AT87F51-24AI Equivalent & Substitute Parts

Part Overview

The AT87F51-24AI is an 8-bit microcontroller from Microchip Technology's 87F series, featuring 4KB OTP Quick FLASH memory and operating at 24MHz. This device is classified as obsolete, which necessitates identification of functionally equivalent alternatives for ongoing design support and production requirements. The 44-TQFP package and core specifications remain relevant for legacy system maintenance and component replacement scenarios.

Substiute Parts

AT87F51-24AI

Microchip TechnologyIn Stock: 865AT87F51-24AI Datasheet

Current PartRFQ

AT89S51-24AU

Microchip TechnologyIn Stock: 3052AT89S51-24AU Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the AT87F51-24AI is determined by strict alignment across the following critical parameters:

• Core Architecture: 8051-based processor family
• Memory Configuration: 4KB program memory and 128 x 8 RAM
• Operating Speed: 24MHz clock frequency
• I/O Count: 32 input/output pins
• Package Format: 44-TQFP (10x10) surface mount
• Voltage Range: Supply voltage compatibility within specified operating window
• Temperature Range: -40°C to 85°C operating specification

The AT89S51-24AU qualifies as a direct substitute based on matching all core parameters. The primary distinction lies in memory technology (FLASH vs. OTP Quick FLASH) and product lifecycle status, which do not preclude functional equivalence in application circuits.

Parameter Comparison

Engineering Selection Recommendations

The AT89S51-24AU is the qualified substitute for the AT87F51-24AI based on the following engineering criteria:

Product Lifecycle: The AT89S51-24AU maintains active product status with verified programmability and current manufacturing support, whereas the AT87F51-24AI is obsolete. This distinction is critical for long-term supply chain continuity and technical support availability.

Regulatory Compliance: The AT89S51-24AU achieves ROHS3 compliance, meeting current environmental and material restriction standards. The AT87F51-24AI does not meet these requirements, making the substitute preferable for new designs and updated production runs.

Memory Technology: Both devices provide 4KB program memory at identical speed and capacity. The AT89S51-24AU employs standard FLASH technology versus OTP Quick FLASH in the main part. This transition does not affect functional compatibility in application circuits.

Voltage Specification: The AT89S51-24AU operates within 4V to 5.5V, which is a subset of the AT87F51-24AI's 4V to 6V range. Designs operating above 5.5V require verification against the substitute's absolute maximum ratings.

Electrical and Mechanical Compatibility: Pin count, package format, I/O configuration, and thermal operating range are identical, ensuring direct PCB-level compatibility without layout modifications.

Frequently Asked Questions (FAQ)

Q: Can the AT89S51-24AU replace the AT87F51-24AI in existing designs without PCB modifications?

A: Yes. Both devices share identical pin counts, package format (44-TQFP), I/O configuration (32 pins), and thermal specifications. No PCB layout changes are required for mechanical and electrical compatibility.

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

A: OTP (One-Time Programmable) Quick FLASH in the AT87F51-24AI is programmed once during manufacturing. Standard FLASH in the AT89S51-24AU supports multiple program/erase cycles. This distinction does not affect functional operation in applications where reprogramming is not required.

Q: Is the AT89S51-24AU suitable for designs requiring operation above 5.5V?

A: The AT89S51-24AU is specified for 4V to 5.5V operation. Designs requiring 5.5V to 6V operation must be evaluated against the substitute's absolute maximum ratings and may require the original AT87F51-24AI or alternative components rated for higher voltage.

Q: What is the significance of the ROHS3 compliance difference?

A: ROHS3 compliance indicates adherence to current environmental and material restriction directives. The AT89S51-24AU meets these standards, making it suitable for modern production environments and regulatory requirements. The AT87F51-24AI's non-compliance may restrict its use in certain markets and applications.

Q: Are there any connectivity or peripheral differences between these devices?

A: Both devices feature UART/USART connectivity and internal oscillators. The AT89S51-24AU includes a Watchdog Timer (WDT) peripheral not listed for the AT87F51-24AI. This addition does not preclude substitution and may provide enhanced functionality in applications requiring watchdog protection.

Q: What inventory considerations apply to this substitution?

A: The AT89S51-24AU is available in significantly higher quantities (3031 pcs) compared to the AT87F51-24AI (797 pcs), with active manufacturing status ensuring continued availability. This supply advantage supports long-term production planning and reduces obsolescence risk.