AT89C55WD-24AI Equivalent & Substitute Parts

Part Overview

The AT89C55WD-24AI is an 8-bit microcontroller from Microchip Technology's 89C series, featuring 20KB of FLASH program memory and operating at 24MHz. This device is classified as obsolete, which necessitates identification of functionally equivalent alternatives for ongoing design support and component procurement. The part is housed in a 44-TQFP surface mount package and operates across the industrial temperature range of -40°C to 85°C.

Substiute Parts

AT89C55WD-24AI

Microchip TechnologyIn Stock: 2087AT89C55WD-24AI Datasheet

Current PartRFQ

AT89C55WD-24AU

Microchip TechnologyIn Stock: 4194AT89C55WD-24AU Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the AT89C55WD-24AI is determined by strict equivalence across the following critical parameters:

• Core processor architecture (8051)
• Core size (8-Bit)
• Operating frequency (24MHz)
• Program memory capacity and type (20KB FLASH)
• RAM configuration (256 x 8)
• I/O pin count (32)
• Supply voltage range (4.5V ~ 5.5V)
• Package type and pin count (44-TQFP)
• Operating temperature range (-40°C ~ 85°C)

The AT89C55WD-24AU meets all these criteria and is therefore a direct functional equivalent. The primary distinction between these parts is product status and packaging format, not electrical or mechanical specifications.

Parameter Comparison

Engineering Selection Recommendations

The AT89C55WD-24AU is the direct substitute for the AT89C55WD-24AI. Both parts are electrically and mechanically identical across all functional parameters. The AT89C55WD-24AU is preferred for new designs and ongoing procurement due to its active product status and ROHS3 compliance. The AT89C55WD-24AI, being obsolete and RoHS non-compliant, should be replaced in production environments where regulatory compliance is required.

Frequently Asked Questions (FAQ)

Q: Are the AT89C55WD-24AI and AT89C55WD-24AU pin-for-pin compatible?

A: Yes. Both parts use the 44-TQFP package with identical pin assignments, voltage requirements, and signal definitions. No PCB redesign is required for substitution.

Q: What is the difference between the -AI and -AU packaging designations?

A: The -AI designation indicates tube packaging, while -AU indicates tray packaging. This is a packaging format difference only and does not affect electrical performance or functionality.

Q: Can the AT89C55WD-24AU be used as a direct replacement in existing designs using the AT89C55WD-24AI?

A: Yes. The AT89C55WD-24AU is a direct functional equivalent with identical electrical specifications, memory configuration, I/O count, and operating parameters. No firmware or hardware modifications are necessary.

Q: What is the significance of the RoHS compliance difference?

A: The AT89C55WD-24AU is ROHS3 compliant, meeting current environmental and regulatory standards for electronic components. The AT89C55WD-24AI is RoHS non-compliant and may not be acceptable for applications subject to RoHS regulations.

Q: Are there any differences in memory specifications between these parts?

A: No. Both parts feature identical 20KB FLASH program memory, 256 x 8 RAM, and support the same instruction set and memory addressing modes.

Q: What is the moisture sensitivity level, and does it differ between these parts?

A: Both parts have an MSL rating of 3 (168 Hours), indicating identical moisture handling requirements and storage conditions.