AT28HC256F-90JC Equivalent & Substitute Parts

Part Overview

The AT28HC256F-90JC is a 256Kbit parallel EEPROM memory IC manufactured by Microchip Technology, housed in a 32-PLCC package with 90 ns access time. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing system support and new designs. The device operates within the 4.5V to 5.5V supply range and supports 32K x 8 memory organization with a 3ms write cycle time.

Key Parameters

Parameter	Value
Memory Size	256Kbit
Memory Organization	32K x 8
Memory Interface	Parallel
Access Time	90 ns
Write Cycle Time	3ms
Voltage Supply	4.5V ~ 5.5V
Package Type	32-PLCC (13.97x11.43)
Mounting Type	Surface Mount
Operating Temperature	0°C ~ 70°C

Substitute Part Grouping Explanation

Substitution for the AT28HC256F-90JC is determined by strict equivalence in the following parameters: 256Kbit memory capacity, 32K x 8 organization, parallel interface, 32-PLCC package, and 4.5V to 5.5V supply voltage. Access time and write cycle time define performance tiers within the substitution group. The AT28HC256F-90JC operates at 90 ns access time with a 3ms write cycle.

Substitute parts are grouped into two categories:

Direct Performance Match (90 ns access time): Parts maintaining identical 90 ns access time performance.

Extended Temperature Range Variants: Parts with identical electrical specifications but expanded operating temperature ranges, suitable for applications requiring wider thermal operation.

Slower Access Time Variants (120 ns, 150 ns): Parts with degraded access time performance but identical memory capacity and organization, applicable only where timing constraints permit.

Parameter Comparison

Part Number	Manufacturer	Access Time (ns)	Write Cycle (ms)	Operating Temp (°C)	Product Status	RoHS Compliance	Packaging
AT28HC256F-90JC	Microchip Technology	90	3	0 ~ 70	Obsolete	Non-compliant	Tube
AT28HC256F-90JU	Microchip Technology	90	3	-40 ~ 85	Active	ROHS3 Compliant	Tube
AT28HC256F-12JC	Microchip Technology	120	3	0 ~ 70	Active	Non-compliant	Tube
X28HC256JIZ-90T1	Renesas Electronics	90	5	-40 ~ 85	Active	ROHS3 Compliant	Tape & Reel
X28HC256JIZ-15T1	Renesas Electronics	150	5	-40 ~ 85	Active	ROHS3 Compliant	Tape & Reel
X28HC256JZ-15T1	Renesas Electronics	150	5	0 ~ 70	Active	ROHS3 Compliant	Tape & Reel

Engineering Selection Recommendations

For Direct Replacement with Extended Temperature Support: AT28HC256F-90JU is the primary substitute, maintaining 90 ns access time and 3ms write cycle while extending operating temperature to -40°C to 85°C. This part is active and ROHS3 compliant, addressing the obsolescence of the original part.

For RoHS3 Compliance with Identical Temperature Range: AT28HC256F-12JC provides active product status and RoHS non-compliance matching, though with 120 ns access time. This part is suitable only where timing margins accommodate the 30 ns degradation.

For Extended Temperature and RoHS3 Compliance: X28HC256JIZ-90T1 maintains 90 ns access time with -40°C to 85°C operation and ROHS3 compliance. The 5ms write cycle time represents a 2ms increase from the original specification.

For Cost-Optimized Solutions with Relaxed Timing: X28HC256JIZ-15T1 and X28HC256JZ-15T1 provide 150 ns access time variants suitable for applications where timing constraints permit slower memory access.

Frequently Asked Questions (FAQ)

Q: Can AT28HC256F-90JU directly replace AT28HC256F-90JC?

A: Yes. Both parts maintain 256Kbit capacity, 32K x 8 organization, parallel interface, 32-PLCC package, 4.5V to 5.5V supply, 90 ns access time, and 3ms write cycle. AT28HC256F-90JU extends the operating temperature range to -40°C to 85°C and is ROHS3 compliant, making it the preferred active substitute.

Q: What is the impact of using X28HC256JIZ-90T1 instead of AT28HC256F-90JC?

A: Electrical and memory specifications remain identical. The write cycle time increases from 3ms to 5ms, and the part is supplied in Tape & Reel packaging rather than Tube. Operating temperature extends to -40°C to 85°C with ROHS3 compliance.

Q: Are 150 ns access time variants suitable substitutes?

A: 150 ns variants (X28HC256JIZ-15T1, X28HC256JZ-15T1) are substitutes only where system timing design accommodates the 60 ns access time degradation. Memory capacity, organization, and interface remain equivalent.

Q: What packaging differences exist among substitute parts?

A: AT28HC256F-90JC and AT28HC256F-90JU are supplied in Tube packaging. Renesas X28HC256 variants are supplied in Tape & Reel (TR) packaging. Both packaging formats are compatible with standard pick-and-place assembly equipment.

Q: Does RoHS compliance affect electrical compatibility?

A: No. RoHS compliance status reflects manufacturing process and material composition but does not alter electrical specifications, memory capacity, or functional performance. ROHS3 compliant parts are suitable for applications requiring environmental compliance.

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