AT28C256-25JC EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The AT28C256-25JC is a 256Kbit parallel EEPROM memory IC manufactured by Microchip Technology in a 32-PLCC package. This part is classified as obsolete, making substitute components necessary for new designs and ongoing production requirements. The AT28C256-25JC operates with a 250 ns access time and supports standard 4.5V to 5.5V supply voltage operation across the commercial temperature range of 0°C to 70°C.

Key Parameters

Parameter	Value
Memory Size	256Kbit
Memory Organization	32K x 8
Memory Interface	Parallel
Access Time	250 ns
Write Cycle Time	10 ms
Voltage Supply Range	4.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C
Package Type	32-PLCC (13.97x11.43)
Mounting Type	Surface Mount

Substitute Part Grouping Explanation

Substitution of the AT28C256-25JC is determined by the following critical parameters:

Memory Capacity & Organization: All substitute parts maintain 256Kbit capacity with 32K x 8 organization
Package & Pinout: All substitutes use 32-PLCC (J-Lead) packaging with identical mechanical dimensions (13.97x11.43)
Voltage Supply: All substitutes operate within the 4.5V to 5.5V range
Memory Interface: All substitutes maintain parallel interface architecture
Access Time: Substitutes may have equal or faster access times (90 ns to 250 ns); faster access times are backward compatible
Write Cycle Time: Substitutes range from 3 ms to 10 ms; faster write cycles are backward compatible
Operating Temperature Range: Substitutes may have equal or extended temperature ranges; extended ranges are backward compatible
RoHS & Compliance Status: Substitutes may differ in RoHS compliance and MSL ratings

Parameter Comparison

Part Number	Manufacturer	Access Time (ns)	Write Cycle (ms)	Temp Range (°C)	Product Status	RoHS Status	Package
AT28C256-25JC	Microchip Technology	250	10	0 ~ 70	Obsolete	Non-compliant	32-PLCC
AT28C256-15JU	Microchip Technology	150	10	-40 ~ 85	Active	ROHS3 Compliant	32-PLCC
AT28HC256F-12JC	Microchip Technology	120	3	0 ~ 70	Active	Non-compliant	32-PLCC
X28HC256JIZ-15T1	Renesas Electronics	150	5	-40 ~ 85	Active	ROHS3 Compliant	32-PLCC
X28HC256JIZ-90T1	Renesas Electronics	90	5	-40 ~ 85	Active	ROHS3 Compliant	32-PLCC
X28HC256JZ-15T1	Renesas Electronics	150	5	0 ~ 70	Active	ROHS3 Compliant	32-PLCC

Engineering Selection Recommendations

For Commercial Temperature Range (0°C ~ 70°C) Applications:

AT28HC256F-12JC offers the fastest access time (120 ns) and shortest write cycle (3 ms) while maintaining the original commercial temperature specification. This part is active and available. RoHS compliance status matches the original part.

X28HC256JZ-15T1 provides an alternative from Renesas Electronics with 150 ns access time and ROHS3 compliance, suitable for designs where extended temperature capability is not required.

For Extended Temperature Range (-40°C ~ 85°C) Applications:

AT28C256-15JU is the Microchip direct upgrade, offering faster access time (150 ns), extended temperature range, and ROHS3 compliance. This part is active with established inventory.

X28HC256JIZ-15T1 and X28HC256JIZ-90T1 from Renesas Electronics provide extended temperature operation with ROHS3 compliance. The 90 ns variant offers superior performance for timing-critical applications.

For RoHS3 Compliance Requirements:

All substitute parts except AT28HC256F-12JC carry ROHS3 compliance certification. Selection should prioritize AT28C256-15JU, X28HC256JIZ-15T1, X28HC256JIZ-90T1, or X28HC256JZ-15T1 based on temperature and performance requirements.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with faster access time than the original AT28C256-25JC?

A: Yes. Faster access times (90 ns, 120 ns, 150 ns) are backward compatible with designs specified for 250 ns operation. The system will function correctly with improved timing margins.

Q: Are all substitute parts pin-compatible with the AT28C256-25JC?

A: Yes. All substitute parts use the 32-PLCC (J-Lead) package with identical pinout and mechanical dimensions (13.97x11.43 mm). Direct socket replacement is possible.

Q: What is the difference between AT28C256-15JU and X28HC256JIZ-15T1?

A: Both parts offer 150 ns access time and -40°C to 85°C temperature range. AT28C256-15JU is supplied in Tube packaging from Microchip Technology. X28HC256JIZ-15T1 is supplied in Tape & Reel from Renesas Electronics with MSL 3 (168 Hours) versus MSL 2 (1 Year) for the Microchip part.

Q: Which substitute offers the best performance?

A: X28HC256JIZ-90T1 provides the fastest access time at 90 ns with extended temperature range (-40°C to 85°C) and ROHS3 compliance. This part is suitable for performance-critical applications.

Q: Is the AT28HC256F-12JC suitable for extended temperature applications?

A: No. AT28HC256F-12JC operates only across 0°C to 70°C, matching the original part's temperature range. For extended temperature requirements, select AT28C256-15JU or the Renesas X28HC256 series.

Q: What packaging options are available for substitutes?

A: Microchip parts are supplied in Tube packaging. Renesas parts are supplied in Tape & Reel (TR) format. Both formats are compatible with standard assembly processes.

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