AT87F51RC-24PC Equivalent & Substitute Parts

Part Overview

The AT87F51RC-24PC is an 8-bit microcontroller from Microchip Technology's 87F series, featuring 32KB OTP Quick FLASH memory and a 24MHz clock speed in a 40-DIP package. This device is classified as obsolete, making equivalent and substitute parts necessary for new designs and production continuity. The part operates within a 4V to 6V supply range and includes 512 x 8 bytes of RAM with UART/USART connectivity and watchdog timer peripherals.

Key Parameters

Parameter	Value
Core Processor	8051
Core Size	8-Bit
Program Memory Size	32KB (32K x 8)
Program Memory Type	OTP Quick FLASH
RAM Size	512 x 8
Speed	24MHz
Voltage Supply (Vcc/Vdd)	4V ~ 6V
Number of I/O	32
Package	40-DIP
Mounting Type	Through Hole
Operating Temperature	0°C ~ 70°C

Substitute Part Grouping Explanation

Substitution for the AT87F51RC-24PC is determined by compatibility across the following critical parameters:

Package Format: 40-DIP physical compatibility for direct board-level replacement
Core Architecture: 8051 or 8052 processor family compatibility
Memory Configuration: Minimum 32KB program memory to support existing firmware
I/O Count: 32 I/O pins to maintain signal routing
Supply Voltage Range: Overlap with 4V ~ 6V requirement
Connectivity: UART/USART support for serial communication

The substitute parts listed below meet these criteria while offering improvements in memory capacity, speed, voltage flexibility, and product status.

Parameter Comparison

Parameter	AT87F51RC-24PC	W78E058DDG	W78E516DDG
Manufacturer	Microchip Technology	Nuvoton Technology Corporation	Nuvoton Technology Corporation
Core Processor	8051	8052	8052
Core Size	8-Bit	8-Bit	8-Bit
Program Memory Size	32KB (32K x 8)	32KB (32K x 8)	64KB (64K x 8)
Program Memory Type	OTP Quick FLASH	FLASH	FLASH
RAM Size	512 x 8	512 x 8	512 x 8
Speed	24MHz	40MHz	40MHz
Voltage Supply (Vcc/Vdd)	4V ~ 6V	2.4V ~ 5.5V	2.4V ~ 5.5V
Number of I/O	32	32	32
Connectivity	UART/USART	EBI/EMI, UART/USART	EBI/EMI, UART/USART
Peripherals	WDT	POR, WDT	POR, WDT
Package	40-DIP	40-DIP	40-DIP
Mounting Type	Through Hole	Through Hole	Through Hole
Operating Temperature	0°C ~ 70°C	-40°C ~ 85°C (TA)	-40°C ~ 85°C (TA)
Product Status	Obsolete	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant
MSL Rating	Not Applicable	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

W78E058DDG is the direct functional equivalent for applications requiring 32KB program memory. This part maintains identical memory capacity and I/O configuration while offering active product status, ROHS3 compliance, and extended operating temperature range (-40°C to 85°C). The voltage supply range (2.4V ~ 5.5V) encompasses the original 4V ~ 6V requirement. The 40MHz speed provides performance headroom over the original 24MHz specification.

W78E516DDG is suitable for applications where increased program memory (64KB) provides design flexibility or future expansion capability. This part shares the same core architecture, I/O count, and package format as the AT87F51RC-24PC while offering the same compliance and temperature advantages as the W78E058DDG. The additional 32KB of program memory does not impact pin compatibility or board-level integration.

Both substitute parts are manufactured by Nuvoton Technology Corporation and carry active product status, ensuring long-term availability and supply chain stability. Both are ROHS3 compliant and carry MSL rating 1, meeting modern manufacturing and environmental standards.

Frequently Asked Questions (FAQ)

Q: Can W78E058DDG or W78E516DDG be used as direct pin-for-pin replacements?

A: Yes. Both substitute parts use the 40-DIP package with identical pinout and I/O configuration (32 pins). Through-hole mounting is identical. No PCB modifications are required for physical replacement.

Q: What is the difference between W78E058DDG and W78E516DDG?

A: The primary difference is program memory capacity. W78E058DDG provides 32KB (matching the original AT87F51RC-24PC), while W78E516DDG provides 64KB. Both parts share identical core architecture, speed (40MHz), RAM (512 x 8), I/O count (32), and package format. Selection depends on firmware size requirements.

Q: Are there voltage supply compatibility concerns?

A: The substitute parts operate at 2.4V ~ 5.5V, which overlaps with the original 4V ~ 6V range. Systems designed for 4V ~ 5.5V operation are fully compatible. Systems requiring operation above 5.5V require voltage regulation or alternative solutions.

Q: What is the significance of the 8052 core in the substitute parts versus the 8051 core in the original?

A: The 8052 is an enhanced variant of the 8051 architecture with additional on-chip peripherals (POR - Power-On Reset). Firmware compiled for 8051 targets executes on 8052 devices without modification. The 8052 provides backward compatibility with 8051 software.

Q: How do the operating temperature ranges compare?

A: The original AT87F51RC-24PC operates from 0°C to 70°C. Both substitute parts operate from -40°C to 85°C, providing extended temperature coverage suitable for industrial and automotive applications.

Q: What compliance advantages do the substitute parts offer?

A: Both W78E058DDG and W78E516DDG are ROHS3 compliant, whereas the original AT87F51RC-24PC is RoHS non-compliant. Both substitute parts carry MSL rating 1 (Unlimited), meeting modern moisture sensitivity standards. These certifications are required for many OEM and regulatory environments.

Q: Is firmware migration required when switching to substitute parts?

A: No firmware migration is required. Both substitute parts execute existing 8051-compiled firmware without modification. The 8052 architecture maintains full backward compatibility with 8051 instruction sets and memory organization.

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