ATMEGA644P-15AT - 8-bit AVR MCU 64KB Flash 16MHz TQFP-44 | Microchip
MPN: ATMEGA644P-15AT ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.9 | $7.90 |
| 10 | $7.11 | $71.10 |
| 100 | $6.32 | $632.00 |
| 500 | $5.53 | $2,765.00 |
| 1,000 | $4.74 | $4,740.00 |
ATMEGA644P-15AT Overview
A microcontroller (MCU) is a single-chip computer that integrates a processor core, program memory, data memory, and peripherals such as timers, serial interfaces, and analog-to-digital converters. The ATmega644P sits in the mid-to-high range of the AVR ATmega family hierarchy: ATmega48 < ATmega164P < ATmega324P < ATmega644P < ATmega1284, all sharing the AVR 8-bit RISC architecture and picoPower low-power technology.
Key features include 32 general purpose I/O lines, two USARTs (the 'P' variant adds a second serial port over the ATmega644), an 8-channel 10-bit ADC with optional differential inputs and gain stages, a byte-oriented 2-wire serial interface (TWI/I2C), SPI, three flexible Timer/Counters with compare modes and PWM, a Real Time Counter (RTC), and a programmable Watchdog Timer. The picoPower core supports low-voltage operation down to 1.8V in family variants and delivers decreased power consumption versus earlier ATmega devices.
The device is qualified per AEC-Q100 grade 1 per Microchip qualification documentation, supporting automotive-adjacent and industrial temperature requirements. In-system programmable Flash with Read-While-Write capability allows firmware updates without removing the chip, while boot-code sections enable self-programming for field upgrades.
Typical applications include industrial automation and control nodes, embedded sensor data acquisition using the 10-bit ADC, RS-232/RS-485 communication gateways exploiting the dual USARTs, and hobby/Arduino-compatible designs supported by the MightyCore hardware package.
When designing with this part, budget the two-cycle load/store architecture and verify crystal drive levels; keep VCC and AVCC decoupled and observe the 10x10 mm TQFP land pattern for reflow.
This page synthesizes verified distributor listings, AEC-Q100 qualification references, drop-in family alternatives (including the ATmega644PA successor), and practical design notes not consolidated in the manufacturer datasheet.
Drop-in alternatives for ATMEGA644P-15AT — 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-15AT (same form factor and footprint) — differing in RoHS Status, Core Architecture, Program Memory Size, Timers/Counters, ADC.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA644PA-AU
✅ Drop-In✓ In Stock
$2.49 / Unit
View Datasheet →ATMEGA644P-20AU
✅ Drop-In✓ In Stock
$3.95 / Unit
View Datasheet →ATMEGA644PA-AUR
✅ Drop-In✓ In Stock
$1.78 / Unit
View Datasheet →ATMEGA644-20AU
✅ Drop-In✓ In Stock
$4.96 / Unit
View Datasheet →ATMEGA644PV-10AUR
✅ Drop-In📋 Reference alternative (not in catalog)
ATMEGA644P-15AT Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR enhanced RISC |
| Core Size | 8-bit |
| Program Memory Size | 64KB (32K x 16) Flash |
| Program Memory Type | FLASH (In-System Programmable, Read-While-Write) |
| SRAM Size | 4KB |
| EEPROM Size | 2KB |
| Clock Speed | 16 MHz |
| MIPS | Up to 1 MIPS per MHz (approx. 16 MIPS at 16 MHz) |
| Supply Voltage (VCC) | 5 V (family supports 2.5V/3.3V/5V variants) |
| GPIO Count | 32 general purpose I/O lines |
| ADC Resolution | 10-bit, 8 channels |
| USART Count | 2 |
| Serial Interfaces | 2x USART, TWI (I2C), SPI |
| Timers/Counters | 3 Timer/Counters with compare modes and PWM; Real Time Counter (RTC) |
| Package | 44-TQFP (10x10 mm) |
| Mounting Type | Surface Mount |
| Qualification | AEC-Q100 grade 1 (per product qualification documentation) |
| Technology | picoPower low-power CMOS |
| Watchdog Timer | Yes, programmable with separate oscillator |
ATMEGA644P-15AT 44-tqfp (10x10 mm) Pin Configuration Guide
Pin configuration for ATMEGA644P-15AT (44-tqfp (10x10 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 ATMEGA644P-15AT.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA644P-15AT is suitable for 6 applications: Industrial Automation and Control Nodes, Embedded Sensor Data Acquisition, Serial Communication Gateways and Converters, Arduino-Compatible Development and Prototyping, Automotive Auxiliary Control Units, Low-Power Battery-Powered Instruments.
Industrial Automation and Control Nodes
The ATMEGA644P-15AT fits industrial control nodes because its 64KB Flash accommodates protocol stacks and state machines that outgrow 32KB parts, while AEC-Q100 grade 1 qualification supports the extended temperature reliability that factory-floor environments demand. In a typical node it reads sensors through the 8-channel 10-bit ADC (optionally differential with gain for bridge sensors), drives actuators and PWM channels via its three Timer/Counters, and reports upstream over RS-485 using one of the two USARTs. Running at 16MHz yields roughly 16 MIPS, adequate for deterministic scan loops under 1ms. The programmable Watchdog Timer with its own oscillator recovers from firmware hangs, and in-system programmable Flash with Read-While-Write lets technicians update firmware in the field without desoldering the MCU from the control PCB.
Recommended
Embedded Sensor Data Acquisition
For multi-channel data acquisition, the ATMEGA644P-15AT offers an 8-channel 10-bit ADC with optional differential inputs and programmable gain, letting one MCU capture several analog sensor outputs without an external converter. The 4KB SRAM buffers sample blocks, and the 2KB EEPROM stores calibration constants that survive power cycles, eliminating external nonvolatile memory in many designs. Data streams to a host over the dual USARTs, or to a local display and touch interface over TWI (I2C) or SPI. At 16MHz the AVR executes the averaging and filtering routines fast enough for kHz-class sample rates. picoPower technology reduces consumption in battery-powered loggers, and the Real Time Counter supports timestamping when an external 32.768kHz crystal is fitted, making the part a compact single-chip acquisition and logging engine.
Recommended
Serial Communication Gateways and Converters
The defining feature for gateway designs is the dual USART of the 'P' variant: two independent hardware serial ports allow protocol translation between, for example, an RS-232 field device and an RS-485 backbone inside one 44-TQFP chip. The 64KB Flash hosts both protocol stacks plus buffering, and 4KB SRAM provides FIFO depth that smaller ATmega parts lack, reducing overflow at sustained baud rates. TWI and SPI interfaces extend the design to Ethernet or CAN companion controllers if higher-layer connectivity is needed. A 16MHz clock comfortably supports 115200 baud on both ports simultaneously with interrupt-driven ring buffers. Because firmware is field-updatable through self-programming boot sections, deployed gateways can gain new protocol support without hardware changes, an advantage in long-lifetime industrial installations.
Recommended
Arduino-Compatible Development and Prototyping
The ATMEGA644P-15AT is a popular heart of Arduino-compatible boards through the MightyCore hardware package, which supports ATmega1284, 644, 324, 164, 32, 16 and 8535 in the Arduino IDE. Compared with the classic ATmega328P (32KB/2KB), the 644P doubles Flash to 64KB and SRAM to 4KB and adds a second USART, giving room for Ethernet libraries, large LCD buffers, or SD-card logging that exhaust an ATmega328P. The 44-TQFP exposes all four 8-bit ports, maximizing GPIO for shields. Developers use an external 16MHz crystal with standard MightyCore fuse settings and load the Optiboot-compatible bootloader via an ISP programmer. Prototype boards built on the 644P can move to production using the same footprint and codebase, shortening time to market.
Recommended
Automotive Auxiliary Control Units
Because the ATmega164P/324P/644P family completed regular product qualification as per AEC-Q100 grade 1, and Microchip USA lists the ATMEGA644P-15AT as AEC-Q100 qualified, the part historically served auxiliary automotive control units such as seat controllers, lighting modules, and sensor hubs in 5V domains. The dual USART supports LIN-style and K-line diagnostics on legacy vehicle platforms, while the 10-bit ADC reads resistive position sensors and NTC temperature probes. The Watchdog Timer and brown-out detection improve functional robustness in electrically noisy vehicle environments. Caveat for new programs: the device is obsolete and not recommended for new designs per Microchip, so new automotive developments should adopt the ATmega644PA successor or a current AEC-Q100-qualified AVR to secure long-term supply and lifecycle support.
Recommended
Low-Power Battery-Powered Instruments
Handheld meters, portable testers, and battery instruments benefit from the ATmega644P's picoPower CMOS technology, which the datasheet describes as enabling power-versus-speed optimization by executing instructions in a single cycle - the MCU finishes work quickly and returns to sleep. Power-down and power-save sleep modes pair with the Real Time Counter (RTC) driven by a 32.768kHz crystal to wake the chip on schedule for periodic measurements. The 2KB EEPROM retains user settings and calibration between battery changes. Designers should gate sensor power with a GPIO, decouple AVCC separately for clean ADC readings, and select the ATMEGA644PV low-voltage variant if the instrument runs from two AA cells at 1.8-3V rather than the 5V supply of the -15AT grade.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA644P-15AT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA644PA-AU | ATMEGA644P-20AU | ATMEGA644-20AU | ATMEGA644PV-10AUR |
|---|---|---|---|---|---|
| Package | 44-TQFP (10x10 mm) | 44-TQFP (10x10 mm) - same | 44-TQFP (10x10 mm) - same | 44-TQFP (10x10 mm) - same | 44-TQFP (10x10 mm) - same |
| Brand | Microchip Technology (Atmel) | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 64KB (32K x 16) | 64KB | 64KB | 64KB | 64KB |
| SRAM | 4KB | 4KB | 4KB | 4KB | 4KB |
| Max Clock Speed | 16 MHz | 20 MHz | 20 MHz | 20 MHz | 10 MHz |
| USART Count | 2 | 2 | 2 | 1 | 2 |
| Lifecycle Status | Obsolete (not recommended for new designs) | Active (official replacement) | Mature / last-time-buy | Mature / not recommended for new designs | Mature |
Key Differentiators
- Dual USART in the 'P' variant (vs ATMEGA644-20AU)
- AEC-Q100 grade 1 qualification (vs ATMEGA644-20AU)
- Lower price than the active successor (vs ATMEGA644PA-AU)
Design Notes
The ATmega644P runs from a 5V supply in the -15AT grade. Decouple both VCC (pins per datasheet pin configuration) and AVCC separately: use a 100nF ceramic directly at each supply pin plus 4.7-10uF bulk per rail. AVCC must be connected to VCC even if the ADC is unused, per the datasheet electrical connections guidance. Feed the ADC through an LC filter (ferrite bead + 1uF) when switching regulators share the 5V rail, keeping ADC reference noise below the ~2.4mV LSB of the 10-bit converter at 5V full scale.
The -15AT suffix denotes a 16MHz speed grade; running a 20MHz crystal violates the maximum frequency specification and can cause marginal operation at low temperature. Also note the ATmega644P is obsolete - Microchip's product page states it is 'not recommended for new designs. Replaced by ATmega644PA.' When migrating, review the fuse map and errata differences between 644P and 644PA, and confirm the second USART is actually used; if not, the non-P ATmega644 is a lower-risk BOM substitution. Verify JTAG/ISP pin conflicts before routing TRACE or JTAG signals on shared port pins.
Use the datasheet-recommended 44-TQFP (10x10 mm) land pattern with 0.5mm pitch. Place the 16MHz crystal within 10mm of XTAL1/XTAL2 with 22pF-class load capacitors tuned to the crystal specification, and guard the crystal traces with ground pour to avoid digital coupling from adjacent port pins. Provide at least one solid ground plane under the MCU; stitch vias near the crystal guard and the AREF decoupling capacitor. Keep RESET trace short with a 10k pull-up to support reliable ISP programming during production.
Compliance Information
AEC-Q100 grade 1 qualification is stated in the ATmega164P/324P/644P family qualification extract (datasheets.com) and Microchip USA product page. RoHS/REACH status not explicitly stated in provided web data - verify on Microchip's official product page.