AT27C1024-90VC Equivalent & Substitute Parts

Part Overview

The AT27C1024-90VC is a 1Mbit EPROM (Erasable Programmable Read-Only Memory) manufactured by Microchip Technology, designed for non-volatile data storage in parallel interface applications. This device operates with a 90 ns access time and is packaged in a 40-VSOP surface mount configuration with 64K x 16 memory organization.

The AT27C1024-90VC is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure component availability, and support legacy system maintenance and production requirements.

Substiute Parts

AT27C1024-90VC

Microchip TechnologyIn Stock: 904AT27C1024-90VC Datasheet

Current PartRFQ

AT27C1024-70JU

Microchip TechnologyIn Stock: 1467AT27C1024-70JU Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the AT27C1024-90VC is determined by the following critical parameters that must remain constant or compatible:

Core Functional Parameters (Must Match):

• Memory Type: Non-Volatile EPROM
• Memory Size: 1Mbit
• Memory Organization: 64K x 16
• Memory Interface: Parallel
• Supply Voltage Range: 4.5V ~ 5.5V

Performance Parameters (May Improve):

• Access Time: 90 ns or faster (lower values are acceptable)
• Operating Temperature Range: May extend beyond 0°C ~ 70°C

Physical Parameters (May Differ):

• Package Type: Alternative surface mount packages acceptable if pinout compatibility is maintained
• Mounting Type: Surface Mount (required)

The AT27C1024-70JU qualifies as a substitute because it maintains identical memory capacity, organization, interface type, and supply voltage specifications while offering improved access time (70 ns versus 90 ns) and extended operating temperature range (-40°C ~ 85°C versus 0°C ~ 70°C).

Parameter Comparison

Engineering Selection Recommendations

AT27C1024-70JU as Primary Substitute:

The AT27C1024-70JU is the manufacturer-recommended substitute for the obsolete AT27C1024-90VC. This substitution is supported by:

1. Functional Equivalence: Identical memory capacity (1Mbit), organization (64K x 16), interface type (Parallel), and supply voltage specifications (4.5V ~ 5.5V) ensure direct functional compatibility in parallel EPROM applications.

2. Performance Enhancement: The 70 ns access time is faster than the original 90 ns specification, providing improved system performance without functional degradation.

3. Extended Operating Range: The -40°C ~ 85°C operating temperature range exceeds the original 0°C ~ 70°C specification, enabling deployment in broader environmental conditions.

4. Regulatory Compliance: The AT27C1024-70JU is ROHS3 compliant and carries Active product status, ensuring long-term availability and compliance with current environmental regulations. The original part is RoHS non-compliant and obsolete.

5. Availability: The substitute part maintains active inventory status (1402 units in stock) compared to the obsolete original part.

Package Consideration: The substitute uses a 44-PLCC package versus the original 40-VSOP package. PCB layout modification is required to accommodate the different package footprint and pin configuration.

Frequently Asked Questions (FAQ)

Q: Can the AT27C1024-70JU directly replace the AT27C1024-90VC without circuit modifications?

A: The AT27C1024-70JU is functionally equivalent in memory capacity, organization, interface, and voltage specifications. However, the package change from 40-VSOP to 44-PLCC requires PCB layout redesign. Pinout verification is mandatory before implementation.

Q: What is the significance of the access time difference (90 ns vs. 70 ns)?

A: The 70 ns access time of the substitute is faster than the original 90 ns specification. This represents improved performance and is backward compatible with designs requiring 90 ns or slower access times. No timing violations will occur in systems designed for the original part.

Q: Why is the operating temperature range different?

A: The AT27C1024-70JU supports -40°C ~ 85°C versus the original 0°C ~ 70°C. This extended range provides greater flexibility for deployment in industrial and extended-temperature applications. Systems operating within the original 0°C ~ 70°C range will function without issues.

Q: Is the AT27C1024-70JU RoHS compliant?

A: Yes, the AT27C1024-70JU is ROHS3 compliant. The original AT27C1024-90VC is RoHS non-compliant. This compliance status is relevant for new designs and applications subject to environmental regulations.

Q: What does the different package designation (40-VSOP vs. 44-PLCC) mean for implementation?

A: VSOP (Very Small Outline Package) and PLCC (Plastic Leaded Chip Carrier) are distinct package types with different physical dimensions and pin layouts. The 40-VSOP is a smaller, thinner package, while the 44-PLCC is larger with J-leads. PCB footprint, socket compatibility, and assembly processes differ between these packages.

Q: Is the AT27C1024-70JU the only available substitute?

A: Based on the provided data, the AT27C1024-70JU is the manufacturer-recommended substitute listed for the AT27C1024-90VC. Other variants of the AT27C1024 base product number may exist with different speed grades or packages, but only the AT27C1024-70JU is documented as an equivalent substitute in this reference.

Q: What is the significance of "Active" product status for the substitute?

A: Active product status indicates that the AT27C1024-70JU is currently manufactured, supported, and available through normal distribution channels. The obsolete status of the original part means it is no longer in production and availability is limited to existing inventory.