ATMEGA644P-15MT - 8-bit AVR MCU, 64KB Flash, 44-VQFN | Microchip
MPN: ATMEGA644P-15MT β End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.35 | $7.35 |
| 10 | $6.95 | $69.50 |
| 100 | $6.55 | $655.00 |
| 500 | $6.2 | $3,100.00 |
| 1,000 | $5.9 | $5,900.00 |
ATMEGA644P-15MT Overview
An 8-bit AVR microcontroller is a Harvard-architecture RISC processor that executes most instructions in a single clock cycle, delivering throughput close to 1 MIPS per MHz. In the power-management hierarchy of embedded systems, a microcontroller such as the ATmega644P sits at the application layer, integrating CPU, program memory, data memory, analog peripherals, and serial interfaces into a single semiconductor device.
Key features include 131 powerful instructions, most executed in a single cycle; 32 general purpose I/O lines; two USARTs for dual serial communication; a byte-oriented 2-wire interface (TWI/I2C); an SPI interface; and an 8-channel 10-bit ADC with an optional internal reference. Three flexible Timer/Counters with compare modes and PWM outputs support motor control and lighting applications, and a Real Time Counter (RTC) with separate oscillator supports timekeeping.
Technically, the picoPower CMOS process gives the ATmega644P very low active and sleep current consumption, with six power-saving modes including Idle, Power-down, Power-save, and Standby. Software-selectable clock prescalers let designers trade throughput for current, and the internal RC oscillator removes external crystals in cost-sensitive designs. The 64KB Flash supports Read-While-Write operation for safe in-system self-programming via the bootloader.
Typical applications include automotive body electronics and sensor nodes (leveraging the AEC-Q100 qualification), industrial control and HMI boards, battery-powered instrumentation, and dual-UART gateways bridging RS-232/RS-485 to system diagnostics. The dual USART and 4KB SRAM make it well suited to protocol conversion tasks that exceed smaller ATmega parts.
A key design consideration is that Microchip lists this part as a mature product, not recommended for new designs, replaced by the ATmega644PA; pin-to-pin migration to the PA variant preserves the footprint while improving power performance. Verify end-of-life status and long-term supply before committing to new layouts.
This page synthesizes distributor pricing, drop-in alternatives, design notes, and lifecycle guidance not found in the manufacturer datasheet alone.
Drop-in alternatives for ATMEGA644P-15MT 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 ATMEGA644P-15MT (same form factor and footprint) β differing in EEPROM Size, Oscillator Type, Package / Case, Program Memory Size, RAM Size.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA644PA-15MT
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA644P-20MT
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA1284P-15MT
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA324P-15MT
β Drop-Inβ In Stock
$2.97 / Unit
View Datasheet βATMEGA164P-15MT
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA644P-15MT Maximum Ratings & Electrical Characteristics
| Core Architecture | AVR 8-bit RISC |
| Program Memory Size | 64KB (32K x 16) Flash |
| RAM Size | 4KB SRAM |
| EEPROM Size | 2KB |
| Maximum Clock Speed | 16MHz |
| Supply Voltage Range | 2.7V to 5.5V |
| Number of I/O | 32 |
| USART Interfaces | 2 |
| ADC | 8-channel, 10-bit |
| Timers | 3 Timer/Counters with compare modes and PWM |
| Serial Interfaces | 2 USART, TWI (2-wire), SPI |
| Oscillator Type | Internal RC (external crystal optional) |
| Package / Case | 44-VQFN (7x7 mm) with exposed pad |
| Qualification | Automotive, AEC-Q100 |
| Technology | picoPower low-power CMOS |
| Instructions | 131, most single-cycle |
| Packaging | Tape & Reel (TR) |
| Mounting Type | Surface Mount |
| MIPS | ~1 MIPS per MHz (up to 16 MIPS at 16MHz) |
ATMEGA644P-15MT 44-vqfn (7x7 mm) with exposed pad Pin Configuration Guide
Pin configuration for ATMEGA644P-15MT (44-vqfn (7x7 mm) with exposed pad 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 ATMEGA644P-15MT.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA644P-15MT is suitable for 6 applications: Automotive Body Electronics, Industrial Control and HMI Boards, Battery-Powered Portable Instruments, Dual-UART Protocol Gateways, Sensor Acquisition Nodes, LED Lighting and PWM Control.
Automotive Body Electronics
The ATMEGA644P-15MT is AEC-Q100 qualified, making it directly suitable for automotive body modules such as light controllers, seat adjustment units, and window lift boards. Its 32 general purpose I/O lines drive relays and read switch matrices, while the three Timer/Counters with PWM outputs handle lamp dimming and motor duty control. The 8-channel 10-bit ADC reads potentiometer position and battery-sense dividers, and the dual USARTs support K-Line style diagnostics on one channel plus LIN-adjacent serial links on the other. The 2.7V to 5.5V supply range fits 5V regulated automotive rails. The 44-pin VQFN (7x7) exposed-pad package dissipates heat efficiently on automotive PCBs, and picoPower sleep modes keep standby current within module quiescent budgets.
Recommended
Industrial Control and HMI Boards
In factory automation panels and operator interfaces, the ATMEGA644P-15MT combines enough Flash for menu graphics and protocol code with enough SRAM for display buffers and command queues. The byte-oriented 2-wire interface (TWI) drives I2C displays and EEPROMs, SPI connects to encoders or external ADCs, and the 8-channel 10-bit ADC samples analog setpoint pots and sensor inputs. Two USARTs allow simultaneous RS-485 fieldbus communication and a local service/debug port. PWM-capable Timer/Counters control heater or pump drives through external power stages. The 16MHz AVR core delivers roughly 16 MIPS, sufficient for scan-cycle rates typical of small PLC logic, while the AEC-Q100 qualification provides the robustness margins industrial environments demand.
Recommended
Battery-Powered Portable Instruments
The picoPower technology of the ATmega644P makes the -15MT attractive for handheld meters, data loggers, and portable measurement instruments that must run for months on batteries. Six software-selectable sleep modes, including Power-down and Power-save, allow the Real Time Counter to wake the CPU periodically for ADC sampling of the 8-channel 10-bit converter, then return to microwatt-level standby. Software clock prescaling trades 16MHz throughput for current when full speed is unnecessary. The 64KB Flash holds logging firmware plus calibration tables, and 2KB EEPROM stores nonvolatile calibration without external memory. Designers should budget GPIO for pushbuttons and use the internal RC oscillator in low-accuracy modes to eliminate crystal cost and startup delay.
Recommended
Dual-UART Protocol Gateways
The defining peripheral of the ATmega644P versus single-UART ATmega parts is its second USART, which makes the ATMEGA644P-15MT a natural fit for protocol conversion gateways. One USART can terminate an RS-232 or RS-485 field link while the other services a modem, wireless module, or debug console. The 4KB SRAM provides room for frame buffering, CRC computation, and state machines bridging Modbus RTU, ASCII telemetry, or custom protocols. The 64KB Flash accommodates two complete protocol stacks with firmware update support via the bootloader using Read-While-Write Flash. PWM timers can additionally manage link-activity LEDs or actuator outputs, consolidating gateway and I/O functions in one AEC-Q100 qualified 44-pin VQFN device.
Recommended
Sensor Acquisition Nodes
Distributed sensor nodes benefit from the ATMEGA644P-15MT combination of an 8-channel 10-bit ADC, dual USARTs, and both SPI and TWI serial interfaces on a single MCU. Analog channels can sample voltage, current, and bridge-style sensors sequentially under firmware control, while SPI external ADCs or TWI digital sensors extend the input count beyond eight channels. The 10-bit resolution suits 0-5V industrial transducers with ratiometric measurement against the ADC reference. Sampled data streams out over USART to a host or logger, and the 2KB EEPROM retains node configuration through power cycles. The picoPower sleep modes reduce average current between sampling bursts, which is essential for nodes powered by shared 4-20mA loops or small solar supplies.
Recommended
LED Lighting and PWM Control
The three Timer/Counters with compare modes and PWM outputs let the ATMEGA644P-15MT manage multi-channel LED dimming without dedicated driver ICs on the logic side. PWM channels can independently drive MOSFET gate stages for RGB or multi-zone fixtures, with 8-bit or higher effective resolution through firmware dithering at 16MHz. The 10-bit ADC reads potentiometer or ambient-light feedback for closed-loop brightness control, and the TWI interface coordinates DALI-adjacent or DMX-style control messages over USART. The 5V-tolerant 2.7V to 5.5V operation simplifies integration with standard LED driver supply rails, and the AEC-Q100 grade supports lighting modules installed in vehicles or harsh industrial environments where qualification matters.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA644P-15MT β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA644PA-15MT | ATMEGA1284P-15MT | ATMEGA324P-15MT | ATMEGA164P-15MT |
|---|---|---|---|---|---|
| Package | 44-VQFN (7x7 mm) | 44-VQFN (7x7 mm) - same | 44-VQFN (7x7 mm) - same | 44-VQFN (7x7 mm) - same | 44-VQFN (7x7 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 64KB | 64KB | 128KB | 32KB | 16KB |
| SRAM | 4KB | 4KB | 16KB | 2KB | 1KB |
| EEPROM | 2KB | 2KB | 4KB | 1KB | 512B |
| Maximum Clock Speed | 16MHz | 16MHz (20MHz for PA-20 variants) | 16MHz | 16MHz | 16MHz |
| Supply Voltage | 2.7V to 5.5V | 1.8V to 5.5V | 2.7V to 5.5V | 2.7V to 5.5V | 2.7V to 5.5V |
| Lifecycle Status | Mature product / NRND | Active (recommended replacement) | Active | Mature product / NRND | Mature product / NRND |
| AEC-Q100 Qualification | Yes (Automotive grade) | Yes (Automotive grade) | Yes (Automotive grade) | Yes (Automotive grade) | Yes (Automotive grade) |
Key Differentiators
- Dual USARTs in the ATmega generation (vs ATMEGA324P-15MT)
- AEC-Q100 automotive qualification at 64KB Flash (vs ATMEGA1284P-15MT)
- Mature-but-replaceable lifecycle (vs ATMEGA644PA-15MT)
- picoPower low-power operation (vs ATMEGA164P-15MT)
Design Notes
The ATmega644P family has two VCC pins and two GND pins plus a separate AVCC in the 44-pin package. All supply pins must be connected: AVCC powers the ADC and Port A, and must not float even if the ADC is unused. Decouple every VCC pin with a 100nF ceramic capacitor placed within a few millimeters of the pin, plus bulk 10uF capacitance on the board. The exposed pad of the 44-VQFN (7x7) should be soldered to a ground plane for thermal and ground-integrity reasons - this is critical for ADC accuracy and EMI performance.
Because Microchip marks the ATmega644P as 'mature product; not recommended for new designs', verify lifetime supply before releasing new layouts. Plan the migration path to ATMEGA644PA-15MT early: it is pin-to-pin compatible, but check the PA datasheet for minor electrical characteristic differences (especially sleep current figures and 20MHz speed-grade availability) before reusing firmware calibration constants. Also confirm your programmer supports the part - older ISP dongles may need firmware updates for the P-generation signature bytes.
Route the ADC ground return as a quiet analog island connected to the main ground at one point near the exposed pad, keeping switching PWM return currents away from AREF and AVCC traces. Place a 100nF capacitor directly on AREF and avoid long traces from XTAL1/XTAL2 to the crystal - keep the crystal within 5mm with 22pF load capacitors per the datasheet. Since the QFN exposed pad must be grounded, ensure sufficient via stitching (at least 5-9 vias) beneath the pad for reliable soldering and low-inductance ground.
Estimated: an ATmega644P running at 5V, 16MHz with all peripherals active typically draws on the order of 10-20mA, dissipating roughly 50-100mW - well within the 44-VQFN (7x7) exposed-pad package capability with no heatsink. Thermal design becomes a concern only if the device drives high continuous GPIO loads; per datasheet absolute maximum, limit total package power dissipation and per-pin sink/source current (20mA DC per I/O pin) to avoid exceeding junction ratings.
Compliance Information
AEC-Q100 automotive qualification is explicitly stated in verified distributor data ('Automotive, AEC-Q100'). RoHS/REACH/lead-free status not stated in provided data - verify on the Microchip product page or datasheet.