AT27C256R-12PI Equivalent & Substitute Parts

Part Overview

The AT27C256R-12PI is a 256Kbit parallel EPROM (Erasable Programmable Read-Only Memory) manufactured by Microchip Technology in a 28-DIP package with 120 ns access time. This part is classified as obsolete, making substitute components necessary for new designs and ongoing system support. The AT27C256R-12PI operates within the 4.5V to 5.5V supply voltage range and supports industrial temperature specifications from -40°C to 85°C.

Substiute Parts

AT27C256R-12PI

Microchip TechnologyIn Stock: 1711AT27C256R-12PI Datasheet

Current PartRFQ

AT27C256R-70PU

Microchip TechnologyIn Stock: 6959AT27C256R-70PU Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the AT27C256R-12PI is determined by strict equivalence across the following parameters:

• Memory capacity: 256Kbit (32K x 8 organization)
• Memory interface: Parallel configuration
• Package type: 28-DIP form factor
• Supply voltage: 4.5V ~ 5.5V compatibility
• Operating temperature range: -40°C ~ 85°C
• Mounting technology: Through Hole

The AT27C256R-70PU qualifies as a direct substitute based on identical memory specifications, package configuration, and electrical operating parameters. Access time differences do not prevent substitution, as the substitute part features faster performance (70 ns versus 120 ns), ensuring backward compatibility with existing system timing requirements.

Parameter Comparison

Engineering Selection Recommendations

The AT27C256R-70PU is the qualified substitute for the AT27C256R-12PI. Selection is based on the following engineering criteria:

Product Status: The AT27C256R-70PU maintains active product status with verified programmability, whereas the main part is obsolete. This ensures long-term availability and supply chain continuity.

Compliance: The AT27C256R-70PU achieves ROHS3 compliance and REACH unaffected status, meeting modern regulatory requirements. The main part does not meet current RoHS standards.

Performance: The substitute part delivers superior access time performance (70 ns) compared to the main part (120 ns), ensuring compatibility with existing system timing specifications without modification.

Electrical and Mechanical Compatibility: Both parts share identical memory capacity, organization, interface type, supply voltage range, operating temperature range, and 28-DIP package configuration, enabling direct socket replacement.

Frequently Asked Questions (FAQ)

Q: Can the AT27C256R-70PU directly replace the AT27C256R-12PI in existing designs?

A: Yes. Both parts are manufactured by Microchip Technology and share identical memory specifications (256Kbit, 32K x 8 organization), parallel interface, supply voltage (4.5V ~ 5.5V), operating temperature range (-40°C ~ 85°C), and 28-DIP package configuration. The substitute part's faster access time (70 ns) ensures backward compatibility.

Q: What is the primary difference between these two parts?

A: The main differences are access time (120 ns versus 70 ns), product status (obsolete versus active), and compliance certifications. The AT27C256R-70PU is ROHS3 compliant while the AT27C256R-12PI is not.

Q: Are there packaging differences between the main part and substitute?

A: No. Both parts use the 28-DIP (0.600", 15.24mm) package with through-hole mounting technology, enabling direct PCB compatibility without layout modifications.

Q: Why is the AT27C256R-12PI classified as obsolete?

A: The AT27C256R-12PI has reached end-of-life status in Microchip Technology's product portfolio. The AT27C256R-70PU remains in active production and is the recommended alternative for new designs and system maintenance.

Q: Does the faster access time of the substitute part affect system operation?

A: No. Faster access time improves system performance characteristics without introducing compatibility issues. Existing system timing requirements are satisfied by the substitute part's superior performance specification.