AT90LS4433-4AI Equivalent & Substitute Parts

Part Overview

The AT90LS4433-4AI is an 8-bit AVR microcontroller from Microchip Technology's AVR 90LS series, featuring 4KB FLASH program memory, 128 bytes of RAM, and 256 bytes of EEPROM. This device operates at 4MHz with a supply voltage range of 2.7V to 6V and is housed in a 32-TQFP package. The AT90LS4433-4AI has reached obsolete product status, making equivalent substitutes necessary for new designs and ongoing production requirements.

Key Parameters

Parameter	AT90LS4433-4AI
Core Processor	AVR
Core Size	8-Bit
Speed	4MHz
Program Memory Size	4KB (2K x 16)
Program Memory Type	FLASH
EEPROM Size	256 x 8
RAM Size	128 x 8
Voltage - Supply (Vcc/Vdd)	2.7V ~ 6V
Number of I/O	20
Data Converters	A/D 6x10b
Connectivity	SPI, UART/USART
Peripherals	Brown-out Detect/Reset, POR, PWM, WDT
Package / Case	32-TQFP (7x7)
Operating Temperature	-40°C ~ 85°C
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the AT90LS4433-4AI is determined by the following critical parameters:

Core Processor Architecture: AVR architecture compatibility ensures instruction set and development tool compatibility
Core Size: 8-bit processing capability
Program Memory: Minimum 4KB FLASH to accommodate existing firmware
Package Type: 32-TQFP (7x7) form factor for PCB layout compatibility
Operating Temperature Range: -40°C ~ 85°C for environmental consistency
Supply Voltage Range: Overlap with 2.7V ~ 6V to ensure power supply compatibility
Connectivity Interfaces: SPI and UART/USART support for peripheral communication

The ATMEGA48-20AU meets these substitution criteria while offering enhanced specifications including higher clock speed (20MHz), increased RAM (512 x 8 bytes), additional I/O pins (23), and active product status with full RoHS3 compliance.

Parameter Comparison

Parameter	AT90LS4433-4AI	ATMEGA48-20AU	Compatibility Notes
Core Processor	AVR	AVR	Identical architecture
Core Size	8-Bit	8-Bit	Identical
Program Memory Size	4KB (2K x 16)	4KB (2K x 16)	Identical capacity
Program Memory Type	FLASH	FLASH	Identical type
EEPROM Size	256 x 8	256 x 8	Identical capacity
RAM Size	128 x 8	512 x 8	Substitute offers increased capacity
Speed	4MHz	20MHz	Substitute operates at higher frequency; firmware timing adjustments may be required
Voltage - Supply (Vcc/Vdd)	2.7V ~ 6V	2.7V ~ 5.5V	Substitute range is subset of original; compatible for 2.7V ~ 5.5V applications
Number of I/O	20	23	Substitute provides additional I/O pins
Data Converters	A/D 6x10b	A/D 8x10b	Substitute offers additional ADC channels
Connectivity	SPI, UART/USART	I2C, SPI, UART/USART	Substitute includes additional I2C interface
Peripherals	Brown-out Detect/Reset, POR, PWM, WDT	Brown-out Detect/Reset, POR, PWM, WDT	Identical peripheral set
Package / Case	32-TQFP (7x7)	32-TQFP (7x7)	Identical package; direct PCB replacement
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	Identical range
Mounting Type	Surface Mount	Surface Mount	Identical mounting technology
Product Status	Obsolete	Active	Substitute is in active production
RoHS Status	RoHS non-compliant	ROHS3 Compliant	Substitute meets current environmental regulations

Engineering Selection Recommendations

The ATMEGA48-20AU is the qualified substitute for the AT90LS4433-4AI based on the following engineering criteria:

Product Status: The AT90LS4433-4AI is obsolete, while the ATMEGA48-20AU maintains active production status, ensuring long-term availability and supply chain stability.

Regulatory Compliance: The ATMEGA48-20AU is ROHS3 compliant, meeting current environmental and regulatory requirements. The original AT90LS4433-4AI is RoHS non-compliant, making the substitute preferable for new designs and markets with RoHS mandates.

Package Compatibility: Both devices use identical 32-TQFP (7x7) packaging, enabling direct PCB replacement without layout modifications.

Electrical Compatibility: The ATMEGA48-20AU operates within the 2.7V ~ 5.5V supply range, which overlaps with the original device's 2.7V ~ 6V specification. Applications operating above 5.5V require alternative solutions.

Memory Architecture: Identical program memory (4KB FLASH) and EEPROM (256 x 8) ensure firmware compatibility. The increased RAM (512 x 8 versus 128 x 8) provides additional runtime flexibility without firmware modification requirements.

Performance Considerations: The ATMEGA48-20AU operates at 20MHz compared to the original 4MHz. Firmware timing-dependent code may require adjustment to maintain original timing behavior.

Frequently Asked Questions (FAQ)

Q: Can the ATMEGA48-20AU directly replace the AT90LS4433-4AI without PCB modifications?

A: Yes. Both devices use the 32-TQFP (7x7) package with identical pinout compatibility for direct PCB replacement.

Q: Will existing firmware for the AT90LS4433-4AI run on the ATMEGA48-20AU without modification?

A: Firmware will execute on the ATMEGA48-20AU. However, code sections dependent on clock frequency timing (delay loops, baud rate calculations, PWM frequencies) require adjustment due to the 5x speed increase (4MHz to 20MHz).

Q: What is the impact of the reduced maximum supply voltage (5.5V versus 6V)?

A: Applications requiring operation above 5.5V cannot use the ATMEGA48-20AU. For such applications, alternative substitutes must be evaluated.

Q: Does the ATMEGA48-20AU provide additional functionality beyond the AT90LS4433-4AI?

A: The ATMEGA48-20AU includes I2C connectivity (not present in the original), 8 ADC channels (versus 6), 23 I/O pins (versus 20), and 512 bytes of RAM (versus 128 bytes). These enhancements are backward compatible and do not require firmware modification.

Q: Is the ATMEGA48-20AU suitable for low-power applications?

A: Both devices support identical peripheral power management features (Brown-out Detect/Reset, POR, WDT). The higher clock speed of the ATMEGA48-20AU may increase power consumption in continuous operation; however, power-down modes provide equivalent low-power capability.

Q: What is the MSL (Moisture Sensitivity Level) for the ATMEGA48-20AU?

A: The ATMEGA48-20AU has MSL 3 (168 Hours), identical to the AT90LS4433-4AI, requiring equivalent moisture control during storage and handling.

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