AT28C256F-15TU-T Equivalent & Substitute Parts

Part Overview

The AT28C256F-15TU-T is a 256Kbit parallel EEPROM memory integrated circuit manufactured by Microchip Technology. This device features a 28-TSSOP surface mount package with 150 ns access time and operates across the industrial temperature range of -40°C to 85°C. The part is classified as obsolete, necessitating identification of functionally equivalent alternatives for new designs and ongoing production requirements. Substitute parts must maintain identical electrical specifications and compatible packaging configurations to ensure direct replacement capability.

Key Parameters

Parameter	Value
Memory Type	Non-Volatile EEPROM
Memory Size	256Kbit
Memory Organization	32K x 8
Memory Interface	Parallel
Access Time	150 ns
Write Cycle Time	3 ms
Supply Voltage	4.5V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Mounting Type	Surface Mount
Package Type	28-TSSOP
RoHS Status	ROHS3 Compliant
MSL Rating	3 (168 Hours)

Substitute Part Grouping Explanation

Substitution of the AT28C256F-15TU-T is determined by strict equivalence across the following critical parameters:

Memory capacity and organization (256Kbit, 32K x 8 configuration)
Parallel interface architecture
Access time specification (150 ns maximum)
Write cycle time (3 ms)
Supply voltage range (4.5V ~ 5.5V)
Operating temperature range (-40°C ~ 85°C)
Surface mount technology compatibility
RoHS3 compliance and MSL rating

The AT28C256F-15SU-T qualifies as a direct substitute based on identical electrical performance across all specified parameters. The primary distinction between these parts is the package configuration: the main part uses 28-TSSOP (0.465" width), while the substitute employs 28-SOIC (0.295" width). Both packages maintain the same pin count and electrical interface, enabling functional equivalence when PCB layout accommodates the different package footprint.

Parameter Comparison

Parameter	AT28C256F-15TU-T	AT28C256F-15SU-T	Match Status
Manufacturer	Microchip Technology	Microchip Technology	Identical
Memory Type	Non-Volatile EEPROM	Non-Volatile EEPROM	Identical
Memory Size	256Kbit	256Kbit	Identical
Memory Organization	32K x 8	32K x 8	Identical
Memory Interface	Parallel	Parallel	Identical
Access Time	150 ns	150 ns	Identical
Write Cycle Time	3 ms	3 ms	Identical
Supply Voltage	4.5V ~ 5.5V	4.5V ~ 5.5V	Identical
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	Identical
Mounting Type	Surface Mount	Surface Mount	Identical
Package / Case	28-TSSOP (0.465", 11.80mm Width)	28-SOIC (0.295", 7.50mm Width)	Different
Product Status	Obsolete	Active	Substitute is Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Identical
MSL Rating	3 (168 Hours)	3 (168 Hours)	Identical

Engineering Selection Recommendations

The AT28C256F-15SU-T is the qualified substitute for the obsolete AT28C256F-15TU-T. Selection of this alternative is supported by:

Identical electrical specifications across all memory performance parameters
Active product status ensuring continued availability and manufacturing support
Equivalent RoHS3 compliance and MSL rating, maintaining regulatory and environmental standards
Same base product number (AT28C256) confirming common design lineage and compatibility

The primary consideration for implementation is PCB layout modification to accommodate the 28-SOIC package footprint (0.295" width) in place of the original 28-TSSOP footprint (0.465" width). Both packages maintain identical pin assignments and electrical interface characteristics, requiring only physical layout adjustment without circuit design changes.

Frequently Asked Questions (FAQ)

Q: Can AT28C256F-15SU-T directly replace AT28C256F-15TU-T without circuit modifications?

A: Yes, the electrical interface is identical. The substitute requires only PCB layout modification to accommodate the different package footprint. No schematic changes are necessary.

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

A: The package configuration differs. AT28C256F-15TU-T uses 28-TSSOP (0.465" width), while AT28C256F-15SU-T uses 28-SOIC (0.295" width). All electrical specifications remain identical.

Q: Why is the original part classified as obsolete?

A: AT28C256F-15TU-T is listed as obsolete by the manufacturer. The AT28C256F-15SU-T maintains active product status, ensuring long-term availability and manufacturing continuity.

Q: Are there any compliance or certification differences between these parts?

A: No. Both parts maintain identical RoHS3 compliance, MSL rating (3, 168 Hours), and regulatory certifications (REACH Unaffected, ECCN EAR99).

Q: What is the memory capacity and organization of these devices?

A: Both parts provide 256Kbit capacity organized as 32K x 8 (32,768 words of 8 bits each) with parallel interface architecture.

Q: What are the timing specifications for these EEPROM devices?

A: Both parts feature 150 ns maximum access time and 3 ms write cycle time across the full operating temperature range of -40°C to 85°C.

Q: Are these parts suitable for industrial temperature applications?

A: Yes. Both parts operate across the industrial temperature range of -40°C to 85°C and maintain specifications across this full range.

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