AT27C256R-45JC Equivalent & Substitute Parts

Part Overview

The AT27C256R-45JC is a 256Kbit EPROM (Erasable Programmable Read-Only Memory) manufactured by Microchip Technology in a 32-PLCC package with 45 ns access time. This part is classified as obsolete, making substitute components necessary for new designs, repairs, or production continuity. The device operates as a parallel interface non-volatile memory suitable for embedded systems requiring permanent code storage.

Substiute Parts

AT27C256R-45JC

Microchip TechnologyIn Stock: 2285AT27C256R-45JC Datasheet

Current PartRFQ

AT27C256R-45JU

Microchip TechnologyIn Stock: 2237AT27C256R-45JU Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the AT27C256R-45JC is determined by strict equivalence across the following critical parameters:

• Memory capacity: 256Kbit (32K x 8 organization)
• Access time: 45 ns maximum
• Interface type: Parallel
• Package: 32-PLCC (J-Lead) with identical pinout
• Supply voltage: 4.5V ~ 5.5V compatibility
• Mounting: Surface mount configuration

The AT27C256R-45JU qualifies as a direct substitute based on identical electrical specifications, memory organization, access time, voltage requirements, and physical package dimensions. Differences in operating temperature range and product status do not affect functional substitution in applications designed for the original part.

Parameter Comparison

Engineering Selection Recommendations

The AT27C256R-45JU is the direct functional equivalent for the obsolete AT27C256R-45JC. Selection between these parts is determined by regulatory and compliance requirements:

Use AT27C256R-45JU for new designs and production applications requiring RoHS3 compliance and extended operating temperature range (-40°C ~ 85°C). This part is actively manufactured and available.

Use AT27C256R-45JC only for legacy system repairs or applications with existing inventory constraints. This part is obsolete and subject to availability limitations.

Both parts are electrically and mechanically identical in all critical parameters: memory capacity, access time, voltage specifications, and physical package dimensions. The extended temperature range of the AT27C256R-45JU provides operational margin in industrial environments.

Frequently Asked Questions (FAQ)

Q: Can AT27C256R-45JU replace AT27C256R-45JC in existing designs?

A: Yes. Both parts are electrically and mechanically equivalent. The AT27C256R-45JU operates across a wider temperature range (-40°C ~ 85°C versus 0°C ~ 70°C) and meets RoHS3 compliance, making it suitable for direct substitution in all applications designed for the original part.

Q: What is the difference between the -45JC and -45JU suffix?

A: The suffix indicates packaging and temperature grade. The -JC designation specifies commercial temperature range (0°C ~ 70°C) in standard packaging. The -JU designation specifies extended temperature range (-40°C ~ 85°C) in tube packaging. Both use identical 32-PLCC packages with J-lead configuration.

Q: Are the pinouts identical between these parts?

A: Yes. Both AT27C256R-45JC and AT27C256R-45JU use the 32-PLCC (J-Lead) package with identical pinout and physical dimensions (13.97 x 11.43 mm). Direct PCB substitution is possible without layout modifications.

Q: What memory capacity do these parts provide?

A: Both parts provide 256Kbit capacity organized as 32K x 8 bits. This supports applications requiring 32,768 addressable 8-bit memory locations.

Q: Are these parts programmable?

A: The AT27C256R-45JU is verified as programmable by DiGi-Electronics. The AT27C256R-45JC programmability status is not verified. Both are EPROM devices requiring external programming equipment.

Q: What is the significance of the 45 ns access time?

A: The 45 ns specification indicates maximum time from address valid to data output valid. This parameter determines maximum system clock frequency compatibility. Both parts meet this specification identically.