AT28HC256-12JC EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The AT28HC256-12JC is a 256Kbit parallel EEPROM memory IC manufactured by Microchip Technology in a 32-PLCC package with 120 ns access time. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing system support and new designs. The part operates within a 4.5V to 5.5V supply range and supports 32K x 8 memory organization with 10ms write cycle time.

Key Parameters

Parameter	Value
Memory Size	256Kbit
Memory Organization	32K x 8
Memory Interface	Parallel
Access Time	120 ns
Write Cycle Time	10ms
Voltage Supply	4.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C
Package Type	32-PLCC (13.97x11.43)
Mounting Type	Surface Mount
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution for the AT28HC256-12JC is determined by the following critical parameters: memory size (256Kbit), memory organization (32K x 8), parallel interface, 32-PLCC package footprint, and supply voltage range (4.5V ~ 5.5V). Access time and write cycle time are secondary parameters that may vary within acceptable limits for functional compatibility.

Substitute parts are grouped into two categories:

Direct Microchip Technology Substitutes: Parts maintaining the same manufacturer lineage with identical core electrical specifications and package compatibility.

Cross-Manufacturer Substitutes: Renesas Electronics Corporation parts offering equivalent memory capacity and interface with compatible packaging, though with variations in access time and write cycle performance.

Parameter Comparison

Part Number	Manufacturer	Memory Size	Access Time (ns)	Write Cycle (ms)	Temp Range (°C)	Product Status	RoHS Status
AT28HC256-12JC	Microchip Technology	256Kbit	120	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 Active Product Status Requirement: AT28HC256-12JU is the direct active substitute from Microchip Technology, maintaining identical electrical specifications with extended temperature range (-40°C to 85°C) and ROHS3 compliance. This part is verified as programmable and available in higher inventory quantities.

For Improved Write Performance: AT28HC256F-12JC reduces write cycle time from 10ms to 3ms while maintaining 120 ns access time and identical temperature range. This part remains active but is non-RoHS compliant.

For Extended Temperature and RoHS Compliance: X28HC256JIZ-90T1 provides the fastest access time (90 ns) with ROHS3 compliance and -40°C to 85°C operating range. Write cycle time is 5ms.

For Temperature-Matched Substitution: X28HC256JZ-15T1 maintains the original 0°C to 70°C temperature range while offering ROHS3 compliance and active product status. Access time is 150 ns with 5ms write cycle.

For Cost-Optimized Selection: X28HC256JIZ-15T1 provides ROHS3 compliance and extended temperature range with moderate access time (150 ns) and 5ms write cycle.

Frequently Asked Questions (FAQ)

Q: Can AT28HC256-12JU directly replace AT28HC256-12JC?

A: Yes. Both parts share identical memory capacity (256Kbit), organization (32K x 8), access time (120 ns), write cycle time (10ms), supply voltage (4.5V ~ 5.5V), and 32-PLCC package. AT28HC256-12JU is active and ROHS3 compliant, with extended temperature range (-40°C to 85°C).

Q: What is the primary difference between Microchip and Renesas substitutes?

A: Microchip substitutes (AT28HC256 series) maintain identical access time (120 ns) and write cycle specifications. Renesas substitutes (X28HC256 series) offer variations in access time (90-150 ns) and write cycle time (5ms), with ROHS3 compliance and extended temperature ranges as standard.

Q: Is the 32-PLCC package compatible across all substitutes?

A: Yes. All listed substitutes use the 32-PLCC (13.97x11.43) package with surface mount J-lead configuration, ensuring mechanical and electrical compatibility on existing PCB layouts.

Q: Which substitute is recommended for new designs?

A: Selection depends on design requirements. For performance-critical applications, X28HC256JIZ-90T1 offers the fastest access time (90 ns). For standard applications with RoHS compliance, AT28HC256-12JU or X28HC256JZ-15T1 are suitable. For improved write performance, AT28HC256F-12JC is recommended.

Q: Are all substitutes RoHS compliant?

A: No. AT28HC256-12JC and AT28HC256F-12JC are RoHS non-compliant. AT28HC256-12JU, X28HC256JIZ-90T1, X28HC256JIZ-15T1, and X28HC256JZ-15T1 are ROHS3 compliant.

Q: What is the inventory status of these parts?

A: AT28HC256-12JU has the highest inventory (4815 pcs). X28HC256JZ-15T1 has the lowest (707 pcs). All listed substitutes are available as new original stock.

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