AT89C51-24AC Equivalent & Substitute Parts

Part Overview

The AT89C51-24AC is an 8-bit microcontroller from Microchip Technology's 89C series, featuring 4KB FLASH program memory, 128 bytes of RAM, and 32 I/O pins in a 44-TQFP surface mount package. Operating at 24MHz with a supply voltage range of 4V to 6V, this device is designed for embedded applications requiring UART/USART connectivity and internal oscillator support.

The AT89C51-24AC is classified as obsolete. Identifying equivalent and substitute parts is necessary to ensure design continuity, maintain supply chain reliability, and support legacy system maintenance or redesign initiatives.

Substiute Parts

AT89C51-24AC

Microchip TechnologyIn Stock: 2132AT89C51-24AC Datasheet

Current PartRFQ

AT89S51-24AU

Microchip TechnologyIn Stock: 3052AT89S51-24AU Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the AT89C51-24AC is determined by the following critical parameters:

• Core Processor Architecture: Must be 8051-compatible
• Core Size: Must be 8-Bit
• Speed: Must support 24MHz operation
• Program Memory: Must provide minimum 4KB FLASH
• RAM: Must provide minimum 128 x 8 bytes
• I/O Count: Must provide minimum 32 I/O pins
• Package: Must be 44-TQFP (10x10) surface mount
• Connectivity: Must include UART/USART interface
• Oscillator: Must support internal oscillator

The AT89S51-24AU meets all substitution criteria. It maintains identical core architecture, memory configuration, I/O count, package form factor, and connectivity specifications. Differences in supply voltage range, operating temperature, and product status do not prevent functional substitution in applications designed for the AT89C51-24AC.

Parameter Comparison

Engineering Selection Recommendations

The AT89S51-24AU is the primary substitute for the AT89C51-24AC based on the following engineering criteria:

Product Status: The AT89S51-24AU is classified as Active, ensuring ongoing availability and manufacturer support. The AT89C51-24AC is Obsolete, making the AT89S51-24AU the appropriate choice for new designs and legacy system maintenance.

Compliance & Certifications: The AT89S51-24AU is ROHS3 Compliant, meeting current environmental and regulatory requirements. The AT89C51-24AC is RoHS non-compliant. Both devices carry identical ECCN (EAR99) and HTSUS (8542.31.0001) classifications.

Functional Compatibility: All critical electrical and mechanical parameters are identical between the two devices. The AT89S51-24AU operates within a narrower supply voltage range (4V ~ 5.5V versus 4V ~ 6V) and supports an extended operating temperature range (-40°C ~ 85°C versus 0°C ~ 70°C). These differences do not prevent substitution in applications designed for the AT89C51-24AC, provided the supply voltage is maintained within the AT89S51-24AU specification.

Inventory & Availability: The AT89S51-24AU has higher current inventory (3031 Pcs) compared to the AT89C51-24AC (2100 Pcs), supporting supply chain continuity.

Frequently Asked Questions (FAQ)

Q: Can the AT89S51-24AU directly replace the AT89C51-24AC in existing designs?

A: Yes. Both devices share identical core processor architecture (8051), memory configuration (4KB FLASH, 128 bytes RAM), I/O count (32 pins), package form factor (44-TQFP), and connectivity specifications (UART/USART). The AT89S51-24AU operates within a narrower supply voltage range; verify that your power supply maintains 4V to 5.5V output.

Q: What is the difference between the 89C and 89S series designations?

A: The 89C and 89S designations indicate different product lines within Microchip's 8051 microcontroller family. Both are functionally equivalent 8051-based devices with identical core specifications. The 89S series (represented by AT89S51-24AU) is currently active in production, while the 89C series (represented by AT89C51-24AC) is obsolete.

Q: Are there any temperature or voltage considerations when substituting?

A: The AT89S51-24AU supports an extended operating temperature range (-40°C to 85°C) compared to the AT89C51-24AC (0°C to 70°C). The AT89S51-24AU supply voltage range is 4V to 5.5V, which is narrower than the AT89C51-24AC range of 4V to 6V. Ensure your application's power supply and thermal environment fall within the AT89S51-24AU specifications.

Q: Is the 44-TQFP package identical between both devices?

A: Yes. Both devices use the 44-TQFP (10x10mm) surface mount package with identical pin assignments and mechanical dimensions. No PCB layout modifications are required for substitution.

Q: What is the RoHS compliance difference?

A: The AT89C51-24AC is RoHS non-compliant, while the AT89S51-24AU is ROHS3 Compliant. For applications subject to RoHS regulations or customer requirements, the AT89S51-24AU is the appropriate choice.