ATMEGA644P-15AT Equivalent & Substitute Parts

Part Overview

The ATMEGA644P-15AT is an 8-bit AVR microcontroller from Microchip Technology's ATmega series, featuring 64KB FLASH memory, 4KB RAM, and 2KB EEPROM. Designed for embedded applications requiring moderate processing capability and I/O flexibility, this device integrates 32 I/O pins, multiple communication interfaces (I2C, SPI, UART/USART), and integrated analog-to-digital conversion. The part carries Automotive grade qualification (AEC-Q100) and operates across the industrial temperature range of -40°C to 85°C.

The ATMEGA644P-15AT is classified as Obsolete. Identifying functionally equivalent substitute parts is necessary to maintain design continuity, ensure supply chain reliability, and support long-term production requirements.

Key Parameters

Parameter	Value
Core Processor	AVR
Core Size	8-Bit
Speed	16MHz
Program Memory Size	64KB (32K x 16)
Program Memory Type	FLASH
EEPROM Size	2K x 8
RAM Size	4K x 8
Number of I/O	32
Connectivity	I2C, SPI, UART/USART
Peripherals	Brown-out Detect/Reset, POR, PWM, WDT
Data Converters	A/D 8x10b
Voltage Supply (Vcc/Vdd)	2.7V ~ 5.5V
Operating Temperature	-40°C ~ 85°C (TA)
Package / Case	44-TQFP (10x10)
Mounting Type	Surface Mount
Grade	Automotive
Qualification	AEC-Q100
RoHS Status	ROHS3 Compliant
MSL Rating	3 (168 Hours)

Substitute Part Grouping Explanation

Substitution of the ATMEGA644P-15AT is determined by strict equivalence across the following critical parameters:

Core architecture and instruction set compatibility require identical AVR core processor and 8-bit core size. Memory configuration must match exactly: 64KB FLASH program memory, 4KB RAM, and 2KB EEPROM. Functional I/O and peripheral requirements mandate 32 I/O pins, identical connectivity interfaces (I2C, SPI, UART/USART), and matching peripheral features (Brown-out Detect/Reset, POR, PWM, WDT). Electrical specifications must remain within the 2.7V to 5.5V supply voltage range and support 16MHz operation. Package and mounting specifications require 44-TQFP (10x10) surface mount configuration. Automotive qualification (AEC-Q100) and ROHS3 compliance must be maintained.

The substitute part ATMEGA644P-A15AZ meets all these criteria while offering improved product status and extended operating temperature range.

Parameter Comparison

Parameter	ATMEGA644P-15AT (Main)	ATMEGA644P-A15AZ (Substitute)
Manufacturer	Microchip Technology	Microchip Technology
Core Processor	AVR	AVR
Core Size	8-Bit	8-Bit
Speed	16MHz	16MHz
Program Memory Size	64KB (32K x 16)	64KB (32K x 16)
Program Memory Type	FLASH	FLASH
EEPROM Size	2K x 8	2K x 8
RAM Size	4K x 8	4K x 8
Number of I/O	32	32
Connectivity	I2C, SPI, UART/USART	I2C, SPI, UART/USART
Peripherals	Brown-out Detect/Reset, POR, PWM, WDT	Brown-out Detect/Reset, POR, PWM, WDT
Data Converters	A/D 8x10b	A/D 8x10b
Voltage Supply (Vcc/Vdd)	2.7V ~ 5.5V	2.7V ~ 5.5V
Operating Temperature	-40°C ~ 85°C (TA)	-40°C ~ 125°C (TA)
Package / Case	44-TQFP (10x10)	44-TQFP (10x10)
Mounting Type	Surface Mount	Surface Mount
Grade	Automotive	Automotive
Qualification	AEC-Q100	AEC-Q100
RoHS Status	ROHS3 Compliant	ROHS3 Compliant
MSL Rating	3 (168 Hours)	3 (168 Hours)
Product Status	Obsolete	Active

Engineering Selection Recommendations

The ATMEGA644P-A15AZ is a direct functional substitute for the ATMEGA644P-15AT. Both devices maintain identical core architecture, memory configuration, I/O count, and peripheral feature set. Both carry Automotive grade classification and AEC-Q100 qualification, ensuring compliance with automotive reliability standards. Both are ROHS3 compliant and share identical MSL ratings.

The ATMEGA644P-A15AZ offers two distinct advantages: Active product status ensures ongoing availability and manufacturing support, whereas the ATMEGA644P-15AT is classified as Obsolete. The substitute part supports an extended operating temperature range of -40°C to 125°C compared to the original part's -40°C to 85°C specification, providing additional thermal margin for demanding applications.

Selection of the ATMEGA644P-A15AZ is appropriate for new designs, production continuity, and applications requiring long-term component availability.

Frequently Asked Questions (FAQ)

Q: Are the ATMEGA644P-15AT and ATMEGA644P-A15AZ pin-compatible?

A: Yes. Both devices use the 44-TQFP (10x10) package with identical pin assignments, I/O configuration, and peripheral mapping. Direct PCB substitution is supported without layout modification.

Q: What is the difference between these two part numbers?

A: The primary differences are product status and operating temperature range. The ATMEGA644P-15AT is Obsolete with a -40°C to 85°C operating range. The ATMEGA644P-A15AZ is Active with a -40°C to 125°C operating range. All other electrical and functional specifications are identical.

Q: Can I use the ATMEGA644P-A15AZ in applications originally designed for the ATMEGA644P-15AT?

A: Yes. The substitute part maintains full functional equivalence across all critical parameters: core processor, memory configuration, I/O count, connectivity interfaces, and peripheral features. The extended temperature range of the substitute part provides additional operational margin.

Q: Are both parts qualified for automotive applications?

A: Yes. Both the ATMEGA644P-15AT and ATMEGA644P-A15AZ carry Automotive grade classification and AEC-Q100 qualification. Both are ROHS3 compliant and share identical MSL ratings.

Q: What is the inventory status of these parts?

A: The ATMEGA644P-15AT (Obsolete) has 946 pieces in stock. The ATMEGA644P-A15AZ (Active) has 2756 pieces in stock, providing greater supply availability.

Q: Are there any firmware or software changes required when switching to the substitute part?

A: No. Both devices share identical AVR core architecture and instruction set. Existing firmware compiled for the ATMEGA644P-15AT will execute without modification on the ATMEGA644P-A15AZ.

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