AT28HC64B-90SC EEPROM Equivalent & Substitute Parts

Part Overview

The AT28HC64B-90SC is a 64Kbit parallel EEPROM memory IC manufactured by Microchip Technology in a 28-SOIC package. This part is classified as obsolete, making substitute components necessary for new designs and production continuity. The device operates with a 90 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	64Kbit
Memory Organization	8K x 8
Memory Format	EEPROM
Memory Interface	Parallel
Access Time	90 ns
Write Cycle Time	10 ms
Voltage Supply	4.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C
Package Type	28-SOIC
Mounting Type	Surface Mount

Substitute Part Grouping Explanation

Substitution for the AT28HC64B-90SC is determined by the following critical parameters: 64Kbit memory capacity, 8K x 8 organization, parallel interface, 28-SOIC package, and 4.5V to 5.5V supply voltage compatibility. Access time and write cycle time are secondary considerations that may vary within acceptable operational limits for most applications.

The substitute parts are grouped into two categories:

Direct Microchip Substitute: AT28HC64B-90SU maintains identical electrical specifications and memory organization, differing only in packaging format (Tube vs. unspecified) and product status (Active vs. Obsolete).

Cross-Manufacturer Substitutes: X28HC64SIZ-12, X28HC64SIZ-12T1, and X28HC64SZ-12 from Renesas Electronics Corporation provide equivalent 64Kbit parallel EEPROM functionality in the same 28-SOIC package with compatible supply voltage and memory organization. These parts feature faster write cycle times (5 ms vs. 10 ms) and operate across extended temperature ranges.

Parameter Comparison

Parameter	AT28HC64B-90SC	AT28HC64B-90SU	X28HC64SIZ-12	X28HC64SIZ-12T1	X28HC64SZ-12
Manufacturer	Microchip Technology	Microchip Technology	Renesas Electronics	Renesas Electronics	Renesas Electronics
Memory Size	64Kbit	64Kbit	64Kbit	64Kbit	64Kbit
Memory Organization	8K x 8	8K x 8	8K x 8	8K x 8	8K x 8
Access Time	90 ns	90 ns	120 ns	120 ns	120 ns
Write Cycle Time	10 ms	10 ms	5 ms	5 ms	5 ms
Voltage Supply	4.5V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	0°C ~ 70°C
Package Type	28-SOIC	28-SOIC	28-SOIC	28-SOIC	28-SOIC
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For new designs and production applications, AT28HC64B-90SU is the primary substitute, offering identical electrical performance with active product status and ROHS3 compliance. This part is recommended when Microchip Technology component continuity is required.

For applications where cross-manufacturer sourcing is acceptable, the Renesas X28HC64 series (X28HC64SIZ-12, X28HC64SIZ-12T1, X28HC64SZ-12) provides equivalent functionality with improved write cycle performance and extended temperature range options. X28HC64SZ-12 maintains the original 0°C to 70°C operating range, while X28HC64SIZ-12 and X28HC64SIZ-12T1 support -40°C to 85°C operation. All Renesas alternatives are ROHS3 compliant and actively produced.

Packaging format selection depends on assembly requirements: X28HC64SIZ-12T1 is supplied in Tape & Reel format for automated assembly, while X28HC64SZ-12 is supplied in Tube format for manual or semi-automated processes.

Frequently Asked Questions (FAQ)

Q: Can AT28HC64B-90SU directly replace AT28HC64B-90SC in existing designs?

A: Yes. Both parts share identical memory capacity (64Kbit), organization (8K x 8), access time (90 ns), write cycle time (10 ms), supply voltage (4.5V to 5.5V), and 28-SOIC package specifications. The primary difference is product status and compliance certification.

Q: What is the impact of the 120 ns access time in Renesas substitutes versus the 90 ns specification of the original part?

A: The 120 ns access time in X28HC64 series parts is slower than the original 90 ns specification. System designs must accommodate this timing difference. The faster 5 ms write cycle time in Renesas parts partially offsets this consideration.

Q: Are the Renesas X28HC64 parts pin-compatible with the AT28HC64B-90SC?

A: Yes. All substitute parts use the 28-SOIC package with identical pinout and electrical interface specifications, enabling direct socket replacement.

Q: What is the difference between X28HC64SIZ-12 and X28HC64SIZ-12T1?

A: Both parts are electrically identical. The primary difference is packaging format: X28HC64SIZ-12T1 is supplied in Tape & Reel format for high-volume automated assembly, while X28HC64SIZ-12 uses standard packaging. Select based on assembly process requirements.

Q: Does the extended temperature range of Renesas parts (-40°C to 85°C) affect compatibility with designs specified for 0°C to 70°C operation?

A: No. Extended temperature range parts are backward compatible with narrower temperature specifications. Designs requiring 0°C to 70°C operation function correctly with parts rated to -40°C to 85°C.

Q: Are all substitute parts RoHS compliant?

A: AT28HC64B-90SC is RoHS non-compliant. All substitute parts (AT28HC64B-90SU and all Renesas X28HC64 variants) are ROHS3 compliant, meeting current environmental and regulatory requirements.

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