AT28C64-25SC EEPROM Equivalent & Substitute Parts

Part Overview

The AT28C64-25SC is a 64Kbit parallel EEPROM memory IC manufactured by Microchip Technology in a 28-SOIC package. This part is classified as obsolete, making substitute components necessary for new designs and ongoing production requirements. The AT28C64-25SC operates with a 250 ns access time and supports standard 4.5V to 5.5V supply voltage across a 0°C to 70°C operating temperature range. Equivalent and substitute parts must maintain compatibility across memory capacity, interface type, package form factor, and electrical specifications.

Key Parameters

Parameter	AT28C64-25SC
Memory Size	64Kbit
Memory Organization	8K x 8
Memory Format	EEPROM
Memory Interface	Parallel
Access Time	250 ns
Write Cycle Time	1 ms
Voltage Supply	4.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C
Package / Case	28-SOIC (0.295", 7.50mm Width)
Mounting Type	Surface Mount
Product Status	Obsolete
RoHS Status	RoHS non-compliant

Substitute Part Grouping Explanation

Substitute parts for the AT28C64-25SC are qualified based on the following critical parameters:

Memory capacity: 64Kbit (8K x 8 organization)
Memory type: EEPROM with parallel interface
Package: 28-SOIC form factor with identical pin configuration
Supply voltage: 4.5V to 5.5V compatibility
Mounting: Surface mount technology

Substitutes are grouped into two categories based on operating temperature range and access time performance:

Category 1 (Extended Temperature, Faster Access): AT28C64B-15SU operates at -40°C to 85°C with 150 ns access time and includes RoHS3 compliance.

Category 2 (High-Speed Variants): X28HC64SIZ-12, X28HC64SIZ-12T1, and X28HC64SZ-12 are Renesas Electronics equivalents with 120 ns access time. These parts differ in packaging format (Tape & Reel, standard, or Tube) and operating temperature ranges (0°C to 70°C or -40°C to 85°C).

Parameter Comparison

Parameter	AT28C64-25SC	AT28C64B-15SU	X28HC64SIZ-12	X28HC64SIZ-12T1	X28HC64SZ-12
Manufacturer	Microchip Technology	Microchip Technology	Renesas Electronics	Renesas Electronics	Renesas Electronics
Memory Size	64Kbit	64Kbit	64Kbit	64Kbit	64Kbit
Memory Organization	8K x 8	8K x 8	8K x 8	8K x 8	8K x 8
Access Time	250 ns	150 ns	120 ns	120 ns	120 ns
Write Cycle Time	1 ms	10 ms	5 ms	5 ms	5 ms
Voltage Supply	4.5V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	0°C ~ 70°C
Package / Case	28-SOIC	28-SOIC	28-SOIC	28-SOIC	28-SOIC
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	RoHS non-compliant	RoHS3 Compliant	RoHS3 Compliant	RoHS3 Compliant	RoHS3 Compliant

Engineering Selection Recommendations

For RoHS3 Compliant Designs: AT28C64B-15SU is the primary Microchip substitute, offering active product status and full RoHS3 compliance. This part provides improved access time (150 ns) and extended operating temperature range (-40°C to 85°C) compared to the obsolete AT28C64-25SC.

For High-Speed Applications: X28HC64SIZ-12, X28HC64SIZ-12T1, and X28HC64SZ-12 deliver superior access time performance at 120 ns. All three variants are RoHS3 compliant and active products. Selection between these Renesas parts depends on packaging requirements and operating temperature specifications.

For Standard Temperature Range (0°C to 70°C): X28HC64SZ-12 maintains the original operating temperature window while providing faster access time and RoHS3 compliance.

For Extended Temperature Range (-40°C to 85°C): AT28C64B-15SU, X28HC64SIZ-12, or X28HC64SIZ-12T1 support wider temperature operation. X28HC64SIZ-12T1 is packaged in Tape & Reel format for automated assembly.

All substitute parts maintain identical 28-SOIC package geometry, 4.5V to 5.5V supply voltage compatibility, and 8K x 8 memory organization, ensuring direct functional replacement in existing circuit designs.

Frequently Asked Questions (FAQ)

Q: Can AT28C64B-15SU directly replace AT28C64-25SC in existing designs?

A: Yes. Both parts share identical 28-SOIC package dimensions, 4.5V to 5.5V supply voltage, and 8K x 8 memory organization. AT28C64B-15SU offers faster access time (150 ns vs. 250 ns) and extended temperature range (-40°C to 85°C vs. 0°C to 70°C), making it a compatible upgrade.

Q: What is the difference between X28HC64SIZ-12 and X28HC64SIZ-12T1?

A: Both parts are functionally identical Renesas EEPROM devices with 120 ns access time and 5 ms write cycle time. The primary difference is packaging: X28HC64SIZ-12 uses standard packaging, while X28HC64SIZ-12T1 is supplied in Tape & Reel format for high-volume automated assembly.

Q: Why does X28HC64SZ-12 have a different operating temperature range than other Renesas substitutes?

A: X28HC64SZ-12 is specified for 0°C to 70°C operation, matching the original AT28C64-25SC temperature range. X28HC64SIZ-12 and X28HC64SIZ-12T1 extend to -40°C to 85°C for applications requiring wider temperature tolerance.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. AT28C64B-15SU, X28HC64SIZ-12, X28HC64SIZ-12T1, and X28HC64SZ-12 are all RoHS3 compliant, whereas the original AT28C64-25SC is RoHS non-compliant.

Q: What is the impact of faster access time on circuit design?

A: Substitute parts with faster access times (150 ns or 120 ns) are backward compatible with designs requiring 250 ns access time. Faster access times reduce data retrieval latency and improve system performance without requiring circuit modifications.

Q: Can these EEPROM parts be used interchangeably in production?

A: Yes, provided the selected substitute meets the application's operating temperature, access time, and compliance requirements. All listed substitutes maintain identical pin configuration and 28-SOIC package geometry for direct board-level replacement.

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