AT28HC256-90PI Equivalent & Substitute Parts

Part Overview

The AT28HC256-90PI is a 256Kbit parallel EEPROM memory IC manufactured by Microchip Technology, housed in a 28-DIP package with 90 ns access time. This part is classified as obsolete, making substitute components necessary for new designs and ongoing production requirements. The AT28HC256-90PI remains functionally viable but is no longer in active production, necessitating identification of compatible alternatives that maintain electrical and mechanical compatibility.

Substiute Parts

AT28HC256-90PI

Microchip TechnologyIn Stock: 8367AT28HC256-90PI Datasheet

Current PartRFQ

AT28C256-15PU

Microchip TechnologyIn Stock: 1908AT28C256-15PU Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the AT28HC256-90PI is determined by the following critical parameters:

• Memory capacity (256Kbit) and organization (32K x 8)
• Memory format and interface type (EEPROM, Parallel)
• Package and pinout compatibility (28-DIP)
• Voltage supply range (4.5V ~ 5.5V)
• Operating temperature range (-40°C ~ 85°C)

The AT28C256-15PU qualifies as a direct substitute based on matching all critical electrical and mechanical parameters. The primary difference is access time (150 ns versus 90 ns), which represents a relaxed timing specification suitable for applications where the original 90 ns performance is not required. Both parts share identical memory capacity, organization, interface, package, voltage, and temperature specifications.

Parameter Comparison

Engineering Selection Recommendations

The AT28C256-15PU is the qualified substitute for the AT28HC256-90PI based on the following factors:

• Both parts are manufactured by Microchip Technology and share identical memory specifications (256Kbit, 32K x 8 organization, EEPROM format, parallel interface)
• Electrical parameters are fully compatible: voltage supply range (4.5V ~ 5.5V) and operating temperature range (-40°C ~ 85°C) are identical
• Package and pinout are identical (28-DIP, 0.600" spacing, through-hole mounting)
• The AT28C256-15PU is in active production status, ensuring long-term availability
• The AT28C256-15PU carries ROHS3 compliance, whereas the AT28HC256-90PI is RoHS non-compliant
• Access time difference (150 ns versus 90 ns) represents a relaxed timing specification; applications requiring the faster 90 ns access time must evaluate system timing margins before substitution

Frequently Asked Questions (FAQ)

Q: Can the AT28C256-15PU directly replace the AT28HC256-90PI in existing designs?

A: Yes, for applications where 150 ns access time meets system timing requirements. Both parts share identical memory capacity, organization, interface type, voltage supply range, operating temperature range, and 28-DIP package. System timing analysis is required to confirm that the slower access time does not violate setup or hold time constraints.

Q: What is the primary difference between these two parts?

A: The access time specification differs: AT28HC256-90PI operates at 90 ns, while AT28C256-15PU operates at 150 ns. All other electrical and mechanical parameters are identical.

Q: Are the pinouts identical between AT28HC256-90PI and AT28C256-15PU?

A: Yes. Both parts use the 28-DIP package with identical pinout and 0.600" (15.24mm) spacing, enabling direct socket compatibility.

Q: What is the RoHS compliance status difference?

A: The AT28HC256-90PI is RoHS non-compliant. The AT28C256-15PU is ROHS3 compliant. For applications subject to RoHS regulations, the AT28C256-15PU is the required choice.

Q: Is the AT28C256-15PU currently available?

A: Yes. The AT28C256-15PU is in active production status with documented inventory availability, whereas the AT28HC256-90PI is obsolete.

Q: What voltage supply range do these parts require?

A: Both parts operate within the 4.5V to 5.5V supply voltage range and are suitable for standard 5V logic systems.

Q: Are the write cycle times identical?

A: Yes. Both the AT28HC256-90PI and AT28C256-15PU have a write cycle time of 10ms for word and page operations.