AT89C51-24PC Equivalent & Substitute Parts

Part Overview

The AT89C51-24PC is an 8-bit microcontroller from Microchip Technology's 89C series, featuring 4KB of FLASH program memory and operating at 24MHz. This device is classified as obsolete, which necessitates identification of functionally equivalent alternatives for new designs and production continuity. The part is housed in a 40-DIP package with 32 I/O pins and includes UART/USART connectivity for serial communication applications.

Substiute Parts

AT89C51-24PC

Microchip TechnologyIn Stock: 15811AT89C51-24PC Datasheet

Current PartRFQ

AT89S51-24PU

Microchip TechnologyIn Stock: 11094AT89S51-24PU Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the AT89C51-24PC is determined by strict alignment of the following electrical and mechanical parameters:

• Core Architecture: Both main and substitute parts must be based on the 8051 processor family (80C51 or 8051 core)
• Memory Configuration: Program memory must be 4KB FLASH with 128 x 8 RAM
• Operating Speed: 24MHz clock frequency
• Package Format: 40-DIP through-hole package with identical pin count (32 I/O)
• Supply Voltage Range: Compatible voltage specifications for system integration
• Connectivity: UART/USART interface requirement

The AT89S51-24PU qualifies as a direct substitute based on these parameters. Both devices share identical memory architecture, clock speed, I/O configuration, and package format. The primary distinction lies in series designation (89C versus 89S) and product lifecycle status.

Parameter Comparison

Engineering Selection Recommendations

The AT89S51-24PU is the designated substitute for the obsolete AT89C51-24PC. Selection of the AT89S51-24PU is supported by the following factors:

• Product Lifecycle: The AT89S51-24PU maintains active product status with ongoing manufacturer support, whereas the AT89C51-24PC is classified as obsolete
• Regulatory Compliance: The AT89S51-24PU achieves ROHS3 compliance, meeting current environmental and regulatory requirements
• Electrical Compatibility: Core electrical parameters—memory size, clock speed, I/O count, and connectivity—are identical between both devices
• Package Compatibility: Both devices utilize the 40-DIP through-hole package with matching pinout and mechanical dimensions
• Enhanced Temperature Range: The AT89S51-24PU supports an extended operating temperature range (-40°C ~ 85°C) compared to the original part (0°C ~ 70°C), providing greater flexibility for industrial and extended-temperature applications
• Additional Peripherals: The AT89S51-24PU includes a Watchdog Timer (WDT) peripheral not specified in the original part

Frequently Asked Questions (FAQ)

Q: Can the AT89S51-24PU be used as a direct replacement for the AT89C51-24PC in existing designs?

A: Yes. Both devices share identical core memory architecture (4KB FLASH, 128 x 8 RAM), clock frequency (24MHz), I/O configuration (32 pins), and package format (40-DIP). The pinout and electrical interface are compatible for direct substitution in through-hole applications.

Q: What is the difference between the 89C and 89S series designations?

A: The series designation reflects different product lines within Microchip's 8051-based microcontroller portfolio. The 89S series (represented by AT89S51-24PU) is the active production line, while the 89C series (AT89C51-24PC) has reached end-of-life status.

Q: Are there voltage supply differences between these parts?

A: The AT89C51-24PC operates at 4V ~ 6V, while the AT89S51-24PU operates at 4V ~ 5.5V. The substitute part has a narrower upper voltage limit. System designs operating at or below 5.5V will experience no functional difference. Designs requiring operation above 5.5V must retain the original part or redesign the power supply.

Q: Does the addition of the Watchdog Timer (WDT) in the AT89S51-24PU affect compatibility?

A: The WDT is an additional peripheral that does not interfere with existing functionality. Designs not utilizing the WDT will operate identically. Designs that benefit from watchdog functionality can enable this feature in the substitute part without modification to core application code.

Q: What is the impact of the extended operating temperature range?

A: The AT89S51-24PU supports -40°C ~ 85°C compared to the original 0°C ~ 70°C. This extended range provides greater operational flexibility for industrial, automotive, and temperature-extreme environments. Existing designs operating within 0°C ~ 70°C will experience no change in performance.

Q: Is the AT89S51-24PU RoHS compliant?

A: Yes. The AT89S51-24PU is ROHS3 compliant, meeting current environmental regulations. The original AT89C51-24PC is RoHS non-compliant. New designs and production runs should utilize the compliant substitute part.

Q: Are there any package or pinout differences?

A: No. Both devices use the 40-DIP package with identical mechanical dimensions (0.600", 15.24mm) and pinout configuration. Through-hole PCB designs require no modification for physical compatibility.