ATMEGA649A-AUR - 8-Bit AVR MCU, 64KB Flash, TQFP-64 | Microchip
MPN: ATMEGA649A-AUR β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $9.02 | $9.02 |
| 10 | $8.12 | $81.20 |
| 100 | $7.05 | $705.00 |
| 500 | $6.35 | $3,175.00 |
| 1,000 | $5.72 | $5,720.00 |
ATMEGA649A-AUR Overview
A microcontroller unit (MCU) is a complete self-contained computing system on a single chip, integrating a processor core, program memory, data memory, and peripherals. In the voltage regulator hierarchy of embedded systems, an MCU sits at the application layer, orchestrating sensors, displays, and actuators. The AVR family, originally developed by Atmel and now manufactured by Microchip Technology, is one of the most widely adopted 8-bit RISC MCU architectures, also forming the basis of the classic Arduino platform.
Key differentiating features include self-programming Flash with read-while-write capability for field firmware updates, 54 general-purpose I/O lines, an integrated LCD controller with internal contrast control capable of driving segmented glass displays without an external driver, and a JTAG interface for boundary-scan testing and on-chip debugging and programming.
Technically, the ATmega649A uses an advanced AVR RISC Harvard architecture with 32 general-purpose working registers directly connected to the arithmetic logic unit, allowing one-cycle execution of most instructions. Three flexible timer/counters with compare modes, internal and external interrupt sources, a programmable serial USART, and a byte-oriented two-wire serial interface round out the peripheral set.
Typical applications include utility metering and battery-powered instruments that require an LCD display, industrial control panels, hand-held measurement devices, and consumer appliances needing segment-display feedback with minimal external components.
When designing, note the 5V operating window of 4.5V to 5.5V; select the ATmega649V variant for lower-voltage 2.7V to 5.5V operation at reduced clock speed.
This page synthesizes verified distributor data, pin-compatible drop-in alternatives, drop-in comparison tables, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA649A-AUR 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 ATMEGA649A-AUR (same form factor and footprint) β differing in Package, RoHS Status, Supply Voltage Range, EEPROM, SRAM.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA645P-AU
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA645A-AU
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA640-16AUR
β Drop-Inβ In Stock
$5.9 / Unit
View Datasheet βATMEGA3290P-20AUR
β Drop-Inβ In Stock
Contact for price
View Datasheet βATMEGA3290PA-AUR
β Drop-Inβ In Stock
$2.95 / Unit
View Datasheet βATMEGA649A-AUR Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Flash Program Memory | 64 KB (32K x 16) |
| EEPROM | 2 KB |
| SRAM | 4 KB |
| Maximum Clock Speed | 16 MHz |
| Supply Voltage Range | 4.5 V to 5.5 V |
| I/O Ports | 53 general-purpose I/O lines |
| LCD Controller | Yes, on-chip with internal contrast control |
| JTAG Interface | Yes (boundary-scan, on-chip debug, programming) |
| Instructions | 130 instructions, most single-cycle |
| Package | 64-TQFP (14x14 mm) |
| Mounting Type | Surface Mount |
| Flash Programming | In-System Programmable (ISP), read-while-write |
| Operating Temperature Grade | Industrial |
| Data Bus Width | 8 bit |
| Lifecycle Status | Active |
ATMEGA649A-AUR 64-tqfp (14x14 mm) Pin Configuration Guide
Pin configuration for ATMEGA649A-AUR (64-tqfp (14x14 mm) 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-AUR.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA649A-AUR is suitable for 6 applications: Utility Metering, Hand-held Instruments, Industrial Control Panels, Consumer Appliances, Building Automation Nodes, Test and Measurement Equipment.
Utility Metering
The ATMEGA649A-AUR fits electricity, water, and gas metering designs because its integrated LCD controller with internal contrast control drives segmented meter glass directly, removing the external segment-driver IC and its associated BOM cost and wiring. The 2 KB EEPROM retains calibration constants and tariff tables through power cycles, while 64 KB ISP Flash with read-while-write self-programming supports consumption logging and field firmware updates without halting measurement. Operating at 16 MHz from a 4.5V to 5.5V industrial supply, it delivers roughly 16 MIPS for DSP-style sampling routines. The JTAG boundary-scan capability simplifies production test of assembled meter PCBs.
Recommended
Hand-held Instruments
Portable measurement tools benefit from the ATMEGA649A-AUR's single-chip integration of MCU, LCD controller, EEPROM, and JTAG debug. The on-chip LCD contrast control adapts display drive to temperature without external potentiometers, and 53 general-purpose I/O lines interface keypad matrices, buzzers, and sensor front ends. The 64 KB Flash accommodates complex multi-function instrument firmware with lookup tables, while most single-cycle instructions keep scan loops deterministic. Because the A-grade device runs at 16 MHz on 5V rails supplied by common wall adapters, designers avoid boost converters. For battery-only handhelds, drop to the ATmega329PA picoPower variant in the same footprint to cut standby current.
Recommended
Industrial Control Panels
The ATMEGA649A-AUR suits industrial panel controllers that need a status segment display plus moderate logic. Its 64 KB self-programming Flash supports field-updatable control sequences, and read-while-write operation lets the panel log event data to internal EEPROM/Flash while running. The USART handles Modbus RTU links to PLCs, and the two-wire serial interface reads remote I/O expanders and temperature sensors. Three timers generate PWM outputs for actuators and precise timebases. The industrial temperature grade and 5V noise-margin operation are robust in electrically noisy cabinets, while JTAG boundary-scan accelerates manufacturing test of densely populated panel boards.
Recommended
Consumer Appliances
White goods and small appliances use the ATMEGA649A-AUR to drive segmented display glass for user feedback while running control firmware. The integrated LCD controller eliminates a driver chip, cutting BOM cost in high-volume products, and internal contrast control maintains display legibility across kitchen temperature swings. The 2 KB EEPROM stores user settings and last-cycle state across power interruptions, and 64 KB Flash hosts multiple language packs and wash-cycle profiles. The 5V supply aligns with legacy appliance transformer-based power supplies, and in-system programming enables late-stage firmware customization on the assembly line without socket changes.
Recommended
Building Automation Nodes
Wall-mounted room controllers and thermostats combine a segment LCD with serial networking, a niche the ATMEGA649A-AUR addresses directly. The LCD controller renders setpoints and schedules, the USART connects to RS-485 BACnet or custom bus segments through an external transceiver, and the two-wire interface reads humidity and temperature sensors. Self-programming Flash supports over-the-bus firmware upgrades without removing devices from walls, and EEPROM keeps user schedules through outages. At 16 MHz the core handles PID loop execution alongside display refresh. Designers should budget the 4.5V to 5.5V rail or select the V/picoPower variants in the same TQFP-64 footprint for 3V systems.
Recommended
Test and Measurement Equipment
Bench and field test instruments use the ATMEGA649A-AUR as a front-panel controller managing the segment display, keypads, and configuration storage while a dedicated analog front end performs measurement. The JTAG interface supports on-chip debugging during firmware development and boundary-scan production test - both valuable for instrument OEMs maintaining long product lives. Read-while-write self-programming lets the instrument store calibration data and usage logs without external memory. The 16 MHz, 130-instruction RISC core provides deterministic timing for scan sequencing and relay control. The 5V industrial grade interfaces directly with legacy TTL-level instrument backplanes without level translation.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA649A-AUR β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA645P-AU | ATMEGA645A-AU | ATMEGA640-16AUR | ATMEGA3290P-20AUR |
|---|---|---|---|---|---|
| Package | 64-TQFP (14x14 mm) | 64-TQFP (14x14 mm) - same | 64-TQFP (14x14 mm) - same | 64-TQFP (14x14 mm) - same | 64-TQFP (14x14 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 64 KB | 64 KB | 64 KB | 64 KB | 32 KB |
| SRAM | 4 KB | 4 KB | 4 KB | 8 KB | 2 KB |
| Max Clock Speed | 16 MHz | 20 MHz | 16 MHz | 16 MHz | 20 MHz |
| LCD Controller | Yes | No (analog set) | No (analog set) | No | Yes |
| Supply Voltage | 4.5 V to 5.5 V | 2.7 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V |
| JTAG Interface | Yes | Yes | Yes | Yes | Yes |
Key Differentiators
- Integrated LCD controller with internal contrast control (vs ATMEGA640-16AUR)
- Double the Flash of LCD-equipped siblings (vs ATMEGA3290P-20AUR)
- Lower-cost LCD-plus-MCU single-chip solution (vs ATMEGA645P-AU)
Design Notes
The 'A' speed grade of the ATmega649A only reaches 16 MHz at 4.5V-5.5V. Designs specified for 3.3V operation cannot use this ordering code - select the V-grade (ATmega649V) or picoPower variants instead. Also note the peripheral mix difference versus same-footprint siblings: the 649A has an LCD controller but no ADC/DAC analog set like the 645A; verifying the peripheral map before PCB layout prevents costly respins.
Decouple each VCC pin with a 100 nF ceramic capacitor placed within a few millimeters of the pin, and connect AVCC to VCC through a low-pass RC network (e.g., 10 ohm resistor and 100 nF capacitor) to keep LCD and analog noise low. Use a solid ground plane on layer 2 of the PCB. The JTAG pins (TMS, TCK, TDO, TDI) double as port C GPIO - if they are used as outputs, include JTAG-disable firmware options or a header to retain reprogramming access.
Estimated: with 53 I/O lines, dynamic power scales with total capacitive loading - driving 20 outputs at 16 MHz with 20 pF loads each yields roughly P = C*V^2*f = 20*20pF*25V^2*16MHz approx 160 mW of I/O switching power in addition to core consumption; budget the 5V regulator accordingly. Per Microchip AVR hardware design guidance, keep unused I/O as inputs with internal pull-ups enabled to avoid floating-pin oscillation and excess current draw.
Compliance Information
The verified web data retrieved does not explicitly state RoHS/REACH/lead-free certificate values for this ordering code. As a current-production Microchip surface-mount MCU, compliance documentation should be confirmed on the Microchip product page or via certificate of conformance request.
