ATMEGA645-16MI - 8-Bit AVR MCU 16MHz 64KB Flash | Microchip
MPN: ATMEGA645-16MI ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.2 | $6.20 |
| 10 | $5.58 | $55.80 |
| 100 | $4.96 | $496.00 |
| 500 | $4.4 | $2,200.00 |
| 1,000 | $3.92 | $3,920.00 |
ATMEGA645-16MI Overview
An 8-bit AVR microcontroller is a Harvard-architecture RISC processor that executes most of its 130 powerful instructions in a single clock cycle. In the system hierarchy, the ATmega645 sits in the ATmega family of flash-based MCUs, positioned above the ATmega325 and below the ATmega1281, and is a core building block of embedded power management and control systems.
Key features include a 16MHz maximum core clock (16 MIPS throughput at 16MHz Dhrystone), 53 programmable I/O lines, an 8-channel 10-bit ADC, and an on-chip JTAG interface for boundary-scan and on-chip debugging. The device also integrates a segment LCD controller, making it distinct from the ATmega644 and other same-pin-count AVR parts. Boot-code self-programming enables in-system reprogramming over SPI, UART, or JTAG.
Architecturally, the ATmega645 uses the advanced AVR RISC core with 32 general-purpose working registers directly connected to the ALU, allowing two independent registers to be accessed in one instruction executed in one clock cycle. Read-While-Write Flash capability allows code updates while the program is running. Low-power modes including Idle, Power-down, Power-save, and Standby reduce consumption for battery-powered designs.
Typical applications include industrial control panels with LCD user interfaces, battery-powered metering, HVAC controllers, and consumer appliances that benefit from the integrated LCD driver and 10-bit ADC.
Design consideration: the -16MI speed grade is rated for 16MHz across the full industrial temperature range, but analog ADC accuracy and Flash endurance figures degrade near the extremes, so verify operating margins at maximum ambient.
This page synthesizes distributor stock data, drop-in alternative analysis, and practical design guidance not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA645-16MI — 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 ATMEGA645-16MI (same form factor and footprint) — differing in Package, ADC Channels, Debug Interface, Number of I/O, Program Memory Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA645-16MU
✅ Drop-In✓ In Stock
$4.65 / Unit
View Datasheet →ATMEGA325-16MI
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$3.05 / Unit
View Datasheet →ATMEGA645-16MI Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Core Clock Speed | 16 MHz |
| Program Memory Size | 64 KB (32K x 16) Flash |
| Program Memory Type | In-System Programmable FLASH |
| SRAM Size | 4 KB |
| EEPROM Size | 2 KB |
| Number of I/O | 53 programmable I/O lines |
| ADC Resolution | 10-bit |
| ADC Channels | 8 |
| LCD Controller | Yes (segment LCD driver) |
| Debug Interface | JTAG (on-chip debug, boundary scan) |
| Package | 64-QFN (9x9 mm) |
| Mounting Type | Surface Mount |
| Temperature Grade | Industrial (-I suffix) |
| Instructions | 130 powerful instructions, most single-cycle |
ATMEGA645-16MI 64-qfn (9x9 mm) Pin Configuration Guide
Pin configuration for ATMEGA645-16MI (64-qfn (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 ATMEGA645-16MI.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA645-16MI is suitable for 6 applications: Industrial Control Panels with LCD, Battery-Powered Metering, HVAC and Building Automation Controllers, Consumer Appliance Displays, Portable Test and Measurement Instruments, Automotive-Adjacent and Security Panel Electronics.
Industrial Control Panels with LCD
The ATMEGA645-16MI is a natural fit for industrial HMI panels because it integrates a segment LCD controller directly on-chip, eliminating an external LCD driver IC and its SPI/I2C bus overhead. With 53 programmable I/O lines, one device can drive the LCD, scan a key matrix, and control relays or LEDs simultaneously. The 64KB ISP Flash accommodates multi-language menu structures and firmware field updates via boot-loader self-programming, while the 8-channel 10-bit ADC reads potentiometers, sensors, and supply-monitoring dividers. The 16MHz core executes most of its 130 instructions in a single cycle, keeping menu response times well under human-perception thresholds. Industrial temperature grading (-I suffix) supports panel environments up to the datasheet industrial limit.
Recommended
Battery-Powered Metering
For electricity, water, and heat meters, the ATMEGA645-16MI combines the segment LCD driver, a low-power AVR core, and multiple sleep modes (Idle, Power-down, Power-save, Standby) in one die, minimizing bill-of-materials and quiescent drain. The 8-channel 10-bit ADC samples current and voltage sensing channels, while 2KB EEPROM stores calibration coefficients and accumulated consumption records through power cycles. The 16MHz single-cycle RISC core lets the meter complete accumulation math rapidly and return to Power-save, extending battery life in the field. Boot-loader-based Flash reprogramming over UART or SPI allows metrology firmware updates without opening the meter enclosure, an important field-service cost saver for utilities deploying large installed bases.
Recommended
HVAC and Building Automation Controllers
The ATMEGA645-16MI suits thermostat and zone-controller boards where a display, sensors, and actuation converge. The integrated LCD controller drives temperature and setpoint digits directly, the 10-bit ADC reads NTC thermistors and humidity dividers across its 8 channels, and the 53 I/O lines operate valve and damper drives. The 64KB Flash is large enough to hold PID control loops, scheduling tables, and communication stacks, and the JTAG interface supports boundary-scan test on production boards as well as on-chip debugging during development. Industrial temperature grading tolerates control-cabinet ambient conditions, and Read-While-Write Flash allows the boot section to update application firmware over a building-management UART link without interrupting control output during the update cycle.
Recommended
Consumer Appliance Displays
Appliances such as ovens, washing machines, and coffee machines need a segmented display, a key-scanner, and relay or triac control - exactly the combination the ATMEGA645-16MI integrates. The on-chip LCD controller drives digits and icons without external drivers, cutting BOM cost and board area in cost-sensitive products. The 16MHz throughput handles UI event processing and safety-logic polling with margin, and the 64KB Flash stores multiple wash/heat programs plus diagnostics logs in EEPROM. In-system programmability supports end-of-line firmware configuration on the production floor: the same unprogrammed PCB serves multiple SKU variants, reducing inventory complexity. The 64-pin QFN 9x9 mm footprint keeps controller electronics compact behind the user interface panel.
Recommended
Portable Test and Measurement Instruments
Handheld meters and dataloggers benefit from the ATMEGA645-16MI's balance of low power, LCD, ADC, and debug capability. The 8-channel 10-bit ADC digitizes measurement front ends, while the JTAG interface enables both on-chip debugging during firmware bring-up and boundary-scan manufacturing test of the populated PCB. The 16MHz clock gives sufficient compute for averaging, scaling, and linearization math in firmware, and the 4KB SRAM holds rolling data buffers for logging to EEPROM. Sleep modes keep standby drain low between measurements, and the industrial-grade -16MI speed rating holds across the specified temperature range for field instruments. The self-programming Flash supports in-field firmware updates through a maintenance UART or USB-serial bridge.
Recommended
Automotive-Adjacent and Security Panel Electronics
Access-control keypads, alarm panels, and parking/entry terminals use the ATMEGA645-16MI for its combination of a large I/O count, LCD feedback, and robust Flash architecture. The 53 GPIO lines scan large key matrices and drive locking outputs, the LCD controller shows entry status and menus, and the 2KB EEPROM retains user codes and event counters through power interruptions. The 64KB program space supports rolling-code algorithms and multi-tenant menu logic. JTAG boundary scan simplifies production test of densely populated security boards, and Power-save mode keeps standby current acceptable for mains-backed battery-reserve operation. Note that this part is not AEC-Q100 qualified, so it targets building and light-vehicle-adjacent electronics rather than in-powertrain automotive systems.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA645-16MI — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA645-16MU | ATMEGA325-16MI |
|---|---|---|---|
| Package | 64-QFN (9x9 mm) | 64-QFN (9x9 mm) - same | 64-QFN (9x9 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology |
| Core Clock | 16 MHz | 16 MHz | 16 MHz |
| Program Flash | 64 KB | 64 KB | 32 KB (-50%) |
| SRAM | 4 KB | 4 KB | 2 KB (-50%) |
| EEPROM | 2 KB | 2 KB | 1 KB |
| LCD Controller | Yes | Yes | Yes |
| I/O Lines | 53 | 53 | 53 |
| Temperature Grade | Industrial (-I) | Industrial | Industrial (-I) |
Key Differentiators
- Integrated segment LCD controller (vs ATMEGA64-16MI)
- Double the program memory of the footprint-identical sibling (vs ATMEGA325-16MI)
- Single-cycle RISC efficiency (vs ATMEGA645-16MU)
Design Notes
Estimated: a 64-QFN 9x9 AVR running at 16MHz with 20pF load capacitance typically draws several mA active plus I/O load current; budget the 3.3V or 5V rail accordingly and place 100nF ceramic decoupling on every VCC/AVCC pin pair plus 10uF bulk near the package. The ADC needs a clean AVCC, so feed it through an LC filter or ferrite bead from the digital rail to keep 10-bit ENOB across all 8 channels.
The 64-QFN (9x9) MLF package has an exposed die pad underneath that must be soldered to a grounded copper area with an array of thermal vias - this pad is the primary ground and heat path, and skipping it causes both elevated junction temperature and unreliable ground returns. Use ~4 to 5 mil stencil apertures with roughly 50-60% coverage on the pad to avoid voiding and floating.
Do not assume pin compatibility outside the ATmega325/645 family: the ATmega644 has a similar peripheral set but a different pinout on its packages, so substituting it on an ATmega645 footprint will not work. When programming via ISP, the 64KB device needs the correct device signature check in the programmer settings; selecting the wrong ATmega signature causes verification failure. Also verify JTAG fuse state - enabling JTAG consumes four port pins.
Compliance Information
Compliance data was not present in the retrieved web data; verify RoHS/REACH status on the official Microchip product page before ordering. Not AEC-Q100 qualified - do not use in automotive powertrain/safety applications.
