AT28C64X-25JC Equivalent & Substitute Parts

Part Overview

The AT28C64X-25JC is a 64Kbit parallel EEPROM memory IC manufactured by Microchip Technology, housed in a 32-PLCC package with 250 ns access time. This part is classified as obsolete and is no longer in active production. Finding equivalent or substitute components is necessary due to limited availability and the discontinuation of this specific model variant. The AT28C64 base product family offers multiple active alternatives that maintain core functional compatibility while providing improved specifications and compliance certifications.

Key Parameters

Parameter	Value
Memory Type	Non-Volatile EEPROM
Memory Size	64Kbit
Memory Organization	8K x 8
Memory Interface	Parallel
Access Time	250 ns
Write Cycle Time	1 ms
Voltage Supply Range	4.5V ~ 5.5V
Operating Temperature Range	0°C ~ 70°C
Package Type	32-PLCC (13.97x11.43)
Mounting Type	Surface Mount
RoHS Status	Non-compliant

Substitute Part Grouping Explanation

Substitution of the AT28C64X-25JC is determined by strict adherence to the following electrical and mechanical parameters:

Core Compatibility Requirements:

Memory capacity: 64Kbit (8K x 8 organization)
Memory type: Non-volatile EEPROM
Interface: Parallel
Package: 32-PLCC (13.97x11.43)
Supply voltage: 4.5V ~ 5.5V
Mounting: Surface Mount

Acceptable Parameter Variations:

Access time: Equal to or faster than 250 ns
Write cycle time: Equal to or faster than 1 ms
Operating temperature range: Equal to or wider than 0°C ~ 70°C
RoHS compliance: May differ from original part

The AT28C64B-15JU meets all core compatibility requirements and represents the primary active substitute within the AT28C64 product family.

Parameter Comparison

Parameter	AT28C64X-25JC (Main Part)	AT28C64B-15JU (Substitute)
Manufacturer	Microchip Technology	Microchip Technology
Memory Size	64Kbit	64Kbit
Memory Organization	8K x 8	8K x 8
Memory Interface	Parallel	Parallel
Access Time	250 ns	150 ns
Write Cycle Time	1 ms	10 ms
Voltage Supply	4.5V ~ 5.5V	4.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C	-40°C ~ 85°C
Package Type	32-PLCC (13.97x11.43)	32-PLCC (13.97x11.43)
Mounting Type	Surface Mount	Surface Mount
Product Status	Obsolete	Active
RoHS Status	Non-compliant	ROHS3 Compliant

Engineering Selection Recommendations

The AT28C64B-15JU is the designated substitute for the obsolete AT28C64X-25JC. This part maintains identical memory capacity, organization, interface type, package configuration, and supply voltage specifications. The substitute offers improved performance characteristics with faster access time (150 ns versus 250 ns) and an extended operating temperature range (-40°C ~ 85°C versus 0°C ~ 70°C). The AT28C64B-15JU carries Active product status with ROHS3 compliance certification, ensuring long-term availability and regulatory alignment. The write cycle time specification differs (10 ms versus 1 ms); this parameter must be evaluated against specific application timing requirements.

Frequently Asked Questions (FAQ)

Q: Can the AT28C64B-15JU directly replace the AT28C64X-25JC in existing designs?

A: Yes, provided that the application timing requirements accommodate the 10 ms write cycle time of the substitute part. The faster access time (150 ns) and identical package footprint ensure mechanical and electrical compatibility.

Q: What is the significance of the different write cycle times between these parts?

A: Write cycle time defines the duration required to complete a single write operation. The AT28C64X-25JC specifies 1 ms while the AT28C64B-15JU specifies 10 ms. Applications requiring rapid sequential writes must account for this difference in timing calculations.

Q: Does the extended temperature range of the AT28C64B-15JU affect compatibility?

A: No. An extended operating temperature range (-40°C ~ 85°C) is a superset of the original specification (0°C ~ 70°C) and does not create compatibility issues. The part functions correctly within the original temperature envelope.

Q: Is the ROHS3 compliance of the substitute part a concern for legacy systems?

A: ROHS3 compliance indicates adherence to current environmental and material restrictions. This does not affect electrical or mechanical compatibility with existing designs. Legacy systems may use either compliant or non-compliant parts without functional impact.

Q: Are there other substitutes available within the AT28C64 family?

A: The AT28C64B-15JU is the primary active substitute. Additional variants within the AT28C64 family (AT28HC64B-70JU, AT28HC64B-90JU, AT28HC64B-12JU) exist but are not listed as direct substitutes for the AT28C64X-25JC in the provided data.

Q: What packaging format is used for the AT28C64B-15JU?

A: The substitute part is supplied in Tube packaging, identical to the 32-PLCC (13.97x11.43) package configuration of the original part.

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