AT28C64X-15SC Equivalent & Substitute Parts

Part Overview

The AT28C64X-15SC is a 64Kbit parallel EEPROM memory IC manufactured by Microchip Technology, housed in a 28-SOIC package with 150 ns access time. This device is classified as obsolete, which necessitates identification of functionally equivalent alternatives for ongoing system support and new design implementations. The obsolete status indicates limited availability and potential discontinuation of supply, making substitute part identification critical for procurement and design continuity.

Substiute Parts

AT28C64X-15SC

Microchip TechnologyIn Stock: 1951AT28C64X-15SC Datasheet

Current PartRFQ

AT28C64B-15SU

Microchip TechnologyIn Stock: 17897AT28C64B-15SU Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the AT28C64X-15SC is determined by strict equivalence across the following critical parameters:

• Memory capacity and organization (64Kbit, 8K x 8 configuration)
• Parallel interface architecture
• Access time specification (150 ns)
• Supply voltage compatibility (4.5V ~ 5.5V range)
• Physical package compatibility (28-SOIC form factor)
• Surface mount mounting type

The AT28C64B-15SU meets all these core electrical and mechanical requirements, establishing it as a direct functional equivalent. Both devices share identical memory specifications, interface characteristics, and package geometry, enabling pin-for-pin replacement in existing circuit designs.

Parameter Comparison

Engineering Selection Recommendations

The AT28C64B-15SU is the qualified substitute for the AT28C64X-15SC based on the following engineering criteria:

Functional Equivalence: Both devices provide identical 64Kbit parallel EEPROM functionality with matching memory organization, interface architecture, and access time specifications. Pin-for-pin compatibility is established through identical package geometry and pinout.

Product Status: The AT28C64B-15SU maintains active product status with verified availability (17,844 units in stock), whereas the AT28C64X-15SC is obsolete with limited remaining inventory (1,900 units). Selection of the active substitute ensures long-term supply continuity.

Compliance Posture: The AT28C64B-15SU achieves ROHS3 compliance, whereas the AT28C64X-15SC is RoHS non-compliant. For applications subject to RoHS regulatory requirements, the substitute part satisfies compliance obligations.

Operating Range: The substitute part extends the operating temperature range to -40°C ~ 85°C compared to the main part's 0°C ~ 70°C specification, providing broader environmental compatibility without compromising core functionality.

Write Cycle Time Consideration: The AT28C64B-15SU specifies 10 ms write cycle time versus 1 ms for the AT28C64X-15SC. This parameter difference does not affect functional substitution for standard EEPROM applications but must be evaluated for time-critical write operations.

Frequently Asked Questions (FAQ)

Q: Can the AT28C64B-15SU replace the AT28C64X-15SC in existing designs?

A: Yes. Both devices are pin-for-pin compatible with identical 28-SOIC package geometry, memory capacity (64Kbit), organization (8K x 8), parallel interface, and access time (150 ns). Direct substitution is supported without circuit modification.

Q: What is the significance of the write cycle time difference?

A: The AT28C64B-15SU specifies 10 ms write cycle time compared to 1 ms for the AT28C64X-15SC. This affects the duration required to complete individual byte or page write operations. Applications performing sequential writes must account for this timing difference in firmware or system timing calculations.

Q: Does the extended operating temperature range of the substitute part affect compatibility?

A: No. The AT28C64B-15SU's extended range (-40°C ~ 85°C) encompasses the original part's specification (0°C ~ 70°C). Designs operating within the original temperature window remain fully compatible.

Q: Is RoHS compliance a mandatory consideration for substitution?

A: RoHS compliance is a regulatory requirement for products sold into markets with RoHS directives. The AT28C64B-15SU's ROHS3 compliance satisfies these requirements, whereas the AT28C64X-15SC does not. Compliance status must be evaluated based on target market and application requirements.

Q: Are there any package or mounting differences between these parts?

A: No. Both devices use identical 28-SOIC surface mount packaging with 0.295" width (7.50mm). PCB footprints, solder reflow profiles, and assembly processes remain unchanged.

Q: What inventory considerations apply to this substitution?

A: The AT28C64X-15SC (obsolete) has 1,900 units available. The AT28C64B-15SU (active) has 17,844 units in stock. For new designs or long-term production, the active substitute ensures supply availability and eliminates obsolescence risk.