AT89C4051-12SC Equivalent & Substitute Parts

Part Overview

The AT89C4051-12SC is an 8-bit microcontroller from Microchip Technology's 89C series, featuring 4KB FLASH program memory, 128 bytes of RAM, and 15 I/O pins. Designed for embedded applications requiring low-cost 8051-compatible processing, this device operates at 12MHz with integrated brown-out detection, LED control, and power-on reset functionality.

The AT89C4051-12SC is classified as obsolete. Locating equivalent substitute parts is necessary to maintain design continuity, ensure supply chain reliability, and support legacy system maintenance or redesigns requiring compatible alternatives.

Key Parameters

Parameter	Value
Core Processor	8051
Core Size	8-Bit
Speed	12MHz
Program Memory Size	4KB (4K x 8)
Program Memory Type	FLASH
RAM Size	128 x 8
Number of I/O	15
Voltage Supply (Vcc/Vdd)	4V ~ 6V
Connectivity	UART/USART
Peripherals	Brown-out Detect/Reset, LED, POR
Mounting Type	Surface Mount
Package	20-SOIC (0.295", 7.50mm Width)
Operating Temperature	0°C ~ 70°C (TA)

Substitute Part Grouping Explanation

Substitution eligibility for the AT89C4051-12SC is determined by strict alignment with the following core parameters:

Core Processor Architecture: Must be 8051-compatible
Core Size: Must be 8-Bit
Speed: Must operate at 12MHz
Program Memory: Must be 4KB FLASH
RAM: Must be 128 x 8 bytes
I/O Count: Must provide 15 I/O pins
Connectivity: Must include UART/USART
Peripherals: Must include Brown-out Detect/Reset, LED, and POR
Package: Must be 20-SOIC form factor
Mounting: Must be Surface Mount

The AT89C4051-12SU meets all substitution criteria. Differences in voltage supply range, operating temperature range, product status, and compliance certifications do not affect functional compatibility for applications within the overlapping electrical specifications.

Parameter Comparison

Parameter	AT89C4051-12SC (Main)	AT89C4051-12SU (Substitute)	Compatibility
Core Processor	8051	8051	Identical
Core Size	8-Bit	8-Bit	Identical
Speed	12MHz	12MHz	Identical
Program Memory Size	4KB (4K x 8)	4KB (4K x 8)	Identical
Program Memory Type	FLASH	FLASH	Identical
RAM Size	128 x 8	128 x 8	Identical
Number of I/O	15	15	Identical
Connectivity	UART/USART	UART/USART	Identical
Peripherals	Brown-out Detect/Reset, LED, POR	Brown-out Detect/Reset, LED, POR	Identical
Mounting Type	Surface Mount	Surface Mount	Identical
Package	20-SOIC (0.295", 7.50mm Width)	20-SOIC (0.295", 7.50mm Width)	Identical
Voltage Supply (Vcc/Vdd)	4V ~ 6V	2.7V ~ 6V	Overlapping (4V ~ 6V)
Operating Temperature	0°C ~ 70°C (TA)	-40°C ~ 85°C (TA)	Overlapping (0°C ~ 70°C)
Product Status	Obsolete	Active	Substitute is current production
RoHS Status	RoHS non-compliant	ROHS3 Compliant	Substitute meets current compliance

Engineering Selection Recommendations

The AT89C4051-12SU is a direct functional substitute for the AT89C4051-12SC. Both devices share identical core architecture, memory configuration, I/O capability, and peripheral feature set. The substitute part operates within the voltage and temperature range of the original part for standard applications.

The AT89C4051-12SU carries Active product status, ensuring ongoing availability and supply chain support. The device is ROHS3 compliant, meeting current environmental and regulatory requirements. The original AT89C4051-12SC is classified as Obsolete, making the AT89C4051-12SU the appropriate choice for new designs, production continuity, and legacy system support.

Selection between these parts should be based on supply availability, packaging requirements (Tube for the substitute), and compliance mandates applicable to the end application.

Frequently Asked Questions (FAQ)

Q: Can the AT89C4051-12SU replace the AT89C4051-12SC in existing designs?

A: Yes. Both devices are pin-compatible, functionally identical 8051 microcontrollers with 4KB FLASH, 128 bytes RAM, 15 I/O pins, and 12MHz operation. The substitute operates within the overlapping voltage range (4V ~ 6V) and temperature range (0°C ~ 70°C) of the original part for standard applications.

Q: What is the difference in packaging between these parts?

A: The AT89C4051-12SC is supplied in standard packaging, while the AT89C4051-12SU is supplied in Tube packaging. Both use the 20-SOIC form factor with identical pinout and mechanical dimensions (0.295", 7.50mm Width).

Q: Why is the AT89C4051-12SC classified as Obsolete?

A: The AT89C4051-12SC has reached end-of-life status. The AT89C4051-12SU remains in active production and is the recommended alternative for ongoing supply and support.

Q: Does the wider operating temperature range of the AT89C4051-12SU affect compatibility?

A: No. The substitute's extended temperature range (-40°C ~ 85°C) encompasses the original part's range (0°C ~ 70°C). Applications operating within the original temperature specification remain fully compatible.

Q: Are there compliance differences between these parts?

A: The AT89C4051-12SU is ROHS3 compliant, while the AT89C4051-12SC is RoHS non-compliant. For applications subject to RoHS requirements, the substitute is the appropriate choice.

Q: What is the voltage supply difference?

A: The AT89C4051-12SC operates at 4V ~ 6V. The AT89C4051-12SU operates at 2.7V ~ 6V. For designs operating at 4V ~ 6V, both parts are electrically compatible. The substitute offers extended low-voltage capability not required by the original specification.

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