ATMEGA644A-MU Equivalent & Substitute Parts

Part Overview

The ATMEGA644A-MU is an 8-bit AVR microcontroller manufactured by Microchip Technology, featuring 64KB FLASH program memory, 4KB RAM, and 2KB EEPROM. This Surface Mount device in 44-VQFN packaging operates at 20MHz with a supply voltage range of 1.8V to 5.5V. The part is currently in Active product status with ROHS3 compliance and is suitable for embedded applications requiring moderate processing capability and integrated peripheral support including I2C, SPI, and UART/USART connectivity.

Identifying equivalent and substitute parts is necessary when the primary part number becomes unavailable, when inventory constraints require alternative sourcing, or when design flexibility permits component optimization while maintaining functional compatibility.

Key Parameters

Parameter	Value
Core Processor	AVR
Core Size	8-Bit
Speed	20MHz
Program Memory Size	64KB (32K x 16)
Program Memory Type	FLASH
RAM Size	4K x 8
EEPROM Size	2K x 8
Voltage - Supply (Vcc/Vdd)	1.8V ~ 5.5V
Number of I/O	32
Connectivity	I2C, SPI, UART/USART
Data Converters	A/D 8x10b
Peripherals	Brown-out Detect/Reset, POR, PWM, WDT
Operating Temperature	-40°C ~ 85°C (TA)
Mounting Type	Surface Mount
Supplier Device Package	44-VQFN (7x7)
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	3 (168 Hours)

Substitute Part Grouping Explanation

Substitute parts for the ATMEGA644A-MU are identified based on strict parametric equivalence across the following critical dimensions:

Core Architecture & Processing: AVR 8-bit processor architecture with identical instruction set compatibility.

Memory Configuration: Identical program memory (64KB FLASH), RAM (4K x 8), and EEPROM (2K x 8) specifications ensure software and data storage compatibility.

Electrical Specifications: Matching supply voltage range (1.8V ~ 5.5V), operating temperature range (-40°C ~ 85°C), and peripheral feature set including I2C, SPI, UART/USART, PWM, WDT, and Brown-out Detect/Reset.

Physical Package: Identical 44-VQFN (7x7) Surface Mount package with exposed pad ensures PCB layout and thermal management compatibility.

Compliance & Certifications: ROHS3 compliance and identical MSL rating (3, 168 Hours) maintain regulatory and manufacturing process compatibility.

The ATMEGA644PA-MU meets all these criteria as a parametric equivalent substitute.

Parameter Comparison

Parameter	ATMEGA644A-MU	ATMEGA644PA-MU
Manufacturer	Microchip Technology	Microchip Technology
Core Processor	AVR	AVR
Core Size	8-Bit	8-Bit
Speed	20MHz	20MHz
Program Memory Size	64KB (32K x 16)	64KB (32K x 16)
Program Memory Type	FLASH	FLASH
RAM Size	4K x 8	4K x 8
EEPROM Size	2K x 8	2K x 8
Voltage - Supply (Vcc/Vdd)	1.8V ~ 5.5V	1.8V ~ 5.5V
Number of I/O	32	32
Connectivity	I2C, SPI, UART/USART	I2C, SPI, UART/USART
Data Converters	A/D 8x10b	A/D 8x10b
Peripherals	Brown-out Detect/Reset, POR, PWM, WDT	Brown-out Detect/Reset, POR, PWM, WDT
Operating Temperature	-40°C ~ 85°C (TA)	-40°C ~ 85°C (TA)
Mounting Type	Surface Mount	Surface Mount
Supplier Device Package	44-VQFN (7x7)	44-VQFN (7x7)
Package / Case	44-VFQFN Exposed Pad	44-VFQFN Exposed Pad
Product Status	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	3 (168 Hours)	3 (168 Hours)
REACH Status	REACH Unaffected	REACH Unaffected
ECCN	EAR99	EAR99
HTSUS	8542.31.0001	8542.31.0001

Engineering Selection Recommendations

Both the ATMEGA644A-MU and ATMEGA644PA-MU are Active product status components from Microchip Technology with identical ROHS3 compliance and REACH Unaffected status. Selection between these parts should be based on availability and inventory requirements, as all electrical, mechanical, and regulatory parameters are equivalent. Both parts maintain identical MSL ratings and packaging specifications, ensuring compatibility in manufacturing processes and thermal management applications. The ATMEGA644PA-MU variant is suitable as a direct substitute when the primary ATMEGA644A-MU part number is unavailable.

Frequently Asked Questions (FAQ)

Q: Can ATMEGA644PA-MU be used as a direct replacement for ATMEGA644A-MU in existing designs?

A: Yes. The ATMEGA644PA-MU is a parametric equivalent with identical core processor architecture, memory configuration, I/O count, peripheral feature set, supply voltage range, operating temperature range, and physical package. No design modifications are required.

Q: Are there any differences in the 44-VQFN package between these parts?

A: No. Both parts use the identical 44-VQFN (7x7) Surface Mount package with exposed pad. PCB layout, footprint, and thermal management characteristics are identical.

Q: Do both parts have the same compliance certifications?

A: Yes. Both ATMEGA644A-MU and ATMEGA644PA-MU are ROHS3 compliant, REACH Unaffected, and classified as EAR99 for export control purposes. Both carry identical HTSUS classification.

Q: What is the significance of the MSL rating for these parts?

A: Both parts carry MSL 3 (168 Hours) rating, indicating identical moisture sensitivity and requiring the same storage and handling procedures. Parts must be stored in controlled humidity environments and baked according to IPC standards before reflow soldering.

Q: Are the memory specifications identical between these microcontrollers?

A: Yes. Both parts feature 64KB FLASH program memory (32K x 16), 4KB RAM (4K x 8), and 2KB EEPROM (2K x 8). Software compiled for one part executes identically on the other.

Q: Can these parts operate across the same voltage and temperature ranges?

A: Yes. Both parts operate with supply voltage from 1.8V to 5.5V and across the industrial temperature range of -40°C to 85°C (TA). Electrical performance is identical across these ranges.

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