ATMEGA645P-MU - 8-Bit AVR MCU 64KB 16MHz 64-QFN | Microchip
MPN: ATMEGA645P-MU ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.42 | $6.42 |
| 10 | $5.78 | $57.80 |
| 100 | $5.12 | $512.00 |
| 500 | $4.65 | $2,325.00 |
| 1,000 | $4.21 | $4,210.00 |
ATMEGA645P-MU Overview
An 8-bit AVR microcontroller is a Harvard-architecture RISC processor that executes most instructions in a single clock cycle, making it a mainstay of the broader embedded microcontroller and power-management hierarchy for cost-sensitive control applications. The ATmega family from Microchip (originally Atmel) is one of the most widely deployed 8-bit MCU platforms in industrial and consumer designs.
Key features include 64 KB of self-programmable ISP Flash with read-while-write capability, a picoPower technology portfolio for low active and sleep currents, 32 general-purpose working registers, an on-chip LCD controller (segment drive) inherited from the ATmega645/6490 family, JTAG for on-chip debugging, and a rich peripheral set including 8-channel 10-bit ADC, USART, SPI, and two-wire interface (I2C).
Technically, the AVR core achieves close to 1 MIPS per MHz, so at the 16 MHz maximum clock the device delivers roughly 16 MIPS throughput. Operating voltage spans 2.7 V to 5.5 V for the 16 MHz speed grade, and the picoPower P-suffix die improves sleep-mode consumption relative to the non-P ATmega645, benefiting battery-powered designs.
Typical applications include industrial control panels with LCD displays, building automation and HVAC controllers, battery-operated metering, and consumer appliance user interfaces where on-chip segment LCD driving reduces BOM cost.
A key design consideration: the 64-QFN package exposes a large center die pad that must be soldered to a grounded PCB thermal pad for reliable operation and mechanical integrity, and QFN rework requires skilled profiling.
This page synthesizes distributor pricing, drop-in family alternatives, and practical design notes not found in the manufacturer datasheet, with all key data verified against live distributor listings as of 2026-09-18.
Drop-in alternatives for ATMEGA645P-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 ATMEGA645P-MU (same form factor and footprint) — differing in Package, ADC Resolution, Core Processor, Flash Memory, Number of I/O.
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Request AlternativesATMEGA645P-MU Maximum Ratings & Electrical Characteristics
| Core Processor | AVR 8-bit RISC |
| Core Size | 8-bit |
| Speed | 16 MHz |
| Flash Memory | 64 KB (32K x 16) ISP |
| EEPROM | 2 KB |
| SRAM | 4 KB |
| GPIO Count | 54 |
| Operating Voltage Range | 2.7 V to 5.5 V |
| ADC Resolution | 10-bit |
| ADC Channels | 8 |
| Peripherals | LCD controller, Brown-out Detect/Reset, POR, PWM, WDT |
| Connectivity | SPI, UART/USART, TWI (I2C) |
| Package | 64-QFN (9x9 mm) MLF, surface mount |
| Technology Feature | picoPower low-power technology |
| Debug Interface | JTAG |
| RoHS Status | Green / RoHS compliant (per FindIC listing) |
| Mounting Type | Surface Mount |
ATMEGA645P-MU 64-qfn (9x9 mm) mlf, surface mount Pin Configuration Guide
Pin configuration for ATMEGA645P-MU (64-qfn (9x9 mm) mlf, surface mount 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-MU.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA645P-MU is suitable for 6 applications: Industrial Control Panels with LCD, Battery-Powered Metering, Building Automation and HVAC Controllers, Consumer Appliance User Interfaces, Portable Instrumentation and Handheld Test Tools, Security and Access Control Panels.
Industrial Control Panels with LCD
The ATMEGA645P-MU fits industrial HMI panels because its integrated segment LCD controller drives the display directly, and its 54 GPIO lines handle keypad scanning, relays, and status LEDs without port expanders. The 10-bit, 8-channel ADC reads potentiometers, thermistors, and 4-20 mA-conditioned sensor inputs, while the USART connects to RS-485 transceivers for Modbus-style field buses. In a typical panel, the MCU runs at 8-16 MHz from a 5 V rail with brown-out reset enabled, using the 64 KB Flash to hold multi-language menu structures and logged data in the 2 KB EEPROM. Because LCD drive is on-chip, BOM cost and board area shrink versus a discrete LCD driver plus generic MCU, and the picoPower die keeps standby current low when the panel is dimmed or asleep.
Recommended
Battery-Powered Metering
Utility submeters and battery-powered gauge products benefit from the ATMEGA645P-MU's combination of picoPower sleep modes, 2.7 V minimum supply, and on-chip LCD drive. The MCU spends most of its life in power-down, waking on a UART byte, timer, or ADC event to sample energy pulses from an ADE-class or shunt-based front end via the 10-bit ADC. The 2 KB EEPROM stores calibration coefficients and billing registers that must survive battery replacement, and the 64 KB Flash accommodates tabulated tariff schedules and communication stacks. A design running from a 3 V lithium cell should disable unused peripherals in the power reduction register and use the internal RC oscillator in sleep-adjacent states, resuming the 16 MHz crystal clock only during measurement and radio bursts.
Recommended
Building Automation and HVAC Controllers
Zone controllers, thermostats, and damper actuators use the ATMEGA645P-MU's blend of analog and communication peripherals. The 8-channel 10-bit ADC digitizes NTC thermistor networks for room, coil, and outdoor temperature sensing, while PWM outputs from the timers drive triac or DC-fan stages through optocoupled drivers. The TWI (I2C) bus reads humidity and pressure sensors, and the USART, buffered by an RS-485 transceiver, participates in BACnet-MS/TP-style multidrop networks. The 64 KB Flash is large enough for PID control law, scheduling tables, and OTA-style firmware staging into EEPROM shadow regions. The wide 2.7-5.5 V supply range allows direct operation from transformer-derived supplies with modest regulation, and brown-out detection protects EEPROM writes during brown-out events on HVAC line sags.
Recommended
Consumer Appliance User Interfaces
Ovens, washing machines, and coffee machines need exactly the feature mix the ATMEGA645P-MU provides: a segment LCD for cycle display, button and encoder inputs on the 54 GPIO lines, ADC for temperature probes and user analog controls, and robust 64 KB Flash for multi-mode firmware. The device is typically clocked from an internal RC or ceramic resonator to save cost, with the 16 MHz ceiling reserved for responsiveness during display multiplexing. EEPROM retains user preferences and cycle counters across power cycles. The industrial temperature listing tolerates the elevated ambient near appliance control boards, though designers should keep the MCU away from heating elements and verify that the QFN center pad solder joint remains reliable under long-term thermal cycling typical of kitchen environments.
Recommended
Portable Instrumentation and Handheld Test Tools
Handheld meters, data loggers, and portable measurement instruments exploit the ATMEGA645P-MU's low sleep current, LCD interface, and 10-bit ADC in a single chip. A typical logger sleeps at microamp-class draw, wakes on a push-button or RTC tick, takes an ADC reading through an op-amp-conditioned front end, stores results in EEPROM or external SPI Flash via the hardware SPI port, and updates the segment LCD. The 64 KB Flash holds calibration tables, USB- or UART-based dump routines, and multi-protocol instrument logic. Because the whole signal chain runs from 2 AA cells through a small LDO, the picoPower die's reduced standby consumption directly extends battery service intervals compared with the non-P ATmega645, which is the primary reason to specify the P suffix in portable designs.
Recommended
Security and Access Control Panels
Keypad access controllers and small alarm panels map naturally onto the ATMEGA645P-MU: GPIO scans a 4x4 keypad and drives zone LEDs, the ADC reads tamper-loop and backup-battery voltages, and the USART with an RS-485 transceiver reports to a panel master. The 2 KB EEPROM stores user code tables and event queues that must persist through power loss, while the WDT guards against firmware lockups in an always-on security context. The 64 KB Flash accommodates encryption routines for rolling-code or challenge-response credential checking. Designers should enable brown-out detection and write EEPROM update routines with wear-leveling, since credential writes accumulate over the product's life, and should power the MCU from a supervised, battery-backed rail given the security-critical role.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA645P-MU — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA645-16MUR | ATMEGA6450P-MU | ATMEGA325P-MU | ATMEGA3250P-MU |
|---|---|---|---|---|---|
| Package | 64-QFN (9x9 mm) MLF | 64-QFN (9x9 mm) MLF - same | 64-QFN (9x9 mm) MLF - same | 64-QFN (9x9 mm) MLF - same | 64-QFN (9x9 mm) MLF - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 64 KB | 64 KB | 64 KB | 32 KB | 32 KB |
| SRAM | 4 KB | 4 KB | 4 KB | 2 KB | 2 KB |
| EEPROM | 2 KB | 2 KB | 2 KB | 1 KB | 1 KB |
| Max Clock Speed | 16 MHz | 16 MHz | 16 MHz | 16 MHz | 16 MHz |
| picoPower Low-Power Die | Yes (P suffix) | No (non-P die) | Yes (P die) | Yes (P die) | Yes (P die) |
| LCD Controller | Yes (segment LCD) | Yes (segment LCD) | Yes (extended segments) | Yes (segment LCD) | Yes (extended segments) |
Key Differentiators
- picoPower low-power die in LCD-capable 64-pin package (vs ATMEGA645-16MUR)
- Full 64 KB Flash with integrated segment LCD drive (vs ATMEGA325P-MU)
- Single-chip HMI integration (vs ATMEGA6450P-MU)
Design Notes
The 64-QFN (MLF) package has a large exposed center die pad that is the device's ground and thermal anchor. The PCB must include a matching center pad with an array of via stitching (typically 4x4 or more) to the ground plane. Incomplete or voided center-pad soldering is the leading cause of intermittent ground returns and field failures on MLF megaAVR designs. Follow Microchip's MLF reflow profiling guidance; hand soldering is practical only with hot-air and via-in-pad inspection.
Decouple AVCC separately from VCC with an LC or RC filter (for example a 10 uH inductor or 100-ohm resistor plus 100 nF capacitor) so ADC noise from the digital rail is suppressed; tie AVCC to VCC through this filter and never leave AVCC unconnected. Place 100 nF ceramic capacitors at each VCC/AVCC pin pair. Enable brown-out detection at a threshold above the minimum 2.7 V operating point appropriate to your clock speed to protect EEPROM writes during supply collapse.
JTAG shares pins with port C and is enabled by fuse on most megaAVR parts; if your application uses port C as GPIO, disable JTAG via fuse or the JTD bit in MCUCSR early in initialization. Also note that Flash self-programming (read-while-write) requires careful bootloader section fuse configuration, and EEPROM writes are blocked for the duration of a write cycle - poll EEWE before issuing new writes to avoid silent data loss.
Compliance Information
Listed as Green/RoHS compliant per FindIC and distributor listings. AEC-Q100 not claimed in provided data; treat as not automotive qualified. REACH and halogen-free status not found in verified sources.
