AT27C1024-12JC Equivalent & Substitute Parts

Part Overview

The AT27C1024-12JC is a 1Mbit parallel EPROM (Erasable Programmable Read-Only Memory) manufactured by Microchip Technology in a 44-PLCC package with 120 ns access time. This component is classified as obsolete, indicating it has been discontinued and is no longer in active production. Finding equivalent or substitute parts is necessary due to the obsolete status and potential supply constraints for new designs or legacy system maintenance.

Substiute Parts

AT27C1024-12JC

Microchip TechnologyIn Stock: 1278AT27C1024-12JC Datasheet

Current PartRFQ

AT27C040-90JU

Microchip TechnologyIn Stock: 1363AT27C040-90JU Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the AT27C1024-12JC is based on the following critical parameters:

• Memory interface type (Parallel)
• Memory technology (EPROM - OTP)
• Supply voltage compatibility (4.5V ~ 5.5V)
• Access time performance (120 ns or faster)
• Package form factor and pin compatibility

The AT27C040-90JU qualifies as a substitute based on matching parallel interface, EPROM-OTP technology, and compatible supply voltage. However, this substitute introduces differences in memory organization, package size, and product status that must be evaluated for specific application requirements.

Parameter Comparison

Engineering Selection Recommendations

The AT27C040-90JU is available as an active product with ROHS3 compliance, addressing supply continuity concerns associated with the obsolete AT27C1024-12JC. The substitute offers improved access time (90 ns versus 120 ns) and extended operating temperature range (-40°C ~ 85°C versus 0°C ~ 70°C).

Critical considerations for selection include package form factor differences (44-PLCC versus 32-PLCC), memory organization changes (64K x 16 versus 512K x 8), and total memory capacity increase (1Mbit versus 4Mbit). These differences require verification of PCB layout compatibility, address/data bus configuration, and application memory requirements before implementation.

Frequently Asked Questions (FAQ)

Q: Can AT27C040-90JU directly replace AT27C1024-12JC without circuit modifications?

A: Direct replacement is not guaranteed. While both components share parallel interface, EPROM-OTP technology, and compatible supply voltage, the different package sizes (44-PLCC versus 32-PLCC), pin counts, and memory organization require PCB layout and firmware verification.

Q: What are the key differences in memory organization between these parts?

A: AT27C1024-12JC uses 64K x 16 organization (1Mbit total), while AT27C040-90JU uses 512K x 8 organization (4Mbit total). This affects address line requirements and data bus width configuration in the circuit design.

Q: Does the faster access time of AT27C040-90JU (90 ns) provide any advantage?

A: Yes. The 90 ns access time is faster than the 120 ns specification of the main part, which can improve system performance. However, this advantage is only realized if the circuit design supports the faster timing.

Q: Are there compliance differences between these parts?

A: Yes. AT27C040-90JU is ROHS3 compliant and currently in active production status, while AT27C1024-12JC is RoHS non-compliant and obsolete. For new designs or regulated applications, the substitute offers better long-term compliance and availability.

Q: What should be verified before implementing AT27C040-90JU as a substitute?

A: Verify PCB footprint compatibility with the 32-PLCC package, confirm address and data bus configuration matches the 512K x 8 organization, validate that application firmware accommodates the increased memory capacity, and test timing parameters in the target circuit.