AT89S51-24JC Equivalent & Substitute Parts

Part Overview

The AT89S51-24JC is an 8-bit microcontroller from Microchip Technology's 89S series, featuring 4KB FLASH program memory, 128 bytes of RAM, and 32 I/O pins. Operating at 24MHz with integrated UART/USART connectivity and watchdog timer functionality, this device is designed for embedded control applications requiring moderate processing capability and on-chip memory.

The AT89S51-24JC carries an Obsolete product status. Identifying equivalent substitute parts is necessary to ensure design continuity, maintain supply chain reliability, and support long-term production requirements for systems currently utilizing this microcontroller.

Key Parameters

Parameter	Value
Core Processor	8051
Core Size	8-Bit
Speed	24MHz
Program Memory Size	4KB (4K x 8)
Program Memory Type	FLASH
RAM Size	128 x 8
Number of I/O	32
Voltage Supply (Vcc/Vdd)	4V ~ 5.5V
Connectivity	UART/USART
Peripherals	WDT
Oscillator Type	Internal
Mounting Type	Surface Mount
Package / Case	44-LCC (J-Lead)
Supplier Device Package	44-PLCC (16.6x16.6)

Substitute Part Grouping Explanation

Substitution eligibility for the AT89S51-24JC is determined by strict equivalence across the following critical parameters:

Core Architecture: 8051-based processor
Memory Configuration: 4KB FLASH program memory, 128 bytes RAM
Clock Speed: 24MHz operation
I/O Count: 32 I/O pins
Supply Voltage: 4V to 5.5V operating range
Package Geometry: 44-PLCC (16.6x16.6) footprint with 44-LCC J-Lead configuration
Connectivity & Peripherals: UART/USART and watchdog timer functionality

The AT89S51-24JU qualifies as a direct substitute based on identical electrical specifications, memory architecture, pin configuration, and physical packaging. Differences in product status, operating temperature range, and compliance certifications do not affect functional interchangeability within the specified electrical and mechanical parameters.

Parameter Comparison

Parameter	AT89S51-24JC (Main Part)	AT89S51-24JU (Substitute)
Manufacturer	Microchip Technology	Microchip Technology
Series	89S	89S
Core Processor	8051	8051
Core Size	8-Bit	8-Bit
Speed	24MHz	24MHz
Program Memory Size	4KB (4K x 8)	4KB (4K x 8)
Program Memory Type	FLASH	FLASH
RAM Size	128 x 8	128 x 8
Number of I/O	32	32
Voltage Supply (Vcc/Vdd)	4V ~ 5.5V	4V ~ 5.5V
Connectivity	UART/USART	UART/USART
Peripherals	WDT	WDT
Oscillator Type	Internal	Internal
Mounting Type	Surface Mount	Surface Mount
Package / Case	44-LCC (J-Lead)	44-LCC (J-Lead)
Supplier Device Package	44-PLCC (16.6x16.6)	44-PLCC (16.6x16.6)
Operating Temperature	0°C ~ 70°C (TA)	-40°C ~ 85°C (TA)
Product Status	Obsolete	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	2 (1 Year)	3 (168 Hours)

Engineering Selection Recommendations

The AT89S51-24JU is the qualified substitute for the AT89S51-24JC based on the following factors:

Functional Equivalence: Both devices share identical core architecture, memory configuration, clock speed, I/O count, and peripheral set. Pin-for-pin and functional compatibility is assured.

Product Status: The AT89S51-24JU maintains Active product status with verified programmability, ensuring ongoing availability and manufacturing support. The AT89S51-24JC is Obsolete, making the substitute necessary for continued supply chain access.

Compliance & Certifications: The AT89S51-24JU is ROHS3 compliant and REACH unaffected, meeting current regulatory requirements. The AT89S51-24JC is RoHS non-compliant, presenting potential compliance constraints for new designs or production batches.

Operating Temperature Range: The AT89S51-24JU supports -40°C to 85°C operation, providing extended thermal performance compared to the AT89S51-24JC range of 0°C to 70°C. This expanded range accommodates broader environmental deployment scenarios.

Packaging & Handling: Both devices utilize identical 44-PLCC (16.6x16.6) footprints. The AT89S51-24JU specifies MSL 3 (168 hours) versus MSL 2 (1 year) for the original part, requiring standard moisture control during storage and assembly.

Frequently Asked Questions (FAQ)

Q: Are the AT89S51-24JC and AT89S51-24JU pin-compatible?

A: Yes. Both devices use the 44-PLCC (16.6x16.6) package with 44-LCC J-Lead configuration. Pin assignments, electrical characteristics, and functional behavior are identical, enabling direct PCB-level substitution without layout modifications.

Q: What is the primary reason for substitution?

A: The AT89S51-24JC is classified as Obsolete. The AT89S51-24JU is an Active product from the same manufacturer and series, ensuring reliable supply availability and manufacturing continuity.

Q: Do the devices differ in memory or processing capability?

A: No. Both devices feature 4KB FLASH program memory, 128 bytes RAM, 8-bit 8051 core architecture, 24MHz clock speed, and 32 I/O pins. Memory organization and processing performance are identical.

Q: What is the difference in operating temperature range?

A: The AT89S51-24JC operates from 0°C to 70°C. The AT89S51-24JU extends this range to -40°C to 85°C, providing enhanced thermal performance for applications requiring wider environmental tolerance.

Q: Are there compliance differences between the two parts?

A: Yes. The AT89S51-24JU is ROHS3 compliant, while the AT89S51-24JC is RoHS non-compliant. For applications subject to RoHS regulations, the AT89S51-24JU is the required choice.

Q: What is the moisture sensitivity level difference?

A: The AT89S51-24JC specifies MSL 2 (1 Year shelf life). The AT89S51-24JU specifies MSL 3 (168 hours shelf life). Standard moisture control procedures during storage and assembly apply to both devices.

Q: Can I use the AT89S51-24JU in existing designs without firmware changes?

A: Yes. Functional equivalence is complete. No firmware modifications are required. Existing code compiled for the AT89S51-24JC executes identically on the AT89S51-24JU.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message