AT28HC256F-12SC EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The AT28HC256F-12SC is a 256Kbit parallel EEPROM memory IC manufactured by Microchip Technology, housed in a 28-SOIC surface mount package. This component is classified as obsolete, making identification of compatible substitute parts essential for ongoing system support and component procurement. The part operates with a 120 ns access time and requires a 4.5V to 5.5V supply voltage, serving applications requiring non-volatile parallel memory storage with standard industrial temperature ranges.

Substiute Parts

AT28HC256F-12SC

Microchip TechnologyIn Stock: 921AT28HC256F-12SC Datasheet

Current PartRFQ

AT28HC256F-90SU

Microchip TechnologyIn Stock: 939AT28HC256F-90SU Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the AT28HC256F-12SC is determined by strict equivalence across the following critical parameters:

• Memory capacity: 256Kbit (32K x 8 organization)
• Interface type: Parallel
• Package: 28-SOIC surface mount
• Supply voltage: 4.5V ~ 5.5V compatibility
• Write cycle time: 3 ms

The AT28HC256F-90SU qualifies as a direct substitute based on identical memory specifications, package form factor, and electrical operating parameters. Differences in access time (90 ns versus 120 ns) and operating temperature range represent performance enhancements rather than compatibility constraints, as faster access times and extended temperature ranges are backward compatible with the original specification.

Parameter Comparison

Engineering Selection Recommendations

The AT28HC256F-90SU is the qualified substitute for AT28HC256F-12SC applications. Selection is based on the following engineering criteria:

Product Status: The AT28HC256F-90SU maintains active product status with current manufacturing support, whereas the AT28HC256F-12SC is obsolete and subject to availability constraints.

Compliance: The AT28HC256F-90SU achieves ROHS3 compliance, meeting modern regulatory requirements for electronic component procurement. The original part is RoHS non-compliant.

Performance Compatibility: The substitute part delivers improved access time (90 ns versus 120 ns) and extended operating temperature range (-40°C to 85°C versus 0°C to 70°C), providing enhanced performance margins without introducing compatibility issues.

Electrical Equivalence: Both parts share identical memory capacity, organization, interface type, write cycle time, and supply voltage specifications, ensuring direct functional replacement in existing circuit designs.

Frequently Asked Questions (FAQ)

Q: Can AT28HC256F-90SU directly replace AT28HC256F-12SC in existing designs?

A: Yes. Both parts are electrically and mechanically equivalent across all critical parameters: 256Kbit capacity, 32K x 8 organization, parallel interface, 3 ms write cycle time, and 4.5V to 5.5V supply voltage. The 28-SOIC package dimensions are identical, enabling direct PCB substitution.

Q: What is the significance of the access time difference (120 ns vs. 90 ns)?

A: The AT28HC256F-90SU provides faster memory access (90 ns) compared to the AT28HC256F-12SC (120 ns). This represents a performance improvement and is backward compatible with designs specified for 120 ns access time, as the substitute meets or exceeds the original timing requirement.

Q: Why does the operating temperature range differ between the two parts?

A: The AT28HC256F-90SU supports an extended temperature range (-40°C to 85°C) versus the AT28HC256F-12SC (0°C to 70°C). This expanded range accommodates industrial and automotive applications requiring broader thermal operation. Designs operating within the original 0°C to 70°C window remain fully compatible.

Q: What is the impact of RoHS compliance differences?

A: The AT28HC256F-90SU is ROHS3 compliant, meeting current environmental and regulatory standards for electronic component manufacturing. The AT28HC256F-12SC is RoHS non-compliant. For new designs or procurement requiring regulatory compliance, the substitute part is the appropriate selection.

Q: Are the packaging and mounting specifications identical?

A: Yes. Both parts use the 28-SOIC surface mount package with identical dimensions (0.295" width, 7.50mm). No PCB layout modifications or reflow process adjustments are required when substituting the AT28HC256F-90SU for the AT28HC256F-12SC.