ATMEGA645-16AI Equivalent & Substitute Parts

Part Overview

The ATMEGA645-16AI is an 8-bit AVR microcontroller manufactured by Microchip Technology, featuring 64KB FLASH memory, 4KB RAM, and 2KB EEPROM. This device operates at 16MHz with a supply voltage range of 2.7V to 5.5V and is housed in a 64-TQFP package. The ATMEGA645-16AI is classified as obsolete, making identification of compatible substitute parts essential for ongoing design support and production continuity.

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
Voltage - Supply (Vcc/Vdd)	2.7V ~ 5.5V
Number of I/O	53
Data Converters	A/D 8x10b
Connectivity	SPI, UART/USART, USI
Peripherals	Brown-out Detect/Reset, POR, PWM, WDT
Operating Temperature	-40°C ~ 85°C (TA)
Package / Case	64-TQFP (14x14)
Mounting Type	Surface Mount

Substitute Part Grouping Explanation

Substitution eligibility for the ATMEGA645-16AI is determined by strict equivalence across the following critical parameters:

Core Architecture: AVR processor family
Memory Configuration: 64KB FLASH, 4KB RAM, 2KB EEPROM
Operating Frequency: 16MHz
Supply Voltage Range: 2.7V ~ 5.5V
I/O Count: 53 pins
Package Format: 64-TQFP (14x14)
Peripheral Set: SPI, UART/USART, USI connectivity with Brown-out Detect/Reset, POR, PWM, WDT
Data Conversion: A/D 8x10b

The ATMEGA645-16AU meets all substitution criteria as a direct equivalent, differing only in packaging format (Tray vs. standard packaging) and product status (Active vs. Obsolete).

Parameter Comparison

Parameter	ATMEGA645-16AI	ATMEGA645-16AU
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
Voltage - Supply (Vcc/Vdd)	2.7V ~ 5.5V	2.7V ~ 5.5V
Number of I/O	53	53
Data Converters	A/D 8x10b	A/D 8x10b
Connectivity	SPI, UART/USART, USI	SPI, UART/USART, USI
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)
Package / Case	64-TQFP (14x14)	64-TQFP (14x14)
Mounting Type	Surface Mount	Surface Mount
Product Status	Obsolete	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	3 (168 Hours)	3 (168 Hours)
REACH Status	REACH Unaffected	REACH Unaffected

Engineering Selection Recommendations

The ATMEGA645-16AU is the direct functional equivalent of the ATMEGA645-16AI. Selection between these parts should be based on the following factors:

Product Status: The ATMEGA645-16AI is classified as obsolete. The ATMEGA645-16AU maintains active product status with Microchip Technology, ensuring continued availability and manufacturing support.

Regulatory Compliance: The ATMEGA645-16AU is ROHS3 compliant, whereas the ATMEGA645-16AI is RoHS non-compliant. For applications subject to RoHS directives or customer requirements mandating RoHS compliance, the ATMEGA645-16AU is the appropriate selection.

Packaging and Supply: Both devices are supplied in 64-TQFP packages with identical pinouts and electrical characteristics. The ATMEGA645-16AU is available in Tray packaging format. Inventory availability and supply chain considerations may influence procurement decisions.

Functional Equivalence: All electrical parameters, memory configurations, operating ranges, and peripheral sets are identical between the two parts. Pin-for-pin compatibility is maintained, allowing direct substitution in existing PCB designs without layout modifications.

Frequently Asked Questions (FAQ)

Q: Can the ATMEGA645-16AU be used as a direct replacement for the ATMEGA645-16AI in existing designs?

A: Yes. The ATMEGA645-16AU is functionally equivalent to the ATMEGA645-16AI. Both devices share identical pinouts, electrical specifications, memory configurations, and operating parameters. No PCB layout modifications are required for substitution.

Q: What is the primary difference between the ATMEGA645-16AI and ATMEGA645-16AU?

A: The primary differences are product status and regulatory compliance. The ATMEGA645-16AI is obsolete and RoHS non-compliant, while the ATMEGA645-16AU is active and ROHS3 compliant. Packaging format also differs (standard vs. Tray).

Q: Are there any pin compatibility concerns when substituting these parts?

A: No. Both the ATMEGA645-16AI and ATMEGA645-16AU are housed in 64-TQFP (14x14) packages with identical pin assignments, voltage levels, and signal definitions. Pin-for-pin compatibility is complete.

Q: Does the ATMEGA645-16AU support the same operating voltage range as the ATMEGA645-16AI?

A: Yes. Both devices operate across the identical supply voltage range of 2.7V to 5.5V and maintain the same operating temperature range of -40°C to 85°C.

Q: What are the memory specifications for these microcontrollers?

A: Both the ATMEGA645-16AI and ATMEGA645-16AU feature 64KB FLASH program memory (32K x 16), 4KB RAM, and 2KB EEPROM. Memory organization and access methods are identical.

Q: Are there connectivity or peripheral differences between these parts?

A: No. Both devices provide identical connectivity options (SPI, UART/USART, USI) and peripheral features (Brown-out Detect/Reset, POR, PWM, WDT). The 8x10-bit analog-to-digital converter is present in both variants.

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