AT27C040-70PC EPROM Memory IC Equivalent & Substitute Parts

Part Overview

The AT27C040-70PC is a 4Mbit parallel EPROM (Erasable Programmable Read-Only Memory) manufactured by Microchip Technology, packaged in a 32-DIP configuration with 70 ns access time. This component is classified as obsolete, which necessitates identification of functionally equivalent alternatives for ongoing system support and component procurement. The part operates within the 4.5V to 5.5V supply voltage range and supports through-hole mounting applications typical of legacy embedded systems and industrial equipment.

Key Parameters

Parameter	Value
Memory Type	Non-Volatile EPROM
Memory Format	EPROM - OTP (One-Time Programmable)
Memory Size	4Mbit
Memory Organization	512K x 8
Memory Interface	Parallel
Access Time	70 ns
Voltage Supply Range	4.5V ~ 5.5V
Mounting Type	Through Hole
Package Type	32-DIP (0.600", 15.24mm)
Base Product Number	AT27C040

Substitute Part Grouping Explanation

Substitution of the AT27C040-70PC is determined by strict equivalence across the following critical parameters:

Memory Capacity & Organization: 4Mbit capacity with 512K x 8 organization is mandatory for address and data bus compatibility
Access Time: 70 ns specification ensures timing compatibility with host system requirements
Voltage Supply: 4.5V ~ 5.5V range maintains electrical compatibility with existing power distribution
Package & Pinout: 32-DIP form factor with identical pin configuration enables direct socket replacement
Memory Interface: Parallel interface architecture must match the host system's memory bus protocol
Memory Technology: EPROM - OTP technology classification ensures functional equivalence

The AT27C040-70PU qualifies as a direct substitute based on identical electrical specifications, memory organization, access time, and package configuration.

Parameter Comparison

Parameter	AT27C040-70PC (Main Part)	AT27C040-70PU (Substitute)	Compatibility
Manufacturer	Microchip Technology	Microchip Technology	Identical
Memory Size	4Mbit	4Mbit	Identical
Memory Organization	512K x 8	512K x 8	Identical
Access Time	70 ns	70 ns	Identical
Voltage Supply	4.5V ~ 5.5V	4.5V ~ 5.5V	Identical
Operating Temperature	0°C ~ 70°C	-40°C ~ 85°C	Extended Range
Package Type	32-DIP (0.600", 15.24mm)	32-DIP (0.600", 15.24mm)	Identical
Mounting Type	Through Hole	Through Hole	Identical
Memory Interface	Parallel	Parallel	Identical
Memory Format	EPROM - OTP	EPROM - OTP	Identical
Product Status	Obsolete	Active	Substitute is Current
RoHS Status	Non-compliant	ROHS3 Compliant	Improved Compliance
Packaging Format	Tube	Tube	Identical

Engineering Selection Recommendations

The AT27C040-70PU is a direct functional equivalent to the AT27C040-70PC and serves as the primary substitute for component replacement and new procurement activities.

Selection Basis:

Electrical Equivalence: Identical memory capacity, organization, access time, and supply voltage specifications ensure seamless integration into existing circuit designs without modification
Product Status: The substitute part maintains active production status, ensuring long-term availability and supply chain continuity
Compliance Enhancement: The AT27C040-70PU achieves ROHS3 compliance, whereas the original part is non-compliant, providing improved environmental and regulatory alignment for systems requiring compliance documentation
Temperature Range: The substitute offers an extended operating temperature range (-40°C ~ 85°C) compared to the original (0°C ~ 70°C), providing greater thermal margin for industrial and extended-temperature applications
Pin Compatibility: Identical 32-DIP package configuration and pinout enable direct socket replacement without PCB redesign

Frequently Asked Questions (FAQ)

Q: Can the AT27C040-70PU be used as a direct replacement for the AT27C040-70PC in existing designs?

A: Yes. Both parts share identical memory capacity (4Mbit), organization (512K x 8), access time (70 ns), supply voltage (4.5V ~ 5.5V), and 32-DIP package configuration. Direct socket substitution is supported without circuit modification.

Q: What is the difference in operating temperature range between these parts?

A: The AT27C040-70PC operates from 0°C to 70°C, while the AT27C040-70PU operates from -40°C to 85°C. The substitute provides a wider temperature envelope suitable for industrial and extended-temperature environments.

Q: Does the AT27C040-70PU meet RoHS compliance requirements?

A: Yes. The AT27C040-70PU is ROHS3 compliant. The original AT27C040-70PC is non-compliant. Systems requiring RoHS documentation should specify the substitute part.

Q: Are there any packaging differences between these parts?

A: Both parts are supplied in tube packaging and use identical 32-DIP (0.600", 15.24mm) form factors. No packaging-related compatibility issues exist.

Q: What is the significance of the -70 designation in the part number?

A: The -70 suffix indicates the 70 nanosecond access time specification. This timing parameter is critical for memory bus compatibility and must be maintained when selecting substitutes.

Q: Can these parts be used interchangeably in production?

A: Yes, provided that system requirements do not mandate the specific product status or compliance profile of the original part. The AT27C040-70PU is recommended for new designs and ongoing production due to its active status and improved compliance.

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