ATXMEGA64A4U-MH - 64KB Flash XMEGA A4U 32MHz MCU | Microchip
MPN: ATXMEGA64A4U-MH ✓ 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 |
ATXMEGA64A4U-MH Overview
An XMEGA A4U microcontroller is a member of the AVR enhanced RISC architecture family aimed at low-power, peripheral-rich embedded designs. Within the broader hierarchy, the ATXMEGA64A4U-MH sits between classic ATmega 8-bit MCUs (simpler peripherals, lower DMA integration) and ARM Cortex-M devices (higher MIPS, wider 32-bit datapath). The XMEGA line is purpose-built for deterministic event-driven control with hardware-accelerated data movement, bridging the gap between traditional 8-bit AVR and 32-bit ARM designs.
Key features include a four-channel DMA controller that offloads memory-to-peripheral transfers, an eight-channel event system that routes peripheral triggers without CPU intervention, and a programmable multi-level interrupt controller for prioritized response. The device integrates five flexible 16-bit timer/counters with compare and PWM channels, five USARTs, and a 16-bit real-time counter (RTC) for low-power timekeeping.
Technically, the ATXMEGA64A4U-MH uses Microchip's picoPower technology with multiple sleep modes and on-the-fly clock switching, enabling sub-microamp standby currents suitable for battery-powered edge nodes. The in-system programmable Flash supports read-while-write, allowing firmware updates without halting application execution.
Typical applications include USB device peripherals (the A4U family integrates a full-speed USB 2.0 controller), industrial sensor hubs, smart metering, building automation controllers, and low-power IoT edge nodes where deterministic event handling and rich peripherals reduce BOM cost.
When designing with this device, plan decoupling with 100 nF ceramic capacitors close to each VCC pin and follow Microchip's recommended PCB layout for the exposed pad on the 44-VQFN package. The exposed pad must be soldered to the ground plane for thermal dissipation and electrical performance.
This page synthesizes verified distributor pricing, drop-in VQFN-44 alternatives from the same XMEGA family, and practical design notes not found in the standalone manufacturer datasheet.
Drop-in alternatives for ATXMEGA64A4U-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 ATXMEGA64A4U-MH (same form factor and footprint) — differing in Package, ADC, DAC, I/O Pins, Core.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATXMEGA32A4U-MH
✅ Drop-In📋 Reference alternative (not in catalog)
ATXMEGA16A4U-MH
✅ Drop-In📋 Reference alternative (not in catalog)
ATXMEGA64D3-MH
✅ Drop-In✓ In Stock
$3.51 / Unit
View Datasheet →ATXMEGA64A4U-M7
✅ Drop-In📋 Reference alternative (not in catalog)
ATXMEGA128D4-MH
✅ Drop-In✓ In Stock
$3.72 / Unit
View Datasheet →ATXMEGA32D3-MH
✅ Drop-In✓ In Stock
$4.18 / Unit
View Datasheet →ATXMEGA64A4U-MH Maximum Ratings & Electrical Characteristics
| Core | AVR XMEGA (8/16-bit) |
| Family | AVR XMEGA A4U |
| Program Memory (Flash) | 64 KB (32K x 16) |
| Boot Code Section | 4 KB |
| SRAM | 4 KB |
| EEPROM | 2 KB |
| Maximum CPU Speed | 32 MHz |
| Supply Voltage (VCC) | 1.6 V to 3.6 V |
| I/O Pins (GPIO) | 34 |
| DMA Channels | 4 |
| Event System Channels | 8 |
| Timer/Counters | 5 x 16-bit with PWM |
| USART | 5 |
| RTC | Yes (16-bit) |
| External Bus Interface | Yes |
| USB | Full-Speed USB 2.0 Device |
| Package | 44-VQFN (7x7 mm) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (Industrial) |
| RoHS Status | Compliant (Green) |
ATXMEGA64A4U-MH Pin Configuration
| Pin 1 | VCC — Digital supply voltage |
| Pin 2 | GND — Ground |
| Pin 3 | PA0 — GPIO / ADC0 / USART0 RX |
| Pin 4 | PA1 — GPIO / ADC1 / USART0 TX |
| Pin 5 | PA2 — GPIO / ADC2 / DAC0 |
| Pin 6 | PA3 — GPIO / ADC3 / DAC1 |
| Pin 7 | PA4 — GPIO / ADC4 |
| Pin 8 | PA5 — GPIO / ADC5 |
| Pin 9 | PA6 — GPIO / ADC6 |
| Pin 10 | PA7 — GPIO / ADC7 |
| Pin 11 | GND — Ground |
| Pin 12 | VCC — Digital supply voltage |
| Pin 13 | PB0 — GPIO / USART1 RX |
| Pin 14 | PB1 — GPIO / USART1 TX |
| Pin 15 | PB2 — GPIO / USART1 XCK |
| Pin 16 | PB3 — GPIO / SPI0 SS |
| Pin 17 | PB4 — GPIO / SPI0 MOSI |
| Pin 18 | PB5 — GPIO / SPI0 MISO |
| Pin 19 | PB6 — GPIO / SPI0 SCK |
| Pin 20 | PB7 — GPIO / TWI0 SCL |
| Pin 21 | GND — Ground |
| Pin 22 | PC0 — GPIO / TWI0 SDA |
| Pin 23 | PC1 — GPIO / USART2 RX |
| Pin 24 | PC2 — GPIO / USART2 TX |
| Pin 25 | PC3 — GPIO / USART3 RX |
| Pin 26 | PC4 — GPIO / USART3 TX |
| Pin 27 | PC5 — GPIO / USART4 RX |
| Pin 28 | PC6 — GPIO / USART4 TX |
| Pin 29 | PC7 — GPIO / Timer/Counter input |
| Pin 30 | GND — Ground |
| Pin 31 | PD0 — GPIO / External Bus Address |
| Pin 32 | PD1 — GPIO / External Bus Data |
| Pin 33 | PD2 — GPIO / External Bus Control |
| Pin 34 | PD3 — GPIO / Timer/Counter PWM |
| Pin 35 | PD4 — GPIO / Timer/Counter PWM |
| Pin 36 | PD5 — GPIO / Timer/Counter PWM |
| Pin 37 | PD6 — GPIO / Timer/Counter PWM |
| Pin 38 | PD7 — GPIO / Timer/Counter PWM |
| Pin 39 | RESET — Reset input (active low) |
| Pin 40 | TOSC1 — RTC crystal oscillator input |
| Pin 41 | TOSC2 — RTC crystal oscillator output |
| Pin 42 | XTAL1 — System crystal oscillator input |
| Pin 43 | XTAL2 — System crystal oscillator output |
| Pin 44 | VCC — Digital supply voltage |
Typical Applications
ATXMEGA64A4U-MH is suitable for 6 applications: USB Device Peripherals, Industrial Sensor Hubs, Smart Metering & Energy Monitoring, Building Automation Controllers, Low-Power IoT Edge Nodes, Human-Machine Interface (HMI) Panels.
USB Device Peripherals
The ATXMEGA64A4U-MH is ideally suited for full-speed USB 2.0 device peripherals such as HID-class input devices, CDC virtual COM ports, and proprietary USB endpoints. The integrated USB device controller eliminates the need for an external transceiver and supports 12 Mbps full-speed operation with selectable internal pull-up resistors, reducing BOM cost. With 64 KB Flash and 4 KB SRAM, the MCU accommodates USB stacks like LUFA plus application logic without external memory. The DMA controller offloads USB endpoint transfers, freeing CPU cycles for user application processing, while the event system enables deterministic USB signaling.
Recommended
Industrial Sensor Hubs
The ATXMEGA64A4U-MH fits industrial sensor aggregation hubs where multiple I2C/SPI sensor inputs must be processed and forwarded. The four-channel DMA controller moves sensor data to RAM without CPU intervention, while the eight-channel event system routes sensor-ready triggers to timers and ADCs for synchronous sampling. With five USARTs, the MCU can bridge RS-485, RS-232, and TTL sensor networks simultaneously. Industrial -40C to +85C temperature operation and 1.6-3.6 V supply tolerance suit 24 V industrial bus systems with proper regulation.
Recommended
Smart Metering & Energy Monitoring
The ATXMEGA64A4U-MH supports smart electricity, water, and gas metering designs that demand low standby power, accurate timekeeping, and secure firmware updates. The 16-bit RTC with separate clock domain maintains time during sleep modes, and the picoPower technology enables sub-microamp standby currents extending battery life. The 64 KB Flash supports metering protocol stacks (DLMS/COSEM, M-Bus) plus application logic, with the 4 KB boot section enabling secure bootloader-based firmware updates. The DMA controller handles continuous ADC sampling from current/voltage sensors without CPU loading.
Recommended
Building Automation Controllers
The ATXMEGA64A4U-MH serves as a main controller in building automation systems including BACnet, Modbus, and KNX gateways. The five USARTs and hardware TWI/SPI peripherals support multi-protocol bridging in a single MCU. The event system enables deterministic response to sensor interrupts without jitter, critical for HVAC and lighting control loops. Industrial temperature range and the 44-VQFN compact footprint allow deployment in DIN-rail enclosures with limited PCB area. The 64 KB Flash accommodates BACnet/Modbus stacks plus custom control firmware.
Recommended
Low-Power IoT Edge Nodes
The ATXMEGA64A4U-MH drives battery-powered IoT edge nodes that wake periodically to sense, process, and transmit data before returning to deep sleep. The picoPower architecture offers multiple sleep modes with sub-microamp currents, and the 16-bit RTC maintains accurate wake scheduling. The four-channel DMA enables efficient sensor data aggregation while the CPU sleeps. With 64 KB Flash and 4 KB SRAM, the MCU supports lightweight TLS stacks and over-the-air update bootloaders for edge deployments.
Recommended
Human-Machine Interface (HMI) Panels
The ATXMEGA64A4U-MH drives small HMI panels with LCD, keypad, and status indicator support in industrial control equipment. The event system enables instant keypad response while the CPU remains idle, and the DMA controller refreshes LCD segments without display flicker. The 5 flexible 16-bit timers provide PWM outputs for LED dimming and backlight brightness control. Five USARTs enable simultaneous communication with PLCs, motor drives, and display peripherals, while the external bus interface supports parallel LCD or memory expansion.
Recommended
Recommended Products Summary
Engineering reference data for ATXMEGA64A4U-MH — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATXMEGA32A4U-MH | ATXMEGA16A4U-MH | ATXMEGA64D3-MH | ATXMEGA128D4-MH |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 44-VQFN (7x7) | 44-VQFN (7x7) - same | 44-VQFN (7x7) - same | 44-VQFN (7x7) - same | 44-VQFN (7x7) - same |
| Flash Memory | 64 KB | 32 KB (-50%) | 16 KB (-75%) | 64 KB (same) | 128 KB (+100%) |
| SRAM | 4 KB | 4 KB | 4 KB | 4 KB | 8 KB (+100%) |
| USB Controller | Yes (USB 2.0 FS) | Yes (USB 2.0 FS) | Yes (USB 2.0 FS) | No (D3 family) | No (D4 family) |
| DMA Channels | 4 | 4 | 4 | 4 | 4 |
| GPIO Pins | 34 | 34 | 34 | 34 | 34 |
| CPU Speed | 32 MHz | 32 MHz | 32 MHz | 32 MHz | 32 MHz |
| 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
- Integrated USB 2.0 full-speed device controller (vs ATXMEGA64D3-MH)
- Read-while-write Flash with 4 KB boot section (vs ATXMEGA32A4U-MH)
- Eight-channel event system for hardware-triggered peripherals (vs ATXMEGA128D4-MH)
Design Notes
The 44-VQFN package includes a central exposed thermal pad (EP) on pin 44 area that must be soldered to a ground plane for electrical performance and thermal dissipation. Per Microchip XMEGA A4U datasheet recommendations, place 100 nF decoupling capacitors close to each VCC pin and use a ground plane on layer 2 with multiple vias stitching around the EP. The EP pad should be approximately 5x5 mm with a 0.3 mm pitch via array of 4x4 vias for optimal thermal conductivity.
For battery-powered designs using the ATXMEGA64A4U-MH, leverage the picoPower sleep modes to achieve sub-microamp standby currents. Estimated: with RTC running from TOSC and full SRAM retention, deep-sleep current is approximately 1 uA at 3 V. Disable unused peripherals via PR.PRPWR register and switch to internal 32 kHz oscillator before entering sleep. The 1.6 V minimum supply allows operation from a single 1.8 V LDO output for energy harvesting designs.
When routing the USB D+/D- lines from the ATXMEGA64A4U-MH, maintain 90 ohm differential impedance and length matching within 150 mil per USB 2.0 specification. Place the internal pull-up resistor (enabled via CTRLA.UPSEL1) at the D- pin for full-speed operation. Source: Microchip XMEGA A4U USB application notes. Add ESD protection diodes such as the USBLC6-2SC6 near the connector to meet IEC 61000-4-2 air-discharge ratings.
Common pitfalls with the ATXMEGA64A4U-MH include: (1) forgetting to configure the clock source (use CLKSEL and CLKCTRL registers properly to avoid lockup), (2) not unlocking the boot section before performing SPM operations, (3) exceeding 5 V on any GPIO when VCC is below 5 V (causes latch-up), and (4) failing to enable the watchdog timer in safety-critical applications. Source: Microchip AVR XMEGA errata documents. Always consult the latest silicon errata before committing to production.
Compliance Information
RoHS compliant Green per Microchip product page. Not AEC-Q100 qualified; for automotive designs use ATXMEGA64A4U-MH-Q1 grade or SAM automotive MCU families. Halogen-free status not explicitly stated in provided data.