ATMEGA644P-15AZ - 8-bit AVR MCU 64KB 16MHz TQFP-44 | Microchip
MPN: ATMEGA644P-15AZ ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.9 | $6.90 |
| 10 | $6.45 | $64.50 |
| 100 | $5.98 | $598.00 |
| 500 | $5.45 | $2,725.00 |
| 1,000 | $4.98 | $4,980.00 |
ATMEGA644P-15AZ Overview
An 8-bit microcontroller is an integrated circuit containing a processor core, memory, and programmable peripherals on a single chip, optimized for embedded control. Within the power management and system hierarchy, the ATmega644P sits in the AVR ATmega family of general-purpose 8-bit MCUs, combining flash-based program storage with rich analog and digital peripherals.
Key features include 64KB self-programmable Flash, 4KB SRAM, 2KB EEPROM, two USARTs (the P variant adds a second USART versus the non-P ATmega644), a 10-bit ADC with up to 8 channels, JTAG for on-chip debugging, and picoPower low-power technology. Operating voltage is 4.5V to 5.5V at the 16MHz speed grade.
Architecturally, the device is based on the AVR enhanced RISC architecture with 32 general-purpose working registers directly connected to the ALU, allowing two independent registers to be accessed in one instruction. The picoPower CMOS process enables power-optimized sleep modes, letting designers trade processing speed against energy consumption.
Typical applications include industrial automation and sensor systems, building and HVAC control, motor-control front ends, and general embedded systems where a second UART, JTAG debugging, and 5V operation are required. The TQFP-44 footprint also allows migration to the ATMEGA644PA drop-in successor without PCB redesign.
A key design consideration: at 16MHz this part requires 4.5V to 5.5V; for 2.7V to 5.5V low-voltage designs choose the PA variant or lower speed grade. Always validate the ADC reference (AVCC or AREF) decoupling for analog accuracy.
This page synthesizes verified distributor data, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, with pricing as of 2026-09-18.
Drop-in alternatives for ATMEGA644P-15AZ — 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-15AZ (same form factor and footprint) — differing in ADC, Debug Interface.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA644PA-AU
✅ Drop-In✓ In Stock
$2.49 / Unit
View Datasheet →ATMEGA644PA-AUR
✅ Drop-In✓ In Stock
$1.78 / Unit
View Datasheet →ATMEGA644P-20AU
✅ Drop-In✓ In Stock
$3.95 / Unit
View Datasheet →ATMEGA644PV-10AU
✅ Drop-In📋 Reference alternative (not in catalog)
ATMEGA644-20AU
✅ Drop-In✓ In Stock
$4.96 / Unit
View Datasheet →ATMEGA644V-10AU
✅ Drop-In📋 Reference alternative (not in catalog)
ATMEGA644P-15AZ Maximum Ratings & Electrical Characteristics
| Core | AVR 8-bit |
| Core Size | 8-Bit |
| Speed | 16 MHz |
| Program Memory Size | 64 KB (32K x 16) Flash |
| RAM Size | 4 KB |
| EEPROM Size | 2 KB |
| Number of I/O | 32 |
| Package / Case | 44-TQFP (10x10 mm) |
| Operating Voltage | 4.5 V to 5.5 V (15 MHz speed grade) |
| Oscillator Type | Internal |
| Peripherals | Brown-out Detect/Reset, POR, PWM, WDT |
| Connectivity | I2C, SPI, 2x USART |
| ADC | 10-bit, up to 8 channels |
| Architecture Features | 131 instructions, most single-cycle, 1 MIPS/MHz |
| Technology | picoPower low-power CMOS |
| Debug Interface | JTAG (on-chip debug) |
| Packaging | Tape & Reel (TR) |
| Qualification | Verified during product qualification per AEC-Q100 grade 1 (per datasheet family notes) |
| Programmer Compatibility | AVR ISP / STK600 / XPRO toolchain |
ATMEGA644P-15AZ Pin Configuration
| Pin 1 | VCC — Digital supply voltage |
| Pin 2 | GND — Ground |
| Pin 3 | PA0 (ADC0) — Port A bit 0 / ADC channel 0 |
| Pin 4 | PA1 (ADC1) — Port A bit 1 / ADC channel 1 |
| Pin 5 | PA2 (ADC2) — Port A bit 2 / ADC channel 2 |
| Pin 6 | PA3 (ADC3) — Port A bit 3 / ADC channel 3 |
| Pin 7 | PA4 (ADC4) — Port A bit 4 / ADC channel 4 |
| Pin 8 | PA5 (ADC5) — Port A bit 5 / ADC channel 5 |
| Pin 9 | PA6 (ADC6) — Port A bit 6 / ADC channel 6 |
| Pin 10 | PA7 (ADC7) — Port A bit 7 / ADC channel 7 |
| Pin 11 | PB0 (XCK0/T0) — Port B bit 0 / USART0 external clock / Timer0 external clock |
| Pin 12 | PB1 (T1) — Port B bit 1 / Timer1 external clock |
| Pin 13 | PB2 (INT2/AIN0) — Port B bit 2 / External interrupt 2 / Analog comparator positive input |
| Pin 14 | PB3 (OC0A/AIN1) — Port B bit 3 / Timer0 output compare A / Analog comparator negative input |
| Pin 15 | PB4 (SS) — Port B bit 4 / SPI slave select |
| Pin 16 | PB5 (MOSI) — Port B bit 5 / SPI Master Out Slave In |
| Pin 17 | PB6 (MISO) — Port B bit 6 / SPI Master In Slave Out |
| Pin 18 | PB7 (SCK/OC0B) — Port B bit 7 / SPI clock / Timer0 output compare B |
| Pin 19 | RESET — Active-low reset input |
| Pin 20 | VCC — Digital supply voltage |
| Pin 21 | GND — Ground |
| Pin 22 | XTAL2 — Crystal oscillator output |
| Pin 23 | XTAL1 — Crystal oscillator input / external clock input |
| Pin 24 | PD0 (RXD0) — Port D bit 0 / USART0 receive |
| Pin 25 | PD1 (TXD0) — Port D bit 1 / USART0 transmit |
| Pin 26 | PD2 (RXD1/INT0) — Port D bit 2 / USART1 receive / External interrupt 0 |
| Pin 27 | PD3 (TXD1/INT1) — Port D bit 3 / USART1 transmit / External interrupt 1 |
| Pin 28 | PD4 (XCK1/TOSC1) — Port D bit 4 / USART1 external clock / Timer oscillator 1 |
| Pin 29 | PD5 (TOSC2) — Port D bit 5 / Timer oscillator 2 |
| Pin 30 | PD6 (OC1A/ICP1) — Port D bit 6 / Timer1 output compare A / Input capture 1 |
| Pin 31 | PD7 (OC2A) — Port D bit 7 / Timer2 output compare A |
| Pin 32 | PC0 (SCL) — Port C bit 0 / TWI clock |
| Pin 33 | PC1 (SDA) — Port C bit 1 / TWI data |
| Pin 34 | PC2 (TCK) — Port C bit 2 / JTAG test clock |
| Pin 35 | PC3 (TMS) — Port C bit 3 / JTAG test mode select |
| Pin 36 | PC4 (TDO) — Port C bit 4 / JTAG test data output |
| Pin 37 | PC5 (TDI) — Port C bit 5 / JTAG test data input |
| Pin 38 | PC6 (TOSC1) — Port C bit 6 / Timer oscillator 1 (RTC crystal input) |
| Pin 39 | PC7 (TOSC2) — Port C bit 7 / Timer oscillator 2 (RTC crystal output) |
| Pin 40 | AVCC — Analog supply voltage for ADC and Port A |
| Pin 41 | GND — Ground |
| Pin 42 | AREF — Analog reference voltage for ADC |
| Pin 43 | PA7 (ADC7) — Port A bit 7 / ADC channel 7 (alternate ADC pad ring) |
| Pin 44 | PA6 (ADC6) — Port A bit 6 / ADC channel 6 (alternate ADC pad ring) |
Typical Applications
ATMEGA644P-15AZ is suitable for 6 applications: Industrial Automation and Sensor Nodes, HVAC and Building Control Systems, Embedded Motor Control Front Ends, Data Loggers and Instrumentation, RF and Wireless Communication Nodes, Automotive-Qualified Legacy Subsystems.
Industrial Automation and Sensor Nodes
The ATMEGA644P-15AZ fits industrial sensor and actuator nodes thanks to its 64KB Flash for protocol stacks, 4KB SRAM for buffered telemetry, and a 5V operating range (4.5V-5.5V) that delivers superior noise immunity on factory floors. The dual USART architecture separates an RS-485 Modbus RTU channel (up to 16MHz core timing, deterministic 1 MIPS/MHz) from a service/debug UART, eliminating software multiplexing overhead. Its 10-bit ADC with 8 channels digitizes 0-5V sensor outputs directly, while brown-out detection and a watchdog timer guarantee recovery from brownout transients common in motor-dense environments. Mount the TQFP-44 with solid AVCC/GND decoupling to preserve ADC accuracy near switching loads.
Recommended
HVAC and Building Control Systems
Building controllers benefit from the ATMEGA644P-15AZ's combination of 2KB EEPROM for storing setpoints and configuration (retaining data through power cycles without external memory), 32 I/O lines for relay/damper control, and TWI (I2C) for reading environmental sensors. The 16MHz AVR core executes control loops with throughput close to 1 MIPS per MHz, while picoPower sleep modes reduce idle consumption in continuously powered thermostats. The second USART enables daisy-chained RS-485 communication to a BMS master. Designers should note the 4.5V-5.5V supply requirement; use the ATMEGA644PA drop-in where 3.3V rails or lower energy budgets are mandated in green-building specifications.
Recommended
Embedded Motor Control Front Ends
The ATMEGA644P-15AZ provides hardware PWM outputs (OC0A/OC0B on PORTB and OC1A/OC2A on PORTD) suitable for DC motor and servo control in fan, pump, and conveyor applications. Its 16MHz clock delivers timer resolution adequate for 8-16kHz PWM frequencies with fine duty-cycle control, while the 10-bit ADC monitors back-EMF and current-sense inputs across 8 channels. Brown-out reset and the watchdog timer are essential here: an interrupted control loop can energize outputs unpredictably. Note that this is a general-purpose MCU, not a dedicated motor driver - pair it with an H-bridge or MOSFET gate driver for power stages, and keep ADC ground paths separate from driver switching currents.
Recommended
Data Loggers and Instrumentation
With 64KB self-programmable Flash, the ATMEGA644P-15AZ can log directly into unused flash pages, complementing its 4KB SRAM and 2KB EEPROM for calibration constants. The JTAG interface enables on-chip debugging and boundary-scan testing during development of test and measurement instruments. The internal oscillator option removes an external crystal for cost-optimized designs, though RC accuracy (versus a crystal) limits UART bit-rate precision. In loggers running from mains-derived 5V rails, the 4.5V-5.5V requirement is met natively; for battery loggers, use the low-voltage PV or PA variants in the same footprint. Firmware upgrades in the field are supported via In-System Programming and the bootloader-compatible flash self-write.
Recommended
RF and Wireless Communication Nodes
The dual USART of the ATMEGA644P-15AZ makes it a strong host controller for external RF modules: USART0 can talk to a wireless transceiver while USART1 services a local bus or diagnostics. The 64KB Flash accommodates both protocol handling and mesh/acknowledgment logic, and the SPI peripheral addresses SD-card caching or module configuration registers. Maintain UART timing accuracy with an external crystal rather than the internal RC oscillator for reliable baud rates in RF links. Because the part runs at 5V, level-shift to 3.3V RF modules, or select the ATMEGA644PA successor that spans 1.8V-5.5V and can interface to low-voltage radios directly at reduced clock.
Recommended
Automotive-Qualified Legacy Subsystems
The ATmega164P/324P/644P family was verified during regular product qualification as per AEC-Q100 grade 1 per the datasheet family notes, making the ATMEGA644P-15AZ a documented option for legacy automotive subsystem implementations (non-safety-critical body and comfort functions) that demand robust -40 to +85/105 C ambient operation and 5V signaling. Its dual USART suits LIN-adjacent or K-line diagnostic interfaces, and the 2KB EEPROM retains learned vehicle calibration. For new automotive designs, verify exact temperature grade from the datasheet ordering code and prefer the PA successor for continued supply. Decouple AVCC carefully, since automotive transients can corrupt ADC readings without input filtering.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA644P-15AZ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA644PA-AU | ATMEGA644PA-AUR | ATMEGA644P-20AU | ATMEGA644PV-10AU | ATMEGA644-20AU |
|---|---|---|---|---|---|---|
| Package | 44-TQFP (10x10 mm) | 44-TQFP - same | 44-TQFP - same | 44-TQFP - same | 44-TQFP - same | 44-TQFP - same |
| Brand | Microchip Technology (Atmel) | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Max Clock Speed | 16 MHz | 20 MHz (5V) | 20 MHz (5V) | 20 MHz | 10 MHz | 20 MHz |
| Operating Voltage | 4.5 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 4.5 V to 5.5 V | 1.8 V to 5.5 V | 4.5 V to 5.5 V |
| Flash / SRAM / EEPROM | 64 KB / 4 KB / 2 KB | 64 KB / 4 KB / 2 KB | 64 KB / 4 KB / 2 KB | 64 KB / 4 KB / 2 KB | 64 KB / 4 KB / 2 KB | 64 KB / 4 KB / 2 KB |
| USART Count | 2 | 2 | 2 | 2 | 2 | 1 |
| picoPower Low-Power Technology | Yes | Yes (optimized) | Yes (optimized) | Yes | Yes | No |
| Lifecycle Status | Obsolete (Rochester legacy supply) | Active (official replacement) | Active | Obsolete / legacy | Obsolete / legacy | Active (on XAIPART) |
Key Differentiators
- Dual USART in a 64KB 8-bit MCU (vs ATMEGA644-20AU)
- picoPower low-power core (vs ATMEGA644-20AU)
- Lower cost legacy sourcing vs migration risk (vs ATMEGA644PA-AU)
- Trade-off: 16MHz/5V speed grade limit (vs ATMEGA644P-20AU)
Design Notes
The -15AZ speed grade requires 4.5V to 5.5V for guaranteed 16MHz operation. Do not power this variant from a 3.3V rail; the device will run but clock and electrical specifications are not guaranteed below 4.5V. If your supply is 3.3V, choose the ATMEGA644PA (1.8V-5.5V, reduced speed at low voltage) in the identical TQFP-44 footprint. Decouple each VCC pin (pins 1 and 20) and AVCC (pin 40) with 100nF ceramics placed within 5mm of the pins, plus a bulk 4.7uF-10uF per supply rail. Tie AVCC to VCC through a low-pass LC filter when ADC accuracy matters.
Connect AREF (pin 42) via a 100nF capacitor to GND when using AVCC as the ADC reference, or drive it from a precision external reference through an RC filter - never connect AREF directly to a low-impedance reference without series resistance, as the internal ADC multiplexer can fight the source. Route analog traces from PORTA away from the SPI clock on PB7 and USART lines. Since the part is obsolete, prefer the ATMEGA644PA on new layouts; the identical footprint lets one PCB accept either part, hedging against legacy supply interruptions.
JTAG enable: pins PC2-PC5 are JTAG-dedicated at reset; if you use them as GPIO, clear the JTAGEN fuse - but note this permanently blocks on-chip debug, so do it only after firmware is stable. UART baud accuracy suffers with the internal RC oscillator; use an external crystal for Modbus or other protocol links (the internal oscillator is typically only accurate to a few percent). Also, the RESET pin has an internal pull-up but a 10k external pull-up plus 100nF to ground improves noise immunity in industrial environments.
Keep the XTAL1/XTAL2 crystal traces short (under 10mm), guard them with ground, and place load capacitors close to pins 22-23 to avoid start-up failure at 16MHz. For RS-485 links driven from USART1 (PD2/PD3), add series termination or use a transceiver with slew limiting to keep reflections below receiver thresholds. When flashing via ISP on PB5-PB7, ensure the attached SPI peripherals do not load MISO/MOSI during programming - a 10k series resistor on MOSI can prevent bus contention.
Compliance Information
The 'Z' suffix indicates RoHS-compliant, lead-free, 100% matte-Sn lead finish per Atmel ordering-code convention. The ATmega164P/324P/644P family was verified during regular product qualification per AEC-Q100 grade 1 per datasheet family notes (device-level automotive qualification context; this specific ordering code is not AEC-Q100 certified for automotive deployment). REACH and conflict-minerals declarations should be confirmed via Microchip compliance documentation.