMD21E15B-AU)
- Native USB Full-Speed vs no USB on SAM D20 (vs ATSAMD20E16A-AU)
- Capacitive touch (PTC) hardware engine (vs ATSAMD20E16A-AU)
- Latest silicon revision with errata fixes (vs ATSAMD21E18A-AU)
Design Notes
Decouple VDD with one 100 nF ceramic per supply pin plus a single 4.7 uF bulk capacitor near the IC. VDDCORE (pin 32) requires a 1 uF X7R ceramic to GND, as specified in the SAM D21 datasheet (40001882A) section on voltage regulator decoupling. Place all decoupling capacitors within 2 mm of their respective pins to avoid instability in the on-chip LDO.
Route USB DP and DM as a 90-ohm differential pair with controlled impedance, maximum trace length 50 mm, and a 1.5 kohm pull-up resistor on D+ to VDD (configured in software via the DP pull-up register). Standard March ports should avoid routing DP/DM across split ground planes or under crystals; keep the differential pair over a continuous ground reference for EMI compliance.
For capacitive touch electrodes routed in flex or PCB, allocate a 2 mm minimum keep-out around each electrode to ground, copper pours, and digital traces. Use a 100-mil copper hatch density (50% fill) on adjacent layers to reduce parasitic capacitance to ground. The PTC hardware engine performs capacitance measurement automatically; sensor PCB design rules appear in Microchip AN2546 (PTC PCB Layout).
Do not drive SWDIO/SWCLK pins in firmware before initializing the ARM core, as the SAMD21 uses these pins for serial wire debug. Locking the SWD interface via the GPNVM bits requires special sequence; always include a 2-wire SWD header on the prototype PCB even for production designs. Note that pin PA30 is SWDIO, PA31 is SWCLK - misconfiguration can brick the device until an external debug probe recovers it.
Compliance Information
RoHS compliant per Microchip product page. Industrial -40C to +85C temperature grade; AEC-Q100 qualified variants are not offered in this sub-family (use SAM DA1 or SAM V71 for automotive).
