AT28HC256-70JC Equivalent & Substitute Parts

Part Overview

The AT28HC256-70JC is a 256Kbit parallel EEPROM memory IC manufactured by Microchip Technology in a 32-PLCC package with 70 ns access time. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing system support and new designs. The AT28HC256-70JC operates within the 4.5V to 5.5V supply range and supports industrial temperature specifications from 0°C to 70°C.

Key Parameters

Parameter	Value
Memory Size	256Kbit
Memory Organization	32K x 8
Memory Interface	Parallel
Access Time	70 ns
Write Cycle Time	10 ms
Voltage Supply	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 AT28HC256-70JC is determined by the following critical parameters:

Core Compatibility Requirements:

Memory capacity: 256Kbit (32K x 8 organization)
Interface type: Parallel
Package: 32-PLCC (13.97x11.43)
Supply voltage: 4.5V ~ 5.5V
Mounting: Surface Mount

Performance Considerations:

Access time must be equal to or faster than 70 ns
Write cycle time must be equal to or faster than 10 ms
Operating temperature range must encompass or exceed 0°C ~ 70°C

The substitute parts listed below meet all core compatibility requirements. Variations in access time, write cycle time, and operating temperature range are noted where they differ from the main part.

Parameter Comparison

Part Number	Manufacturer	Memory Size	Access Time (ns)	Write Cycle Time (ms)	Operating Temp (°C)	Product Status	RoHS Status
AT28HC256-70JC	Microchip Technology	256Kbit	70	10	0 ~ 70	Obsolete	Non-compliant
AT28HC256-12JU	Microchip Technology	256Kbit	120	10	-40 ~ 85	Active	ROHS3 Compliant
AT28HC256F-12JC	Microchip Technology	256Kbit	120	3	0 ~ 70	Active	Non-compliant
X28HC256JIZ-90T1	Renesas Electronics	256Kbit	90	5	-40 ~ 85	Active	ROHS3 Compliant
X28HC256JIZ-15T1	Renesas Electronics	256Kbit	150	5	-40 ~ 85	Active	ROHS3 Compliant
X28HC256JZ-15T1	Renesas Electronics	256Kbit	150	5	0 ~ 70	Active	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement (Microchip Technology):

AT28HC256-12JU is the primary active substitute from Microchip Technology. It maintains the same memory capacity and parallel interface while offering extended operating temperature range (-40°C to 85°C) and ROHS3 compliance. Access time is 120 ns, which is slower than the original 70 ns specification but remains within acceptable parameters for most applications. This part is actively manufactured and widely available.

AT28HC256F-12JC provides an alternative within the Microchip product line with improved write cycle time (3 ms versus 10 ms). Operating temperature range matches the original specification (0°C to 70°C). This part is actively produced but does not carry ROHS3 compliance.

For Cross-Manufacturer Substitution (Renesas Electronics):

X28HC256JIZ-90T1 offers the closest access time performance (90 ns) among Renesas alternatives and supports extended temperature range (-40°C to 85°C) with ROHS3 compliance. Write cycle time is 5 ms.

X28HC256JIZ-15T1 and X28HC256JZ-15T1 both provide 150 ns access time with 5 ms write cycle time and ROHS3 compliance. X28HC256JIZ-15T1 supports -40°C to 85°C operating range, while X28HC256JZ-15T1 matches the original 0°C to 70°C specification.

All substitute parts maintain the 32-PLCC package format and 4.5V to 5.5V supply voltage compatibility with the original AT28HC256-70JC.

Frequently Asked Questions (FAQ)

Q: Can AT28HC256-12JU directly replace AT28HC256-70JC in existing designs?

A: Yes. Both parts share identical memory capacity (256Kbit), organization (32K x 8), parallel interface, package format (32-PLCC), and supply voltage range (4.5V ~ 5.5V). The 120 ns access time of AT28HC256-12JU is slower than the original 70 ns, but this difference is typically transparent to system-level performance unless timing-critical applications depend on the faster specification.

Q: What is the difference between Microchip and Renesas substitute options?

A: Both manufacturers provide 256Kbit parallel EEPROM devices in 32-PLCC packages with compatible electrical specifications. Microchip options (AT28HC256 series) and Renesas options (X28HC256 series) differ in access time, write cycle time, and operating temperature ranges. Selection depends on specific application requirements and supply chain availability.

Q: Are all substitute parts RoHS compliant?

A: No. AT28HC256F-12JC is RoHS non-compliant, matching the original part's status. AT28HC256-12JU and all Renesas parts (X28HC256JIZ-90T1, X28HC256JIZ-15T1, X28HC256JZ-15T1) carry ROHS3 compliance certification.

Q: Does package format differ between substitute parts?

A: No. All substitute parts use the 32-PLCC (13.97x11.43) package with surface mount J-lead configuration, ensuring mechanical and electrical compatibility with existing PCB layouts designed for AT28HC256-70JC.

Q: Which substitute offers the best performance match to the original part?

A: X28HC256JIZ-90T1 provides the closest access time performance at 90 ns, compared to the original 70 ns specification. This Renesas part also offers extended temperature range (-40°C to 85°C) and ROHS3 compliance, making it suitable for applications requiring performance consistency with the original design.

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