ATMEGA645P-MUR - 8-bit AVR MCU 64KB Flash 16MHz | Microchip
MPN: ATMEGA645P-MUR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.84 | $6.84 |
| 10 | $6.5 | $65.00 |
| 100 | $5.95 | $595.00 |
| 500 | $5.5 | $2,750.00 |
| 1,000 | $5.05 | $5,050.00 |
ATMEGA645P-MUR Overview
An 8-bit AVR microcontroller is a Harvard-architecture processor that executes most instructions in a single clock cycle, sitting within the broader hierarchy of embedded processors: ATmega family -> AVR 8-bit MCU -> microcontroller unit (MCU) -> semiconductor integrated circuit. MCUs integrate CPU, memory, and peripherals such as timers, UART, SPI, and ADC on one die, replacing multi-chip solutions in cost- and space-sensitive embedded designs.
Key features of the ATMEGA645P include picoPower technology for low power consumption, read-while-write Flash for self-programming bootloaders, 32 general purpose working registers, and an on-chip 10-bit ADC. The picoPower process and multiple sleep modes make it suitable for battery-aware and low-duty-cycle applications without sacrificing the industry-standard AVR instruction set and toolchain compatibility.
Technically, the device is based on the enhanced AVR RISC core with single-cycle instruction execution, achieving up to 16 MIPS throughput at 16 MHz. In-system programmable (ISP) Flash with read-while-write support enables firmware updates in the field via SPI or a bootloader, while JTAG-boundary considerations and lock bits protect intellectual property. Supply operation at 4.5-5.5 V targets 5 V industrial noise-margin environments.
Typical applications include industrial control and automation nodes, consumer appliances, HVAC and building control systems, and sensor-interface boards where 5 V compatibility and a large peripheral set simplify board-level design.
A key design consideration: the ATmega645P-16 is a 5 V part (4.5-5.5 V); for 2.7-5.5 V operation at reduced speed, select the ATmega645V speed-grade variant instead. Ensure adequate decoupling and exposed-pad grounding on the QFN for signal integrity.
This page synthesizes verified distributor pricing, drop-in family alternatives, practical design notes, and application guidance not consolidated in the manufacturer datasheet.
Drop-in alternatives for ATMEGA645P-MUR — 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 ATMEGA645P-MUR (same form factor and footprint) — differing in Package, LCD Controller, Operating Temperature, ADC, Communication Interfaces.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA649P-MUR
✅ Drop-In✓ In Stock
$5.1 / Unit
View Datasheet →ATMEGA645A-MU
✅ Drop-In✓ In Stock
$3.7 / Unit
View Datasheet →ATMEGA645-16MUR
✅ Drop-In✓ In Stock
$3.35 / Unit
View Datasheet →ATMEGA649A-MUR
✅ Drop-In📋 Reference alternative (not in catalog)
ATMEGA329PA-MUR
✅ Drop-In✓ In Stock
$3.85 / Unit
View Datasheet →ATMEGA645P-MUR Maximum Ratings & Electrical Characteristics
| Core Processor | AVR |
| Core Size | 8-Bit |
| Speed | 16 MHz |
| Flash Memory | 64 KB (32K x 16) |
| EEPROM | 2 KB |
| SRAM | 4 KB |
| Supply Voltage | 4.5 V to 5.5 V |
| I/O Count | 53 (54/69 general purpose I/O per family) |
| Connectivity | SPI, UART/USART |
| Package | 64-VFQFN Exposed Pad (9x9 mm) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (IND grade) |
| Architecture | AVR RISC, single-cycle instructions |
| Programming | In-System Programmable (ISP) Flash, read-while-write |
| Technology | picoPower |
| Life Cycle Stage | Active |
| Packaging | Tape & Reel (TR) |
ATMEGA645P-MUR 64-vfqfn exposed pad (9x9 mm) Pin Configuration Guide
Pin configuration for ATMEGA645P-MUR (64-vfqfn exposed pad (9x9 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 ATMEGA645P-MUR.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA645P-MUR is suitable for 6 applications: Industrial Control and Automation, Building Automation and HVAC, Sensor Interface and Data Acquisition, Consumer Appliances, Instrumentation and Test Equipment, Motor Control and Actuation.
Industrial Control and Automation
The ATMEGA645P-MUR fits industrial control nodes because its 4.5-5.5 V supply matches 5 V industrial logic with high noise margin, its industrial grade supports -40C to +85C, and 53 I/O lines interface directly with relays, sensors, and front panels. The 16 MHz AVR core delivers up to 16 MIPS for deterministic control loops, while SPI and UART handle field communication to drivers and HMI boards. Designers typically run the MCU from a regulated 5 V rail with TVS protection on field-wired inputs; the 64 KB Flash accommodates protocol stacks and diagnostics that smaller AVRs cannot hold, making the 645P a cost-effective single-chip controller for PLC I/O modules and machine sub-controllers.
Recommended
Building Automation and HVAC
HVAC and building-control boards benefit from the ATMEGA645P-MUR's combination of picoPower sleep modes, 53 GPIOs for damper/valve control and keypad scanning, and a 10-bit ADC for temperature and humidity sensor acquisition. Its 4.5-5.5 V supply tolerates poorly regulated 5 V rails common in HVAC control cabinets, and the industrial temperature grade covers rooftop and mechanical-room environments. Firmware for PID loops, schedules, and Modbus-style UART protocols fits comfortably in 64 KB Flash with 4 KB SRAM for data logging. In use, the MCU sleeps between task ticks to cut average current, waking via timer; the read-while-write Flash enables in-field firmware updates through a UART bootloader without removing the unit from service.
Recommended
Sensor Interface and Data Acquisition
For multi-channel sensor boards, the ATMEGA645P-MUR provides a 10-bit ADC multiplexed across many port pins, 4 KB SRAM for sample buffering, and 2 KB EEPROM for calibration constants that persist across power cycles. The 5 V supply simplifies interfacing with ratiometric sensors whose full-scale output is tied to the 5 V rail, eliminating level-shifting stages. Its 16 MIPS throughput supports oversampling and digital filtering in firmware, and the QFN-64 footprint concentrates 53 I/O lines in 9x9 mm, letting one MCU replace several smaller devices on dense acquisition boards. Designers should keep analog reference routing separate from digital grounds and use the exposed pad as a low-impedance ground return to protect ADC accuracy.
Recommended
Consumer Appliances
White goods and appliance control boards use the ATMEGA645P-MUR for its generous 64 KB Flash (supporting multi-language UIs and motor-control code), 53 I/O for button matrices, LEDs, and load relays, and robust 5 V operation tolerant of noisy appliance environments. The picoPower process keeps standby current low enough for energy-star standby requirements when the MCU idles in power-down mode between user inputs. The industrial temperature rating adds margin for compartments near heat sources such as ovens or compressor electronics. In these designs the UART typically links to a display module or main board, while SPI manages external EEPROM or RF modules; bootloader-based firmware updates allow feature upgrades after production without board recall.
Recommended
Instrumentation and Test Equipment
Bench and portable instruments leverage the ATMEGA645P-MUR's single-cycle AVR RISC core for responsive front-panel handling, its ADC for metering functions, and 64 KB Flash for menu systems, calibration routines, and communication firmware. The 5 V supply directly drives LED segments and drives 5 V logic interfaces found on legacy instrument backplanes, while SPI supports high-speed links to dedicated converter or display ICs. The QFN-64 exposed-pad package provides a compact, thermally sound footprint for handheld enclosures, and read-while-write Flash lets the device log calibration data to its own program Flash region or EEPROM during operation. For precision front ends, pair the MCU with an external higher-resolution ADC over SPI rather than relying solely on the internal 10-bit converter.
Recommended
Motor Control and Actuation
The ATMEGA645P-MUR supervises small motor and actuator systems: 53 GPIOs generate PWM for H-bridge or gate drivers, timer peripherals schedule commutation, and the 16 MHz core executes control loops fast enough for DC and stepper motor applications. Its 5 V I/O drives standard MOSFET driver logic thresholds directly, and the ADC reads current-sense shunt amplifiers for protection. The 64-QFN package's low-inductance grounded exposed pad helps contain PWM switching noise, provided decoupling capacitors sit at every supply pin. For three-phase or high-power systems, the ATmega645P acts as the supervisory controller communicating over UART/SPI with a dedicated driver stage, combining protocol handling and safety logic in one 5 V industrial-grade device.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA645P-MUR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA649P-MUR | ATMEGA645A-MU | ATMEGA645-16MUR | ATMEGA329PA-MUR |
|---|---|---|---|---|---|
| Package | 64-VFQFN (9x9) Exposed Pad | 64-VFQFN (9x9) Exposed Pad - same | 64-VFQFN (9x9) Exposed Pad - same | 64-VFQFN (9x9) Exposed Pad - same | 64-VFQFN (9x9) Exposed Pad - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Core / Speed | AVR 8-bit, 16 MHz | AVR 8-bit, 16 MHz | AVR 8-bit, 16 MHz | AVR 8-bit, 16 MHz | AVR 8-bit, 16 MHz |
| Flash Memory | 64 KB | 64 KB | 64 KB | 64 KB | 32 KB |
| LCD Controller | No | Yes | No | No | Yes |
| Technology Generation | picoPower (P) | picoPower (P) | A generation | Original generation | picoPower (PA) |
Key Differentiators
- picoPower generation with lower sleep current (vs ATMEGA645-16MUR)
- Maximum memory in 64-pin non-LCD family member (vs ATMEGA329PA-MUR)
- Lower cost than LCD-equipped siblings (vs ATMEGA649P-MUR)
Design Notes
The 64-VFQFN exposed pad must be soldered to a grounded thermal pad on the PCB. Use a 4x4 or 5x5 via array under the pad, connected to the internal ground plane, to provide both heat dissipation and a low-inductance ground return. For assembly, apply solder paste in an array of small apertures (60-70% coverage) rather than one large window to prevent voiding and component float during reflow. Per Microchip QFN layout guidance, do not route signals directly under the exposed pad region.
Place 100 nF ceramic decoupling capacitors at every VCC/GND pin pair, as close to the package as possible, plus one bulk 10 uF capacitor near the supply entry. The ATmega645P-16 is specified for 4.5-5.5 V; if your rail is 3.3 V the part will not meet the 16 MHz speed specification and may fail to start. Verify the datasheet speed-versus-voltage curve before finalizing the power tree, and budget active current using the datasheet ICC tables rather than estimates for battery-powered designs.
Keep the ADC reference (AVCC/AREF) routing star-connected to the analog supply with its own RC filter, separate from digital return currents flowing to the exposed pad. Route crystal (XTAL1/XTAL2) traces short and guarded by ground, with load capacitors selected per the crystal datasheet. GPIO driving relay coils or PWM motor drivers should use series resistors and flyback protection; do not exceed the datasheet per-pin and total current limits. These practices preserve the 10-bit ADC accuracy in mixed-signal layouts.
A frequent substitution error is swapping ATmega645P for family members with an LCD controller (ATmega649P): the die is largely pin-compatible, but pins shared with LCD segment drives change electrical behavior when the LCD is enabled. Also, firmware compiled for non-picoPower generations may need updated sleep-mode register settings to achieve specified picoPower currents. Always re-verify the pin multiplexing table and fuse settings from the current Microchip datasheet revision before migrating BOMs between generations.
Compliance Information
Compliance statuses not stated in the provided verified data; confirm on the Microchip product page before ordering. Commercial/industrial (not automotive) AVR part.
