ATMEGA649A-MU - 8-bit AVR MCU 64KB Flash 16MHz | Microchip
MPN: ATMEGA649A-MU ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.92 | $6.92 |
| 10 | $6.23 | $62.30 |
| 100 | $5.54 | $554.00 |
| 500 | $4.98 | $2,490.00 |
| 1,000 | $4.42 | $4,420.00 |
ATMEGA649A-MU Overview
An 8-bit microcontroller is a single-chip computer whose CPU processes data in 8-bit words. Within the embedded systems hierarchy, the AVR ATmega family sits under the broader microcontroller (MCU) category, which combines a processor core, program memory, data memory, and peripherals in one integrated circuit, making it a fundamental building block of embedded control systems alongside competing architectures such as PIC, 8051, and ARM Cortex-M based devices.
Key features of the ATMEGA649A-MU include 64KB of in-system programmable Flash with read-while-write capability, 54 to 69 general purpose I/O lines depending on package, 32 general purpose working registers, and an on-chip JTAG interface for boundary-scan and in-system debugging. The AVR enhanced RISC core executes most instructions in a single clock cycle, delivering throughput of up to 16 MIPS at 16 MHz.
Technically, the device belongs to the ATmega169A/PA/329A/PA/3290A/PA/649A/P/6490A/P family and operates from a supply voltage of 4.5V to 5.5V at the full 16 MHz speed grade (industrial temperature, 20 MHz capable per some package grades). Peripherals typically include USART, SPI, and two-wire interfaces, timers/counters, and an LCD controller on the 649 variant, enabling direct segment LCD driving.
Typical applications include industrial control panels with segment LCD displays, consumer appliance user interfaces, metering products, and low-power battery-backed measurement instruments where single-cycle RISC execution and rich I/O reduce external component count.
A key design consideration is supply voltage versus clock speed: at 4.5V to 5.5V the device runs at its rated 16 MHz; operating at lower voltages requires derating the maximum clock frequency per the datasheet speed-versus-voltage curve.
This page synthesizes distributor pricing, drop-in alternatives, pinout guidance, and practical design notes not consolidated in the manufacturer datasheet, giving engineers a single decision-ready reference for the ATMEGA649A-MU.
Drop-in alternatives for ATMEGA649A-MU — 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 ATMEGA649A-MU (same form factor and footprint) — differing in Package, Supply Voltage Range, LCD Controller, Flash Memory, RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA649A-AUR
✅ Drop-In✓ In Stock
$5.72 / Unit
View Datasheet →ATMEGA329A-MUR
✅ Drop-In✓ In Stock
$3.61 / Unit
View Datasheet →ATMEGA3290PA-AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$4.48 / Unit
View Datasheet →ATMEGA645-16MUR
✅ Drop-In✓ In Stock
$3.35 / Unit
View Datasheet →ATMEGA649P-MU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$3.91 / Unit
View Datasheet →ATMEGA649A-MU Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Flash Memory | 64 KB (32K x 16) ISP Flash |
| EEPROM | 2 KB |
| SRAM | 4 KB |
| Maximum Clock Speed | 16 MHz |
| Supply Voltage Range | 1.8 V to 5.5 V (4.5 V to 5.5 V for 16 MHz operation) |
| General Purpose I/O | 54/69 I/O lines |
| Working Registers | 32 general purpose registers |
| Debug Interface | JTAG (boundary scan and on-chip debug) |
| Package | 64-QFN (9x9 mm) with exposed pad (64-VFQFN) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (Industrial) |
| Program Memory Type | Flash (read-while-write) |
| Series | AVR ATmega |
| RoHS Status | Compliant (Green package) |
| Core Performance | Up to 16 MIPS at 16 MHz (single-cycle instructions) |
ATMEGA649A-MU 64-qfn (9x9 mm) with exposed pad (64-vfqfn) Pin Configuration Guide
Pin configuration for ATMEGA649A-MU (64-qfn (9x9 mm) with exposed pad (64-vfqfn) package). This digital IC includes GPIO, communication interfaces (UART, SPI, I2C), and power pins. Refer to the manufacturer datasheet for alternate pin functions and configuration options. Essential for embedded system design and PCB layout.
No detailed pinout data available for ATMEGA649A-MU.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA649A-MU is suitable for 6 applications: Industrial Control Panels with Segment LCD, Utility Metering and Energy Measurement, Appliance User Interface Boards, Portable Test and Measurement Instruments, Building Automation and Access Control Nodes, Legacy 5V Embedded System Maintenance.
Industrial Control Panels with Segment LCD
The ATMEGA649A-MU fits industrial control panels because its integrated segment LCD controller drives multi-digit and custom-segment displays directly, eliminating an external LCD driver and its I2C/SPI wiring. Its 4.5V to 5.5V operation at the full 16 MHz matches legacy 24V-logic industrial panels that run from 5V derived rails, and 54/69 GPIO lines provide abundant keys, relays, and indicator connections. With 64KB ISP Flash and 2KB EEPROM, panel firmware plus logged configuration data fit entirely on-chip. Using the JTAG interface, production panels can be boundary-scan tested and field-serviced without removing the MCU from the 64-QFN footprint.
Recommended
Utility Metering and Energy Measurement
In electricity, water, and heat metering products, the ATMEGA649A-MU combines an LCD controller for the consumption display with 4KB SRAM for accumulation buffers and 2KB EEPROM for tamper-resistant storage of calibration and billing registers. The read-while-write Flash allows the meter to log events into Flash without stalling the measurement loop. Single-cycle AVR execution at 16 MHz provides ample headroom for pulse-counting and communication protocols such as M-Bus or DLMS over USART. Its industrial -40C to +85C temperature range and 5V noise margin make it reliable inside sealed outdoor meter enclosures.
Recommended
Appliance User Interface Boards
White-goods and HVAC appliance UI boards benefit from the ATMEGA649A-MU because one 64-QFN IC can display temperature, cycle status, and errors on a segment LCD, scan a capacitive or mechanical key matrix, and drive buzzer and relay outputs. The 16 MHz AVR core executes the scanning loops and UART link to the main appliance controller with predictable deterministic timing, simplifying EMC-friendly firmware. Read-while-write Flash supports last-state retention through power interruptions. The 9x9 mm QFN with exposed pad reflows onto standard 4-layer appliance PCBs and withstands industrial reflow profiles in Green, lead-free finish.
Recommended
Portable Test and Measurement Instruments
Handheld multimeters, environmental meters, and battery testers use the ATMEGA649A-MU for its balance of display driving and measurement I/O. The LCD controller renders readings on a segment display with minimal current, while the 10-bit ADC-class peripherals and timers sample sensor front-ends; 4KB SRAM holds waveform and statistics buffers. Idle and power-down sleep modes extend battery life between measurements, though designs targeting multi-year coin-cell life should compare picoPower variants. The JTAG port enables factory calibration and firmware update through a bed-of-nails fixture without disassembling the instrument housing.
Recommended
Building Automation and Access Control Nodes
Door controllers, room thermostats, and zone displays in building automation leverage the ATMEGA649A-MU's USART, SPI, and I2C-class serial interfaces to connect readers, sensors, and RS-485 backbones, while the segment LCD shows codes and status locally. The 64KB Flash accommodates protocol stacks and event logs, and EEPROM preserves credential tables across power cycles with byte-level endurance suited to frequent updates. Operating at 5V provides robust noise immunity in electrically busy riser environments. The single-chip integration reduces BOM count in high-volume panel builds where every cent and every square centimeter matter.
Recommended
Legacy 5V Embedded System Maintenance
Many mature industrial products still specify 5V-only MCUs, and the ATMEGA649A-MU is a primary sourcing choice for maintaining and extending those platforms. Its 4.5V to 5.5V operation, JTAG in-system programming, and long-lived megaAVR documentation allow engineers to re-spin boards without translating designs to 3.3V ARM parts. Availability through Rochester Electronics and multiple distributors mitigates discontinuation risk. For BOM risk management, qualifying the ATMEGA649A-AUR TQFP sibling and the ATMEGA649P-MU as second sources on the same footprint family provides multi-layer supply resilience for end-of-life service commitments.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA649A-MU — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA649A-AUR | ATMEGA649P-MU | ATMEGA645-16MUR | ATMEGA329A-MUR |
|---|---|---|---|---|---|
| Package | 64-QFN (9x9 mm) exposed pad | 64-TQFP | 64-QFN (9x9 mm) - same | 64-QFN (9x9 mm) - same | 64-QFN (9x9 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 64 KB | 64 KB | 64 KB | 64 KB | 16 KB |
| SRAM | 4 KB | 4 KB | 4 KB | 4 KB | 2 KB |
| EEPROM | 2 KB | 2 KB | 2 KB | 2 KB | 1 KB |
| Max Clock Speed | 16 MHz | 16 MHz | 16 MHz | 16 MHz | 16 MHz |
| Segment LCD Controller | Yes | Yes | Yes | Yes | Yes |
| Lifecycle Status | Active | Active | Active | Active | Active |
Key Differentiators
- Integrated segment LCD controller with maximum memory in family (vs ATMEGA329A-MUR)
- P-variant die with matured errata fixes (vs ATMEGA649P-MU)
- Package flexibility across the same die (vs ATMEGA649A-AUR)
Design Notes
The 64-QFN (9x9 mm) exposed pad must be soldered to a contiguous ground area on the PCB. Define an array of thermal vias (typically 5x5, 0.3 mm drill) under the pad connecting to internal ground planes, and use an opening in the solder mask paste split into multiple small apertures (60-80% coverage) to prevent paste voiding during reflow. Peripheral QFN castellations need standard 0.5 mm pitch land patterns per the Microchip package drawing.
Clock frequency is voltage-dependent: 16 MHz operation requires VCC of 4.5V to 5.5V. If your system runs from a 3.3V rail, you must either derate the clock (per the datasheet speed-vs-voltage curve) or add a 5V regulator. Decouple VCC and AVCC independently with 100 nF ceramics at each supply pin plus a 10 uF bulk capacitor; connect AVCC to VCC through a low-pass LC filter when ADC accuracy matters. Unused GPIO should be configured as inputs with internal pull-ups to avoid floating-node current.
The JTAG interface is enabled by default; JTAG pins (TCK/TMS/TDO/TDI) are then unavailable as general I/O. If your application needs those port pins, disable JTAG via the JTD bit or fuse configuration early in firmware - note the JTD bit write sequence requires two writes within four cycles. Also verify the RESET pin fuse setting before enabling debugWire-style workflows, since disabling external reset can permanently complicate reprogramming.
Drive the crystal oscillator with a fundamental-mode crystal matched to Microchip's load-capacitance guidance in the ATmega649A family datasheet; keep crystal traces under 10 mm and guard them with ground. Segment LCD lines carrying the multiplexed waveform should route away from the crystal and analog front-end, since LCD com voltages couple capacitively into high-impedance nodes and cause visible ghosting or ADC noise on mixed-signal boards.
Compliance Information
EU RoHS Compliant and REACH Compliant per distributor compliance records for the ATmega649A family (Green package). DRC Conflict Free status listed for family parts. Not AEC-Q100 qualified - for automotive designs consult Microchip automotive-grade AVR offerings.
