AT87F51-24PC Equivalent & Substitute Parts

Part Overview

The AT87F51-24PC is an 8-bit microcontroller from Microchip Technology's 87F series, featuring 4KB OTP Quick FLASH program memory and 128 bytes of RAM. This device operates at 24MHz with 32 I/O pins and UART/USART connectivity in a 40-PDIP package. The product is currently obsolete, necessitating identification of functionally equivalent active alternatives for new designs and production continuity.

Substiute Parts

AT87F51-24PC

Microchip TechnologyIn Stock: 1903AT87F51-24PC Datasheet

Current PartRFQ

AT89S51-24PU

Microchip TechnologyIn Stock: 11094AT89S51-24PU Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

The AT89S51-24PU qualifies as a direct substitute based on the following critical parameters:

• Core Processor: Both devices use the 8051 architecture, ensuring instruction set compatibility
• Core Size & Speed: Identical 8-bit core operating at 24MHz
• Program Memory: Both provide 4KB (4K x 8) capacity; the AT89S51-24PU uses FLASH instead of OTP Quick FLASH, offering superior reprogrammability
• RAM Size: Matching 128 x 8 byte configuration
• I/O Count: Both feature 32 I/O pins
• Package: Identical 40-PDIP form factor with matching pin assignments
• Connectivity: Both include UART/USART interface

The primary difference is program memory technology: the substitute uses standard FLASH memory versus OTP Quick FLASH, which is advantageous for development and field updates.

Parameter Comparison

Engineering Selection Recommendations

The AT89S51-24PU is the appropriate substitute for the obsolete AT87F51-24PC based on the following factors:

Product Status: The AT89S51-24PU maintains active production status with 11,000 units in stock, ensuring long-term availability compared to the obsolete AT87F51-24PC.

Compliance: The AT89S51-24PU is ROHS3 compliant, meeting current environmental and regulatory requirements. The original part is RoHS non-compliant.

Electrical Compatibility: The substitute operates within a narrower voltage range (4V ~ 5.5V versus 4V ~ 6V). Applications designed for the original part's 4V ~ 5.5V window will function identically. Designs requiring operation above 5.5V require voltage regulation or redesign.

Temperature Range: The AT89S51-24PU supports -40°C ~ 85°C, exceeding the original part's 0°C ~ 70°C range, providing greater operational flexibility.

Additional Peripheral: The AT89S51-24PU includes a Watchdog Timer (WDT) not present in the original part, offering enhanced system reliability without functional impact.

Frequently Asked Questions (FAQ)

Q: Are the AT87F51-24PC and AT89S51-24PU pin-compatible?

A: Yes. Both devices use the 40-PDIP package with identical pin assignments and electrical characteristics for all signal pins.

Q: What is the key difference between OTP Quick FLASH and standard FLASH?

A: OTP Quick FLASH is one-time programmable, while standard FLASH is reprogrammable. The AT89S51-24PU's FLASH memory allows multiple program cycles, beneficial for development and field updates.

Q: Can I use the AT89S51-24PU in applications requiring operation above 5.5V?

A: No. The AT89S51-24PU maximum supply voltage is 5.5V, compared to the original part's 6V maximum. Applications requiring 5.5V ~ 6V operation require external voltage regulation or alternative components.

Q: Does the Watchdog Timer on the AT89S51-24PU affect compatibility?

A: No. The WDT is an additional feature that does not interfere with existing firmware. It can remain disabled if not required by the application.

Q: What is the temperature operating range difference?

A: The AT89S51-24PU operates from -40°C ~ 85°C, while the original part operates from 0°C ~ 70°C. The substitute supports extended low-temperature operation and higher maximum temperature, suitable for broader environmental conditions.

Q: Is the AT89S51-24PU available in the same packaging?

A: Yes. The AT89S51-24PU is supplied in 40-PDIP packaging identical to the original part. Packaging is specified as Tube for the substitute.