ATMEGA644P-A15AZ - 64KB Flash AVR MCU 16MHz | Microchip
MPN: ATMEGA644P-A15AZ ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.95 | $6.95 |
| 10 | $6.35 | $63.50 |
| 100 | $5.75 | $575.00 |
| 500 | $5.25 | $2,625.00 |
| 1,000 | $4.85 | $4,850.00 |
ATMEGA644P-A15AZ Overview
An 8-bit microcontroller is a single-chip computer whose data bus, ALU, and registers operate on 8-bit words. In the system hierarchy it belongs to the embedded processor family: microcontroller -> embedded MCU -> semiconductor IC. Microcontrollers such as the ATMEGA644P-A15AZ integrate CPU, program memory, data memory, peripherals (USART, SPI, I2C/TWI, timers, ADC), and I/O ports on a single die, replacing multi-chip processor boards in cost- and power-sensitive designs. The AVR architecture executes most instructions in a single clock cycle, delivering throughput approaching 1 MIPS per MHz.
Key features of the ATMEGA644P-A15AZ include 64KB of self-programmable Flash memory, 4KB of internal SRAM, 2KB of EEPROM for non-volatile data storage, and 53 general-purpose I/O lines across four 8-bit ports. The picoPower 'P' suffix denotes low-power AVR core operation, and the device provides two USARTs for serial communication.
Technically, the AVR enhanced RISC core combines a rich instruction set with 32 general-purpose working registers, all directly connected to the ALU, allowing two independent registers to be accessed in one instruction executed in one clock cycle. This architecture lets system designers optimize power consumption versus processing speed, an explicit design goal stated in the ATmega644P datasheet family description.
Typical applications include industrial control and automation nodes, embedded instrumentation and data loggers, and consumer appliance control boards, where the 5V-tolerant I/O and 53 I/O lines simplify direct connection to sensors, keypads, displays, and actuators without level shifting.
Design consideration: the ATMEGA644P-A15AZ is specified for a 4.5V to 5.5V supply; designs targeting 3.3V operation must instead select the picoPower ATMEGA644PA family or a low-voltage variant, since this A15AZ speed-grade part is characterized at 5V and 16 MHz. Note that Microchip lists the ATmega644P family as a mature product, not recommended for new designs, replaced by the ATmega644PA.
This page synthesizes distributor stock and pricing signals, drop-in alternative cross-references from verified web data, and practical design guidance not found in the manufacturer datasheet alone, providing engineers a single decision-ready resource.
Drop-in alternatives for ATMEGA644P-A15AZ — 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-A15AZ (same form factor and footprint) — differing in Maximum Clock Frequency, ADC, Package, Core, Debug Interface.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA644PA-AU
✅ Drop-In✓ In Stock
$2.49 / Unit
View Datasheet →ATMEGA644P-15AZ
✅ Drop-In✓ In Stock
$4.98 / Unit
View Datasheet →ATMEGA644P-20AU
✅ Drop-In✓ In Stock
$3.95 / Unit
View Datasheet →ATMEGA644PV-20AU
✅ Drop-In📋 Reference alternative (not in catalog)
ATMEGA644-20AU
✅ Drop-In✓ In Stock
$4.96 / Unit
View Datasheet →ATMEGA644V-10AU
✅ Drop-In✓ In Stock
$6.88 / Unit
View Datasheet →ATMEGA644P-A15AZ Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Flash Memory | 64 KB |
| SRAM | 4 KB |
| EEPROM | 2 KB |
| Maximum Clock Frequency | 16 MHz |
| Supply Voltage Range | 4.5 V to 5.5 V |
| I/O Ports / Lines | 53 I/O |
| Data Bus Width | 8 bit |
| Program Memory Type | Flash |
| USARTs | 2 |
| Package | 44-TQFP |
| Mounting Type | Surface Mount |
| Product Family | ATmega644P (AVR ATmega) |
| Lifecycle Stage | Active (mature product, NRND per Microchip; replaced by ATmega644PA) |
| Programming / Debug Interface | ICSP (In-Circuit Serial Programming), supports MPLAB SNAP debugging |
ATMEGA644P-A15AZ 44-tqfp Pin Configuration Guide
Pin configuration for ATMEGA644P-A15AZ (44-tqfp 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-A15AZ.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA644P-A15AZ is suitable for 6 applications: Industrial Control and Automation, Embedded Instrumentation and Data Logging, Consumer Appliance Control Boards, Building Automation and Smart Home Nodes, Motor Control and PWM Actuation, Educational and Prototyping Platforms.
Industrial Control and Automation
The ATMEGA644P-A15AZ fits industrial control nodes because its 53 I/O lines allow direct interfacing to relays, limit switches, keypads, and status LEDs without external port expanders, and its 4.5V to 5.5V supply matches legacy 5V industrial logic levels. The two USARTs support simultaneous RS-485/Modbus fieldbus communication and a local debug or HMI link, while the 64KB Flash accommodates protocol stacks and OTA-style firmware updates via self-programming. Placed as the main controller with a watchdog timer enabled and ICSP header populated for field reprogramming, the AVR's single-cycle RISC execution delivers deterministic timing for scan-loop control at 16 MHz, approaching 16 MIPS throughput for polling-based automation tasks.
Recommended
Embedded Instrumentation and Data Logging
For data loggers and bench instrumentation, the ATMEGA644P-A15AZ provides 2KB EEPROM for storing calibration constants that survive power cycles, and 4KB SRAM for circular sample buffers. Its on-chip ADC and timers let designers sample analog sensors directly, while the second USART separates a data uplink from a configuration console. At 16 MHz the core executes roughly one instruction per clock, giving predictable loop timing for time-stamped acquisitions. A typical topology runs the MCU from a 5V linear regulator with 100nF decoupling per supply pin, uses SPI or TWI for external SD-card or RTC devices, and leverages the picoPower sleep modes between samples to extend battery or energy-harvesting life in field-deployed instruments.
Recommended
Consumer Appliance Control Boards
Appliance control boards benefit from the ATMEGA644P-A15AZ's 5V-tolerant 53 I/O lines, which drive seven-segment displays, relays, triac interfaces, and membrane keypads directly at logic levels common on appliance PCBs. The 64KB Flash is sufficient for menu-driven UI state machines, motor sequencing, and fault diagnostic routines, while the 2KB EEPROM stores user settings and cycle counters. The device's single-cycle RISC core at 16 MHz provides ample headroom for debouncing, PWM generation for heaters or fans, and serial communication to a display or Wi-Fi module via one of the two USARTs. Its TQFP-44 footprint is also economical for two-layer appliance boards, and the mature, field-proven silicon reduces qualification risk for long-lived white-goods programs.
Recommended
Building Automation and Smart Home Nodes
The ATMEGA644P-A15AZ serves as a robust wired node controller in building automation, where its dual USARTs simultaneously handle an RS-485 bus (for example BACnet MS/TP-style polling) and a local service interface. The 4.5V to 5.5V supply tolerates noisy linear supplies typical of distributed building wiring, and 53 I/O lines read occupancy sensors, door contacts, and actuate dampers or relays. Firmware stored in 64KB Flash can include full protocol handling plus a boot loader for field updates over the bus, with 2KB EEPROM preserving node addresses and schedules. Although newer designs should consider the ATmega644PA for lower consumption, the 644P remains an economical choice for mains-powered wired nodes where sleep current is not critical.
Recommended
Motor Control and PWM Actuation
The ATMEGA644P-A15AZ is well suited to low-end motor control: its hardware timers generate multiple PWM channels for DC motor speed control or stepper sequencing, while the 16 MHz single-cycle core closes simple PI control loops in software with microsecond-level jitter. The 4.5V to 5.5V supply range matches gate-driver and optocoupler input thresholds, and the 53 I/O lines accommodate encoder inputs, limit switches, and start/stop panels alongside the PWM outputs. Firmware in 64KB Flash can include ramp generators, stall detection, and fault logging to the 2KB EEPROM. Designers should route PWM lines away from analog inputs and use the ADC's differential mode for current-sense shunt measurement, keeping the switching loop compact to limit EMI.
Recommended
Educational and Prototyping Platforms
Universities and makers continue to use ATmega644P-class parts for teaching embedded systems because the AVR architecture is transparent: 32 registers, single-cycle execution, and a simple memory map of 64KB Flash, 4KB SRAM, and 2KB EEPROM are easy to explain and profile. The ATMEGA644P-A15AZ's 53 I/O lines and two USARTs support breadboard-style labs connecting switches, LEDs, LCDs, and serial terminals simultaneously, and programming requires only an ICSP header plus a low-cost MPLAB SNAP or legacy AVR ISP tool, per Microchip documentation. Its TQFP-44 package is also available on adapter boards for prototyping. Because the part is NRND, teaching platforms should design sockets/footprints compatible with the ATmega644PA to preserve long-term sourcing.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA644P-A15AZ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA644PA-AU | ATMEGA644P-15AZ | ATMEGA644P-20AU | ATMEGA644PV-20AU | ATMEGA644-20AU |
|---|---|---|---|---|---|---|
| Package | 44-TQFP | 44-TQFP - same | 44-TQFP - same | 44-TQFP - same | 44-TQFP - same | 44-TQFP - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 64 KB | 64 KB | 64 KB | 64 KB | 64 KB | 64 KB |
| SRAM | 4 KB | 4 KB | 4 KB | 4 KB | 4 KB | 4 KB |
| EEPROM | 2 KB | 2 KB | 2 KB | 2 KB | 2 KB | 2 KB |
| Max Clock Frequency | 16 MHz | 20 MHz | 16 MHz class (15-speed grade) | 20 MHz | 20 MHz | 20 MHz |
| Supply Voltage | 4.5 V to 5.5 V | 1.8 V low-voltage capable (wider range) | 4.5 V to 5.5 V | 4.5 V to 5.5 V | Low-voltage V variant (2.5V/3.3V/5V class) | 4.5 V to 5.5 V |
| picoPower / Low-Power Features | Yes (P family) | Yes (enhanced picoPower) | Yes (P family) | Yes (P family) | Yes (P family, V speed) | No (base ATmega644) |
| Recommended for New Designs | No (NRND, replaced by ATmega644PA) | Yes | No (same NRND family) | No (same NRND family) | No (same NRND family) | No (same NRND family) |
| I/O Lines | 53 | 53 | 53 | 53 | 53 | 53 |
Key Differentiators
- Enhanced low-power successor available pin-to-pin (vs ATMEGA644PA-AU)
- Dual USART in the P family (vs ATMEGA644-20AU)
- Mature, widely second-sourced silicon (vs ATMEGA644PV-20AU)
Design Notes
The ATMEGA644P-A15AZ is a 4.5V to 5.5V device. Connecting it to a 3.3V rail or feeding 3.3V logic signals into its I/O without level shifting risks out-of-spec operation and latch-up. If your system runs at 3.3V, migrate to the pin-compatible ATMEGA644PA-AU, which supports low-voltage operation down to 1.8V per Microchip application note AVR505. Also note Microchip lists the ATmega644P as a mature, not-recommended-for-new-designs product; budget a migration path to ATmega644PA before committing to long production runs.
Decouple every VCC pin pair with 100nF ceramic capacitors placed within a few millimeters of the pins, plus one 4.7uF to 10uF bulk capacitor near the MCU. Keep the ICSP (MOSI/MISO/SCK/RESET) traces short and accessible, and include the standard 6-pin ISP header since the MPLAB SNAP debugger programs the device through ICSP using two I/O pins plus reset. Provide test points on RESET and XTAL lines; unused TQFP-44 pins configured as inputs should have defined pull-ups to prevent floating-input noise.
Estimate: an AVR core running at 16 MHz from 5V draws on the order of 10-15 mA active plus I/O load currents, so a 100 mA linear regulator typically suffices for the MCU alone. Power dissipation in the regulator is the dominant thermal concern, not the MCU itself; for a 12V-to-5V linear supply at 100 mA that is roughly 0.7W, so verify regulator package thermal capability. Use the picoPower sleep modes between tasks; note that sleep current figures differ between the 644P and the enhanced 644PA, another reason to prefer the PA for battery designs.
Compliance Information
Compliance data was not present in the provided verified web data. Verify RoHS/REACH status on the Microchip product page or distributor compliance sheets before ordering.
