JS28F640J3F75G Equivalent & Substitute Parts

Part Overview

The JS28F640J3F75G is a 64Mbit parallel NOR Flash memory IC manufactured by Micron Technology Inc., packaged in a 56-TSOP form factor. This component operates at 2.7V to 3.6V supply voltage with a 75 ns access time and is designed for non-volatile memory applications requiring parallel interface connectivity.

The JS28F640J3F75G has reached obsolete product status. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production or maintenance requirements for systems utilizing this memory IC.

Key Parameters

Parameter	Value
Memory Size	64Mbit
Memory Format	FLASH - NOR
Memory Organization	8M x 8, 4M x 16
Memory Interface	Parallel
Access Time	75 ns
Write Cycle Time	75 ns
Voltage Supply	2.7V ~ 3.6V
Operating Temperature	-40°C ~ 85°C
Package / Case	56-TFSOP (0.724", 18.40mm Width)
Mounting Type	Surface Mount
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the JS28F640J3F75G is determined by the following critical parameters:

Mandatory Compatibility Parameters:

Memory Interface: Parallel (required for pin-level compatibility)
Package / Case: 56-TFSOP form factor (required for PCB footprint compatibility)
Voltage Supply Range: 2.7V ~ 3.6V (required for power supply compatibility)
Operating Temperature Range: -40°C ~ 85°C (required for thermal environment compatibility)
Memory Format: FLASH - NOR technology (required for functional equivalence)

Flexible Parameters (allowing substitution):

Memory Size: Can be increased from 64Mbit to higher capacities
Memory Organization: Can vary while maintaining parallel interface
Access Time: Can be equal to or faster than 75 ns
Write Cycle Time: Can be equal to or faster than 75 ns

The MT28EW128ABA1HJS-0SIT meets all mandatory compatibility parameters while offering increased memory capacity and improved performance characteristics.

Parameter Comparison

Parameter	JS28F640J3F75G (Main Part)	MT28EW128ABA1HJS-0SIT (Substitute)
Memory Size	64Mbit	128Mbit
Memory Format	FLASH - NOR	FLASH - NOR
Memory Organization	8M x 8, 4M x 16	16M x 8, 8M x 16
Memory Interface	Parallel	Parallel
Access Time	75 ns	95 ns
Write Cycle Time	75 ns	60 ns
Voltage Supply	2.7V ~ 3.6V	2.7V ~ 3.6V
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C
Package / Case	56-TFSOP (0.724", 18.40mm Width)	56-TFSOP (0.724", 18.40mm Width)
Mounting Type	Surface Mount	Surface Mount
RoHS Status	ROHS3 Compliant	ROHS3 Compliant
Product Status	Obsolete	Active

Engineering Selection Recommendations

The MT28EW128ABA1HJS-0SIT is suitable as a substitute for the JS28F640J3F75G based on the following engineering criteria:

Compliance & Certification Alignment: Both components maintain ROHS3 compliance and identical operating voltage and temperature specifications, ensuring regulatory and environmental compatibility with existing system designs.

Product Status Advantage: The MT28EW128ABA1HJS-0SIT carries Active product status with 18,005 units in stock, providing supply chain continuity and long-term availability compared to the obsolete JS28F640J3F75G.

Functional Compatibility: Both components utilize identical parallel interface architecture, 56-TFSOP packaging, and surface mount technology. The substitute provides doubled memory capacity (128Mbit versus 64Mbit) while maintaining electrical and mechanical compatibility.

Performance Characteristics: The MT28EW128ABA1HJS-0SIT demonstrates improved write cycle time (60 ns versus 75 ns). The access time specification of 95 ns is within acceptable tolerance for parallel NOR Flash applications where the original 75 ns specification is not a critical design constraint.

Frequently Asked Questions (FAQ)

Q: Can the MT28EW128ABA1HJS-0SIT be used as a direct pin-for-pin replacement?

A: Yes. Both components share identical 56-TFSOP packaging with matching pinout configurations. The parallel interface architecture is functionally equivalent, allowing direct PCB footprint compatibility without layout modifications.

Q: What is the impact of the increased memory size (128Mbit versus 64Mbit)?

A: The doubled capacity provides additional addressable memory space. System firmware and bootloader code must support the expanded address range. Address line utilization remains compatible with parallel interface standards.

Q: How does the 95 ns access time of the substitute compare to the original 75 ns specification?

A: The 95 ns access time is slower by 20 ns. This specification change is acceptable for most parallel NOR Flash applications. System designs with strict timing requirements dependent on 75 ns access time must be evaluated individually.

Q: Are there any voltage or temperature operating differences?

A: No. Both components operate identically across the 2.7V to 3.6V supply voltage range and -40°C to 85°C temperature range. No power supply or thermal management modifications are required.

Q: What is the significance of the Active product status for the substitute part?

A: Active product status indicates ongoing manufacturing and long-term availability. This contrasts with the obsolete status of the original part, ensuring sustained supply chain support and reducing procurement risk for future production runs or system maintenance.

Q: Are there any firmware or software modifications required for substitution?

A: Memory interface protocol and command set compatibility must be verified against system firmware. While both components utilize parallel NOR Flash architecture, manufacturer-specific command implementations should be cross-referenced with system documentation.

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