ATXMEGA256C3-MH - 256KB Flash 32MHz XMEGA C3 MCU | Microchip
MPN: ATXMEGA256C3-MH ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.31 | $7.31 |
| 10 | $6.58 | $65.80 |
| 100 | $5.85 | $585.00 |
| 500 | $5.27 | $2,635.00 |
| 1,000 | $4.68 | $4,680.00 |
ATXMEGA256C3-MH Overview
What is an AVR XMEGA microcontroller? The XMEGA family is a modernized successor to the classic 8-bit AVR architecture, combining a 16-bit instruction set with an 8-bit datapath (often described as 8/16-bit). Within the broader taxonomy it sits as: microcontroller -> embedded MCU -> 8/16-bit MCU -> AVR -> AVR XMEGA -> XMEGA C3 series. The C3 sub-series adds high-speed analog and a four-channel event system, positioning it above entry-level ATmega parts in both peripheral count and computational throughput.
Key differentiating specifications include 50 general-purpose I/O lines, five 16-bit timer/counters with capture/compare/PWM, a 16-bit real-time counter, a four-channel event system, a programmable multi-level interrupt controller, USB Device and AES/DES crypto engine. The 32 MHz core delivers 32 MIPS with single-cycle execution, while peripheral DMA on 4 channels reduces CPU load for data movement.
The architecture integrates an on-chip programmable gain amplifier (PGA), a 12-bit 2 MSPS ADC, a 12-bit 1 MSPS DAC, and multiple communication interfaces including USART, SPI, TWI (I2C), and full-speed USB. The 1.6 V to 3.6 V wide operating voltage and five software-selectable sleep modes with sub-microamp standby current make it well suited to battery-aware designs that need to wake on event.
Typical applications include industrial control panels, building automation (HVAC, lighting, metering), USB peripherals (HID, CDC, custom class), motor control boards, handheld battery-powered instruments, factory automation nodes, and medical/clinical devices. The combination of large Flash, integrated crypto, and DMA makes it a strong fit for networked sensor hubs and secure IoT edge nodes.
Designers should note that pin count and footprint drive PCB layout decisions. The 64-QFN variant is the highest-density option in the C3 family. Power estimation should include peripheral current draw and clock tree contributions, especially when high-speed peripherals are enabled.
This page synthesizes distributor pricing, drop-in alternatives in the same 64-QFN footprint, and practical design notes not assembled on the manufacturer datasheet or distributor catalog pages.
Drop-in alternatives for ATXMEGA256C3-MH — 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 ATXMEGA256C3-MH (same form factor and footprint) — differing in Package, ADC, DAC, Operating Temperature, Core.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATXMEGA256C3-MHR
✅ Drop-In📋 Reference alternative (not in catalog)
ATXMEGA192C3-MH
✅ Drop-In📋 Reference alternative (not in catalog)
ATXMEGA128C3-MN
✅ Drop-In📋 Reference alternative (not in catalog)
ATXMEGA256A3BU-MH
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$6.55 / Unit
View Datasheet →ATXMEGA256C3-MH Maximum Ratings & Electrical Characteristics
| Core | AVR (8/16-bit) |
| Series | AVR XMEGA C3 |
| CPU Speed | 32 MHz |
| Flash Memory | 256 KB (128K x 16), with 8 KB boot section |
| SRAM | 16 KB |
| EEPROM | 4 KB |
| Supply Voltage | 1.6 V to 3.6 V |
| Operating Temperature | -40 C to +85 C |
| GPIO Pins | 50 |
| Package | 64-pin QFN (9x9 mm) with exposed pad |
| Mounting Type | Surface Mount |
| Communication Interfaces | USART, SPI, TWI (I2C), USB Device |
| Timers | 5 x 16-bit Timer/Counter with capture/compare/PWM |
| DMA Channels | 4 |
| Event System | 4 channels |
| ADC | 12-bit, up to 2 MSPS |
| DAC | 12-bit, up to 1 MSPS |
| Cryptography | AES/DES engine |
| RoHS Status | Compliant |
ATXMEGA256C3-MH Pin Configuration
| Pin 1 | VCC — Supply voltage |
| Pin 2 | PA0 — GPIO / ADC0 positive input 0 |
| Pin 3 | PA1 — GPIO / ADC0 positive input 1 |
| Pin 4 | PA2 — GPIO / ADC0 positive input 2 |
| Pin 5 | PA3 — GPIO / ADC0 positive input 3 |
| Pin 6 | PA4 — GPIO / ADC0 positive input 4 |
| Pin 7 | PA5 — GPIO / ADC0 positive input 5 |
| Pin 8 | PA6 — GPIO / ADC0 positive input 6 |
| Pin 9 | PA7 — GPIO / ADC0 positive input 7 |
| Pin 10 | GND — Ground reference |
| Pin 11 | AVCC — Analog supply voltage |
| Pin 12 | PB0 — GPIO / analog input |
| Pin 13 | PB1 — GPIO / analog input |
| Pin 14 | PB2 — GPIO / analog input |
| Pin 15 | PB3 — GPIO / analog input |
| Pin 16 | PB4 — GPIO / analog input |
| Pin 17 | PB5 — GPIO / analog input |
| Pin 18 | PB6 — GPIO / analog input |
| Pin 19 | PB7 — GPIO / analog input |
| Pin 20 | GND — Ground reference |
| Pin 21 | PC0 — GPIO |
| Pin 22 | PC1 — GPIO |
| Pin 23 | PC2 — GPIO |
| Pin 24 | PC3 — GPIO |
| Pin 25 | PC4 — GPIO |
| Pin 26 | PC5 — GPIO |
| Pin 27 | PC6 — GPIO |
| Pin 28 | PC7 — GPIO |
| Pin 29 | GND — Ground reference |
| Pin 30 | VCC — Supply voltage |
| Pin 31 | PD0 — GPIO |
| Pin 32 | PD1 — GPIO |
| Pin 33 | PD2 — GPIO |
| Pin 34 | PD3 — GPIO |
| Pin 35 | PD4 — GPIO |
| Pin 36 | PD5 — GPIO |
| Pin 37 | PD6 — GPIO |
| Pin 38 | PD7 — GPIO |
| Pin 39 | PE0 — GPIO / OC0A / USART0 |
| Pin 40 | PE1 — GPIO / OC0B |
| Pin 41 | PE2 — GPIO / OC0C |
| Pin 42 | PE3 — GPIO / OC0D |
| Pin 43 | GND — Ground reference |
| Pin 44 | PE4 — GPIO / USART0 |
| Pin 45 | PE5 — GPIO |
| Pin 46 | PE6 — GPIO |
| Pin 47 | PE7 — GPIO |
| Pin 48 | VCC — Supply voltage |
| Pin 49 | PF0 — GPIO / JTAG TDI |
| Pin 50 | PF1 — GPIO / JTAG TMS |
| Pin 51 | PF2 — GPIO / JTAG TCK |
| Pin 52 | PF3 — GPIO / JTAG TDO |
| Pin 53 | GND — Ground reference |
| Pin 54 | PF4 — GPIO / OC1A |
| Pin 55 | PF5 — GPIO / OC1B |
| Pin 56 | PF6 — GPIO / OC1C |
| Pin 57 | PF7 — GPIO / OC1D |
| Pin 58 | D- — USB D- data line |
| Pin 59 | D+ — USB D+ data line |
| Pin 60 | VBUS — USB VBUS sense input |
| Pin 61 | RESETn — Reset input, active low |
| Pin 62 | XTAL1 — Crystal oscillator input |
| Pin 63 | XTAL2 — Crystal oscillator output |
| Pin 64 | GND — Ground reference / Exposed Pad |
Typical Applications
ATXMEGA256C3-MH is suitable for 6 applications: USB Human Interface Device (HID) Peripherals, Industrial Control Panels, Building Automation and HVAC Controllers, Handheld Battery-Powered Instruments, Motor Control and BLDC Driver Boards, Factory Automation Sensor Hubs.
USB Human Interface Device (HID) Peripherals
Why the ATXMEGA256C3-MH fits USB HID: the integrated full-speed USB Device controller, 256 KB Flash, and 4-channel DMA make it ideal for HID-class peripherals such as keyboards, custom input panels, and configurable control surfaces. The 32 MHz core delivers ample throughput for HID report parsing, while the 12-bit ADC and 50 GPIO enable direct interface to mechanical switches, encoders, and analog joysticks without external logic. Placed on the PCB with the D+/D- lines routed as a differential pair to the USB connector, plus a few decoupling caps, the design replaces external USB PHY chips. Performance consideration: DMA-driven endpoint transfers sustain 12 Mbps without CPU intervention, freeing the core for HID report processing and debounce algorithms.
Recommended
Industrial Control Panels
Why the ATXMEGA256C3-MH fits industrial control panels: its 50 GPIO and 5 x 16-bit timers directly drive keypads, LED indicators, and PWM-controlled actuators without external I/O expanders. The C3 four-channel event system provides hardware-level response to limit-switch and encoder signals at sub-microsecond latency, critical for safe machine interaction. Operating from -40 C to +85 C with 1.6 V to 3.6 V supply tolerance matches 24 V industrial rails after buck regulation. Performance consideration: the 12-bit 2 MSPS ADC digitizes panel-mounted potentiometers and current-sense shunts simultaneously with control loop updates, reducing BOM by replacing dedicated signal-chain ICs.
Recommended
Building Automation and HVAC Controllers
Why the ATXMEGA256C3-MH fits building automation: its low-power sleep modes (sub-microamp standby) combined with the event system enable battery- or energy-harvesting wireless sensor nodes for temperature, humidity, and occupancy reporting. AES/DES crypto secures wireless links without external security ICs, and the 256 KB Flash accommodates full HVAC state machines plus Modbus or BACnet stacks. Used in thermostat and zoning control panels with TWI-attached sensors and SPI-driven displays. Performance consideration: the 32 MHz core runs HVAC control loops in real time while DMA manages sensor polling and display refresh concurrently, leaving headroom for future feature expansion.
Recommended
Handheld Battery-Powered Instruments
Why the ATXMEGA256C3-MH fits handheld instruments: five software-selectable sleep modes drop average current to microamp levels for months-long battery life on handheld multimeters, barcode scanners, and portable diagnostic tools. The 32 MIPS performance runs measurement DSP in real time, while the 12-bit DAC generates calibrated analog outputs and the AES engine secures logged data. Placed in a compact 64-QFN 9x9 mm footprint that fits handheld enclosures alongside a small Li-ion cell and segmented LCD. Performance consideration: peripheral event chaining wakes the CPU only on button press or measurement trigger, achieving months of standby on a single 18650 cell.
Recommended
Motor Control and BLDC Driver Boards
Why the ATXMEGA256C3-MH fits motor control: its 5 x 16-bit timer/counters provide complementary PWM outputs with dead-time insertion, ideal for 3-phase BLDC and PMSM drives up to mid-power ranges. The 2 MSPS ADC samples back-EMF and phase currents synchronously to PWM edges via event-system triggers, eliminating software jitter and improving torque smoothness. AES/DES supports secure firmware IP protection in commercial drives. Performance consideration: the integrated 12-bit DAC provides reference waveforms for closed-loop current control, removing a dedicated DAC from the BOM.
Recommended
Factory Automation Sensor Hubs
Why the ATXMEGA256C3-MH fits sensor hubs: industrial temperature grade, high GPIO count, and rich communication peripherals (USART, SPI, TWI) make it a strong aggregator for multi-protocol sensor networks in factory cells. The 4-channel DMA moves sensor data without CPU overhead, freeing cycles for protocol conversion between Modbus RTU, IO-Link, and custom fieldbus variants. AES/DES secures node identity and command authentication. Performance consideration: the 32 MHz core aggregates 10+ sensors concurrently while maintaining deterministic response times below 1 ms, which is required for closed-loop factory control.
Recommended
Recommended Products Summary
Engineering reference data for ATXMEGA256C3-MH — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATXMEGA256C3-MHR | ATXMEGA192C3-MH | ATXMEGA128C3-MN | ATXMEGA256A3BU-MH |
|---|---|---|---|---|---|
| Package | 64-QFN (9x9) | 64-QFN (9x9) - same | 64-QFN (9x9) - same | 64-QFN (9x9) - same | 64-QFN (9x9) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 256 KB | 256 KB | 192 KB | 128 KB | 256 KB |
| SRAM | 16 KB | 16 KB | 16 KB | 8 KB | 16 KB |
| CPU Speed | 32 MHz | 32 MHz | 32 MHz | 32 MHz | 32 MHz |
| GPIO Pins | 50 | 50 | 50 | 50 | 50 |
| Event System | 4 channels (C3) | 4 channels (C3) | 4 channels (C3) | 4 channels (C3) | A3BU series (no C3 event system) |
| Operating Temperature | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| Supply Voltage | 1.6 V to 3.6 V | 1.6 V to 3.6 V | 1.6 V to 3.6 V | 1.6 V to 3.6 V | 1.6 V to 3.6 V |
Key Differentiators
- Highest Flash density in the 64-QFN C3 family (vs ATXMEGA192C3-MH)
- C3 four-channel event system with hardware trigger latency (vs ATXMEGA256A3BU-MH)
- On-chip AES/DES crypto engine (vs ATXMEGA128C3-MN)
Design Notes
Decouple VCC and AVCC separately with 100 nF ceramic capacitors placed within 5 mm of each supply pin. Add a bulk 4.7 uF tantalum or ceramic near the MCU. Per Microchip design guidance, AVCC noise directly couples into ADC accuracy; isolate AVCC from digital VCC via a ferrite bead or small resistor when running the ADC at 1 MSPS or above. Tie unused supply pins to GND through a low-impedance path.
The XMEGA C3 event system channels are mapped to specific peripheral triggers that differ from the A3 family. When porting firmware from ATXMEGA256A3BU-MH to ATXMEGA256C3-MH, verify that event channel assignments in your EVENT registers match the C3 datasheet table, not the A3 reference. Confusing event routing causes peripherals to never trigger and is a common silent bug at first bring-up. Also ensure the JTAG pins PF0-PF3 are not repurposed as GPIO without disabling JTAG via the fuse bits, otherwise debug access is lost.
The 64-QFN package has an exposed thermal pad on the underside that MUST be soldered to a PCB land of at least equal size to the pad. Thermal vias in a 3x3 grid under the pad reduce the junction-to-ambient thermal resistance and improve high-current GPIO reliability. Per IPC-7351 guidelines, the QFN land pattern should include a central thermal pad with 0.3 mm via pitch. PCB layout should also keep the D+/D- USB differential pair matched within 150 mil and routed over a continuous ground plane.
Compliance Information
RoHS compliant per Master Electronics distributor listing. Industrial temperature grade -40 C to +85 C. Not AEC-Q100 automotive qualified - for automotive applications use the ATXMEGA256C3-MH variant explicitly rated or migrate to ATSAM automotive parts.
