AT89C55WD-24AC Equivalent & Substitute Parts

Part Overview

The AT89C55WD-24AC 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 within a 4.5V to 5.5V supply voltage range.

Substiute Parts

AT89C55WD-24AC

Microchip TechnologyIn Stock: 4552AT89C55WD-24AC Datasheet

Current PartRFQ

AT89C55WD-24AU

Microchip TechnologyIn Stock: 4194AT89C55WD-24AU Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

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

• Core Architecture: 8051-based processor
• Memory Configuration: 20KB FLASH program memory, 256 x 8 RAM
• Clock Speed: 24MHz operation
• I/O Count: 32 I/O pins
• Package: 44-TQFP (10x10) surface mount
• Supply Voltage: 4.5V ~ 5.5V
• Connectivity: UART/USART interface
• Peripherals: Watchdog Timer (WDT)

The AT89C55WD-24AU meets all these criteria and is therefore a direct functional equivalent. Differences in product status, operating temperature range, packaging format (tray vs. tube), and RoHS compliance do not affect electrical or mechanical compatibility.

Parameter Comparison

Engineering Selection Recommendations

The AT89C55WD-24AU is the direct substitute for the AT89C55WD-24AC. Selection between these parts should be based on the following factors:

Product Status: The AT89C55WD-24AC is obsolete, while the AT89C55WD-24AU is active. For new designs or long-term production requirements, the AT89C55WD-24AU is the appropriate choice due to continued manufacturer support and availability.

Compliance Requirements: The AT89C55WD-24AU is ROHS3 compliant, whereas the AT89C55WD-24AC is non-compliant. Applications subject to RoHS regulations must use the AT89C55WD-24AU.

Operating Temperature Range: The AT89C55WD-24AU supports -40°C to 85°C, compared to the AT89C55WD-24AC's 0°C to 70°C range. Applications requiring extended temperature operation must use the AT89C55WD-24AU.

Electrical and Mechanical Compatibility: Both parts are electrically and mechanically identical across all functional parameters, including memory configuration, clock speed, I/O count, package type, and supply voltage specifications.

Frequently Asked Questions (FAQ)

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

A: Yes. Both parts share identical electrical specifications, memory configuration, clock speed, I/O pin count, and 44-TQFP package dimensions. No circuit modifications are required for substitution.

Q: What is the difference between the packaging formats (tray vs. tube)?

A: Packaging format refers to the delivery method and does not affect the electrical or mechanical properties of the component. Tray packaging is typically used for automated assembly processes, while tube packaging is used for manual handling. Selection depends on manufacturing process requirements, not component functionality.

Q: Why does the AT89C55WD-24AU have a wider operating temperature range?

A: The AT89C55WD-24AU (-40°C to 85°C) is specified for a broader temperature range than the AT89C55WD-24AC (0°C to 70°C). This reflects different qualification and testing standards applied by the manufacturer. Applications operating within the AT89C55WD-24AC's original temperature range will function identically with the AT89C55WD-24AU.

Q: Is RoHS compliance a functional difference?

A: No. RoHS compliance is a regulatory and material composition specification, not a functional parameter. Both parts perform identically in circuit operation. RoHS compliance is relevant only for applications subject to regulatory requirements or customer specifications.

Q: Are there any pin-to-pin differences between these parts?

A: No. Both parts use the 44-TQFP (10x10) package with identical pin assignments, pin count, and pin functionality. PCB layouts designed for the AT89C55WD-24AC require no modification for the AT89C55WD-24AU.