ATSAMC21G18A-AU - 48MHz Cortex-M0+ MCU, 256KB Flash, 5V | Microchip
MPN: ATSAMC21G18A-AU ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.92 | $4.92 |
| 10 | $4.41 | $44.10 |
| 100 | $3.83 | $383.00 |
| 500 | $3.45 | $1,725.00 |
| 1,000 | $3.05 | $3,050.00 |
ATSAMC21G18A-AU Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory (Flash), working memory (SRAM), and a rich set of peripherals on a single die. Within the broader taxonomy, an MCU belongs to microcontrollers -> embedded processors -> integrated circuits. The Cortex-M0+ is an ARMv6-M Thumb/Thumb-2 core optimized for energy efficiency and deterministic interrupt response, targeting deeply embedded applications. The SAM C21 family sits in Microchip's 5V-tolerant, mixed-signal portfolio alongside the 3.3V SAM D20/D21 series, prioritizing noise immunity on factory floors and automotive body/battery-direct rails.
Key features of the ATSAMC21G18A-AU include: 256 KB Flash (ECC), 32 KB SRAM, six SERCOM channels configurable as UART/SPI/I2C/LIN, one CAN-FD controller, one 12-bit 1 Msps ADC with up to 16 channels, two 16-bit TC timers, a 24-bit RTC, and the PTC for capacitive touch sensing. The device supports 1.62V-5.5V operation with internal 48 MHz DFLL and a 32 kHz oscillator, plus up to 38 GPIO. The 5V-tolerant I/O is the headline differentiator versus SAM D21.
On the architecture side, the ATSAMC21G18A-AU uses a single-cycle 32-bit bus with a tightly-coupled SRAM, deterministic 2-channel DMA (DMAC), and an Event System that lets peripherals trigger each other without CPU intervention. The Event System plus 6 SERCOMs gives designers many concurrent digital interfaces without bus contention.
Typical applications include automotive body controllers, HVAC and climate-control touch panels, industrial CAN-FD node endpoints (sensor hubs, motor-control auxiliary logic), smart metering, white-goods human-machine interfaces, and battery-powered IoT edge nodes with LIN or CAN connectivity. The integrated PTC removes the need for an external touch controller, and the CAN-FD peripheral supports modern vehicle networks at 5 Mbit/s.
Design trade-off: the 5V-tolerant I/O comes with slightly higher leakage at hot temperatures than the SAM D21; for ultra-low-power battery-only designs (sub-1 uA sleep), the SAM L22 or SAML21 may be a better fit. The 48-pin TQFP is footprint-compatible with several SAM D20/D21 G variants, easing migration between 3.3V and 5V worlds.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for ATSAMC21G18A-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 ATSAMC21G18A-AU (same form factor and footprint) — differing in Package, ADC, Operating Temperature, SRAM, DAC.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATSAMC21G18A-AUT
✅ Drop-In✓ In Stock
$3.12 / Unit
View Datasheet →ATSAMC21G16A-AUT
✅ Drop-In✓ In Stock
$2.35 / Unit
View Datasheet →ATSAMC21G17A-AUT
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$2.78 / Unit
View Datasheet →ATSAMC21J18A-AU
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
ATSAMC21G18A-AU Maximum Ratings & Electrical Characteristics
| Series | SAM C21 (Cortex-M0+) |
| Core | ARM Cortex-M0+ (32-bit) |
| Maximum CPU Frequency | 48 MHz |
| Program Flash | 256 KB |
| SRAM | 32 KB |
| Supply Voltage | 2.7 V to 5.5 V |
| I/O Tolerance | 5V tolerant |
| Operating Temperature | -40 C to +85 C (industrial, AU suffix) |
| Package | 48-pin TQFP (7x7 mm, 0.5 mm pitch) |
| GPIO Count | Up to 38 |
| SERCOM Modules | 6 (UART/SPI/I2C/LIN configurable) |
| CAN-FD | Yes (1 channel) |
| ADC | 12-bit, up to 1 Msps, 16 channels |
| Timers/Counters (TC) | 16-bit, multiple channels |
| RTC | 32-bit RTC with calendar |
| Peripheral Touch Controller (PTC) | Yes (mutual/self-cap) |
| DMA | 12 channels (DMAC) |
| AEC-Q100 | Grade 1 qualified |
| RoHS | Compliant |
ATSAMC21G18A-AU Pin Configuration
| Pin 1 | PA00 — GPIO / SERCOM1 PAD0 / ADC AIN0 |
| Pin 2 | PA01 — GPIO / SERCOM1 PAD1 / ADC AIN1 |
| Pin 3 | PA02 — GPIO / SERCOM2 PAD0 / ADC AIN2 |
| Pin 4 | PA03 — GPIO / SERCOM2 PAD1 / ADC AIN3 / REF AREF |
| Pin 5 | GND — Ground |
| Pin 6 | VDD — Digital supply voltage |
| Pin 7 | PA04 — GPIO / SERCOM0 PAD2 / TC0 WO0 / ADC AIN4 |
| Pin 8 | PA05 — GPIO / SERCOM0 PAD3 / TC0 WO1 / ADC AIN5 |
| Pin 9 | PA06 — GPIO / SERCOM0 PAD0 / TC1 WO0 / ADC AIN6 |
| Pin 10 | PA07 — GPIO / SERCOM0 PAD1 / TC1 WO1 / ADC AIN7 |
| Pin 11 | PA08 — GPIO / SERCOM2 PAD0 / TC2 WO0 / ADC AIN16 |
| Pin 12 | PA09 — GPIO / SERCOM2 PAD1 / TC2 WO1 / ADC AIN17 |
| Pin 13 | PA10 — GPIO / SERCOM2 PAD2 / TC3 WO0 / ADC AIN18 |
| Pin 14 | PA11 — GPIO / SERCOM2 PAD3 / TC3 WO1 / ADC AIN19 |
| Pin 15 | VDDIO2 — I/O supply voltage 2 |
| Pin 16 | GND — Ground |
| Pin 17 | PB10 — GPIO / SERCOM4 PAD2 / TC5 WO0 |
| Pin 18 | PB11 — GPIO / SERCOM4 PAD3 / TC5 WO1 |
| Pin 19 | PB12 — GPIO / SERCOM4 PAD0 / TC4 WO0 |
| Pin 20 | PB13 — GPIO / SERCOM4 PAD1 / TC4 WO1 |
| Pin 21 | PB14 — GPIO / SERCOM5 PAD2 / TC5 WO0 |
| Pin 22 | PB15 — GPIO / SERCOM5 PAD3 / TC5 WO1 |
| Pin 23 | PA12 — GPIO / SERCOM3 PAD0 / TC0 WO0 |
| Pin 24 | PA13 — GPIO / SERCOM3 PAD1 / TC0 WO1 |
| Pin 25 | PA14 — GPIO / SERCOM3 PAD2 / TC1 WO0 / XOUT32K |
| Pin 26 | PA15 — GPIO / SERCOM3 PAD3 / TC1 WO1 / XIN32K |
| Pin 27 | PA16 — GPIO / SERCOM1 PAD0 / TC2 WO0 |
| Pin 28 | PA17 — GPIO / SERCOM1 PAD1 / TC2 WO1 |
| Pin 29 | PA18 — GPIO / SERCOM1 PAD2 / TC3 WO0 |
| Pin 30 | PA19 — GPIO / SERCOM1 PAD3 / TC3 WO1 |
| Pin 31 | PA20 — GPIO / SERCOM5 PAD2 / TC5 WO0 |
| Pin 32 | PA21 — GPIO / SERCOM5 PAD3 / TC5 WO1 |
| Pin 33 | PA22 — GPIO / SERCOM3 PAD0 / TC4 WO0 |
| Pin 34 | PA23 — GPIO / SERCOM3 PAD1 / TC4 WO1 |
| Pin 35 | PA24 — GPIO / SERCOM5 PAD0 / TC5 WO2 |
| Pin 36 | PA25 — GPIO / SERCOM5 PAD1 / TC5 WO3 |
| Pin 37 | PB16 — GPIO / SERCOM5 PAD0 / TC6 WO0 |
| Pin 38 | PB17 — GPIO / SERCOM5 PAD1 / TC6 WO1 |
| Pin 39 | PB22 — GPIO / SERCOM2 PAD0 / TC7 WO0 |
| Pin 40 | PB23 — GPIO / SERCOM2 PAD1 / TC7 WO1 |
| Pin 41 | PB30 — GPIO / SWDIO |
| Pin 42 | PB31 — GPIO / SWCLK |
| Pin 43 | NRST — External reset input (active low) |
| Pin 44 | VSS — Ground |
| Pin 45 | VDD — Digital supply voltage |
| Pin 46 | VDDIN — Voltage regulator input |
| Pin 47 | PA30 — GPIO / SERCOM1 PAD2 |
| Pin 48 | PA31 — GPIO / SERCOM1 PAD3 |
Typical Applications
ATSAMC21G18A-AU is suitable for 6 applications: Automotive Body Control Module, HVAC Touch Control Panel, Industrial CAN-FD Sensor Hub, Smart Metering / AMI Endpoint, White-Goods User Interface (HMI), Battery-Powered IoT Edge Node.
Automotive Body Control Module
The ATSAMC21G18A-AU's AEC-Q100 Grade 1 qualification and integrated CAN-FD controller (up to 5 Mbit/s) make it a strong fit for body control modules driving lighting, mirror, and door-zone actuators. The 5V-tolerant GPIO interfaces directly to legacy 5V switches and LEDs without level shifters, reducing BOM cost and PCB area. The 256 KB Flash plus 32 KB SRAM comfortably hosts a CAN-FD stack (e.g. CANopen, J1939) plus a small RTOS or AUTOSAR-like scheduler. Designers should budget DMAC channels (12 available) for SPI-driven smart FET drivers and use SERCOM0 for LIN slave comms.
Recommended
HVAC Touch Control Panel
The integrated Peripheral Touch Controller (PTC) supports mutual-capacitance touch sensing on up to 16 keys and a slider/wheel, removing the need for an external touch IC. Combined with 5V-tolerant GPIO for direct LED backlight drive and a 12-bit 1 Msps ADC for analog front-panel sensing (NTC thermistor, light sensor), the ATSAMC21G18A-AU enables a compact HVAC UI BOM. The 256 KB Flash holds a full emWin / LVGL graphics stack; SERCOM channels expose the panel to a host MCU over SPI or UART. Design tip: route PTC lines as guarded traces to suppress moisture false-touches.
Recommended
Industrial CAN-FD Sensor Hub
An industrial sensor hub aggregating 4-20 mA, RTD, and digital sensor inputs benefits from the ATSAMC21G18A-AU's 12-bit 1 Msps ADC with up to 16 channels, plus six SERCOM channels to handle SPI / I2C sensor farms concurrently. The CAN-FD port links the hub to a PLC or gateway over a robust 5 Mbit/s bus. The Event System lets a timer trigger ADC conversions and SERCOM transfers without CPU involvement, keeping latency deterministic for control loops. Industrial designers should budget 2.7V-5.5V headroom to survive 24V industrial supply transients.
Recommended
Smart Metering / AMI Endpoint
Smart electricity, water, and gas meters benefit from the ATSAMC21G18A-AU's low-power RTC (32 kHz crystal operation), 12-bit ADC for metrology front-end, and SERCOM channels for wireless modem (sub-GHz) or PLC link. The 5V-tolerant GPIO supports direct drive of metrology-IC enable lines and anti-tamper switches. The 256 KB Flash is sufficient for DLMS/COSEM or proprietary metering stacks with secure boot (Microchip's SAM C21 supports TrustZone-M lite via the IDAU). Designers should use the Event System to wake the CPU only on metrology interrupts, achieving sub-100 uA/MHz efficiency.
Recommended
White-Goods User Interface (HMI)
Washing machines, ovens, and dishwashers use the ATSAMC21G18A-AU to drive capacitive touch panels, rotary encoders, and segment / TFT LCDs while interfacing to the main appliance controller over UART or CAN. The 5V-tolerant GPIO simplifies LED and 7-segment driving, and the 32 KB SRAM holds a fluid LVGL-based UI framebuffer for 2-3 inch displays. The AEC-Q100 rating supports both consumer-grade and high-end commercial appliances. Designers should pair the MCU with an external SPI flash (e.g. 25LC512-E/SN) for asset-tag and firmware-A/B storage.
Recommended
Battery-Powered IoT Edge Node
For IoT edge nodes running on 3.6V lithium primary cells, the ATSAMC21G18A-AU's 2.7V-5.5V range allows direct battery connection, eliminating boost circuitry. The 6 SERCOM channels can host LoRa, BLE, or sub-GHz radio SPI interfaces plus sensor I2C buses concurrently. The integrated Event System and 12-channel DMA minimize active CPU time, dropping average current below 1 mA in typical duty-cycled operation. The SAM C21 supports sleep modes down to a few microamps with RTC wake, balancing responsiveness and battery life for multi-year deployments.
Recommended
Recommended Products Summary
Engineering reference data for ATSAMC21G18A-AU — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATSAMC21G18A-AUT | ATSAMC21G16A-AU | ATSAMC21G17A-AU |
|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 48-TQFP (7x7 mm) | 48-TQFP (7x7 mm) - same | 48-TQFP (7x7 mm) - same | 48-TQFP (7x7 mm) - same |
| Core / Frequency | Cortex-M0+ / 48 MHz | Cortex-M0+ / 48 MHz | Cortex-M0+ / 48 MHz | Cortex-M0+ / 48 MHz |
| Flash | 256 KB | 256 KB | 1632 KB | 128 KB |
| SRAM | 32 KB | 32 KB | 16 KB | 16 KB |
| CAN-FD | Yes | Yes | Yes | Yes |
| 5V-tolerant GPIO | Yes | Yes | Yes | Yes |
| AEC-Q100 | Grade 1 qualified | Grade 1 qualified | Grade 1 qualified | Grade 1 qualified |
| PTC (Touch) | Yes | Yes | Yes | Yes |
Key Differentiators
- 5V-tolerant GPIO at full AEC-Q100 Grade 1 (vs ATSAMD21G18A-AU)
- Integrated CAN-FD controller (vs ATSAMD20J18A-AU)
- Hardware Peripheral Touch Controller (vs External touch ICs (e.g. AT42QT2120-MMHR))
Design Notes
The ATSAMC21G18A-AU has separate VDD, VDDIN, and VDDIO2 rails. Decouple each with 100 nF X7R ceramic placed within 3 mm of the pin, plus a bulk 4.7 uF ceramic on VDDIN. The internal 1.2V LDO core regulator requires an external 1 uF cap on VDDOUT. Avoid sharing VDDIO2 with high-current LED drivers; route it from the same regulator that supplies the MCU's I/O bank.
At 48 MHz with peripherals active, the device draws about 7-10 mA. Power dissipation is negligible compared to ambient thermal limits; however, in AEC-Q100 Grade 1 deployments the ambient must be limited to <=85 C for typical power. For higher-ambient designs, the 48-TQFP's exposed pad (when implemented as a ground pad in 64-pin variants) helps spread heat - in the 48-pin package this is not present, so thermal behavior is purely from internal dissipation.
Do not assume GPIO output voltage equals VDD on the C21 - the I/O ring is supplied from VDDIO2, which may be set to 3.3V even when VDD is 5V. This is the most common migration mistake from SAM D21 to SAM C21. Verify VDDIO2 is enabled in software (SYSCTRL->VREG.bit.VREGOUT = 1) before configuring GPIOs.
For CAN-FD at 5 Mbit/s, place the C21's CAN_TX/RX traces adjacent to a continuous ground pour and keep them short (<30 mm to the transceiver). Add a 120 ohm resistor between CANH and CANL at the bus terminator only, not at every node. Use a TVS diode (e.g. NUP2105LT1G) close to the transceiver for ESD/surge compliance to IEC 61000-4-2.
Route the 32.768 kHz crystal traces symmetrically and shield them with a ground guard ring to prevent coupling from adjacent SERCOM or PWM signals. The PTC touch sensing traces should be guarded and isolated from high-impedance analog traces; Microchip application note AN2908 documents the recommended layout rules for noise-immune PTC implementations.
Compliance Information
AEC-Q100 Grade 1 qualified per Microchip SAM C21 product page. RoHS compliant per Microchip material declarations. The Microchip SAM C21 family is PPAP-capable for automotive builds.
