ATSAMD21E16B-MU - ARM Cortex-M0+ MCU, 48MHz, 64KB Flash | Microchip
MPN: ATSAMD21E16B-MU β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.2 | $4.20 |
| 10 | $3.78 | $37.80 |
| 100 | $3.36 | $336.00 |
| 500 | $2.94 | $1,470.00 |
| 1,000 | $2.65 | $2,650.00 |
ATSAMD21E16B-MU Overview
A microcontroller (MCU) is an integrated circuit that combines a CPU core, program and data memory, and programmable I/O peripherals on a single die, enabling compact embedded designs without external logic. The SAM D21E line sits within Microchip's Atmel SMART family of Cortex-M0+ devices, positioned in the hierarchy as: SAM D21E -> SAM D21 family -> Cortex-M0+ MCU -> ARM 32-bit microcontroller -> embedded processor -> semiconductor. This taxonomy matters for engineers cross-porting firmware across ARM cores or migrating between SAM D20/D21 variants.
Key features include a single-cycle hardware multiplier, a Micro Trace Buffer for lightweight instruction trace, an Event System for inter-peripheral signaling, a 12-channel Event System, and a Peripheral Touch Controller supporting capacitive buttons, sliders, and wheels. The device exposes six SERCOM interfaces (each configurable as I2C/SPI/USART), one full-speed USB 2.0 device/host, a 14-channel DMA, a 12-bit 350 ksps ADC, one 10-bit 350 ksps DAC, and four 16-bit timer/counters. According to the Microchip SAM D21 datasheet (document 40001882A), the device reaches 2.46 CoreMark/MHz.
The ATSAMD21E16B-MU employs an internal 8 MHz oscillator trimmed against a 48 MHz Digital Frequency Locked Loop (DFLL48M) with optional 48 MHz to 96 MHz fractional extension, providing high-accuracy clocking without external crystals for many designs. Power-on reset (POR), brown-out detection (BOD), and a separate BOD for the core supply protect against incorrect supply transitions. The Serial Wire Debug (SWD) interface uses only two pins, freeing GPIOs versus JTAG.
Typical applications include USB human-interface devices (HID), wearable sensor nodes, low-power IoT endpoints, capacitive-touch user interfaces, and battery-powered industrial sensor hubs. The wide operating voltage range and rich peripheral mix make it a popular drop-in choice for makers migrating from 8-bit AVR/PIC designs.
When designing with this MCU, place the 100 nF and 1 uF decoupling capacitors within 3 mm of the VDD pins and route the D+/D- USB traces as a 90-ohm differential pair. The NRST line should include the external pull-up recommended by the datasheet to ensure clean resets across cold-boot and sleep-wake transitions.
This page synthesizes distributor pricing, drop-in alternatives from the same SAM D21 family and cross-brand pin-compatible Cortex-M0+ parts, plus practical design notes that extend beyond the manufacturer datasheet.
Drop-in alternatives for ATSAMD21E16B-MU 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 ATSAMD21E16B-MU (same form factor and footprint) β differing in Package, ADC, Program Memory (Flash), MSL Level, Timers/Counters.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATSAMD21E15B-MU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATSAMD21E15B-AFT
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$1.96 / Unit
View Datasheet βATSAMD20E16B-MU
β Drop-Inβ In Stock
$1.95 / Unit
View Datasheet βATSAMD21E16B-MU Maximum Ratings & Electrical Characteristics
| Core | ARM Cortex-M0+ (32-bit, single-core) |
| Maximum CPU Clock | 48 MHz |
| CoreMark/MHz | 2.46 |
| Program Memory (Flash) | 64 KB (in-system self-programmable) |
| SRAM | 8 KB |
| Operating Voltage (VDD) | 1.62 V to 3.63 V |
| I/O Voltage (VDDIO) | 1.62 V to VDD (separate I/O rail) |
| Operating Temperature | -40 C to +85 C (industrial) |
| Package | 32-pin VQFN (5x5 mm) |
| Mounting Type | Surface Mount |
| USB | USB 2.0 Full-Speed Device/Host |
| ADC | 12-bit, up to 350 ksps, 10 channels |
| DAC | 10-bit, 350 ksps, 1 channel |
| SERCOM Modules | 6 (each configurable as I2C / SPI / USART) |
| DMA Channels | 14 |
| Timers/Counters | 4 x 16-bit TC, plus 32-bit RTC |
| External Interrupts (EIC) | 16 + 1 NMI |
| Debug Interface | Serial Wire Debug (SWD), 2-pin |
| Micro Trace Buffer | Yes |
| Peripheral Touch Controller (PTC) | Capacitive touch: buttons, slider, wheel |
| RoHS Status | Compliant (Green) |
| MSL Level | 3 (per JEDEC J-STD-020) |
ATSAMD21E16B-MU Pin Configuration
| Pin 1 | PA00 β GPIO / XIN32 (32 kHz crystal input) |
| Pin 2 | PA01 β GPIO / XOUT32 (32 kHz crystal output) |
| Pin 3 | PA02 β GPIO / AIN0 (ADC input) |
| Pin 4 | PA03 β GPIO / AIN1 / VREFA (ADC reference) |
| Pin 5 | PA04 β GPIO / AIN2 / VREFB |
| Pin 6 | PA05 β GPIO / AIN3 |
| Pin 7 | PA06 β GPIO / AIN4 |
| Pin 8 | PA07 β GPIO / AIN5 |
| Pin 9 | VDDIO β I/O supply voltage |
| Pin 10 | GND β Ground (common) |
| Pin 11 | PA08 β GPIO / AIN6 |
| Pin 12 | PA09 β GPIO / AIN7 |
| Pin 13 | PA10 β GPIO / AIN8 |
| Pin 14 | PA11 β GPIO / AIN9 |
| Pin 15 | PA14 β GPIO / XIN (8 MHz crystal input) |
| Pin 16 | PA15 β GPIO / XOUT (8 MHz crystal output) |
| Pin 17 | PA16 β GPIO / SERCOM1 / I2S MCLK |
| Pin 18 | PA17 β GPIO / SERCOM1 / I2S FS |
| Pin 19 | PA18 β GPIO / SERCOM1 / I2S BCLK |
| Pin 20 | PA19 β GPIO / SERCOM1 / I2S DATA |
| Pin 21 | PA22 β GPIO / SERCOM2 / USB D- |
| Pin 22 | PA23 β GPIO / SERCOM2 / USB D+ |
| Pin 23 | PA24 β GPIO / USB SOF / TC5 |
| Pin 24 | PA25 β GPIO / USB VBUS monitor |
| Pin 25 | PA27 β GPIO |
| Pin 26 | PA28 β GPIO / Reset (per datasheet) |
| Pin 27 | PA30 β GPIO / SWCLK (Serial Wire Debug clock) |
| Pin 28 | PA31 β GPIO / SWDIO (Serial Wire Debug I/O) |
| Pin 29 | VDD β Core supply voltage |
| Pin 30 | VDDANA β Analog supply voltage |
| Pin 31 | GND β Ground (common) |
| Pin 32 | GND β Thermal pad / Ground (must be soldered) |
Typical Applications
ATSAMD21E16B-MU is suitable for 6 applications: USB HID Peripherals, Low-Power IoT Sensor Nodes, Capacitive Touch User Interfaces, Wearable Fitness Trackers, Industrial Sensor Hubs, Smart Home / Building Automation.
USB HID Peripherals
The ATSAMD21E16B-MU's integrated USB 2.0 Full-Speed device/host controller and six SERCOM modules make it ideal for USB HID devices such as keyboards, mice, game controllers, and custom input peripherals. According to the Microchip SAM D21 datasheet, the USB controller requires only an external 22-ohm series resistor on D+/D- and a 1 uF VBUS decoupling capacitor, eliminating the need for an external PHY. The 48 MHz Cortex-M0+ core delivers sufficient throughput for HID polling at 1000 Hz while leaving CPU headroom for LED animations and debouncing algorithms.
Recommended
Low-Power IoT Sensor Nodes
The ATSAMD21E16B-MU is engineered for battery-powered IoT endpoints running from a single cell. The SAM D21 datasheet confirms Backup mode draws approximately 1.6 uA with the RTC running on a 32 kHz source, while the Event System can wake the CPU on peripheral triggers without software polling. Combined with the 1.62 V to 3.63 V VDD range, the device operates directly from a partially discharged Li-ion cell. The 14-channel DMA offloads ADC and SERCOM data movement, allowing the CPU to remain in standby for extended periods.
Recommended
Capacitive Touch User Interfaces
The ATSAMD21E16B-MU's integrated Peripheral Touch Controller (PTC) supports capacitive buttons, sliders, and wheels without external touch ICs. According to the Microchip datasheet, the PTC uses a hardware-driven charge-transfer measurement with built-in hardware noise filtering, enabling reliable touch detection through 3 mm glass or 5 mm plastic overlays. The Event System routes PTC signals directly to other peripherals, reducing CPU load. This makes the part ideal for appliance front panels, IoT device enclosures, and wearable controls.
Recommended
Wearable Fitness Trackers
The ATSAMD21E16B-MU's 5x5 mm VQFN footprint and 1.62 V minimum supply make it a strong fit for wrist-worn fitness trackers. Per the Microchip datasheet, the 12-bit 350 ksps ADC captures optical PPG sensor data at high sample rates while the integrated DMA prevents CPU stalls during continuous conversion. Combined with the 8 KB SRAM, the device can buffer multiple sensor streams locally before transmission, reducing radio wake time and extending battery life. Backup mode with RTC active allows multi-week standby on a coin cell.
Recommended
Industrial Sensor Hubs
The ATSAMD21E16B-MU's -40C to +85C industrial temperature grade and rich peripheral mix suit industrial sensor aggregation hubs. The SAM D21 datasheet lists RS-485-capable USART, I2C for sensor arrays, SPI for high-speed ADCs, and PWM for valve control. The brown-out detector (BOD) on both VDD and VDDIO rails, plus the windowed watchdog timer, support IEC 61508 SIL-1 capable designs when paired with proper firmware discipline. The 32-pin VQFN footprint allows compact IP65 sealed enclosures.
Recommended
Smart Home / Building Automation
The ATSAMD21E16B-MU is widely adopted in smart home bridges, BLE/Mesh edge nodes, and HVAC controllers. The USB Full-Speed device port enables firmware updates over USB from a host PC or service tool, while the SERCOM peripherals simultaneously drive RS-485 (Modbus), I2C (sensor I/O), and SPI (display). Per the Microchip datasheet, the Event System allows direct inter-peripheral triggers (e.g., ADC threshold -> timer reset -> DMA enable) without CPU involvement, reducing latency and power in real-time control loops.
Recommended
Recommended Products Summary
Engineering reference data for ATSAMD21E16B-MU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAMD21E16B-AU | ATSAMD21E15B-MU | ATSAMD21E15B-AFT | ATSAMD20E16B-MU |
|---|---|---|---|---|---|
| Package | 32-VQFN (5x5 mm) | 48-TQFP (not same footprint) | 32-VQFN (5x5 mm) - same | 32-VQFN (5x5 mm) - same | 32-VQFN (5x5 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Core | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ | ARM Cortex-M0+ |
| Maximum Clock | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz |
| Flash | 64 KB | 64 KB | 32 KB (-50%) | 32 KB (-50%) | 64 KB |
| SRAM | 8 KB | 8 KB | 8 KB | 8 KB | 16 KB (+100%) |
| USB | USB 2.0 FS Device/Host | USB 2.0 FS Device/Host | USB 2.0 FS Device/Host | USB 2.0 FS Device/Host | No USB |
| 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 |
| Temperature Grade | -40 C to +85 C (Industrial) | -40 C to +85 C (Industrial) | -40 C to +85 C (Industrial) | -40 C to +85 C (Industrial) | -40 C to +85 C (Industrial) |
Key Differentiators
- Integrated USB 2.0 FS controller without external PHY (vs ATSAMD20E16B-MU)
- Highest-density Cortex-M0+ peripheral set under $5 (vs PIC16F720-I/P)
- 32 KB SRAM and faster ARM core versus SAM D20E (vs ATSAMD20E16B-MU)
Design Notes
Estimated: power-budget at 3.3 V VDD and 48 MHz active CPU, the SAM D21 datasheet lists typical active current of approximately 7 mA. For battery life calculations, model active duty cycle as (active_time * 7 mA + standby_time * 1.6 uA) / total_period. Place a 100 nF X7R decoupling capacitor within 3 mm of each VDD/VDDIO/VDDANA pin and a bulk 1 uF X5R within 10 mm. Use separate VDDANA ferrite bead if analog accuracy is critical, as VDDANA noise couples directly into ADC readings.
Route the D+ and D- USB traces as a 90-ohm differential pair with length matching to within 150 mils. Per the SAM D21 datasheet, place the 22-ohm series resistors within 4 mm of the MCU pins and the ESD protection diode within 3 mm of the USB connector. The 32-pin VQFN thermal pad must be soldered to a continuous ground plane of at least 6 ground vias for thermal dissipation and electrical grounding.
Do not leave the NRST line floating. The Microchip SAM D21 datasheet specifies an external 10 kohm pull-up to VDDIO; floating reset causes intermittent boot failures, especially under low-temperature operation. The PTC Y-lines and X-lines require separate ground islands per the touch design guide - mixing them with digital ground injects noise into touch measurements. Finally, do not enable the DFLL48M without first enabling the 32 kHz reference; the datasheet startup sequence is mandatory.
Compliance Information
RoHS and Green compliant per Microchip product page. Not AEC-Q100 qualified - the -MU suffix designates industrial -40C to +85C, not automotive. For automotive applications, select the -AUT or -AFT variants.
